JP2016158323A - Harmonic restraint device with active filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a number of load current detection circuits for detecting a load current, and reduce a manufacturing cost.SOLUTION: A harmonic restraint device with an active filter 3 can suppress a higher harmonic generated in a converter circuit 7 of an inverter device 2 connected to an AC power supply 1. The converter circuit comprises: a three-phase diode bridge 9 that is connected to the AC power supply; a liner reactor 10 that is connected to the three-phase diode bridge; and an electrolytic capacitor 11 that is connected to the liner reactor and the three-phase diode bridge. The active filter comprises load current detection means for detecting a load current to the converter circuit, and the load current detection means comprises: a bus bar current detection circuit 12 that detects a bus bar current flowing in the liner reactor; and a phase voltage detection circuit that detects a phase voltage of the AC power source, and the load current is calculated on the basis of the bus bar current detected in the bus bar current detection circuit and the phase voltage detected in the phase voltage detection circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a harmonic suppression device including an active filter for suppressing harmonics generated in a converter circuit of an inverter device connected to an AC power supply, and more particularly, to a refrigeration cycle device such as an air conditioner or a refrigerator. It is suitable as a harmonic suppression device that suppresses harmonics generated from the inverter device that drives the compressor.

  In general, an inverter device is used as a driving device for a compressor of a refrigeration cycle apparatus. The inverter device is a built-in converter circuit that converts an input alternating current into a direct current once, further converts this direct current into an alternating current of an arbitrary frequency, and outputs it to the motor of the compressor. To do.

  In the process of conversion to direct current, a current having a frequency component that is an integral multiple of the fundamental wave (fundamental wave current) is generated in the input current to the inverter device. This current is called a harmonic (harmonic current). It is known that harmonics adversely affect devices connected to the same power supply system as the inverter device.

  Various harmonic suppression methods have been studied, and one of them is an active filter. Examples of this type of prior art document include those described in Japanese Patent Application Laid-Open No. 2014-121145 (Patent Document 1). The active filter detects harmonics generated in the converter circuit of the inverter device, and flows a current (compensation current) having a sign (reverse phase) opposite to that of the harmonics between a power source and the inverter device. This suppresses harmonics from flowing through the power supply system.

JP 2014-121145 A

  The active filter needs to detect a load current (input current) to the inverter device that is a source of harmonics and a current (compensation current) flowing from the power source to the active filter. When the power source is three-phase, in the conventional active filter, load current detection circuits are installed in two or three phases of the three-phase load currents as load current detection means. For this reason, it is necessary to install a plurality of load current detection circuits, and there is a problem that the manufacturing cost of the active filter increases.

  An object of the present invention is to obtain a harmonic suppression device including an active filter that can reduce the manufacturing cost by reducing the load current detection circuit for detecting the load current.

  In order to achieve the above object, the present invention provides a harmonic suppression device including an active filter for suppressing harmonics generated in a converter circuit of an inverter device connected to an AC power supply, wherein the converter circuit includes the AC A three-phase diode bridge connected to a power source; a DC reactor connected to the three-phase diode bridge; and an electrolytic capacitor connected to the DC reactor and the three-phase diode bridge, wherein the active filter is the converter circuit Load current detection means for detecting a load current (input current) to the bus, the load current detection means detecting a bus current flowing through the DC reactor, a bus current detection circuit (bus current sensor), and the AC A phase voltage detection circuit for detecting each phase voltage of the power supply is provided and is detected by the bus current detection circuit. A bus current is, from the detected phase voltage at said phase voltage detecting circuit, and calculates the load current in each phase.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect which can obtain the harmonic suppression apparatus provided with the active filter which can reduce a load current detection circuit for detecting load current, and can reduce manufacturing cost.

