阅读说明：本技术 一种pwm整流器控制方法和装置 (PWM rectifier control method and device ) 是由 谢宁 赵伟 赵兵 谢志文 王伟 岳菁鹏 张威 徐琪 于 2020-07-29 设计创作，主要内容包括：本发明公开了一种PWM整流器控制方法和装置,PWM整流器包括PI控制器、PR控制器和逆变器,方法包括：通过PI控制器,定预设期望电压信号和检测电压信号之差为直流分量；基于谐波与无功检测算法确定预置负载的载波电流信号和无功电流信号,结合直流分量和预置负载的功率反馈信号,生成控制电流信号；若逆变器所生成的反馈电流信号与控制电流信号不相等,则对控制电流信号执行反馈叠加操作,生成误差电流信号；通过PR控制器基于模糊算法调整误差电流信号,生成中间电流信号；对中间电流信号执行PWM调制操作,通过逆变器生成目标电流并输出,从而解决现有技术中无法在实现电流的快速跟踪的同时消除稳态误差的技术问题。(The invention discloses a PWM rectifier control method and a device, wherein the PWM rectifier comprises a PI controller, a PR controller and an inverter, and the method comprises the following steps: setting the difference between a preset expected voltage signal and a detection voltage signal as a direct current component through a PI controller; determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generating a control current signal by combining a direct current component and a power feedback signal of the preset load; if the feedback current signal generated by the inverter is not equal to the control current signal, performing feedback superposition operation on the control current signal to generate an error current signal; adjusting the error current signal based on a fuzzy algorithm through a PR controller to generate an intermediate current signal; and performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating and outputting a target current through an inverter, thereby solving the technical problem that the steady-state error cannot be eliminated while the current is quickly tracked in the prior art.)

1. A PWM rectifier control method, wherein the PWM rectifier includes a proportional integral PI controller, a proportional resonant PR controller, and an inverter, the method comprising:

receiving a detection voltage signal generated by performing a voltage detection operation on a direct current side through the PI controller, and determining a difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

if the feedback current signal generated by the inverter is not equal to the control current signal, performing feedback superposition operation on the control current signal to generate an error current signal;

adjusting the error current signal based on a fuzzy algorithm by the PR controller to generate an intermediate current signal;

and performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating and outputting a target current through the inverter.

2. The method of claim 1, wherein the step of determining a pre-load carrier signal and a reactive signal based on a harmonic and reactive detection algorithm, in combination with the dc signal and a power feedback signal of the pre-load, to generate a composite control signal comprises:

detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and executing park DQ inverse transformation operation to generate a superposed signal;

detecting the current value of the preset load, and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

and superposing the harmonic current signal and the reactive current signal on the superposed signal to generate a control current signal.

3. The method of claim 1, wherein the step of performing a feedback superposition operation on the control current signal to generate an error current signal comprises:

receiving, by the PR controller, the control current signal;

adjusting the control current signal according to a preset initial parameter through the PR controller;

receiving the control current signal through the inverter to generate an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

and performing subtraction operation on the control current and the feedback current signal to generate an error current signal.

4. The method of claim 3, wherein the step of generating an intermediate current signal by the PR controller adjusting the error current signal based on a fuzzy algorithm comprises:

calculating an error rate of change of the error current signal;

performing data fuzzification processing on the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

determining the fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

performing data defuzzification operation on the fuzzy correction quantity to obtain a correction quantity;

adjusting the preset initial parameter by using the correction amount to generate a target parameter;

and adjusting the error current signal according to the target parameter through the PR controller to generate an intermediate current signal.

5. The method of claim 1, further comprising:

and if the control signal is equal to the feedback signal, not executing feedback superposition operation.

6. A PWM rectifier control apparatus, wherein the PWM rectifier includes a proportional integral PI controller, a proportional resonant PR controller, and an inverter, the apparatus comprising:

the direct current component determining module is used for receiving a detection voltage signal generated by executing voltage detection operation on a direct current side through the PI controller and determining the difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

the control current signal generation module is used for determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

the error current signal generating module is used for executing feedback superposition operation on the control current signal to generate an error current signal if the feedback current signal generated by the inverter is not equal to the control current signal;

the intermediate current signal generation module is used for adjusting the error current signal through the PR controller based on a fuzzy algorithm to generate an intermediate current signal;

and the output module is used for executing PWM (pulse-width modulation) operation on the intermediate current signal, generating a target current through the inverter and outputting the target current.

