WO2021093838A1

WO2021093838A1 - Pulse width modulation method, inverter and controller

Info

Publication number: WO2021093838A1
Application number: PCT/CN2020/128576
Authority: WO
Inventors: 刘方诚; 许富强; 郭海滨
Original assignee: 华为技术有限公司
Priority date: 2019-11-13
Filing date: 2020-11-13
Publication date: 2021-05-20
Also published as: CN112803823B; CN112803823A

Abstract

A pulse width modulation method, which is applied to a three-phase converter, and is used for improving the system stability of the three-phase converter and reducing interference with the system detection. The pulse width modulation method comprises: acquiring a three-phase initial modulation wave (201); according to the three-phase initial modulation wave and a clamping state of a modulation wave for three-phase discontinuous pulse width modulation (DPWM), generating a first common mode modulation wave (202); performing, according to the clamping state of the modulation wave for three-phase DPWM, smoothing processing on the first common mode modulation wave to obtain a second common mode modulation wave (203); and superimposing waveforms of the three-phase initial modulation wave and the second common mode modulation wave to obtain a three-phase output modulation wave (204).

Description

Pulse width modulation method, inverter and controller

This application claims the priority of the Chinese patent application filed with the Chinese Patent Office on November 13, 2019. The application number is 201911107780.9 and the invention title is "Pulse Width Modulation Method, Inverter and Controller", the entire content of which is incorporated by reference. In this application.

Technical field

This application relates to the field of circuit technology, and in particular to a pulse width modulation method, an inverter, and a controller.

Background technique

With the development of the economy and society, the energy crisis has gradually become prominent and the global environment has gradually deteriorated, the development and use of clean alternative energy has become an important goal of the energy industry. With the continuous development of new energy power generation, energy storage and new energy automobile industries, the converter as the core energy control device has become one of the key factors for clean energy applications. Among the many types of converters, the three-phase converter is one of the most widely used converters. It is used to connect the three-phase AC power system and the DC power system and realize the energy transfer between the two systems. According to the different energy flow direction, it is divided into two working states: rectification and inverter. Among them, the transfer of energy from the DC system to the AC system is called inverter, and the transfer of energy from the AC system to the DC system is called rectification. The conversion efficiency and power quality are the two key technical indicators of the three-phase converter, and the modulation method directly affects the on-off state of the devices of the switching network. Therefore, the modulation method is one of the key factors affecting its conversion and power quality. .

At present, the commonly used three-phase converter modulation methods include pulse width modulation (Pulse Width Modulation, PWM), and PWM can be divided into continuous pulse width modulation (continuous pulse width modulation, CPWM) and discontinuous pulse width modulation (discontinuous pulse width modulation). pulse width modulation, DPWM). Among them, compared with CPWM, DPWM has fewer switching times, so the switching loss is smaller, which can improve the conversion efficiency of the three-phase converter. In specific implementation, the modulation wave of DPWM can be realized by superimposing an equivalent common-mode modulation wave on the modulation wave of CPWM. For example, as shown in Figure 1A, compare the modulation wave of DPWM with the modulation wave of SPWM (power frequency sine wave) in a power frequency cycle of 50 Hz (Hertz) to obtain the difference between the modulation wave of DPWM and the modulation wave of SPWM. It is a modulation wave of a common mode signal, where the frequency of the common mode signal is three times the frequency of the modulation wave of the SPWM, and SPWM is one of the modulation modes of CPWM.

Since the modulation wave of DPWM can be equivalent to the sum of the modulation wave of CPWM and the common mode modulation wave, the output characteristics of the modulation wave of DPWM are jointly affected by the output characteristics of the modulation wave of CPWM and the output characteristics of the common mode modulation wave. The high-frequency harmonic components generated by the common-mode modulation wave will affect the stability of the three-phase converter system and reduce the stability of the system.

Summary of the invention

The embodiments of the present application provide a pulse width modulation method, an inverter, and a controller, which are used to improve the stability of the three-phase converter system and reduce the detection interference to the system.

The first aspect of the embodiments of the present application provides a pulse width modulation method, which is applied to a three-phase converter, and the method includes:

First, obtain the three-phase initial modulation wave, and then generate the first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase DPWM, and then generate the first common-mode modulation wave according to the clamping state of the three-phase DPWM modulation wave. The first common mode modulation wave is smoothed to obtain a second common mode modulation wave; then, the three-phase initial modulation wave and the second common mode modulation wave are waveform superimposed to obtain a three-phase output modulation wave. In the technical solution of the embodiment of the present application, the first common mode modulation wave is smoothed in combination with the clamping state of the three-phase DPWM modulation wave of the three-phase converter to obtain the second common mode modulation wave, which can reduce the first common mode modulation wave. The high-frequency harmonic components of a common-mode modulation wave are then determined according to the second common-mode modulation wave obtained by the smoothing process and the three-phase initial modulation wave to determine the three-phase output modulation wave, thereby improving the system performance of the three-phase converter stability.

In a possible implementation manner, smoothing the first common-mode modulation wave according to the clamping state of the three-phase DPWM modulation wave to obtain the second common-mode modulation wave includes: clamping according to the three-phase DPWM modulation wave The bit state and the amplitude corresponding to the first common-mode modulated wave at the current moment are used to calculate the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation, the amplitude of the first common-mode modulation wave is smoothed by combining the clamping state of the three-phase DPWM modulation wave and the amplitude of the first common-mode modulation wave to reduce the first common-mode modulation wave. The high-frequency harmonic components generated by the wave at the step, thereby improving the stability of the three-phase converter system; and reducing the detection of partial current in the three-phase converter system, the second common mode The high-frequency harmonic components of the modulating wave interfere with the detection, thereby reducing the probability of false alarms.

In another possible implementation manner, calculating the amplitude corresponding to the second common-mode modulation wave at the current moment according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment includes : When the clamp state corresponding to the current moment is a non-negative clamp state, determine whether the amplitude corresponding to the first common mode modulation wave at the current moment is greater than the first preset threshold; if so, according to the preset positive direction The amplitude limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, the first common-mode modulated wave at the current moment The corresponding amplitude is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation, according to the clamping state of the modulation wave of the three-phase DPWM, the non-negative clamping state corresponding to the current moment is determined, and then combined with the amplitude corresponding to the first common-mode modulation wave at the current moment to determine the use of the corresponding smoothing The processing method provides a specific implementation method for smoothing the amplitude corresponding to the first common-mode modulated wave in a non-negative clamping state.

In another possible implementation manner, the method further includes: when the clamp state corresponding to the current moment is a non-positive clamp state, judging whether the amplitude corresponding to the first common mode modulated wave at the current moment is smaller than the second Preset threshold; if so, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment; if If not, the amplitude corresponding to the first common-mode modulated wave at the current moment is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation, according to the clamping state of the modulation wave of the three-phase DPWM, the non-positive clamping state corresponding to the current moment is determined, and then the corresponding amplitude value of the first common-mode modulation wave at the current moment is determined to use the corresponding smoothing The processing method provides a specific implementation method for smoothing the amplitude corresponding to the first common-mode modulated wave in the non-positive clamping state.

