CN107579674B - Method and system for controlling zero offset of sampling circuit - Google Patents
Method and system for controlling zero offset of sampling circuit Download PDFInfo
- Publication number
- CN107579674B CN107579674B CN201710910911.1A CN201710910911A CN107579674B CN 107579674 B CN107579674 B CN 107579674B CN 201710910911 A CN201710910911 A CN 201710910911A CN 107579674 B CN107579674 B CN 107579674B
- Authority
- CN
- China
- Prior art keywords
- output voltage
- current
- current component
- direct
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000005070 sampling Methods 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000012545 processing Methods 0.000 claims description 27
- 238000001914 filtration Methods 0.000 claims description 24
- 230000009467 reduction Effects 0.000 claims description 13
- 230000001629 suppression Effects 0.000 claims description 9
- 230000009471 action Effects 0.000 abstract description 20
- 230000002829 reductive effect Effects 0.000 abstract description 6
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000001276 controlling effect Effects 0.000 description 31
- 238000010586 diagram Methods 0.000 description 14
- 230000008859 change Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 230000010354 integration Effects 0.000 description 5
- 230000000875 corresponding effect Effects 0.000 description 4
- 230000000452 restraining effect Effects 0.000 description 4
- 230000003068 static effect Effects 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 230000002596 correlated effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000002146 bilateral effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
Images
Landscapes
- Control Of Electrical Variables (AREA)
- Inverter Devices (AREA)
Abstract
The application discloses a method for controlling zero offset of a sampling circuit, which comprises the following steps: extracting direct current components contained in output voltage and output current in the circuit to obtain direct current components of the output voltage and the output current; and suppressing the sampling zero offset existing in the output voltage direct-current component by a PI controller by utilizing the output voltage direct-current component and the output current direct-current component. According to the method, two parameters of the output voltage direct current component and the output current direct current component are used as action parameters of negative feedback action, so that a better negative feedback control action can be achieved, the influence caused by zero offset existing in a sampling circuit is reduced, and better control precision is provided. The application also discloses a system for controlling the zero offset of the sampling circuit, and the system has the beneficial effects.
Description
Technical Field
The application relates to the field of inverter manufacturing, in particular to a method and a system for controlling zero offset of a sampling circuit.
Background
With the rapid development of new energy industry, photovoltaic power generation is gradually determined as a key research object by various manufacturers and enterprises due to its cleanliness, wide sources and relatively low threshold. Among them, the off-grid photovoltaic inverter is widely used in photovoltaic power generation, and as an important parameter in the off-grid photovoltaic inverter, research on a parameter of an output voltage direct current component is also being conducted.
In the off-grid photovoltaic inverter manufactured by the existing method, an output voltage direct-current component is usually a parameter to be eliminated, and due to the inherent characteristics of the voltage sampling circuit, zero offset exists in the voltage sampling circuit, that is, a certain output voltage direct-current component inevitably exists. In the prior art, negative feedback is only performed on the output voltage direct-current component, but the influence caused by zero offset is reduced by the limitation of the effect of the negative feedback of the output voltage direct-current component and the precision of the generated output voltage direct-current component.
Therefore, a control mechanism of zero offset of a sampling circuit, which is capable of performing negative feedback control on an output voltage dc component by using other parameters together on the basis of still using the output voltage dc component without canceling a voltage sampling circuit, is a problem to be solved by those skilled in the art.
Disclosure of Invention
The application aims to provide a method and a system for controlling zero offset of a sampling circuit, which take two parameters of an output voltage direct current component and an output current direct current component as action parameters of a negative feedback action, can play a better negative feedback control action, reduce the influence caused by the zero offset of the sampling circuit and provide better control precision.
In order to solve the above technical problem, the present application provides a method for controlling a zero offset of a sampling circuit, including:
extracting direct current components contained in output voltage and output current in the circuit to obtain direct current components of the output voltage and the output current;
utilizing the output voltage direct-current component and the output current direct-current component to suppress sampling zero offset existing in the output voltage direct-current component through a PI controller;
wherein, the direct current component that output voltage and output current contained in the extraction circuit includes:
respectively performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
and carrying out noise reduction processing on the low-pass filtering result to obtain the output voltage direct-current component and the output current direct-current component.
Optionally, the suppressing the sampling zero offset existing in the output voltage dc component by using the output voltage dc component and the output current dc component through a PI controller includes:
weighting the output voltage direct-current component and the output current direct-current component by using a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
and utilizing the weighted output voltage direct-current component and the weighted output current direct-current component to suppress sampling zero offset existing in the output voltage direct-current component through the PI controller.