7. The apparatus of claim 6, wherein the control current signal generation module comprises:

the superposed signal generation submodule is used for detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and executing park DQ inverse transformation operation to generate a superposed signal;

the harmonic and reactive signal determining submodule is used for detecting the current value of the preset load and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

and the control current signal generation submodule is used for superposing the harmonic current signal and the reactive current signal on the superposed signal to generate a control current signal.

8. The apparatus of claim 6, wherein the error current signal generating module comprises:

a control current signal receiving submodule for receiving the control current signal through the PR controller;

the control current signal adjusting submodule is used for adjusting the control current signal according to preset initial parameters through the PR controller;

the feedback current signal generation submodule is used for receiving the control current signal through the inverter and generating an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

and the error current signal generation submodule is used for executing subtraction operation on the control current and the feedback current signal to generate an error current signal.

9. The apparatus of claim 8, wherein the intermediate current signal generating module comprises:

the error change rate calculation submodule is used for calculating the error change rate of the error current signal;

the parameter fuzzy submodule is used for carrying out data fuzzification processing on the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

the fuzzy correction quantity generation submodule is used for determining the fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

the parameter deblurring submodule is used for performing data deblurring operation on the fuzzy correction quantity to obtain the correction quantity;

the target parameter generation submodule is used for adjusting the preset initial parameter by adopting the correction quantity to generate a target parameter;

and the intermediate current generation submodule is used for adjusting the error current signal according to the target parameter through the PR controller to generate an intermediate current signal.

10. The apparatus of claim 6, further comprising:

and the termination module is used for not executing feedback superposition operation if the control signal is equal to the feedback signal.

Technical Field

The invention relates to the technical field of rectifier control, in particular to a PWM rectifier control method and device.

Background

The sustainable development of electric power becomes the basis for realizing the sustainable development of social economy, and the energy conservation of electric power plays an increasingly important role in the process of building a conservation-oriented society in China. The SPWM technology of the inverter circuit is transplanted to the rectifying circuit in the PWM rectifier to form the PWM rectifying circuit, and the input current can be sine wave and in phase with the input voltage through proper control, so that the aim of high power factor is fulfilled. The PWM rectifier is widely applied to various occasions such as energy storage, frequency converters, electroplating metallurgy industries and the like due to the advantages of high efficiency, small volume, low harmonic wave and the like.

In most applications, the PWM rectifier has two major control objectives: on one hand, the output voltage of the direct current side needs to be kept stable at a given voltage value, and is not influenced by the voltage of a power grid and the load change as much as possible; on the other hand, the alternating-current side current of the converter also needs to realize corresponding power factor requirements and fast and accurate current waveform control according to different application occasions. With the development of switching devices, the capacity of the PWM rectifier is also increasing, and at the present stage, the PWM rectifier is mainly applied to single rectification, and the capacity is not fully utilized, so that there is a great waste of resources.

Therefore, the prior art is generally realized by a linear control algorithm such as proportional-integral control (PI), repetitive control or hysteresis control, but the algorithm has the defects of steady-state errors of phase and amplitude and weak disturbance resistance when tracking dispute selection reference signals; the dead-beat control needs less setting parameters, is easy to realize in engineering, has good dynamic performance, but the control precision needs to depend on an accurate mathematical model of a controlled object, and can not eliminate steady-state errors while realizing the rapid tracking of the current.

Disclosure of Invention

The invention provides a PWM rectifier control method and device, and solves the technical problem that in the prior art, the steady-state error cannot be eliminated while the current is quickly tracked.

The invention provides a control method of a PWM (pulse-width modulation) rectifier, wherein the PWM rectifier comprises a proportional-integral (PI) controller, a proportional-resonant (PR) controller and an inverter, and the method comprises the following steps:

receiving a detection voltage signal generated by performing a voltage detection operation on a direct current side through the PI controller, and determining a difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

if the feedback current signal generated by the inverter is not equal to the control current signal, performing feedback superposition operation on the control current signal to generate an error current signal;

adjusting the error current signal based on a fuzzy algorithm by the PR controller to generate an intermediate current signal;

and performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating and outputting a target current through the inverter.