In another possible implementation manner, calculating the amplitude corresponding to the second common-mode modulation wave at the current moment according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment includes : When the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the first preset threshold, judge whether the corresponding clamping state at the current moment is greater than the non-negative clamp according to the clamping state of the three-phase DPWM modulation wave Bit status; if yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive limit smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment; if not , The amplitude corresponding to the first common-mode modulated wave at the current moment is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation manner, it is first determined that the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, and then combined with the clamp state corresponding to the current moment to determine to use the corresponding smoothing processing method, Provides a method for smoothing the amplitude corresponding to the first common-mode modulation wave in combination with the clamping state corresponding to the current moment when the amplitude corresponding to the first common-mode modulation wave is greater than the second preset threshold. The way to achieve it.

In another possible implementation manner, the method further includes: when the amplitude corresponding to the first common-mode modulation wave at the current moment is less than a second preset threshold, judging according to the clamping state of the three-phase DPWM modulation wave Whether the clamp state corresponding to the current moment is a non-positive clamp state; if it is, the first common mode modulation wave corresponding to the current moment is calculated according to the preset negative limit smoothing strategy and the amplitude corresponding to the first common mode modulation wave at the current moment. The amplitude corresponding to the two common-mode modulation waves; if not, the amplitude corresponding to the first common-mode modulation wave at the current moment is taken as the amplitude corresponding to the second common-mode modulation wave at the current moment. In this possible implementation manner, it is first determined that the amplitude corresponding to the first common-mode modulated wave at the current moment is less than the second preset threshold, and the first common-mode modulated wave is compared with the clamp state corresponding to the current moment. The corresponding amplitude value is smoothed.

In another possible implementation manner, calculating the amplitude corresponding to the second common-mode modulation wave at the current moment according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment includes : If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and also does not belong to the negative clamping state, judge whether the amplitude corresponding to the first common mode modulation wave at the current moment is greater than 0 If yes, when the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, then according to the preset positive limit smoothing strategy and the first common-mode modulated wave at the current moment The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, when the amplitude of the first common-mode modulated wave at the current moment is less than the second preset threshold, the The amplitude limiting smoothing strategy in the negative direction and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation, when the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and does not belong to the negative clamping state, combined with the first common mode modulation wave. The corresponding amplitude determines the specific smoothing processing method, and performs smoothing processing on the amplitude corresponding to the first common-mode modulated wave.

In another possible implementation manner, the preset positive-direction clipping and smoothing strategy includes: subtracting the first preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the current moment The first difference between the amplitude corresponding to the first common mode modulation wave and the first preset threshold; then, the first difference is multiplied by the absolute value of the amplitude corresponding to the smooth modulation wave preset at the current moment, and then The first preset threshold is added to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation manner, a specific implementation manner of the preset positive-direction limiting and smoothing strategy is provided, so as to perform positive-direction smoothing processing on the amplitude corresponding to the first common-mode modulated wave.

In another possible implementation manner, the preset negative-direction limiting and smoothing strategy includes: subtracting a second preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the first common-mode The second difference between the amplitude corresponding to the modulating wave and the second preset threshold; then, multiplying the second difference by the absolute value of the amplitude corresponding to the smooth modulating wave preset at the current moment, and adding the second The threshold is preset to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment. In this possible implementation manner, a specific implementation manner of the preset negative-direction limiting and smoothing strategy is provided for smoothing the amplitude corresponding to the first common-mode modulated wave in the negative direction.

In another possible implementation manner, the waveform superposition of the three-phase initial modulation wave and the second common-mode modulation wave to obtain the three-phase output modulation wave includes: separate the initial modulation waves of each phase of the three-phase initial modulation waves Perform a one-to-one corresponding waveform superposition with the second common-mode modulated wave to obtain a three-phase output modulated wave.

In another possible implementation manner, calculating the amplitude corresponding to the second common-mode modulation wave at the current moment according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment includes : If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment belongs to the non-negative clamping state and the amplitude corresponding to the first common mode modulation wave at the current moment is greater than the first preset threshold, then according to the preset The positive limit smoothing strategy and the amplitude corresponding to the first common-mode modulation wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulation wave at the current moment; if the current moment corresponds to the three-phase DPWM modulation wave The clamping state of is a non-positive clamping state and the amplitude corresponding to the first common-mode modulated wave at the current moment is less than the second preset threshold, then according to the preset negative-direction clipping and smoothing strategy and the current moment the first The amplitude corresponding to the common-mode modulated wave obtains the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation manner, calculating the amplitude corresponding to the second common-mode modulation wave at the current moment according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment includes : If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and also does not belong to the negative clamping state, judge whether the amplitude corresponding to the first common mode modulation wave at the current moment is greater than 0; if yes, when the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, then according to the preset positive-direction limiting smoothing strategy and the first common-mode modulated wave at the current moment The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, when the amplitude of the first common-mode modulated wave at the current moment is less than the second preset threshold, it will be calculated according to the preset The amplitude limiting smoothing strategy in the negative direction of and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation manner, when the preset condition is met, the method further includes: taking the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment , The preset condition includes any one of the following: the clamping state of the three-phase DPWM modulation wave corresponding to the current moment is non-negative clamping state, and the amplitude corresponding to the first common-mode modulation wave at the current moment is less than the first preset Set the threshold; the clamping state of the three-phase DPWM modulation wave corresponding to the current moment belongs to the non-positive clamping state and the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the second preset threshold; the current moment corresponds to The clamping state of the modulation wave of the three-phase DPWM does not belong to the non-negative clamping state and the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the first preset threshold; the modulation of the three-phase DPWM corresponding to the current moment The clamping state of the wave does not belong to the non-positive clamping state and the amplitude corresponding to the first common-mode modulated wave at the current moment is smaller than the second preset threshold.

A second aspect of the embodiments of the present application provides an inverter. The inverter includes a DC system, a switching network, a filter, an AC system, and a controller. The controller is connected to the switching network; the controller is used to obtain a three-phase initial Modulation wave; Generate the first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave; and smooth the first common-mode modulation wave according to the clamping state of the three-phase DPWM modulation wave Processing to obtain a second common-mode modulation wave; waveform superimposition of the three-phase initial modulation wave and the second common-mode modulation wave to obtain a three-phase output modulation wave.

In a possible implementation manner, the controller is specifically used for:

According to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common mode modulation wave at the current moment, the amplitude corresponding to the second common mode modulation wave at the current moment is calculated.

In another possible implementation manner, the controller is specifically used for:

When the clamping state corresponding to the current moment is a non-negative clamping state, it is determined whether the amplitude corresponding to the first common mode modulation wave at the current moment is greater than the first preset threshold; if so, according to the preset positive direction The amplitude limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, the first common-mode modulated wave at the current moment is calculated. The corresponding amplitude is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation, the controller is also used to:

When the clamp state corresponding to the current moment is a non-positive clamp state, it is determined whether the amplitude corresponding to the first common mode modulation wave at the current moment is less than the second preset threshold; if so, according to the preset negative direction The amplitude limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, the first common-mode modulated wave at the current moment is calculated. The corresponding amplitude is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment.