Optionally, the weighting the output voltage dc component and the output current dc component by using a first preset weight and a second preset weight, respectively, includes:
judging whether the feedback value of the output voltage direct-current component is greater than a threshold value;
if so, controlling the ratio of the first preset weight to the second preset weight to be at least 3 to obtain a first main weight and a first slave weight;
weighting the output voltage direct-current component and the output current direct-current component by using the first main weight value and the first slave weight value respectively;
if not, controlling the ratio of the second preset weight to the first preset weight to be at least 5 to obtain a second main weight and a second slave weight;
and weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
Optionally, controlling a ratio of the second preset weight to the first preset weight to be at least 5, and obtaining a second master weight and a second slave weight, including:
and setting the first preset weight to be 0 and the second preset weight to be 1 to obtain a second main weight which is 1 and a second slave weight which is 0.
The present application further provides a system for controlling zero offset of a sampling circuit, the system comprising:
the parameter acquisition module is used for extracting direct current components contained in the output voltage and the output current in the circuit to obtain an output voltage direct current component and an output current direct current component;
the zero offset suppression module is used for suppressing the sampling zero offset existing in the output voltage direct-current component by utilizing the output voltage direct-current component and the output current direct-current component through a PI (proportional-integral) controller;
wherein, the parameter acquisition module comprises:
the low-pass filtering processing submodule is used for respectively performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
and the noise reduction processing submodule is used for carrying out noise reduction processing on the low-pass filtering result to obtain the output current direct-current component of the output voltage direct-current component.
Optionally, the zero-bias suppression module includes:
the weighting distribution submodule is used for weighting the output voltage direct-current component and the output current direct-current component by utilizing a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
and the suppression submodule is used for suppressing the sampling zero offset existing in the output voltage direct-current component by the PI controller by utilizing the weighted output voltage direct-current component and the weighted output current direct-current component.
Optionally, the weighting distribution sub-module includes:
the threshold judging unit is used for judging whether the feedback value of the output voltage direct-current component is greater than a threshold value or not;
the first processing unit is used for controlling the ratio of the first preset weight to the second preset weight to be at least 3 to obtain a main weight and a slave weight;
the first weighting unit is used for weighting the output voltage direct-current component and the output current direct-current component by using the main weight value and the slave weight value respectively;
the second processing unit is used for controlling the ratio of the second preset weight to the first preset weight to be at least 5 to obtain a second main weight and a second slave weight;
and the second weighting unit is used for weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
Optionally, the weighting distribution sub-module includes:
preferably, the second processing unit is configured to set the first preset weight to 0 and set the second preset weight to 1, so as to obtain a second master weight of 1 and a second slave weight of 0.
According to the method for controlling the zero offset of the sampling circuit, the direct-current component of the output voltage and the direct-current component of the output current are obtained by extracting the direct-current components contained in the output voltage and the output current in the circuit; and suppressing the sampling zero offset existing in the output voltage direct-current component by a PI controller by utilizing the output voltage direct-current component and the output current direct-current component.
Obviously, according to the technical scheme provided by the application, the output voltage direct-current component and the output current direct-current component are extracted from the circuit forming the off-grid photovoltaic inverter, the two parameters which can react on the output voltage direct-current component are utilized, and negative feedback is commonly utilized to react and reduce the output voltage direct-current component. According to the method, two parameters of the output voltage direct current component and the output current direct current component are used as action parameters of negative feedback action, so that a better negative feedback control action can be achieved, the influence caused by zero offset existing in a sampling circuit is reduced, and better control precision is provided. The application also provides a system for controlling the zero offset of the sampling circuit, which has the beneficial effects and is not repeated herein.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of a method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure;
fig. 2 is a flowchart of another method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure;
fig. 3 is a flowchart of another method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure;
fig. 4 is a block diagram of a system for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure;
fig. 5 is a block diagram of another system for controlling a zero bias of a sampling circuit according to an embodiment of the present disclosure;
fig. 6 is an equivalent circuit diagram for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure;
fig. 7 is an equivalent circuit diagram of an off-grid photovoltaic inverter according to an embodiment of the present application;
fig. 8 is a schematic model diagram of an off-grid photovoltaic inverter according to an embodiment of the present disclosure;
fig. 9 is a schematic diagram illustrating a change in a steady-state position of a sampling value of a dc component of an output voltage when a threshold voltage Uthr is greater than an absolute value of a sampling zero offset Δ U according to an embodiment of the present application;
fig. 10 is a schematic diagram of a steady-state position change of a sampling value of a dc component of an output voltage when a threshold voltage Uthr is smaller than an absolute value of a sampling zero offset Δ U according to an embodiment of the present application.
Detailed Description
The core of the application is to provide a method and a system for controlling zero offset of a sampling circuit, and the method and the system take two parameters of an output voltage direct current component and an output current direct current component as action parameters of a negative feedback effect, can play a better negative feedback control effect, reduce the influence caused by the zero offset of the sampling circuit and provide better control precision.