Optionally, the step of determining a carrier signal and a reactive signal of a preset load based on a harmonic and reactive detection algorithm, and generating a composite control signal by combining the dc signal and a power feedback signal of the preset load includes:

detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and executing park DQ inverse transformation operation to generate a superposed signal;

detecting the current value of the preset load, and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

and superposing the harmonic current signal and the reactive current signal on the superposed signal to generate a control current signal.

Optionally, the step of performing a feedback superposition operation on the control current signal to generate an error current signal includes:

receiving, by the PR controller, the control current signal;

adjusting the control current signal according to a preset initial parameter through the PR controller;

receiving the control current signal through the inverter to generate an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

and performing subtraction operation on the control current and the feedback current signal to generate an error current signal.

Optionally, the step of generating an intermediate current signal by the PR controller adjusting the error current signal based on a fuzzy algorithm includes:

calculating an error rate of change of the error current signal;

performing data fuzzification processing on the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

determining the fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

performing data defuzzification operation on the fuzzy correction quantity to obtain a correction quantity;

adjusting the preset initial parameter by using the correction amount to generate a target parameter;

and adjusting the error current signal according to the target parameter through the PR controller to generate an intermediate current signal.

Optionally, the method further comprises:

and if the control signal is equal to the feedback signal, not executing feedback superposition operation.

The present invention also provides a PWM rectifier control apparatus including a proportional integral PI controller, a proportional resonant PR controller, and an inverter, the apparatus including:

the direct current component determining module is used for receiving a detection voltage signal generated by executing voltage detection operation on a direct current side through the PI controller and determining the difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

the control current signal generation module is used for determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

the error current signal generating module is used for executing feedback superposition operation on the control current signal to generate an error current signal if the feedback current signal generated by the inverter is not equal to the control current signal;

the intermediate current signal generation module is used for adjusting the error current signal through the PR controller based on a fuzzy algorithm to generate an intermediate current signal;

and the output module is used for executing PWM (pulse-width modulation) operation on the intermediate current signal, generating a target current through the inverter and outputting the target current.

Optionally, the control current signal generating module includes:

the superposed signal generation submodule is used for detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and executing park DQ inverse transformation operation to generate a superposed signal;

the harmonic and reactive signal determining submodule is used for detecting the current value of the preset load and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

and the control current signal generation submodule is used for superposing the harmonic current signal and the reactive current signal on the superposed signal to generate a control current signal.

Optionally, the error current signal generating module includes:

a control current signal receiving submodule for receiving the control current signal through the PR controller;

the control current signal adjusting submodule is used for adjusting the control current signal according to preset initial parameters through the PR controller;

the feedback current signal generation submodule is used for receiving the control current signal through the inverter and generating an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

and the error current signal generation submodule is used for executing subtraction operation on the control current and the feedback current signal to generate an error current signal.

Optionally, the intermediate current signal generating module includes:

the error change rate calculation submodule is used for calculating the error change rate of the error current signal;

the parameter fuzzy submodule is used for carrying out data fuzzification processing on the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

the fuzzy correction quantity generation submodule is used for determining the fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

the parameter deblurring submodule is used for performing data deblurring operation on the fuzzy correction quantity to obtain the correction quantity;

the target parameter generation submodule is used for adjusting the preset initial parameter by adopting the correction quantity to generate a target parameter;

and the intermediate current generation submodule is used for adjusting the error current signal according to the target parameter through the PR controller to generate an intermediate current signal.

Optionally, the apparatus further comprises:

and the termination module is used for not executing feedback superposition operation if the control signal is equal to the feedback signal.

According to the technical scheme, the invention has the following advantages:

in the embodiment of the invention, a detection voltage signal is generated by detecting a voltage signal at a direct current side, and the detection voltage signal is input into a PI (proportional-integral) controller to generate a direct current component by making a difference with a preset expected voltage signal; superposing the direct current component and a power feedback signal of a preset load, and further superposing the direct current component and a carrier current signal and a reactive current signal of the preset load, which are generated based on a harmonic and reactive detection algorithm, to generate a control current signal; and comparing the control current signal with a feedback current signal generated by the inverter, if the control current signal is not equal to the feedback current signal, performing feedback superposition operation on the control current signal to generate an error current signal, inputting the error current signal into a PR (positive feedback) controller, adjusting the control parameter of the PR controller through the PR controller based on the error current signal through a fuzzy algorithm, adjusting the error current signal based on the adjusted PR controller to generate an intermediate current signal, performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating a target current signal through the inverter for outputting. Therefore, the technical problem that the steady-state error cannot be eliminated while the current is quickly tracked in the prior art is solved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