When the amplitude corresponding to the first common-mode modulating wave at the current moment is greater than the first preset threshold, judge whether the corresponding clamping state at the current moment is greater than the non-negative clamping according to the clamping state of the three-phase DPWM modulation wave Status; if yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive limit smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment; if not, Then, the amplitude corresponding to the first common-mode modulated wave at the current moment is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation, the controller is also used to:

When the amplitude corresponding to the first common-mode modulating wave at the current moment is less than the second preset threshold, judge whether the corresponding clamping state at the current moment is a non-positive clamp according to the clamping state of the three-phase DPWM modulating wave Status; if yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment; if not, Then the amplitude corresponding to the first common-mode modulated wave at the current moment is taken as the amplitude corresponding to the second common-mode modulated wave at the current moment.

If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and does not belong to the negative clamping state, it is determined whether the amplitude corresponding to the first common mode modulation wave at the current moment is greater than 0; If yes, when the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, then the preset positive-direction limiting smoothing strategy and the current moment corresponding to the first common-mode modulated wave Calculate the amplitude corresponding to the second common-mode modulated wave at the current moment; if not, when the amplitude of the first common-mode modulated wave at the current moment is less than the second preset threshold, it will be based on the preset negative The amplitude limiting and smoothing strategy of the direction and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation manner, the preset positive-direction clipping and smoothing strategy includes: subtracting the first preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the current moment The first difference between the amplitude corresponding to the first common mode modulation wave and the first preset threshold; then, the first difference is multiplied by the absolute value of the amplitude corresponding to the smooth modulation wave preset at the current moment, and then The first preset threshold is added to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.

In another possible implementation manner, the preset negative-direction limiting and smoothing strategy includes: subtracting a second preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the first common-mode The second difference between the amplitude corresponding to the modulating wave and the second preset threshold; then, multiplying the second difference by the absolute value of the amplitude corresponding to the smooth modulating wave preset at the current moment, and adding the second The threshold is preset to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.

The waveforms of each phase of the three-phase initial modulation wave and the second common-mode modulation wave are respectively superimposed in a one-to-one correspondence to obtain a three-phase output modulation wave.

A third aspect of the embodiments of the present application provides a controller, which is applied to a three-phase converter. The controller includes a processor, a memory, and a signal interface connected by a bus, and the memory stores operating instructions of the processor;

This signal interface is used to obtain the three-phase initial modulation wave;

The processor is configured to generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase discontinuous pulse width modulation DPWM; according to the clamping state of the three-phase DPWM modulation wave The state smoothes the first common-mode modulation wave to obtain a second common-mode modulation wave; superimposes the three-phase initial modulation wave and the second common-mode modulation wave to obtain a three-phase output modulation wave.

In a possible implementation manner, the processor is specifically used for:

In another possible implementation manner, the processor is specifically used for:

In another possible implementation, the processor is also used to:

It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

It can be known from the above technical solution that the three-phase initial modulation wave is obtained, and then the first common-mode modulation wave is generated according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave, and according to the three-phase DPWM modulation wave The first common-mode modulation wave is smoothed in the clamped state to obtain a smoothed second common-mode modulation wave, and then the three-phase output modulation wave is determined according to the second common-mode modulation wave and the three-phase initial modulation wave . Therefore, in the technical solution of the embodiment of the present application, the first common mode modulation wave is smoothed in combination with the clamping state of the three-phase DPWM modulation wave of the three-phase converter to obtain the second common mode modulation wave, which can reduce The high-frequency harmonic components of the first common-mode modulation wave are then determined according to the second common-mode modulation wave obtained by the smoothing process and the three-phase initial modulation wave to determine the three-phase output modulation wave, thereby improving the three-phase converter The stability of the system.

Description of the drawings

FIG. 1A is a schematic diagram of a waveform of a common mode signal according to an embodiment of the application;

1B is a schematic diagram of the system structure of a three-phase converter according to an embodiment of the application;

FIG. 1C is a schematic structural diagram of the controller in the three-phase converter according to the embodiment of the application;

2A is a schematic diagram of an embodiment of a pulse width modulation method according to an embodiment of the application;

2B is a schematic diagram of a waveform of a three-phase initial modulation wave according to an embodiment of the application;

2C is a schematic diagram of a waveform of the modulation wave of the a-phase DPWM and the first common mode modulation wave according to the embodiment of the application;

2D is an effect comparison diagram of the first common-mode modulated wave and the second common-mode modulated wave according to an embodiment of the application;

3A is a schematic diagram of another embodiment of a pulse width modulation method according to an embodiment of the application;

3B is a schematic diagram of a periodic waveform of the first common-mode modulated wave according to the embodiment of the application;

3C is another waveform diagram of the modulation wave of the a-phase DPWM and the first common mode modulation wave according to the embodiment of the application;

4 is a schematic diagram of another embodiment of a pulse width modulation method according to an embodiment of the application;

FIG. 5 is a schematic structural diagram of an inverter according to an embodiment of the application;

Fig. 6 is a schematic structural diagram of a controller according to an embodiment of the application.

Detailed ways

The embodiments of the present application provide a pulse width modulation method, an inverter, and a controller, which are used to improve the stability of the system and reduce the detection interference to the system.

The technical solutions of the embodiments of the present application are applied to converters, and are especially widely applied to three-phase converters. The three-phase converter is used to connect the three-phase AC power system and the DC power system and realize the energy transfer between the two systems. According to the energy flow direction, it can be divided into two working conditions: rectification and inverter. Among them, the transfer of energy from the DC system to the AC system is called inverter, and the transfer of energy from the AC system to the DC system is called rectification. In the embodiments of this application, the three-phase converter can be divided into inverter state and rectifier state. The technical solutions of the embodiments of this application can be applied to inverters or rectifiers. Common inverters include motor drive inverters and rectifiers. Photovoltaic inverter. In most application scenarios, both rectification and inverter can be realized by the same system. For example, a battery energy storage system uses the same system to achieve two-way power transmission for battery charging or discharging.

The system structure of a typical three-phase converter is shown in Figure 1B, including a DC system, a switch network, a controller, a filter, and an AC system. Among them, the filter is composed of passive components such as capacitors and inductors, which are used to filter AC power during the rectification process, suppress high-frequency harmonics, and reduce AC distortion. The switching network is composed of semiconductor switching devices and their different topological networks. Typical semiconductor switching devices include insulated gate bipolar transistors (IGBT) and metal-oxide-semiconductor field-effect transistors. effect transistor, MOSFET), etc., and the controller controls the on or off action of each switching device in the switching network through modulation, thereby turning on and off the energy transfer between the AC system and the DC system. The controller can be a digital controller For example, digital signal processing (DSP) or field-programmable gate array (FPGA), etc.

The controller provided by the embodiment of the present application includes a control system, a pulse width modulation system, and a carrier comparison unit. For details, please refer to the schematic diagram of the controller in the three-phase converter shown in FIG. 1C. The main function of the control system is According to the deviation of the sampled signal (voltage or current) and the preset reference value, the system of the three-phase converter is controlled and adjusted to generate a three-phase initial modulation wave.

The pulse width modulation system includes a common mode signal modulation wave (hereinafter referred to as a common mode modulation wave) calculation unit, a common mode modulation wave smoothing unit, and a modulation unit. The common mode modulation wave calculation unit is used to calculate the modulation wave according to the three-phase DPWM. The clamping state of and the three-phase initial modulation wave (the three-phase initial modulation waves are respectively v _a , v _b , v _c ) generate the first common-mode modulation wave v _z , and the common-mode modulation wave smoothing unit is used to generate the first common-mode modulation wave v z The clamping state of the modulation wave of the three-phase DPWM smoothes the first common-mode modulation wave to obtain the smoothed second common-mode modulation wave v ₀ ; the modulation unit is used for the three-phase initial modulation wave and the first common-mode modulation wave. Two common-mode modulation waves v ₀ are superimposed on the waveform to obtain a three-phase output modulation wave.