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 is a flowchart of a method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure.
The method specifically comprises the following steps:
s101: extracting direct current components contained in output voltage and output current in the circuit to obtain direct current components of the output voltage and the output current;
this step is intended to extract the dc components contained in the output voltage from the output current of the output voltage in the circuit to obtain the dc component of the output voltage and the dc component of the output current.
The circuit composition for manufacturing the off-grid photovoltaic inverter is huge, and the operation of extracting the direct-current component of the output voltage and the direct-current component of the output current is only carried out from the part where the direct-current component of the output voltage can cause influence and the relevant part of the sampling circuit.
The output voltage and the output current in the circuit may be obtained in various manners, for example, corresponding components may be connected at suitable positions, or the voltage and the current may be intercepted in the flowing direction by other means, and the like.
There are also many ways of extracting the respective dc components from the obtained output voltage and output current, and one of the common and simple methods is to use a low-pass filter.
A low-pass filter is an electronic filtering device that allows signals below a cutoff frequency to pass, but does not allow signals above the cutoff frequency to pass. The low-pass filter is composed of a resistance-capacitance element or an inductor, the resonant frequency of the low-pass filter is higher, the low-frequency component presents high impedance, so that the direct-current component can be extracted by the low-pass filter, because the bilateral frequency of the direct-current component is 0, infinite impedance cannot be presented to pass through a filter device, the high-pass filter is opposite, the resonant frequency of the high-pass filter is lower, high impedance is presented to high-frequency signals, the direct-current component can almost completely pass through the high-pass filter, and the low-pass filter can be used for extracting the direct-current component.
Of course, there are other ways to extract the dc component, such as by an algorithm or the like that can achieve a similar purpose, and the use of the low-pass filter is only a simple way to use and can be selected according to actual situations.
Generally, the output voltage dc component and the output current dc component obtained by using the low-pass filter are not perfect, and various defects exist, so that the output voltage dc component and the output current dc component cannot be well applied to the subsequent processing steps, and even if the output voltage dc component and the output current dc component are forcibly applied to the subsequent steps, the final purpose cannot be well achieved. Therefore, the output voltage dc component and the output current dc component obtained through the low-pass filter or the like are usually required to be reprocessed to obtain a perfect output voltage dc component and output current dc component. This processing may be performed, for example, by a noise reduction processing device or other similar device.
S102: and inhibiting the sampling zero offset existing in the output voltage direct-current component by using the output voltage direct-current component and the output current direct-current component through a PI controller.
On the basis of S101, this step is intended to suppress the sampling zero offset existing in the output voltage dc component by a PI controller (proportional integral controller) using the output voltage dc component and the output current dc component.
The objective of the output voltage direct-current component control is to make the voltage output by the inverter contain no direct-current component; because the sampling circuit has zero offset, the control of the direct current component of the existing output voltage mostly adopts the output voltage to carry out calculation control, thereby at least relating to the voltage sampling circuit, if the voltage sampling circuit has zero offset, the sampling value with zero offset is taken as the actual sampling value to carry out control, the output voltage obtained by control has no direct current component, if the control parameter is inaccurate, the control result is naturally inaccurate, namely, the direct current component is still contained, and the direct current component of the part can influence the inversion inductance so as to change the inversion current. The direct current component of the inverter current is added to participate in control, and the control output voltage and the inverter current do not contain the direct current component, so that the zero offset influence is overcome through the direct current component of the inverter current, and the precision is improved.
When the two parameters of the output voltage direct-current component and the output current direct-current component are used for restraining sampling zero offset existing in the output voltage direct-current component through the PI controller, because the output voltage direct-current component and the output current direct-current component are different in size, the conditions of restraining the sampling zero offset are different, and further, different weights are given to the two parameters according to the difference of the restraining force of the parameters on the sampling zero offset under different conditions, so that the parameters with strong restraining force are fully utilized to restrain the sampling zero offset more effectively.
The PI regulator is a linear controller, and forms a control deviation according to a given value and an actual output value, and linearly combines the proportion and the integral of the deviation to form a control quantity to control a controlled object. In brief, the functions of each calibration link of the PI controller are as follows: (1) and (3) proportional links: the controller immediately generates a control action to reduce the deviation once the deviation is generated by reflecting the deviation signal of the control system in real time in proportion. Generally, as the value is increased, the overshoot of the closed-loop system is increased, the response speed of the system is increased, but when the overshoot is increased to a certain degree, the system becomes unstable; (2) and (3) an integration step: the method is mainly used for eliminating the static error and improving the non-difference of the system. The strength of the integration depends on the integration constant, and the larger the integration, the weaker the integration and vice versa. Generally, under the condition of no change, the larger the integral effect is, the weaker the overshoot of the closed-loop system is, and the response speed of the system is slower.