Fig. 1 is a flowchart illustrating steps of a PWM rectifier control method according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating steps of a PWM rectifier control method according to an alternative embodiment of the present invention;

FIG. 3 is a schematic diagram of membership function of error current parameters according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating Δ Kp membership functions according to an embodiment of the present invention;

FIG. 5 is a flowchart illustrating steps of a parameter tuning process of a PR controller according to an embodiment of the present invention;

FIG. 6 is a flowchart illustrating steps of a PWM rectifier control method according to another embodiment of the present invention;

fig. 7 is a schematic structural diagram of a PWM rectifying apparatus according to an embodiment of the present invention;

FIG. 8 is a simplified mathematical model of a PWM rectifier according to an embodiment of the present invention;

fig. 9 is a block diagram of a PWM rectifier control apparatus according to an embodiment of the present invention.

Detailed Description

The embodiment of the invention provides a PWM rectifier control method and device, which are used for solving the technical problem that the prior art cannot realize quick tracking of current and eliminate steady-state errors at the same time.

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the 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 invention.

The PI controller is a proportional-integral controller, comprises a proportional regulation link and an integral regulation link, and is used for forming a control deviation according to an expected value and an actual output value, forming a control quantity by linearly combining the proportion and the integral of the deviation, and controlling a controlled object.

The proportional adjustment step is to reflect the deviation signal of the control system in real time in proportion, and once the deviation is generated, the controller immediately generates a control action to reduce the deviation. Generally, as the value increases, the overshoot of the closed loop system increases, and the response speed of the system increases, but when the value increases to a certain extent, the system becomes unstable.

The integral adjustment link is mainly used for eliminating static error and improving the zero-error degree of the system, so that the system eliminates steady-state errors and improves the zero-error degree. Because of the error, the integral adjustment is carried out until no difference exists, the integral adjustment is stopped, and the integral adjustment outputs a constant value.

PR controller, referred to as a proportional resonant controller, is used to reduce steady state errors, but it has less gain at non-fundamental frequencies. When the grid frequency fluctuates, the gain decreases. PR control is implemented by adding 2 closed-loop poles with fixed frequency on the axis of the controller transfer function to form resonance at the frequency, and simultaneously increasing the gain of the fixed frequency by using the resonance, thereby realizing the non-differential tracking of the reference signal at the frequency. The quasi-PR resonance controller is adopted, so that the high gain of PR control can be kept, the influence of power grid frequency offset on output current can be reduced, and the transfer function is as follows:

wherein, ω is₀At fundamental frequency, K_P、K_R、ω_cRespectively, the control parameters thereof.

K_PThe peak gain of the PR controller is correlated, an error signal of a control system is reflected, an error is generated, and the controller acts to reduce deviation; omega_cIs a bandwidth parameter and the gain bandwidth (ideal value) can be changed by changing the controller. K_RControl steady state errors may be reduced.

Referring to fig. 1, fig. 1 is a flowchart illustrating steps of a PWM rectifier control method according to an embodiment of the present invention.

The invention provides a control method of a PWM (pulse-width modulation) rectifier, wherein the PWM rectifier comprises a proportional-integral (PI) controller, a proportional-resonant (PR) controller and an inverter, and the method comprises the following steps:

step 101, receiving a detection voltage signal generated by performing a voltage detection operation on a direct current side through the PI controller, and determining a difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

in the embodiment of the invention, a voltage signal is generated by presetting a direct current side, and a detection voltage signal is generated by executing voltage detection operation on the direct current side; and generating a direct current component by using the difference between a preset expected voltage signal and the detection voltage signal through a PI controller.

102, determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

in an example of the present invention, by obtaining a current of a preset load, a harmonic current and a reactive current of the preset load current are calculated by using a harmonic and reactive detection algorithm, and are simultaneously superimposed with the dc component and a power feedback signal of the preset load to generate a control current signal for use in a subsequent current tracking control process.

103, if the feedback current signal generated by the inverter is not equal to the control current signal, performing feedback superposition operation on the control current signal to generate an error current signal;

in specific implementation, multiple iterations are usually required in the adjustment process, the control current signal is adjusted by a PR controller provided with initial parameters and then output through a PWM modulator and an inverter, at this time, current generated by the inverter is sampled and fed back as a feedback current signal to a position before the control current signal is input to the PR controller, and compared with the control current signal, if the current is not equal to the control current signal, a feedback superposition operation is performed on the control current signal, the control current signal is differed from the feedback current signal, an error current signal is generated and input to the PR controller again, and parameter correction of the PR controller is performed.