The carrier comparison unit is used to compare the amplitude of the three-phase output modulated wave with the high-frequency carrier, and output a high-level or low-level drive signal according to the amplitude comparison result to control the conduction of the switching network of the three-phase converter. On or off state.

It should be noted that the three-phase converter system shown in Figs. 1B and 1C is only used to illustrate the technical solutions of the embodiments of the present application more clearly, and does not constitute a limitation on the technical solutions of the embodiments of the present application. The embodiments of the application are also applicable to other types of converters (for example, single-phase converters). When the systems of other types of converters have similar technical problems, the technical solutions of the embodiments of this application are also applicable. The application is not limited.

Please refer to FIG. 2A. FIG. 2A is a schematic diagram of an embodiment of a pulse width modulation method according to an embodiment of the application. The method includes:

201. Obtain a three-phase initial modulation wave.

In the three-phase converter, the control system in the controller controls and adjusts the system of the three-phase converter according to the deviation between the sampled signal and the preset reference value to generate the three-phase initial modulation wave. For example, taking the modulation wave (power frequency sine wave) of SPWM as an example, as shown in Figure 2B, the three-phase initial modulation wave includes a-phase initial modulation wave, b-phase initial modulation wave, and c-phase initial modulation wave. The phase difference between phase b and phase c is 120 degrees. The example shown in FIG. 2B is only an example. For example, the phase difference between the a-phase, the b-phase, and the c-phase may also be 60 degrees.

202. Generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave.

Specifically, the first common-mode modulation wave is generated by combining the clamping state of the three-phase DPWM modulation wave, the three-phase initial modulation, and the preset DPWM modulation mode. The preset DPWM modulation mode may include DPWM1, DPWM2, and DPWM3. , DPWMMAX, DPWMMIN and GDPWM, etc., the specific application is not limited.

The following is an example with reference to FIG. 2C. Taking the modulation wave of the a-phase DPWM as an example, the vicinity of the maximum and minimum values of the power frequency sine wave respectively correspond to the positive clamping state and the negative clamping state of the modulation wave of the a-phase DPWM. Taking the DPWM modulation method as DPWM1 as an example for modulation, the first common mode modulation wave v _z is equal to {Vmax-v _a , Vmax-v _b , Vmax-v _c , Vmin-v _a , Vmin-v _{b at any moment} , Vmin-v _c } The variable with the smallest absolute value among the six variables, where Vmax is the maximum value of the three-phase DPWM modulation wave, Vmin is the minimum value of the three-phase DPWM modulation wave, v _a , v _b , v _c These are three-phase initial modulation waves. As can be seen from Fig. 1A, Vmax is 1 and Vmin is -1; then the waveform of the first common mode modulation wave is as shown in Fig. 2C.

For another example, take DPWMMAX as an example for modulation, the first common-mode modulation wave v _z is equal to the absolute value of the three variables {Vmax-v _a , Vmax-v _b , Vmax-v _{c} at any moment} The smallest variable. Taking the modulation method of DPWM as DPWMMIN as an example for modulation, the first common-mode modulation wave v _z is equal to the variable with the smallest absolute value among the three variables _{{Vmin-v a} , Vmin-v _b , Vmin-v _{c} at any moment} .

It should be noted that the example shown in FIG. 2C only uses the same length of time the modulation wave of each phase DPWM is in the clamped state as an example to illustrate the first common mode modulation wave. In practical applications, the modulation of each phase DPWM The duration of each wave in the clamped state may also be different, which is not specifically limited by this application.

Secondly, the example shown in Figure 2C only shows that the modulation wave of each phase DPWM is clamped near the maximum and minimum values of the power frequency sine wave. In practical applications, the modulation wave of each phase DPWM can also be The power frequency sine wave is in a clamped state near other positions, for example, at the zero point position of the power frequency sine wave, which is not specifically limited by this application. In addition, the position of the power frequency sine wave corresponding to the clamping state of the DPWM modulation wave of each phase can also be different, as long as the clamping state of the DPWM modulation wave of each phase does not overlap, which is not specifically limited by this application.

203. Perform smoothing processing on the first common mode modulation wave according to the clamping state of the three-phase DPWM modulation wave to obtain a second common mode modulation wave.

In a possible implementation manner, smoothing the first common-mode modulation wave according to the clamping state of the three-phase DPWM modulation wave to obtain the second common-mode modulation wave includes: The clamping state and the amplitude corresponding to the first common-mode modulated wave at the current moment are calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.

The possible implementation can be implemented in the following two possible ways:

Method 1: First determine the clamp state corresponding to the current moment according to the clamp state of the three-phase DPWM modulation wave, and then combine the amplitude corresponding to the first common-mode modulation wave at the current moment to determine the corresponding smoothing processing method. The description will be given by the embodiment shown in FIG. 3A.

Method 2: First determine whether the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the first preset threshold or less than the second preset threshold, and then combined with the clamp state corresponding to the current moment to determine to use the corresponding smoothing The processing method is specifically described through the embodiment shown in FIG. 4.

2B and 2C to illustrate, taking the DPWM1 modulation method as an example, the a-phase power frequency sine modulation wave and the first common mode modulation wave of three times the power frequency are shown in Fig. 2C, and Fig. 2B shows the first common mode The step of the modulation wave is generated near the zero-crossing point of the a-phase power frequency sinusoidal modulation wave. Near the zero point, the first common-mode modulation wave will produce larger high-frequency harmonic components. Therefore, the first common-mode modulation wave will generate larger high-frequency harmonic components at the zero-crossing point. Smoothing the step of a common-mode modulation wave can reduce the high-frequency harmonic components generated by the first common-mode modulation wave at the zero-crossing point.

In the embodiments of the present application, the first common-mode modulation wave is smoothed to reduce the high-frequency harmonic components of the first common-mode modulation wave, thereby reducing the influence of the high-frequency harmonic components on the stability of the system and the three Interference caused by partial current detection in the phase converter system. _{The following figure 2D shows the effect comparison diagram of the first common mode modulated wave v z} and the smoothed second common mode modulated wave v ₀ obtained through the technical solution of the embodiment of the present application, in which, Fig. 2D(a) and FIG. 2D (b) is a waveform diagram of a first common mode modulation wave v _z and the common-mode spectrum of the first modulated wave is a schematic view of v _z, and FIG. 2D (c) and 2D (d) is a second common mode smoothing process obtained v ₀ modulated wave waveform diagram of the modulated wave and a second common mode spectrum v ₀ schematic comparison chart 2D (a) and 2D (c) can be seen, by smoothing a second common mode modulation wave v step change ₀ It is significantly smaller than the first common-mode modulation wave v _z . Comparing Fig. 2D(b) and Fig. 2D(d), it can be seen that the high-frequency harmonic components in the frequency spectrum of the _{second common-mode modulation wave v 0 after smoothing are relative to the first} The frequency spectrum of the common mode modulation wave v _z has fewer high-frequency harmonic components.