Based on the technical scheme, the method for controlling the zero offset of the sampling circuit provided by the embodiment of the application obtains the output voltage direct-current component and the output current direct-current component by extracting in the circuit forming the off-grid photovoltaic inverter, utilizes the parameters which can both react on the output voltage direct-current component, and jointly utilizes the negative feedback to react and reduce the output voltage direct-current component. According to the method, two parameters of the output voltage direct current component and the output current direct current component are used as action parameters of negative feedback action, so that a better negative feedback control action can be achieved, the influence caused by zero offset existing in a sampling circuit is reduced, and better control precision is provided.
Referring to fig. 2, fig. 2 is a flowchart of another method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure.
The method specifically comprises the following steps:
s201: performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
s202: carrying out noise reduction processing on the low-pass filtering result to obtain an output voltage direct-current component and an output voltage direct-current component;
s201 and S202 aim to perform a low-pass filtering operation on the obtained output voltage and output current by using a low-pass filter, that is, extract respective dc components by using a characteristic that the low-pass filter does not allow the dc components to pass through, and perform noise reduction processing on the extracted dc components by using a noise reduction processing device to obtain a perfect output voltage dc component and an output voltage dc component.
S203: weighting the output voltage direct-current component and the output current direct-current component by using a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
the step aims to set a first preset weight and a second preset weight corresponding to the output voltage direct current component and the output current direct current component respectively, and weight the output voltage direct current component and the output current direct current component respectively by utilizing the first preset weight and the second preset weight so as to obtain a weighted output voltage direct current component and a weighted output current direct current component.
The first preset weight and the second preset weight may be different or the same, and depending on the difference of the influence caused by sampling zero offset, the proportional relationship between the first preset weight and the second preset weight may be automatically changed according to the magnitude between the feedback value of the output voltage dc component and the threshold, so as to better control the sampling zero offset.
S204: and suppressing the sampling zero offset existing in the output voltage direct-current component by using the weighted output voltage direct-current component and the weighted output current direct-current component through a PI controller.
On the basis of S203, the present step aims to suppress the sampling zero offset existing in the output voltage dc component by the PI controller using the weighted output voltage dc component and the weighted output current dc component.
Referring to fig. 3, fig. 3 is a flowchart of another method for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure.
The method specifically comprises the following steps:
s301: carrying out noise reduction processing on the low-pass filtering result to obtain an output voltage direct-current component and an output voltage direct-current component;
the step is the same as S202, and the description of the related content can refer to the related part of S202, which is not described herein again.
S302: judging whether the feedback value of the direct-current component of the output voltage is greater than a threshold value;
the step is to determine how to change the proportional relationship between the first preset weight and the second preset weight by feeding back the output voltage DC component to whether the output voltage DC component is greater than a set threshold. In combination with a large amount of test data, the threshold value can be set to be one fifth of the maximum feedback value of the output voltage direct-current component, of course, components in the off-grid photovoltaic inverters of different models are different in composition, actual values are not completely identical, and no specific limitation is made here, but a reference value is given for the scheme provided by the application, and comprehensive selection should be made according to various influence factors under actual conditions.
S303: controlling the ratio of the first preset weight to the second preset weight to be at least 3 to obtain a first main weight and a first slave weight;
in this step, when the determination result of S302 is that the feedback value is greater than the threshold, the ratio of the first preset weight to the second preset weight is at least 3, so that a larger first master weight and a first slave weight that is one third of the first master weight at maximum are obtained. Further, the ratio may be adjusted to be higher again to reach a ratio of 5, 7, even 8 or 9, so as to sufficiently improve the influence degree of the output voltage dc component when the feedback value is greater than the threshold, that is, when the negative feedback degree of the output voltage dc component to itself is the maximum, and the influence degree of the output voltage dc component may be automatically adjusted according to a certain principle according to the degree exceeding the threshold, which is not specifically limited herein.
S304: weighting the output voltage direct-current component and the output current direct-current component by using the first main weight value and the first slave weight value respectively;
s305: controlling the ratio of the second preset weight to the first preset weight to be at least 5 to obtain a second main weight and a second slave weight;
in this step, if the result of the determination in S302 is that the feedback value is smaller than the threshold, the ratio of the first preset weight to the second preset weight is controlled to be at least 5, so that a larger first master weight and a first slave weight that is one fifth of the first master weight at maximum are obtained. It should be noted that the weighted object of the second primary weight in this step is the output current dc component, not the output voltage dc component. In addition, according to the degree smaller than the threshold, the ratio of the second master weight corresponding to the output current dc component to the second slave weight corresponding to the output voltage dc component is continuously increased, for example, to 7 or 9, and even the output current dc component is only used as a parameter for negative feedback to suppress the output voltage dc component.