It is a figure explaining Example 1 of the harmonic suppression apparatus provided with the active filter of this invention, and is the connection diagram which connected the inverter apparatus, the three-phase power supply, and the active filter. It is a figure which shows the load current waveform in one phase among three-phase current, a compensation current waveform, and a power supply current waveform. It is a circuit diagram explaining the structure of the active filter shown in FIG. It is a block diagram explaining the structure of the active filter control part shown in FIG. It is a block diagram explaining the structure of the harmonic separation part shown in FIG.

  Hereinafter, specific examples of the harmonic suppressing device including the active filter of the present invention will be described with reference to the drawings. In each figure, the same reference numerals indicate the same parts.

FIG. 1 is a diagram for explaining a first embodiment of a harmonic suppression device having an active filter according to the present invention, and is a connection diagram in which an inverter device, a three-phase power source, and an active filter are connected.
As shown in FIG. 1, the three-phase power source 1 is connected to an inverter device 2. Further, the wiring between the three-phase power source 1 and the inverter device 2 is branched and connected to the active filter 3. A power supply current 4 is output from the three-phase power supply 1, and this power supply current 4 is branched into a load current 5 flowing on the inverter device 2 side and a compensation current 6 flowing on the active filter 3 side.

  The load current 5 is converted into a direct current in a converter circuit 7 constituting the inverter device 2, and this direct current is inputted to an IPM (Intelligent Power Module) 8 constituting the inverter device 2. The motor 60 of the compressor (not shown) of the refrigeration cycle apparatus is configured to be driven at an arbitrary rotational speed by the alternating current converted into an arbitrary frequency by the IPM 8.

  The converter circuit 7 includes a three-phase diode bridge (three-phase diode bridge) 9, a DC reactor 10, and an electrolytic capacitor A11 as main components. In this embodiment, a bus current sensor 12 for detecting a bus current flowing in the DC reactor 10 is provided in the converter circuit 7, and the bus current detection signal 13 detected by the bus current sensor 12 is the active current signal 13. Input to filter 3.

  In this embodiment, the inverter device 2 and the active filter 3 are stored in the same box 14, and the inverter device 2 and the active filter 3 are connected by a lead pin. More specifically, the substrate provided with the converter circuit 7 and the substrate provided with the active filter 3 are placed in a single box 14 and arranged, and the substrate provided with the converter circuit 7 and the active filter 3 are arranged. Lead pins are used for connection to a substrate provided with

  Thus, by using the lead pin for the connection between the converter circuit 7 and the active filter 3, the manufacturing cost can be reduced as compared with the case where the connection is made using the connector and the wiring.

  In the present embodiment, the inverter device 2 and the active filter 3 are arranged on separate substrates and both are connected by lead pins. However, the inverter device 2 and the active filter 3 are arranged on the same substrate. If the configuration is arranged on the same substrate, the manufacturing cost can be further reduced.

FIG. 2 is a diagram showing a load current waveform 5a, a compensation current waveform 6a, and a power supply current waveform 4a in one phase among the three-phase currents.
The load current waveform 5a is a waveform obtained by adding a harmonic to a fundamental wave that is a sine wave. The compensation current waveform 6a is a waveform in which the sign of the harmonic of the load current waveform 5a is reversed. Since the power supply current waveform 4a is a waveform obtained by adding the load current waveform 5a and the compensation current waveform 6a, the waveform is the same as the fundamental wave of the load current waveform 5a.
Therefore, by injecting the compensation current 6 to the load current 5 side, the power source current 4 with suppressed harmonics can be obtained.

FIG. 3 is a circuit diagram illustrating the configuration of the active filter 3 shown in FIG. 1, and the circuit configuration of the active filter 3 will be described with reference to FIG.
Compensation current 6 branched from power supply current 4 output from three-phase power supply 1 shown in FIG. 1 flows into noise filter circuit 15 of active filter 3 shown in FIG.

  The noise filter circuit 15 is connected to a switching module 16 composed of six switching elements. Further, the P side of the switching module 16 is connected to the positive terminal of the electrolytic capacitor B17, and the N side of the switching module 16 is It is connected to the negative terminal of the electrolytic capacitor B17. Note that the ACL shown in FIG. 3 is an AC reactor.