104, adjusting the error current signal through the PR controller based on a fuzzy algorithm to generate an intermediate current signal;

in the embodiment of the invention, K for PR controller is based on PR control of fuzzy theory and the error current signal_R、K_PAnd adjusting, and further adjusting the error current signal to generate an intermediate current signal.

And 105, performing a PWM (pulse width modulation) operation on the intermediate current signal, and generating and outputting a target current through the inverter.

In a specific implementation, the intermediate current signal is subjected to a PWM modulation operation to rectify the intermediate current signal, and then the modulated target current is converted from a direct current to an alternating current by the inverter and output.

In the embodiment of the invention, a detection voltage signal is generated by detecting a voltage signal at a direct current side, and the detection voltage signal is input into a PI (proportional-integral) controller to generate a direct current component by making a difference with a preset expected voltage signal; superposing the direct current component and a power feedback signal of a preset load, and further superposing the direct current component and a carrier current signal and a reactive current signal of the preset load, which are generated based on a harmonic and reactive detection algorithm, to generate a control current signal; and comparing the control current signal with a feedback current signal generated by the inverter, if the control current signal is not equal to the feedback current signal, performing feedback superposition operation on the control current signal to generate an error current signal, inputting the error current signal into a PR (positive feedback) controller, adjusting the control parameter of the PR controller through the PR controller based on the error current signal through a fuzzy algorithm, adjusting the error current signal based on the adjusted PR controller to generate an intermediate current signal, performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating a target current signal through the inverter for outputting. Therefore, the technical problem that the steady-state error cannot be eliminated while the current is quickly tracked in the prior art is solved.

Referring to fig. 2, fig. 2 is a flowchart illustrating steps of a PWM rectifier control method according to an alternative embodiment of the present invention, including:

step 201, receiving a detection voltage signal generated by performing a voltage detection operation on a direct current side through the PI controller, and determining a difference between a preset expected voltage signal and the detection voltage signal as a direct current component;

in the embodiment of the present invention, the specific implementation process of step 201 is similar to that of step 101, and is not described herein again.

Step 202, determining a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generating a control current signal by combining the direct current component and a power feedback signal of the preset load;

optionally, the step 202 may include the following sub-steps 2021 and 2023:

substep 2021, detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and performing park DQ inverse transformation operation to generate a superposed signal;

substep 2022, detecting a current value of the preset load, and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

substep 2023 of superimposing said harmonic current signal and said reactive current signal on said superimposed signal to generate a control current signal.

In one example of the present invention, a preset load is power-detected, and after receiving a power feedback signal for the preset load, the power feedback signal is superimposed on the dc signal, and then only a two-dimensional current signal is obtained, and then a DQ inverse transformation operation is performed on the obtained current signal to generate a superimposed signal to be input to the next stage.

In order to perform harmonic detection and reactive compensation on the current of the preset load, a harmonic current signal and a reactive current signal of the preset load can be determined based on a harmonic and reactive detection algorithm by detecting the current value of the preset load; and then, superposing the harmonic current signal and the reactive current signal on the superposed signal to provide harmonic and reactive reference signals, and generating a control current signal for a subsequent PR controller to carry out current tracking control based on the control current signal.

The Park Transformation operation is referred to as Park's Transformation, which is currently the most common coordinate Transformation for analyzing the operation of synchronous motors, and was proposed by american engineers Park (r.h. Park) in 1929. The park transformation projects the a, b and c three-phase currents of the stator to a direct axis (d axis), a quadrature axis (q axis) and a zero axis (0 axis) perpendicular to a dq plane along with the rotation of the rotor, so that the diagonalization of a stator inductance matrix is realized, and the operation analysis of the synchronous motor is simplified. Namely, the abc coordinate system is transformed into the dq coordinate system, and the inverse park transformation is the inverse process of the above process.

Step 203, if the feedback current signal generated by the inverter is not equal to the control current signal, performing feedback superposition operation on the control current signal to generate an error current signal;

in an alternative embodiment of the present invention, the step 203 may include the following sub-steps 2031-2034:

sub-step 2031 of receiving, by the PR controller, the control current signal;

substep 2032, adjusting the control current signal by the PR controller according to preset initial parameters;

substep 2033 of receiving said control current signal by said inverter, generating an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

sub-step 2034 of performing a subtraction operation on the control current and the feedback current signal to generate an error current signal.