S306: and weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
Based on the technical scheme, the method for controlling the zero offset of the sampling circuit provided by the embodiment of the application obtains the output voltage direct-current component and the output current direct-current component by extracting in the circuit forming the off-grid photovoltaic inverter, utilizes the parameters which can both react on the output voltage direct-current component, and jointly utilizes the negative feedback to react and reduce the output voltage direct-current component. According to the method, two parameters of the output voltage direct current component and the output current direct current component are used as action parameters of negative feedback action, so that a better negative feedback control action can be achieved, the influence caused by zero offset existing in a sampling circuit is reduced, and better control precision is provided.
Because the situation is complicated and cannot be illustrated by a list, those skilled in the art can realize that many examples exist based on the principle of the basic method provided by the present application in combination with the actual situation, and the method is within the scope of the present application without sufficient inventive effort.
Referring to fig. 4 and fig. 5, fig. 4 is a block diagram of a system for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure; fig. 5 is a block diagram of another system for controlling a zero bias of a sampling circuit according to an embodiment of the present disclosure.
The system may include:
the parameter obtaining module 100 is configured to extract dc components included in the output voltage and the output current in the circuit to obtain a dc component of the output voltage and a dc component of the output current;
and a zero offset suppression module 200, configured to suppress, by using the output voltage dc component and the output current dc component, a sampling zero offset existing in the output voltage dc component through a PI controller.
Wherein, the parameter obtaining module 100 includes:
the low-pass filtering processing submodule is used for respectively performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
and the noise reduction processing submodule is used for carrying out noise reduction processing on the low-pass filtering result to obtain an output current direct-current component of the output voltage direct-current component.
The zero-bias suppression module 200 includes:
the weighting distribution submodule is used for weighting the output voltage direct-current component and the output current direct-current component by utilizing a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
and the suppression submodule is used for suppressing the sampling zero offset existing in the output voltage direct-current component by using the weighted output voltage direct-current component and the weighted output current direct-current component through the PI controller.
Wherein, the weighting distribution submodule comprises:
the threshold judging unit is used for judging whether the feedback value of the output voltage direct-current component is greater than a threshold value or not;
the first processing unit is used for controlling the ratio of the first preset weight to the second preset weight to be at least 3 to obtain a main weight and a slave weight;
the first weighting unit is used for weighting the output voltage direct-current component and the output current direct-current component by using the main weight value and the slave weight value respectively;
the second processing unit is used for controlling the ratio of the second preset weight to the first preset weight to be at least 5 to obtain a second main weight and a second slave weight;
and the second weighting unit is used for weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
Wherein, the weighting distribution submodule comprises:
preferably, the second processing unit is configured to set the first preset weight to 0 and set the second preset weight to 1, so as to obtain a second master weight of 1 and a second slave weight of 0. .
Referring to fig. 6 to 10, fig. 6 is an equivalent circuit diagram for controlling a zero offset of a sampling circuit according to an embodiment of the present disclosure; fig. 7 is an equivalent circuit diagram of an off-grid photovoltaic inverter according to an embodiment of the present application; fig. 8 is a schematic model diagram of an off-grid photovoltaic inverter according to an embodiment of the present disclosure; fig. 9 is a schematic diagram illustrating a change in a steady-state position of a sampling value of a dc component of an output voltage when a threshold voltage Uthr is greater than an absolute value of a sampling zero offset Δ U according to an embodiment of the present application; fig. 10 is a schematic diagram of a steady-state position change of a sampling value of a dc component of an output voltage when a threshold voltage Uthr is smaller than an absolute value of a sampling zero offset Δ U according to an embodiment of the present application.
The above modules can be applied to the following specific practical examples:
referring to fig. 7, Ui is the voltage of the inverter, Ri is the internal resistance of the inverter, Ii is the inverter current, Ro is the load impedance, Uo is the output voltage, Uref shown in fig. 8 is given as the output voltage of the inverter, Uo is the actual output voltage of the inverter, Δ U is the sampling zero offset, and Ui is the equivalent voltage source of the inverter.
When the inverter outputs a steady state, the Uo plus delta U completely tracks the Uref, the direct current component of the output voltage sampling value Uo plus delta U is equal to zero at the moment, the direct current component of the output voltage true value Uo is equal to the minus delta U, and the control precision of the output voltage direct current component is directly influenced by the sampling zero offset.