204. Perform waveform superposition of the three-phase initial modulation wave and the second common-mode modulation wave to obtain a three-phase output modulation wave.

Specifically, each phase of the three-phase initial modulated wave is superimposed with the second common-mode modulated wave in a one-to-one correspondence to obtain a three-phase output modulated wave. For example, if the three-phase output modulated waves are respectively v _{a_mod} , v _{b_mod} , and v _{c_mod} , then v _{a_mod} = v _a + v ₀ ; v _{b_mod} = v _b + v ₀ ; v _{c_mod} = v _c + v ₀ .

In the embodiment of the present application, the three-phase initial modulation wave is obtained, and then the first common-mode modulation wave is generated according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase DPWM, and according to the modulation wave of the three-phase DPWM Smooth the first common-mode modulated wave in the clamping state of, to obtain a second common-mode modulated wave, and then determine the three-phase output modulated wave according to the second common-mode modulated wave and the three-phase initial modulation wave. Therefore, in the technical solution of the embodiment of the present application, the first common mode modulation wave is smoothed in combination with the clamping state of the three-phase DPWM modulation wave of the three-phase converter to obtain the second common mode modulation wave, which can reduce The high-frequency harmonic components of the first common-mode modulation wave are then determined according to the second common-mode modulation wave obtained by the smoothing process and the three-phase initial modulation wave to determine the three-phase output modulation wave, thereby improving the performance of the three-phase converter The stability of the system; and, when the three-phase converter system detects part of the current, the high-frequency harmonic component of the second common-mode modulation wave interferes with the system detection, thereby reducing the probability of false alarms.

Please refer to FIG. 3A. FIG. 3A is a schematic diagram of another embodiment of a pulse width modulation method according to an embodiment of the present application. The method includes:

301. Obtain a three-phase initial modulation wave.

302. Generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave.

Step 301 to step 302 are similar to step 201 to step 202 shown in FIG. 2A. For details, please refer to the related description of step 201 to step 202 shown in FIG. 2A, which will not be repeated here.

303. Determine the clamping state corresponding to the current moment according to the clamping state of the modulation wave of the three-phase DPWM. If the clamping state corresponding to the current moment is a non-negative clamping state, perform step 304; if the current moment corresponds to If the clamped state of is a non-positive clamped state, step 307 is executed.

For example, in conjunction with FIG. 2C, it can be seen from FIG. 2C that the clamping state of the modulation wave of the a-phase DPWM of the three phases at T2 is a positive clamping state, that is, a non-negative clamping state, then step 304 is performed. At T1, the clamping state of the modulation wave of the b-phase DPWM of the three phases is a negative clamping state, that is, a non-positive clamping state, then step 307 is executed.

304. Determine whether the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, if yes, execute step 305; if not, execute step 306.

The following description is given in conjunction with FIG. 3B. For the convenience of description, FIG. 3B only takes _{one period of the first common mode modulated wave v z} in FIG. 2C as an example for description. FIG. 3B shows the corresponding _{first common mode modulated wave v z.} The waveform corresponding to the negative clamping state of the modulation wave of the b-phase DPWM and the waveform corresponding to the positive clamping state of the modulation wave of the a-phase DPWM in the _{first common-mode modulation wave v z, wherein the first preset threshold is} v _lim1 , the second preset threshold is v _lim2 .

As shown in Figure 3B, in the positive clamping state of the modulation wave of the a-phase DPWM, at time T4, the amplitude of V4 is greater than v _lim1 , then step 305 is executed; at time T2, the amplitude of V4 is less than v _lim1 , then Go to step 306.

It should be noted that _{the value range of the first preset threshold v lim1} can be (Vmax-Vpeak, Vmin-(Vpeak/2)), where Vmax is the maximum value of the three-phase DPWM modulation wave, and Vmin is the three-phase The minimum value of the modulation wave of DPWM, Vpeak is the maximum value of the three-phase initial modulation wave of a, b, and c in one cycle. And the first preset threshold can be selected from the value range according to actual needs. For example, the first preset threshold can be set according to the voltage level of the currently used system. For low-voltage systems, the value range can be selected from the value range. Select a smaller value as the first preset threshold.

305. Calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment.

Specifically, the preset positive limiting and smoothing strategy includes subtracting a first preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the first difference; Multiply by the absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment, and add the first preset threshold to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment. That is, when the amplitude corresponding to the first common mode modulation wave at the current moment is greater than the first preset threshold, the second common mode modulation wave v ₀ (t) = v _lim1 + v _d2 (t)·v _s (t), Among them, v ₀ (t)>v _lim1 , v _s (t) is the preset smooth modulated wave, and v _d2 (t) is the difference between the amplitude of the first common mode modulated wave and the first preset threshold.

For example, as shown in Figure 3B, at T4, the amplitude corresponding to the first common-mode modulated wave is V4, then the amplitude corresponding to the second common-mode modulated wave is v _lim1 +(V4-v _lim1 )*v _s (T2), in the example shown in Fig. 3B, v _s (t) can be the absolute value of the triple power frequency sinusoidal modulation wave, that is, v _s (t)=|sin(3·ω _g ·t)| , Where ω _g is the grid frequency, that is, the frequency of the three-phase initial modulation wave (where the frequency of the three-phase initial modulation wave is the same as the grid frequency to ensure that the frequency of the three-phase initial modulation wave is synchronized with the grid frequency), then v _s (T2)=|sin(3·ω _g ·T2)|.

306. Use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.

When the amplitude corresponding to the first common-mode modulation wave at the current moment is not greater than the first preset threshold, the amplitude corresponding to the first common-mode modulation wave at the current moment is taken as the amplitude corresponding to the second common-mode modulation wave at the current moment The amplitude of the second common mode modulation wave v ₀ (t)=v _z (t), v _lim1 _{≥ v 0} (t). For example, as shown in FIG. 3B, at time T2, the amplitude corresponding to the first common-mode modulated wave is V2, and the amplitude corresponding to the second common-mode modulated wave at the current time is V2.

307. Determine whether the amplitude corresponding to the first common-mode modulated wave at the current moment is less than a second preset threshold, if yes, execute step 308; if not, execute step 309.

As shown in Figure 3B, in the negative clamp state of the modulation wave of the b-phase DPWM, at time T1, the amplitude of V1 is less than v _lim2 , then step 308 is performed; at time T3, the amplitude of V3 is greater than v _lim2 , then Go to step 309.

It should be noted that _{the value range of the second preset threshold v lim2} can be (Vmin+(Vpeak/2), Vmin+Vpeak), where Vmax is the maximum value of the modulation wave of the three-phase DPWM, and Vmin is the three-phase DPWM The minimum value of the modulated wave, Vpeak is the maximum value of the three-phase initial modulated wave of a, b, and c in one cycle. And the second preset threshold can be selected from the value range in combination with actual needs. For example, the second preset threshold can be set according to the voltage level of the currently used system.

308. Calculate the amplitude corresponding to the second common-mode modulated wave according to the preset negative-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment.