In another embodiment of the present invention, to achieve fast tracking while eliminating steady state errors, a control current signal may be received through PR control, which is adjusted with initial parameters; receiving the control current signal through an inverter to generate an initial current signal; sampling is carried out on the initial current signal to obtain a feedback current signal, and subtraction operation is carried out on the control current and the feedback current signal to generate an error current signal.

The preset initial parameter may be set by a technician according to the control current signal, which is not limited in the embodiment of the present invention.

Step 204, adjusting the error current signal through the PR controller based on a fuzzy algorithm to generate an intermediate current signal;

further, the step 204 may comprise the following sub-steps 2041 and 2046:

substep 2041, calculating an error rate of change of the error current signal;

in the embodiment of the present invention, the error change rate is obtained by deriving the error current signal with respect to time.

Substep 2042, performing data fuzzification processing to the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

for example, referring to FIG. 3, the error current parameters include the error rate of change and the error current signal, and the controller is designed so that the linguistic values of the input and output variables are averaged to 7 linguistic values: { NB, NM, NS, O, PS, PM, PB }, wherein the membership function adopts a trigonometric function with strong sensitivity.

Blur error signal e and blur error rate of change e_cThe domain of discourse is: [ -6, -5, -4, -3, -2, -1,0,1,2,3,4,5,6]；

Referring to FIG. 4, Δ K is set_PThe domain of discourse is: [ -3, -2, -1,0,1,2,3]；

Where the discourse domain only represents a range of intervals and does not represent true values. In order to enhance the robustness of the system and improve the resolution of the membership function, the function shape near the 0 value is steeper.

Substep 2043, determining a fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

substep 2044, performing data defuzzification operation on the fuzzy correction quantity to obtain a correction quantity;

substep 2045, adjusting the preset initial parameter by using the correction amount to generate a target parameter;

wherein, the preset fuzzy inference rule may be as follows:

referring to fig. 5, fig. 5 includes a PR controller, a PWM modulation part and a rectifier part, receives an error E (i.e., a fuzzy deviation signal) generated by a difference between a control current and a feedback current through the PR control, derives the error E to obtain a fuzzy deviation change rate, and pre-sets K_P、K_RFuzzy inference is carried out on the parameter, the fuzzy deviation signal and the fuzzy deviation change rate to generate an adjustment value △K_P、△K_RThereby achieving the purpose of setting the parameters of the PR controller; PR controller based on new K_P、K_RAnd adjusting the error E by the parameter, and outputting the error E after PWM modulation and rectification.

Referring to fig. 6, fig. 6 is a flowchart illustrating steps of a PWM rectifier control method according to another embodiment of the present application, where the method includes receiving a first difference between a dc-side expected value and a dc-side detected value through PI control, superimposing the first difference with a power feedback signal, superimposing the superimposed first difference with a current obtained by processing a load current based on a harmonic and reactive detection algorithm, generating a composite control current, subtracting the composite control current from current feedback to obtain an error current, inputting the error current into a PR controller for modulation, and finally outputting a target output current through an inverter.

The kernel of the fuzzy inference is a controller parameter setting rule, K in PR controller_PThe function of (1) is to proportionally reflect an error signal E of a control system, an error is generated, and a controller acts to reduce deviation; if K_PIf the value is too large, the system will oscillate and the stability of the system will be damaged. Therefore, when the error is large, to improve the response speed, K_PShould take a larger value, otherwise to ensure system dynamic performance, K_PShould be limited in order to stabilize the system as quickly as possible, K_PThe reduction or increase may be 0.1, which is not limited by the embodiment of the present invention.

Resonance link K of PR controller_RThe method is mainly used for eliminating static errors, integrates the errors, has a hysteresis effect on the control of a system, and leads the overshoot of the system to be increased when the integration is too strong. Thus to K_RAdjustment of and K_PAnd (5) the consistency is achieved.

EC and E are also considered, when the EC and E have the same sign, the output error is increased, and K should be properly increased_PAnd vice versa.

Based on the above analysis, the specific implementation method is as follows:

① when | e | is large, i.e. e ∈ { NB, PB }, for better fast tracking performance of the system, according to e_cSelection of specific value of K_PPair ofWhile avoiding large overshoot in the system response.