Because the direct-current component existing in the real output voltage can be obtained by indirectly sampling the inverter current, the control precision of the direct-current component of the output voltage can be improved by considering the use of the inverter current direct-current component. When the output voltage direct-current component is large, the output voltage direct-current component and the inversion current direct-current component are weighted and superposed to be used as feedback of the controller, so that the adjusting force can be increased, and the effect of quick adjustment is achieved; when the output voltage direct current component is small, because the output voltage direct current component has the sampling zero offset problem, the influence of the sampling zero offset of the output voltage can be eliminated by simply using the inverter current direct current component as the feedback of the controller, the control precision is improved, because the current direct current component is independently used for control, the control target is current, the internal resistance of the system can not be accurately measured, and the conversion from the target voltage to the target current needs complex calculation and is not accurate.
In fig. 9, the left half shows the case (a) in which the output voltage dc component sample value is positively biased when Δ U <0, and the right half shows the case (b) in which the output voltage dc component sample value is negatively biased when Δ U > 0.
The left half of fig. 10 shows that the output voltage dc component sample value is positively biased when Δ U <0 in case (a), and the right half of fig. 10 shows that the output voltage dc component sample value is negatively biased when Δ U >0 in case (b).
As can be seen from fig. 9, when the threshold voltage Uthr is greater than the absolute value of the sampled zero offset Δ U, the steady-state position of the sampled value of the dc component of the output voltage is negatively correlated to the sampled zero offset, i.e. the negative offset of the output voltage corresponds to the positive offset of the sampled zero offset (see the left half of fig. 9), and the positive offset of the output voltage corresponds to the negative offset of the sampled zero offset (see the right half of fig. 9), and the absolute value of the dc component of the true value Uo of the output voltage is equal to zero.
As can be known from fig. 10, when the threshold voltage Uthr is smaller than the absolute value of the sampling zero offset Δ U, the steady-state position of the sampling value of the dc component of the output voltage is also negatively correlated with the sampling zero offset, but the absolute value of the dc component of the true value Uo of the output voltage is equal to Δ U-Uthr (not equal to zero), but compared with the case of simply using the dc component of the output voltage as feedback, the static error of control is reduced from Δ U to | Δ U-Uthr |, thereby improving the control accuracy. The reason why fig. 9 is stable at Δ U and fig. 10 fluctuates at Uthr is that, in the vicinity of the threshold, the two weight ratios are mutually switched and controlled so that they cannot be stable at a fixed value as in fig. 9, but fluctuate at a value, the amplitude of fluctuation being related to the control accuracy and the like.
Under normal conditions, the sampling zero offset DeltaU should be smaller than the output voltage direct current component index requirement Ureq (the index requirement of UPS is 200mV), and if DeltaU is detected to be larger than Ureq, the detection circuit can be judged to be invalid. Based on the above preconditions, when selecting the threshold voltage Uthr for changing the weighting coefficient, it is necessary to comprehensively consider the contradiction between the failure judgment of the detection circuit and the control accuracy. When the threshold voltage Uthr is too large, the failure fault of the detection circuit is easily triggered; when the threshold voltage Uthr is too small, the static error is difficult to control to zero. Choosing Uthr to be equal to 0.2 times Ureq is only a reference value, and the value of Uthr can be adjusted according to practical situations. When the weighting coefficient is selected, the weight of the direct-current component of the output voltage is increased because when the sampling zero offset is greater than the threshold voltage Uthr, the control static error can be clamped at the position of delta U-Uthr quickly, and the stability of the controller is further improved.
The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (6)
1. A method for controlling zero bias of a sampling circuit is applied to an off-grid inverter and comprises the following steps:
extracting direct current components contained in output voltage and output current in the circuit to obtain direct current components of the output voltage and the output current;
utilizing the output voltage direct-current component and the output current direct-current component to suppress sampling zero offset existing in the output voltage direct-current component through a PI controller;
utilizing the output voltage dc component and the output current dc component to suppress a sampled zero offset present in the output voltage dc component by a PI controller, comprising:
weighting the output voltage direct-current component and the output current direct-current component by using a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
utilizing the weighted output voltage direct current component and the weighted output current direct current component to suppress sampling zero offset existing in the output voltage direct current component through the PI controller;
respectively weighting the output voltage direct current component and the output current direct current component by using a first preset weight and a second preset weight, wherein the weighting comprises the following steps:
judging whether the feedback value of the output voltage direct-current component is greater than a threshold value;
if so, controlling the ratio of the first preset weight to the second preset weight to be at least 3 to obtain a first main weight and a first slave weight;
weighting the output voltage direct-current component and the output current direct-current component by using the first main weight value and the first slave weight value respectively;
if not, controlling the ratio of the second preset weight to the first preset weight to be at least 5 to obtain a second main weight and a second slave weight;
and weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
2. The method of claim 1, wherein extracting dc components contained in the output voltage and output current in the circuit comprises:
respectively performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
and carrying out noise reduction processing on the low-pass filtering result to obtain the output voltage direct-current component and the output current direct-current component.