  A U-phase compensation current sensor 18 and a W-phase compensation current sensor 19 are installed between the noise filter circuit 15 and the switching module 16, and the U-phase current detection signal detected by these current sensors 18, 19. 20 and the W-phase current detection signal 21 are input to the active filter control unit 27. The active filter control unit 27 is configured by a microcomputer.

  The active filter control unit 27 includes a power supply voltage detection signal 24 detected by the power supply voltage detection circuit 23 shown in FIG. 3, a bus current detection signal 13 detected by the bus current sensor 12 shown in FIG. A DC voltage detection signal 26 detected by the DC voltage detection circuit 25 shown in FIG. 3 is input.

  Based on these detection signals, the active filter control unit 27 outputs a PWM (Pulse Width Modulation) signal 22 for turning on / off each switching element of the switching module 16 to the switching module 16.

  The power supply voltage detection signal 24 detected by the power supply voltage detection circuit 23 is a line voltage of the three-phase power supply 1 input to the active filter 3. The DC voltage detection signal 26 detected by the DC voltage detection circuit 25 is a DC voltage applied between the positive terminal and the negative terminal of the electrolytic capacitor B17.

  FIG. 4 is a block diagram illustrating the configuration of the active filter control unit 27 shown in FIG. The control configuration shown in FIG. 4 is realized by software on the microcomputer of the active filter control unit 27.

  As shown in FIG. 4, the active filter control unit 27 includes a phase voltage conversion unit 28, a load current calculation unit 31, a DC voltage control unit 35, a harmonic separation unit 33, a V phase current calculation unit 39, an ACR (Automatic Current Regulator). ) A control unit 40, an AVR (Automatic Voltage Regulator) calculation unit 42, a PWM generation unit 44, and the like.

  The phase voltage conversion unit 28 receives the power supply voltage detection signal 24 detected by the power supply voltage detection circuit 23 shown in FIG. The power supply voltage detection signal 24 includes a power supply voltage between UVs (line voltage) and a power supply voltage between WUs (line voltage). According to the following (Equation 1), the power supply voltage between UVs and the WU The power supply voltage between them is converted into a three-phase phase voltage 30 and a power supply phase 29.

  Here, “Vu: U-phase power supply voltage, Vv: V-phase power supply voltage, Vw: W-phase power supply voltage, Vu-v: UV power supply voltage, Vw-u: WU power supply voltage, θ: power supply phase”. .

  The load current calculation unit 31 receives the three-phase phase voltage 30 and the bus current detection signal 13 detected by the bus current sensor 12 shown in FIG. A three-phase load current 32 (load current 5 shown in FIG. 1) is calculated and output from the phase voltage 30 of the phase and the bus current detection signal 13.

  That is, the load current calculation unit 31 compares the magnitude relations of the respective phase power supply voltages in the three-phase phase voltage 30 calculated by the above (Equation 1), and the voltage is the maximum among the three-phase phase voltages 30. Is equivalent to the bus current obtained from the bus current detection signal 13. Further, the load current of the minimum voltage phase at which the voltage is minimized is equivalent to the load current with the opposite sign attached to the bus current (bus current × (−1)). Further, the load current of the voltage intermediate phase where the voltage is intermediate is set to zero.

For example, when the maximum voltage phase is the U phase, the minimum voltage phase is the V phase, and the intermediate voltage phase is the W phase,
"U phase load current = bus current, V phase load current =-bus current, W phase load current = 0"
It becomes.

  However, immediately after the voltage maximum phase and the voltage intermediate phase are switched, the load current of the voltage maximum phase and the bus current do not match, and the load current of the voltage intermediate phase does not become zero. Therefore, it is necessary to correct the load current immediately after the voltage maximum phase and the voltage intermediate phase are switched.