Specifically, the preset negative-direction limiting and smoothing strategy includes subtracting a second preset threshold from the amplitude of the first common-mode modulation wave at the current moment to obtain a second difference, and then multiplying the second difference by The absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment is added to the second preset threshold to obtain the amplitude corresponding to the second common-mode modulated wave. That is, when the amplitude corresponding to the first common mode modulation wave at the current moment is less than the second preset threshold, the second common mode modulation wave v ₀ (t) = v _lim2 + v _d2 (t)·v _s (t), Among them, v ₀ (t)<v _lim2 , v _s (t) is the preset smooth modulated wave, and v _d2 (t) is the difference between the amplitude of the first common mode modulated wave and the second preset threshold.

For example, as shown in FIG. 3B, at T1, the amplitude of the first common mode modulation wave is V1, then the amplitude of the second common mode modulation wave is v _lim2 +(V1-v _lim2 )*v _s (T1) In the example shown in Figure 3B, v _s (t) can be the absolute value of the triple power frequency sinusoidal modulation wave, that is, v _s (t) = |sin(3·ω _g ·t)|, where ω _g is the grid frequency, that is, the frequency of the three-phase initial modulation wave, then v _s (T1) = |sin(3·ω _g ·T1)|.

309. Use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.

When the amplitude corresponding to the first common-mode modulation wave at the current moment is not less than the second preset threshold, the amplitude corresponding to the first common-mode modulation wave at the current moment is taken as the amplitude corresponding to the second common-mode modulation wave at the current moment The amplitude of the second common mode modulation wave v ₀ (t) = v _z (t), v _{lim2 ≥} _{v 0} (t). For example, as shown in FIG. 3B, at time T3, the amplitude corresponding to the first common-mode modulation wave is V3, and the amplitude corresponding to the second common-mode modulation wave at the current time is V3.

It can be seen from Figure 2D that the smoothed waveform of the second common mode modulation wave can be as shown in Figure 2D(c). The step change of the second common mode modulation wave is significantly smaller than that of the first common mode wave in Figure 2D(a). The step change of the mode modulation wave, as shown in Figure 2D(b) and Figure 2D(d), the high frequency harmonic components in the frequency spectrum of the _{second common mode modulation wave v 0 after the smoothing process are relative to the first common mode modulation wave.} The frequency spectrum of wave v _z has fewer high-frequency harmonic components. Finally, the amplitude of the initial modulation wave of each phase of the three-phase initial modulation wave at the current moment and the amplitude of the second common-mode modulation wave at the current moment are superimposed in a one-to-one correspondence to obtain the current three-phase modulation wave. The amplitude of the output modulating wave.

In the embodiment of the present application, the three-phase initial modulation wave is obtained, and the first common-mode modulation wave is generated according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase DPWM, and then according to the clamping state of the three-phase DPWM modulation wave The state smoothes the first common-mode modulation wave to obtain the second common-mode modulation wave, specifically combining the clamping state of the three-phase DPWM and the amplitude of the first common-mode modulation wave on the first common-mode modulation wave. In the clamp state interval of the corresponding three-phase DPWM, smooth the part where the amplitude of the first common mode modulation wave exceeds the preset limit value to reduce the high frequency generated by the first common mode modulation wave at the step. Harmonic components, thereby improving the stability of the three-phase converter system; and reducing the detection of part of the current in the three-phase converter system, the high-frequency harmonic components of the second common-mode modulation wave Detection of interference, thereby reducing the probability of false alarms.

The embodiment of the present application also provides another implementation manner. If it is determined according to the clamping state of the modulation wave of the three-phase DPWM that the clamping state corresponding to the current moment is neither a positive clamping state nor a negative clamping state, Then it is judged whether the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than 0, and if so, the steps 304 to 306 shown in FIG. 3A are executed, that is, the second common-mode modulated wave corresponding to the current moment is calculated. If not, execute step 307 to step 309 shown in FIG. 3A. As shown in Figure 3C, in the interval between the positive clamp state and the negative clamp state corresponding to the three-phase DPWM, the first common-mode modulation wave is symmetrical about 0 point. As shown in Figure 3C, the clamp state corresponding to point A It does not belong to the positive clamp state or the negative clamp state, then it is determined whether the first common mode modulated wave v _z at point A is greater than 0, and if it is, then steps 304 to 306 shown in FIG. 3A are executed. , That is, the amplitude corresponding to the second common-mode modulated wave at the current moment is calculated; if not, execute steps 307 to 309 shown in FIG. 3A, that is, the second common-mode modulated wave at the current moment is calculated. The corresponding amplitude.

Please refer to FIG. 4. FIG. 4 is a schematic diagram of another embodiment of a pulse width modulation method according to an embodiment of the present application. The method includes:

401. Obtain a three-phase initial modulation wave.

402. Generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave.

Step 401 to step 402 are similar to step 201 to step 202 shown in FIG. 2A. For details, please refer to the related description of step 201 to step 202 shown in FIG. 2A, which will not be repeated here.

403. Determine whether the amplitude of the first common-mode modulated wave at the current moment is greater than a first preset threshold or less than a second preset threshold, if it is greater than the first preset threshold, perform step 404; if it is less than the second preset threshold , Go to step 407; if it is greater than the second preset threshold and less than the first preset threshold, go to step 410.

For the introduction of the value ranges of the first preset threshold and the second preset threshold, please refer to the related introduction of step 304 and step 307 in FIG. 3A, which will not be repeated here.

404. According to the clamp state of the three-phase DPWM, determine whether the clamp state corresponding to the current moment is a non-negative clamp state, if yes, execute step 405; if not, execute step 406.

For example, with reference to FIG. 2C, at T2, the clamping state of the modulation wave of the a-phase DPWM of the three phases is a positive clamping state, that is, a non-negative clamping state, then step 405 is executed. Wherein, if the clamp state corresponding to the current moment is not a non-negative clamp state, step 406 is executed, and in this possible implementation manner, the clamp state corresponding to the current moment includes a negative clamp state or other clamp states For example, the clamp state corresponding to the current moment is neither a positive clamp state nor a negative clamp state. It can be seen from step 403 that the amplitude of the first common mode modulation wave is greater than the first preset threshold, then The amplitude of the second common-mode modulated wave at the current moment is calculated according to the preset positive-direction limiting and smoothing strategy and the amplitude of the first common-mode modulated wave at the current moment.

405. Calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment.

406. Use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.

Step 405 to step 406 are similar to step 305 to step 306 shown in FIG. 3A. For details, please refer to the related description of step 305 to step 306 shown in FIG. 3A, which will not be repeated here.

407. According to the clamping state of the three-phase DPWM, judge whether the clamping state corresponding to the current moment is a non-positive clamping state, if yes, proceed to step 408; if not, proceed to step 409.

Described in conjunction with FIG. 2C, the clamping state of the modulation wave of the b-phase DPWM of the three phases at the time T1 is a negative clamping state, that is, it can be understood that the clamping state is not positive, and then step 408 is performed. Wherein, if the clamp state corresponding to the current moment is not a non-positive clamp state, step 409 is executed, and in this possible implementation manner, the clamp state corresponding to the current moment may be a positive clamp state or other clamp states. For example, if the clamp state corresponding to the current moment is neither a positive clamp state nor a negative clamp state, it can be known from step 403 that the amplitude corresponding to the first common-mode modulation wave at the current moment is less than the first common-mode modulation wave. Second, the preset threshold value is calculated according to the preset negative limit smoothing strategy and the amplitude corresponding to the first common mode modulated wave at the current moment to obtain the amplitude corresponding to the second common mode modulated wave at the current moment.

408. Calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment.

409. Use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.

Step 408 to step 409 are similar to step 308 to step 309 shown in FIG. 3A. For details, please refer to the related description of step 308 to step 309 shown in FIG. 3A, which will not be repeated here.

410. Use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.

Step 410 is similar to step 309 shown in FIG. 3A. For details, please refer to the related description of step 309 shown in FIG.

Then, the amplitude of the initial modulation wave of each phase of the three-phase initial modulation wave at the current moment and the amplitude of the second common-mode modulation wave at the current moment are superimposed in a one-to-one correspondence to obtain the current three-phase modulation wave. The amplitude of the output modulating wave.

In the embodiment of the present application, the first common mode modulation wave is generated according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave, and then the first common mode modulation wave is smoothed to obtain the second common mode The modulation wave specifically combines the clamping state of the three-phase DPWM and the amplitude of the first common-mode modulation wave to the first common-mode modulation wave in the corresponding three-phase DPWM clamping state interval. The part whose amplitude exceeds the preset limit value is smoothed to reduce the high-frequency harmonic components generated by the first common-mode modulation wave at the step, thereby improving the stability of the three-phase converter system; In addition, when detecting partial currents in the system of the three-phase converter, the high-frequency harmonic component of the second common-mode modulation wave interferes with the detection of the system and reduces the probability of false alarms.

Please refer to FIG. 5, which is a schematic structural diagram of an inverter according to an embodiment of the application. The inverter includes a DC system, a switching network, a filter, and an AC system, and the controller is connected to the switching network;

The controller is used to obtain the three-phase initial modulation wave; generate the first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave; and according to the clamping state of the three-phase DPWM modulation wave Perform smoothing processing on the first common-mode modulated wave to obtain a second common-mode modulated wave; perform waveform superposition of the three-phase initial modulation wave and the second common-mode modulation wave to obtain a three-phase output modulated wave.

In a possible implementation manner, the controller is specifically used for:

In another possible implementation, the controller is also used to:

In the embodiment of the present application, the controller obtains the three-phase initial modulation wave; then, the controller generates the first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave, and according to the three-phase The clamping state of the modulation wave of the DPWM smoothes the first common mode modulation wave to obtain the smoothed second common mode modulation wave, and then determines the three phases according to the second common mode modulation wave and the three-phase initial modulation wave. Phase output modulation wave. Therefore, in the technical solution of the embodiment of the present application, the controller combines the clamping state of the three-phase DPWM modulation wave to smooth the first common mode modulation wave to obtain the second common mode modulation wave, which can reduce the first common mode modulation wave. The high-frequency harmonic components of the mode modulation wave are then determined according to the second common mode modulation wave obtained by the smoothing process and the three-phase initial modulation wave to determine the three-phase output modulation wave, thereby improving the stability of the inverter system.

Please refer to FIG. 6, which is a schematic structural diagram of the controller of the embodiment of the application, which is applied to a three-phase converter. The controller includes a processor 601, a memory 602, and a signal interface 603 connected by a bus 609. The memory 602 stores The operating instructions of the processor;

The signal interface 603 is used to obtain the three-phase initial modulation wave;

The processor 601 is configured to generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase discontinuous pulse width modulation DPWM; according to the clamping state of the three-phase DPWM modulation wave The bit state smoothes the first common-mode modulation wave to obtain a second common-mode modulation wave; and superimposes the three-phase initial modulation wave and the second common-mode modulation wave to obtain a three-phase output modulation wave.

In a possible implementation manner, the processor 601 is specifically configured to:

In another possible implementation manner, the processor 601 is specifically configured to:

In another possible implementation manner, the processor 601 is further configured to:

In the embodiment of the present application, the signal interface 603 obtains the three-phase initial modulation wave, and the processor 601 generates the first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the three-phase DPWM modulation wave, and according to the three-phase initial modulation wave The clamping state of the modulation wave of the DPWM smoothes the first common mode modulation wave to obtain the smoothed second common mode modulation wave, and then determines the three phases according to the second common mode modulation wave and the three-phase initial modulation wave. Phase output modulation wave. Therefore, in the technical solution of the embodiment of the present application, the processor 601 combines the clamping state of the three-phase DPWM modulation wave acquired by the signal interface 603 to smooth the first common mode modulation wave to obtain the second common mode modulation wave, It can reduce the high-frequency harmonic components of the first common-mode modulation wave, and then determine the three-phase output modulation wave based on the second common-mode modulation wave obtained by the smoothing process and the three-phase initial modulation wave, thereby improving the three-phase conversion The stability of the device’s system.

The controller shown in FIG. 6 also includes one or more storage media 604 (for example, one or one storage device in a large amount) for storing application programs 605 or data 606. Among them, the memory 602 and the storage medium 604 may be short-term storage or persistent storage. The program stored in the storage medium 604 may include one or more modules (not shown in the figure), and each module may include a series of command operations on the server. Further, the processor 601 may be configured to communicate with the storage medium 604, and execute a series of instruction operations in the storage medium 604 on the server.

The controller may also include one or more operating systems 607, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM or FreeBSDTM and so on.

It should be noted that the foregoing method embodiments of the present application may be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, the steps of the foregoing method embodiments can be completed by hardware integrated logic circuits in the processor or instructions in the form of software. The above-mentioned processor may be a general-purpose processor, a digital signal processor (digital signal processor, DSP), an application specific integrated circuit (ASIC), a ready-made programmable gate array (field programmable gate array, FPGA) or other Programming logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps, and logical block diagrams disclosed in the embodiments of the present invention can be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like. The steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

It can be understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory. Among them, non-volatile memory can be read-only memory (Read-only memory, ROM), programmable read-only memory (Programmable ROM, PROM), erasable programmable read-only memory (Erasable PROM, EPROM), and electrically available Erase programmable read-only memory (Electrically EPROM, EEPROM) or flash memory. The volatile memory may be random access memory (RAM), which is used as an external cache. By way of exemplary but not restrictive description, many forms of RAM are available, such as static random access memory (static RAM, SRAM), dynamic random access memory (Dynamic RAM, DRAM), synchronous dynamic random access memory (Synchronous DRAM, SDRAM), double data rate synchronous dynamic random access memory (Souble sata rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (Enhanced SDRAM, ESDRAM), synchronous connection dynamic random access memory (Synchlink DRAM, SLDRAM) ) And Direct RAM Bus RAM (DR RAM). It should be noted that the memories of the systems and methods described herein are intended to include, but are not limited to, these and any other suitable types of memories.

Those skilled in the art can clearly understand that, for the convenience and conciseness of the description, the specific working process of the above-described system, device, and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method may be implemented in other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.

If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disks or optical disks and other media that can store program codes. .