3. The method according to claim 1, wherein controlling the ratio of the second preset weight to the first preset weight to be at least 5, and obtaining a second master weight and a second slave weight comprises:
and setting the first preset weight to be 0 and the second preset weight to be 1 to obtain a second main weight which is 1 and a second slave weight which is 0.
4. A system for controlling zero bias of a sampling circuit is applied to an off-grid inverter and comprises the following components:
the parameter acquisition module is used for extracting direct current components contained in the output voltage and the output current in the circuit to obtain an output voltage direct current component and an output current direct current component;
the zero offset suppression module is used for suppressing the sampling zero offset existing in the output voltage direct-current component by utilizing the output voltage direct-current component and the output current direct-current component through a PI (proportional-integral) controller;
the zero-bias suppression module comprises:
the weighting distribution submodule is used for weighting the output voltage direct-current component and the output current direct-current component by utilizing a first preset weight and a second preset weight respectively to obtain a weighted output voltage direct-current component and a weighted output current direct-current component;
the suppression submodule is used for suppressing the sampling zero offset existing in the output voltage direct-current component through the PI controller by utilizing the weighted output voltage direct-current component and the weighted output current direct-current component;
the weight distribution submodule includes:
the threshold judging unit is used for judging whether the feedback value of the output voltage direct-current component is greater than a threshold value or not;
the first processing unit is used for controlling the ratio of the first preset weight to the second preset weight to be at least 3 when the feedback value of the output voltage direct-current component is larger than the threshold value, so as to obtain a main weight and a slave weight;
the first weighting unit is used for weighting the output voltage direct-current component and the output current direct-current component by using the main weight value and the slave weight value respectively;
the second processing unit is used for controlling the ratio of the second preset weight to the first preset weight to be at least 5 when the feedback value of the output voltage direct-current component is not greater than the threshold value, so as to obtain a second main weight and a second slave weight;
and the second weighting unit is used for weighting the output current direct-current component and the output voltage direct-current component by using the second main weight value and the second slave weight value respectively.
5. The system of claim 4, wherein the parameter acquisition module comprises:
the low-pass filtering processing submodule is used for respectively performing low-pass filtering operation on the output voltage and the output current by using a low-pass filter to obtain a low-pass filtering result;
and the noise reduction processing submodule is used for carrying out noise reduction processing on the low-pass filtering result to obtain the output current direct-current component of the output voltage direct-current component.
6. The system of claim 4, wherein the weight assignment sub-module comprises:
preferably, the second processing unit is configured to set the first preset weight to 0 and set the second preset weight to 1, so as to obtain a second master weight of 1 and a second slave weight of 0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710910911.1A CN107579674B (en) | 2017-09-29 | 2017-09-29 | Method and system for controlling zero offset of sampling circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710910911.1A CN107579674B (en) | 2017-09-29 | 2017-09-29 | Method and system for controlling zero offset of sampling circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107579674A CN107579674A (en) | 2018-01-12 |
| CN107579674B true CN107579674B (en) | 2020-08-28 |
Family
ID=61040242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710910911.1A Active CN107579674B (en) | 2017-09-29 | 2017-09-29 | Method and system for controlling zero offset of sampling circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107579674B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202798016U (en) * | 2012-09-25 | 2013-03-13 | 广东易事特电源股份有限公司 | Grid connection current direct component control system |
| CN103078531A (en) * | 2013-01-07 | 2013-05-01 | 深圳市晶福源电子技术有限公司 | Direct-current component control system and method for three-phase inverter |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7184282B2 (en) * | 2005-03-11 | 2007-02-27 | Origin Electric Company, Limited | Single-phase power conversion device and three-phase power conversion device |
| US7830682B2 (en) * | 2007-12-19 | 2010-11-09 | Honeywell International Inc. | DC component elimination at output voltage of PWM inverters |
| CN101951180A (en) * | 2010-08-31 | 2011-01-19 | 江苏艾索新能源股份有限公司 | DC content detection and control circuit for output side of synchronized inverter |