Specifically, the load current that flows in the voltage maximum phase and the voltage intermediate phase until the difference ΔV between the voltage maximum phase and the voltage intermediate phase becomes _{equal to} or greater than the switching determination voltage (predetermined voltage) V _judage after the voltage maximum phase is switched is A value obtained by multiplying the bus current by a gain. The following (Equation 2) and (Equation 3) are used to calculate the gain.

The switching determination voltage _Vjudege is determined by the characteristics of the diode module 9a (see FIG. 1) of the diode bridge 9.
The same correction is performed immediately after the voltage minimum phase and the voltage intermediate phase are switched. That is, the above-described maximum voltage phase portion may be replaced with the minimum voltage phase. Specifically, after the minimum voltage phase and the intermediate voltage phase are switched, the difference between the minimum voltage phase and the intermediate voltage phase becomes a predetermined voltage or more. Until the load current flowing in the minimum voltage phase and the intermediate voltage phase is a value obtained by multiplying the bus current flowing in the DC reactor by minus 1 and a correction gain, and the correction gain is the minimum voltage phase and the intermediate voltage It may be calculated from the ratio between the phase difference and the predetermined voltage.

  The harmonic separation unit 33 outputs the three-phase load current 32 calculated by the load current calculation unit 31, the power supply phase 29 calculated by the phase voltage conversion unit 28, and a DC voltage control unit 35. The q-axis current command value 36 is input, and the harmonic separation unit 33 calculates and outputs a three-phase fundamental wave current 37. The details of the harmonic separation unit 33 will be described later.

  A deviation between the boost target voltage (Edc_Star) 34 and the DC voltage detection signal 26 detected by the DC voltage detection circuit 25 is input to the DC voltage control unit 35 that outputs the q-axis current command value 36. The DC voltage control unit 35 calculates and outputs the q-axis current command value 36 by PI control based on this deviation.

  The boost target voltage (Edc_Star) is calculated by the following (Equation 4).

  The q-axis current command value 36 calculated in this way is input to the harmonic separation unit 33.

  Next, processing of the three-phase fundamental current 37 output from the harmonic separation unit 33 will be described. First, the three-phase load current 32 is subtracted from the three-phase fundamental current 37 output from the harmonic separation unit 33, and the three-phase compensation current calculated by the V-phase current calculation unit 39 shown in FIG. A value obtained by subtracting the detection value 38 is input to the ACR control unit 40.

  The V-phase current calculation unit 39 for calculating the three-phase compensation current detection value 38 includes a U-phase compensation current detection signal detected by the U-phase compensation current sensor 18 and the W-phase compensation current sensor 19 shown in FIG. 20 and the W-phase compensation current detection signal 21 are input, and the V-phase compensation current is calculated from the following (Equation 5).

  The ACR control unit 40 calculates and outputs a three-phase voltage correction value 41 by PI control. A value (three-phase voltage command value) obtained by adding the three-phase voltage 30 to the three-phase voltage correction value 41 is input to the AVR calculating unit 42.

  In the AVR calculating unit 42, a three-phase voltage modulation rate 43 that is a ratio of the three-phase voltage command value and 1/2 of the DC voltage detection value based on the DC voltage detection signal 26 (DC voltage detection value / 2). Is calculated and output. The three-phase voltage modulation rate 43 is a value that varies within a range of ± 1.

  The three-phase voltage modulation rate 43 is input to the PWM generator 44. The PWM generator 44 compares the three-phase voltage modulation rate 43 with the carrier signal 45 to generate the PWM signal 22. The carrier signal 45 is a triangular wave having an amplitude of ± 1 and a frequency of 15 kHz, for example. When the three-phase voltage modulation rate 43 is larger than the carrier signal 45, the PWM signal 22 for turning on the P-side switching element in the switching module 16 shown in FIG. When 43 is smaller than the carrier signal 45, the PWM signal 22 for turning on the N-side switching element is output.

  FIG. 5 is a block diagram illustrating the configuration of the harmonic separation unit 33 shown in FIG. FIG. 5 shows a method of separating the three-phase load current 32 into a harmonic and a fundamental wave in the harmonic separation unit 33.