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the embodiments are modified, or some of the technical features are equivalently replaced; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

A pulse width modulation method, characterized in that the method is applied to a three-phase converter, and the method includes:

Obtain the three-phase initial modulation wave;

Generating a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase discontinuous pulse width modulation DPWM;

Smoothing the first common mode modulation wave according to the clamping state of the three-phase DPWM modulation wave to obtain a second common mode modulation wave;

Waveform superposition of the three-phase initial modulation wave and the second common mode modulation is performed to obtain a three-phase output modulation wave.
The method according to claim 1, wherein the smoothing the first common mode modulation wave according to the clamping state of the three-phase DPWM modulation wave to obtain the second common mode modulation wave comprises:

The amplitude corresponding to the second common-mode modulation wave at the current moment is calculated according to the clamping state of the modulation wave of the three-phase DPWM and the amplitude corresponding to the first common-mode modulation wave at the current moment.
The method according to claim 2, wherein the first common-mode modulation wave at the current moment is calculated according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment. The amplitudes corresponding to the two common-mode modulation waves include:

When the clamping state corresponding to the current moment is a non-negative clamping state, judging whether the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than a first preset threshold;

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The method according to claim 3, wherein the method further comprises:

When the clamping state corresponding to the current moment is a non-positive clamping state, judging whether the amplitude corresponding to the first common-mode modulated wave at the current moment is less than a second preset threshold;

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The method according to claim 2, wherein the first common-mode modulation wave at the current moment is calculated according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment. The amplitudes corresponding to the two common-mode modulation waves include:

When the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the first preset threshold, judge whether the current clamping state corresponding to the current moment is a non-negative clamping state according to the clamping state of the three-phase DPWM ；

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive limit smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The method according to claim 5, wherein the method further comprises:

When the amplitude corresponding to the first common-mode modulation wave at the current moment is less than the second preset threshold, judge whether the current clamping state corresponding to the current moment is a non-positive clamping state according to the clamping state of the three-phase DPWM ；

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The method according to claim 2, wherein the first common-mode modulation wave at the current moment is calculated according to the clamping state of the three-phase DPWM modulation wave and the amplitude corresponding to the first common-mode modulation wave at the current moment. The amplitudes corresponding to the two common-mode modulation waves include:

If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and does not belong to the negative clamping state, then determine the amplitude corresponding to the first common mode modulation wave at the current moment Is it greater than 0;

If yes, when the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, then the preset positive-direction clipping and smoothing strategy and the first common-mode modulated wave at the current moment The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulation wave at the current moment;

If not, when the amplitude of the first common-mode modulated wave at the current moment is less than the second preset threshold, then the preset negative-direction limiting smoothing strategy and the current moment the first common-mode modulated wave are The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.
The method according to any one of claims 3 to 7, wherein the preset positive limit smoothing strategy comprises:

Subtract the first preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the amplitude corresponding to the first common-mode modulated wave at the current moment and the first preset threshold The first difference;

Multiply the first difference by the absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment, and add the first preset threshold to obtain the second common-mode modulated wave corresponding to the current moment The amplitude.
The method according to any one of claims 3 to 7, wherein the preset negative limit smoothing strategy comprises:

Subtract the second preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the second difference between the amplitude corresponding to the first common-mode modulated wave and the second preset threshold value;

Multiply the second difference value by the absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment, and add the second preset threshold value to obtain the second common-mode modulated wave corresponding to the current moment The amplitude.
The method according to any one of claims 1 to 9, wherein the waveform superposition of the three-phase initial modulation wave and the second common mode modulation to obtain a three-phase output modulation wave comprises:

Each phase of the three-phase initial modulation wave is superimposed with the second common-mode modulation wave in a one-to-one correspondence to obtain a three-phase output modulation wave.
An inverter, characterized in that the inverter includes a DC system, a switching network, a filter, an AC system, and a controller, and the controller is connected to the switching network;

The controller is configured to obtain a three-phase initial modulation wave; generate a first common-mode modulation wave according to the clamping state of the three-phase initial modulation wave and the modulation wave of the three-phase discontinuous pulse width modulation DPWM; The clamping state of the phase DPWM modulation wave smoothes the first common mode modulation wave to obtain a second common mode modulation wave; superimposes the three-phase initial modulation wave and the second common mode modulation wave, Obtain a three-phase output modulation wave.
The inverter according to claim 11, wherein the controller is specifically configured to:

The amplitude corresponding to the second common-mode modulation wave at the current moment is calculated according to the clamping state of the modulation wave of the three-phase DPWM and the amplitude corresponding to the first common-mode modulation wave at the current moment.
The inverter according to claim 12, wherein the controller is specifically configured to:

When the clamping state corresponding to the current moment is a non-negative clamping state, judging whether the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than a first preset threshold;

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The inverter according to claim 13, wherein the controller is further used for:

When the clamping state corresponding to the current moment is a non-positive clamping state, judging whether the amplitude corresponding to the first common-mode modulated wave at the current moment is less than a second preset threshold;

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting and smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The inverter according to claim 12, wherein the controller is specifically configured to:

When the amplitude corresponding to the first common-mode modulation wave at the current moment is greater than the first preset threshold, judge whether the current clamping state corresponding to the current moment is a non-negative clamping state according to the clamping state of the three-phase DPWM ；

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset positive limit smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The inverter according to claim 15, wherein the controller is further used for:

When the amplitude corresponding to the first common-mode modulation wave at the current moment is less than the second preset threshold, judge whether the current clamping state corresponding to the current moment is a non-positive clamping state according to the clamping state of the three-phase DPWM ；

If yes, calculate the amplitude corresponding to the second common-mode modulated wave at the current moment according to the preset negative-direction limiting smoothing strategy and the amplitude corresponding to the first common-mode modulated wave at the current moment;

If not, use the amplitude corresponding to the first common-mode modulated wave at the current moment as the amplitude corresponding to the second common-mode modulated wave at the current moment.
The inverter according to claim 12, wherein the controller is specifically configured to:

If the clamping state of the three-phase DPWM modulation wave corresponding to the current moment does not belong to the positive clamping state and does not belong to the negative clamping state, then determine the amplitude corresponding to the first common mode modulation wave at the current moment Is it greater than 0;

If yes, when the amplitude corresponding to the first common-mode modulated wave at the current moment is greater than the first preset threshold, then the preset positive-direction clipping and smoothing strategy and the first common-mode modulated wave at the current moment The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulation wave at the current moment;

If not, when the amplitude of the first common-mode modulated wave at the current moment is less than the second preset threshold, then the preset negative-direction limiting smoothing strategy and the current moment the first common-mode modulated wave are The corresponding amplitude is calculated to obtain the amplitude corresponding to the second common-mode modulated wave at the current moment.
The inverter according to any one of claims 13 to 17, wherein the preset positive limit smoothing strategy comprises:

Subtract the first preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the amplitude corresponding to the first common-mode modulated wave at the current moment and the first preset threshold The first difference;

Multiply the first difference value by the absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment, and add the first preset threshold value to obtain the second common-mode modulated wave corresponding to the current moment The amplitude.
The inverter according to any one of claims 13 to 17, wherein the preset negative limit smoothing strategy comprises:

Subtract the second preset threshold from the amplitude corresponding to the first common-mode modulated wave at the current moment to obtain the second difference between the amplitude corresponding to the first common-mode modulated wave and the second preset threshold value;

Multiply the second difference value by the absolute value of the amplitude corresponding to the smooth modulated wave preset at the current moment, and add the second preset threshold value to obtain the second common-mode modulated wave corresponding to the current moment The amplitude.
The inverter according to any one of claims 11 to 19, wherein the controller is specifically configured to:

Each phase of the three-phase initial modulation wave is superimposed with the second common-mode modulation wave in a one-to-one correspondence to obtain a three-phase output modulation wave.