| CN102638057A (en) * | 2012-04-24 | 2012-08-15 | 浙江大学 | Grid-connected inverter control device |
| CN103944186B (en) * | 2014-04-23 | 2017-01-04 | 浙江大学 | A kind of three-phase photovoltaic grid-connected inverting device controls device |
| CN105391326B (en) * | 2015-12-22 | 2019-06-28 | 爱士惟新能源技术(江苏)有限公司 | A kind of control method and device of the DC component of photovoltaic inversion |
| CN106452139A (en) * | 2016-10-31 | 2017-02-22 | 上海新时达电气股份有限公司 | Circuit for testing DC component in AC voltage and device for eliminating DC component |
-
2017
- 2017-09-29 CN CN201710910911.1A patent/CN107579674B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202798016U (en) * | 2012-09-25 | 2013-03-13 | 广东易事特电源股份有限公司 | Grid connection current direct component control system |
| CN103078531A (en) * | 2013-01-07 | 2013-05-01 | 深圳市晶福源电子技术有限公司 | Direct-current component control system and method for three-phase inverter |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107579674A (en) | 2018-01-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Ghanes et al. | A new varying-gain-exponent-based differentiator/observer: An efficient balance between linear and sliding-mode algorithms | |
| CN107272421B (en) | Active disturbance rejection control system and method | |
| Grignion et al. | Estimation of load disturbance torque for DC motor drive systems under robustness and sensitivity consideration | |
| DE102012221795A1 (en) | Microphone and method for calibrating a microphone | |
| DE102011102483A1 (en) | Method for operating a Hall sensor arrangement and Hall sensor arrangement | |
| EP2673869A1 (en) | Dc-dc converter with circuit for reproducing a current flowing through a storage inductor | |
| Zhao et al. | Uniform demagnetization diagnosis for permanent-magnet synchronous linear motor using a sliding-mode velocity controller and an ALN-MRAS flux observer | |
| CN110907881A (en) | Current calibration method and system for power distribution network overhead line monitoring device | |
| Daou et al. | Effect of hydropneumatic components nonlinearities on the CRONE suspension | |
| Saleem et al. | A single-phase synchronization technique for grid-connected energy storage system under faulty grid conditions | |
| CN107579674B (en) | Method and system for controlling zero offset of sampling circuit | |
| DE102011075577B4 (en) | Signal processing method, signal processing apparatus and balance with signal processing apparatus | |
| US20150331062A1 (en) | Failure Detection Method and Detection Device for Inverter | |
| DE102012105559A1 (en) | Method for enabling precision signal enhancement using two comparators and control system without signal feedback | |
| Cuong et al. | Design of MRAS-based adaptive control systems | |
| JP6067289B2 (en) | Reduced model creation device, creation method and creation program for power system | |
| CN107831668B (en) | Method and system suitable for follow-up control self-adaptive detection | |
| Roy et al. | Robust adaptive excitation control of synchronous generators in multimachine power systems under parametric uncertainties and external disturbances | |
| US10797615B2 (en) | Uncertainty based controller design for an inverter | |
| CN108983065B (en) | Voltage amplifying circuit, detection circuit and circuit detection method thereof | |
| EP3688874A1 (en) | Switching circuit for checking an analog input circuit of an a-d converter | |
| CN111308892B (en) | Closed-loop control method capable of adjusting noise suppression ratio of sensor based on model observation | |
| CN111693924B (en) | System and method for detecting monitoring performance of voltage transformer on-line monitoring device | |
| DOĞRUER et al. | PID controller design for a fractional order system using bode’s ideal transfer function | |
| Uchiyama et al. | Robust acceleration control of electrodynamic shaker using μ-synthesis |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: 361000 Ma Long Road 457, Torch Garden, Xiamen Torch High-tech Zone, Fujian Province Applicant after: XIAMEN KEHUAHENGSHENG LIMITED BY SHARE Ltd. Applicant after: ZHANGZHOU KEHUA TECHNOLOGY Co.,Ltd. Address before: 361000 torch garden, torch high tech Zone, Xiamen, Fujian 457 Applicant before: XIAMEN KEHUA HENGSHENG Co.,Ltd. Applicant before: ZHANGZHOU KEHUA TECHNOLOGY Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 361000 Ma Long Road 457, Torch Garden, Xiamen Torch High-tech Zone, Fujian Province Patentee after: Kehua Data Co.,Ltd. Patentee after: ZHANGZHOU KEHUA TECHNOLOGY Co.,Ltd. Address before: 361000 Ma Long Road 457, Torch Garden, Xiamen Torch High-tech Zone, Fujian Province Patentee before: XIAMEN KEHUAHENGSHENG LIMITED BY SHARE Ltd. Patentee before: ZHANGZHOU KEHUA TECHNOLOGY Co.,Ltd. |
|
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20231203 Address after: Room 208-38, Hengye Building, No. 100 Xiangxing Road, Xiang'an Industrial Zone, Xiamen Torch High tech Zone, Xiamen, Fujian Province, 361000 Patentee after: Xiamen Kehua shuneng Technology Co.,Ltd. Address before: 361000 Ma Long Road 457, Torch Garden, Xiamen Torch High-tech Zone, Fujian Province Patentee before: Kehua Data Co.,Ltd. Patentee before: ZHANGZHOU KEHUA TECHNOLOGY Co.,Ltd. |