  The three-phase load current 32 and the power supply phase 29 are input to the harmonic separation unit 33, and the dq conversion unit 46 determines that the three-phase load current 32 (Iuvw) is d-axis based on the power supply phase 29. It is converted into a load current 47 and a q-axis load current 48 (Idq). The following (Equation 6) and (Equation 7) are used for this conversion.

Here, “I _α : α-axis load current, I _β : β-axis load current, I _U : U-phase load current, I _V : V-phase load current, I _W : W-phase load current, I _d : d-axis load Current, I _q : q-axis load current, θ: power supply phase ”.

  Harmonic components are removed from the d-axis load current 47 and the q-axis load current 48 by the first-order lag filter A49 and the first-order lag filter B50. The time constant of the first-order lag filters 49 and 50 is, for example, 12.5 msec. The q-axis current command value 36 is added to the q-axis load current that has been subjected to the first-order lag filtering process, and is converted into a three-phase fundamental wave current 37 by the uvw converter 51. (Equation 8) (Equation 9) is used for this conversion.

Here, “I _α : α-axis load current, I _β : β-axis load current, I _u : U-phase fundamental wave current, I _v : V-phase fundamental wave current, I _w : W-phase fundamental wave current, I _d : D-axis load current after primary delay filter processing, I _q2 : q-axis load current after addition of q-axis current command value, θ: power supply phase ”.

  The control in the active filter control unit shown in FIGS. 4 and 5 is performed at the same cycle corresponding to 15 kHz as the carrier signal 45. In FIG. 5, the mathematical expressions shown in the first-order lag filters 49 and 50 show the transfer function of the first-order lag element, T is a constant, and s is a Laplace variable.

  In the embodiment of the present invention described above, the active filter 3 includes load current detection means (load current calculation unit 31) for detecting the load current (input current) to the converter circuit 7, and this load current The detection means includes a bus current detection circuit (bus current sensor 12) for detecting a bus current flowing in the DC reactor 10, and a phase voltage detection circuit (phase voltage conversion unit 28) for detecting each phase voltage of the AC power source, In order to detect the load current, the load current in each phase is calculated from the bus current detected by the bus current detection circuit and each phase voltage detected by the phase voltage detection circuit. The load current detection circuit can be reduced. Therefore, the harmonic suppression device provided with the active filter that can reduce the manufacturing cost can be obtained.

  That is, by providing a detection circuit for the bus current flowing through the DC reactor 10, the load current detection circuit installed in two or three phases of the three-phase load currents can be eliminated, thereby Therefore, the number of current detection circuits can be reduced to one. In order to implement this embodiment, a power supply voltage detection circuit is required. However, the active filter 3 is originally provided with a phase voltage detection circuit (phase voltage conversion unit 28) for detecting the phase of the power supply voltage. Therefore, it is not necessary to add a new circuit for the power supply voltage detection circuit.

In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of the above embodiment.
Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs and tables for realizing each function can be stored in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.
Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

1: Three-phase power supply (AC power supply) 2: Inverter device 3: Active filter
4: power supply current, 4a: power supply current waveform, 5: load current, 5a: load current waveform,
6: compensation current, 6a: compensation current waveform,
7: Converter circuit, 8: IPM,
9: three-phase diode bridge, 9a: diode module,
10: DC reactor, 11: Electrolytic capacitor A,
12: Bus current sensor (bus current detection circuit), 13: Bus current detection signal,
14: box, 15: noise filter circuit, 16: switching module,
17: Electrolytic capacitor B, 18: U-phase compensation current sensor, 19: W-phase compensation current sensor,
20: U-phase compensation current detection signal, 21: W-phase compensation current detection signal, 22: PWM signal,
23: power supply voltage detection circuit, 24: power supply voltage detection signal,
25: DC voltage detection circuit, 26: DC voltage detection signal,
27: Active filter control unit,
28: Phase voltage conversion unit (phase voltage detection circuit), 29: power supply phase, 30: three-phase phase voltage,
31: Load current calculation unit (load current detection means), 32: Three-phase load current,
33: Harmonic separation unit, 34: Boost target voltage, 35: DC voltage control unit,
36: q-axis current command value, 37: three-phase fundamental current, 38: three-phase compensation current detection value,
39: V-phase current calculation unit, 40: ACR control unit, 41: Three-phase voltage correction value,
42: AVR calculation unit, 43: three-phase voltage modulation rate,
44: PWM generation unit, 45: carrier signal,
46: dq conversion unit, 47: d-axis load current, 48: q-axis load current,
49: 1st order lag filter A, 50: 1st order lag filter B, 51: uvw converter,
60: Motor.