② to avoid large overshoot of the system response when | e | is at medium size, e ∈ { NM, PM }, according to e_cSelection of specific value of K_PThe corresponding value of (a).

③ when | e | is small, e ∈ { NS,0, PS }, for better steady state performance of the system, according to e |_cSelection of specific value of K_PThe corresponding value of (a).

According to the actual characteristics and debugging experience of the object, the following rule table is summarized as shown in table 1:

TABLE 1. DELTA.K_PParameter adjustment rule table

3) Defuzzification

After the fuzzy reasoning, 1 correction parameter set by the controller needs to be defuzzified, and accurate quantity is obtained. There are various methods for defuzzification, such as the center of gravity method and the maximum membership method. The controller adopts a gravity center method to obtain an accurate value of the output quantity:

k can be obtained according to the formula_P：

Substep 2046, adjusting the error current signal by the PR controller according to the target parameter to generate an intermediate current signal.

In a specific implementation, K is calculated according to the fuzzy rule_PAnd then, modifying the transfer function of the PR controller, and adjusting the error current signal again to generate an intermediate current signal.

And step 205, performing a PWM modulation operation on the intermediate current signal, and generating and outputting a target current through the inverter.

And performing PWM (pulse-width modulation) operation on the intermediate current signal, generating a target current through the inverter, and outputting the target current.

The PWM modulation operation refers to (Pulse width modulation): the control mode is to control the on-off of the switch device of the inverter circuit, so that a series of pulses with equal amplitude are obtained at the output end, and the pulses are used for replacing sine waves or required waveforms. That is, a plurality of pulses are generated in a half cycle of an output waveform, and the equivalent voltage of each pulse is a sine waveform, so that the obtained output is smooth and has few low-order harmonics. The width of each pulse is modulated according to a certain rule, so that the magnitude of the output voltage of the inverter circuit can be changed, and the output frequency can also be changed.

In step 206, if the control signal is equal to the feedback signal, no feedback superposition operation is performed.

In a specific implementation, if the control signal is equal to the feedback signal, it indicates that PR adjustment is not required at this time, and a feedback superposition operation is not performed.

In the embodiment of the invention, a detection voltage signal is generated by detecting a voltage signal at a direct current side, and the detection voltage signal is input into a PI (proportional-integral) controller to generate a direct current component by making a difference with a preset expected voltage signal; superposing the direct current component and a power feedback signal of a preset load, and further superposing the direct current component and a carrier current signal and a reactive current signal of the preset load, which are generated based on a harmonic and reactive detection algorithm, to generate a control current signal; and comparing the control current signal with a feedback current signal generated by the inverter, if the control current signal is not equal to the feedback current signal, performing feedback superposition operation on the control current signal to generate an error current signal, inputting the error current signal into a PR (positive feedback) controller, adjusting the control parameter of the PR controller through the PR controller based on the error current signal through a fuzzy algorithm, adjusting the error current signal based on the adjusted PR controller to generate an intermediate current signal, performing PWM (pulse-width modulation) operation on the intermediate current signal, and generating a target current signal through the inverter for outputting. Therefore, the technical problem that the steady-state error cannot be eliminated while the current is quickly tracked in the prior art is solved.

Referring to fig. 7, fig. 7 is a schematic structural diagram of a PWM rectifier according to an embodiment of the present invention, in which a dc network side includes a nonlinear load, an inductor Ls and an inductor L, harmonic and reactive detection is performed on the dc network side, current tracking is performed through the inductor L, and a three-phase current i is output through the dc network side_Sa、i_Sb、i_ScInput into the converter valve, through a plurality of power modules T therein_a1T_b1T_c1And T_a2T_b2T_c2Detecting the voltage u on the DC side_dcAfter obtaining the power feedback signal, returning the power feedback signal to the converter valve to adjust the direct current, and outputting the direct current to a receiving side through the converter valve, wherein the current is i_oCapacitance of C_oAt a voltage of V_oInductance of L_oAnd a feedback signal is returned through the DSP control and drive unit.