Claims (8)

In the harmonic suppression device provided with an active filter for suppressing harmonics generated in the converter circuit of the inverter device connected to the AC power supply,
The converter circuit includes a three-phase diode bridge connected to the AC power source, a DC reactor connected to the three-phase diode bridge, and an electrolytic capacitor connected to the DC reactor and the three-phase diode bridge.
The active filter includes load current detection means for detecting a load current to the converter circuit,
The load current detection means includes a bus current detection circuit that detects a bus current flowing in the DC reactor, and a phase voltage detection circuit that detects each phase voltage of the AC power supply, and the bus detected by the bus current detection circuit A harmonic suppression device including an active filter, wherein the load current in each phase is calculated from a current and each phase voltage detected by the phase voltage detection circuit. In the harmonic suppression device provided with the active filter according to claim 1,
A phase voltage detection circuit that detects each phase voltage of the AC power supply includes a circuit that detects a line voltage of a three-phase power supply, and calculates the phase voltage from the line voltage. Harmonic suppression device equipped. In the harmonic suppression device provided with the active filter according to claim 1,
The load current detection means sets the bus current flowing through the DC reactor as the current flowing through the voltage maximum phase of each phase voltage detected by the phase voltage detection circuit, and applies minus 1 to the bus current flowing through the DC reactor. The value is defined as the current flowing in the voltage minimum phase of each phase voltage detected by the phase voltage detection circuit, and the current flowing in the voltage intermediate phase of each phase voltage detected by the phase voltage detection circuit is set to zero. Harmonic suppression device having an active filter as a feature. In the harmonic suppression device provided with the active filter according to claim 3,
The load current flowing in the voltage maximum phase and the voltage intermediate phase from the time when the voltage maximum phase and the voltage intermediate phase are switched until the difference between the voltage maximum phase and the voltage intermediate phase is equal to or greater than a predetermined voltage is the DC reactor. A harmonic gain with an active filter, characterized in that a correction gain is applied to a bus current flowing through the current, and the correction gain is calculated from a ratio between the voltage maximum phase and the voltage intermediate phase and the predetermined voltage. apparatus. In the harmonic suppression device provided with the active filter according to claim 3,
The load current flowing in the minimum voltage phase and the intermediate voltage phase until the difference between the minimum voltage phase and the intermediate voltage phase exceeds a predetermined voltage after the minimum voltage phase and the intermediate voltage phase are switched is the DC reactor. A value obtained by multiplying the bus current flowing through the negative minus 1 by a correction gain, and the correction gain is calculated from a ratio between the difference between the minimum voltage phase and the intermediate voltage phase and the predetermined voltage. Harmonic suppression device with filter. In the harmonic suppression device provided with the active filter according to claim 1,
A harmonic suppression device including an active filter, wherein the substrate including the converter circuit and the substrate including the circuit of the active filter are stored in the same box. In the harmonic suppression device provided with the active filter according to claim 1,
A substrate including the converter circuit and a substrate including the active filter circuit are connected using a lead pin. A harmonic suppression apparatus including an active filter. In the harmonic suppression device provided with the active filter according to claim 1,
The converter circuit and the active filter circuit are arranged and configured on the same substrate. A harmonic suppressing device including an active filter.

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