Referring to fig. 8, fig. 8 is a simplified mathematical model of a PWM rectifier according to an embodiment of the present invention, which includes dc sources e a, e b, and e c, inductors Rs and Ls, and current i_a、i_b、i_cAt a voltage of u_a、u_b、u_cThe converter valve part is equal to Sa, Sb and Sc, and the voltage of the capacitor is U_dc/2。

Assuming that the IGBT in the inverter is ideal, neglecting the turn-on and turn-off dead time, etc., corresponding to the on-off state of each single-phase bridge arm in fig. 1, the switching function is defined as:

wherein i ═ a, b, c, S_iThe upper pipe of the bridge arm 1 is conducted, and the lower pipe is disconnected; s_iThe lower tube of the bridge arm is switched on and the upper tube is switched off, namely-1. u. of_a,u_b,u_cRepresenting the output voltage, S, of a three-phase inverter bridge_a,S_b,S_cIndicating the switching state of the switching element IGBT. The output filter and the network impedance may be equivalent to L_S、R_SThe system can be simplified by Thevenin equivalent theoremWhich is illustrated in fig. 2. From fig. 2, the equation can be derived from kirchhoff's law:

the output voltage of the inverter is obtained and can be expressed by the following formula:

assuming that the capacitance value is C, the direct-current side capacitance shown in the figure is obtained according to kirchhoff's law:

it can be inferred from equations (3) and (4):

then, combining the vertical type (2) and the formula (5), the mathematical model of the system can be obtained as follows:

DX′＝AX+U (6)

wherein:

D＝diag(L_SL_SL_SC)

referring to fig. 9, fig. 9 is a block diagram illustrating a structure of a PWM rectifier control apparatus according to an embodiment of the present invention, the PWM rectifier including a proportional-integral PI controller, a proportional-resonant PR controller, and an inverter, the apparatus including:

a dc component determining module 901, configured to receive, through the PI controller, a detection voltage signal generated by performing a voltage detection operation on a dc side, and determine a difference between a preset expected voltage signal and the detection voltage signal as a dc component;

a control current signal generating module 902, configured to determine a carrier current signal and a reactive current signal of a preset load based on a harmonic and reactive detection algorithm, and generate a control current signal by combining the dc component and a power feedback signal of the preset load;

an error current signal generating module 903, configured to perform feedback superposition on the control current signal to generate an error current signal if the feedback current signal generated by the inverter is not equal to the control current signal;

an intermediate current signal generation module 904 configured to adjust the error current signal based on a fuzzy algorithm by the PR controller to generate an intermediate current signal;

and an output module 905, configured to perform a PWM modulation operation on the intermediate current signal, generate a target current through the inverter, and output the target current.

Optionally, the control current signal generating module 902 includes:

the superposed signal generation submodule is used for detecting a power feedback signal of a preset load, superposing the power feedback signal on the direct current signal, and executing park DQ inverse transformation operation to generate a superposed signal;

the harmonic and reactive signal determining submodule is used for detecting the current value of the preset load and determining a harmonic current signal and a reactive current signal of the preset load based on a harmonic and reactive detection algorithm;

and the control current signal generation submodule is used for superposing the harmonic current signal and the reactive current signal on the superposed signal to generate a control current signal.

Optionally, the error current signal generating module 903 includes:

a control current signal receiving submodule for receiving the control current signal through the PR controller;

the control current signal adjusting submodule is used for adjusting the control current signal according to preset initial parameters through the PR controller;

the feedback current signal generation submodule is used for receiving the control current signal through the inverter and generating an initial current signal and a feedback current signal; the feedback current signal is a sampling signal of the initial current signal;

and the error current signal generation submodule is used for executing subtraction operation on the control current and the feedback current signal to generate an error current signal.

Optionally, the intermediate current signal generating module 904 includes:

the error change rate calculation submodule is used for calculating the error change rate of the error current signal;

the parameter fuzzy submodule is used for carrying out data fuzzification processing on the error signal and the error change rate to obtain a fuzzy error signal and a fuzzy error change rate;

the fuzzy correction quantity generation submodule is used for determining the fuzzy correction quantity of the preset initial parameter according to the fuzzy deviation signal, the fuzzy deviation change rate and a preset fuzzy inference rule;

the parameter deblurring submodule is used for performing data deblurring operation on the fuzzy correction quantity to obtain the correction quantity;

the target parameter generation submodule is used for adjusting the preset initial parameter by adopting the correction quantity to generate a target parameter;

and the intermediate current generation submodule is used for adjusting the error current signal according to the target parameter through the PR controller to generate an intermediate current signal.

Optionally, the apparatus further comprises:

and the termination module is used for not executing feedback superposition operation if the control signal is equal to the feedback signal.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.