VSG-based compensation control system of network construction type railway power regulator

Abstract

The invention relates to a VSG (Virtual Synchronous Generator)-based compensation control system of a network construction type railway power regulator. The VSG technology is fused into an RPC traditional compensation control system, the power grid current compensation effect of the RPC is achieved, meanwhile, the rotation inertia of a traditional power grid is injected into a contact network through the creativity of the VSG, and the impedance multiplication effect caused by the fact that the RPC is connected into the contact network is controlled and relieved through a voltage source of the VSG; the overall inertia of the power grid is improved by using the voltage source characteristics of the VSG, and the stability of the power grid is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrified railway power supply, and in particular to a compensation control system of a grid-type railway power regulator based on VSG. Background Art

[0002] Electrified railways use electricity as a power source, which has significant advantages in many aspects such as environmental protection and locomotive performance, but it also brings considerable challenges. For the power grid, it faces the impact caused by high-power load switching, the degradation of power quality caused by a large amount of harmonic injection, and the three-phase current imbalance caused by the single-phase power supply structure. The Railway Power Conditioner (RPC) can effectively alleviate the above-mentioned harmonic and three-phase current imbalance problems, but its converter control is a grid-following control, which is the same current source as the train, so its access to the overhead contact network will reduce the stability of the system. Summary of the invention

[0003] The present invention provides a compensation control system of a grid-type railway power conditioner based on VSG, which introduces a virtual synchronous generator (VSG) into RPC compensation control. The virtual synchronous generator belongs to the grid-type control and utilizes the voltage source characteristics of the VSG to improve the stability of the contact network.

[0004] The control system includes a phase A contact network and a phase B contact network, which are used to convert the three-phase power grid into single-phase electricity through a V / V transformer; a step-down transformer, which is used to convert the voltage of the single-phase electricity of the contact network and output it to the RPC module, while converting the voltage level of the train power supply.

[0005] The RPC module includes two back-to-back converters, which are used to adjust the output current i according to the action instructions of the switch tubes of the converter. ra and i rb , so as to achieve the effect of negative sequence compensation of the three-phase grid current and balance the energy flowing through the power supply arms on both sides; the RPC module specifically includes an a-phase converter, a b-phase converter and a DC capacitor, and the a-phase and b-phase converters each include two parallel switch tube groups, each switch tube group includes two series switch tube components, and each switch tube component includes a parallel diode and a switch, wherein the diode and the power semiconductor are anti-parallel. The a-phase converter and the b-phase converter are respectively connected in parallel on both sides of the DC capacitor, and the output current i ra and i rb .

[0006] The VSG modules are used to control the a-phase and b-phase converters respectively, according to the voltage control command value U Rxref, the voltage amplitude of the power supply arm at the RPC module interface U′ xcm , where x = a or b, and the current i ra and i rb Get the current control command value i Vrx The VSG module specifically controls the VSG voltage command value U Rxref with U′ xcm / 25 difference, after droop coefficient K RVu After that, with the reactive power command value Q Vxref and the instantaneous value of the converter reactive power Q Rx The difference between the two values ​​is summed and the result is integrated and then added to the VSG voltage control command value U Rxref The result is superimposed with the angle command value θ generated by the VSG module. Rx The corresponding trigonometric function values ​​are multiplied to obtain the voltage command value U generated by VSG for the next level of compensation control RVxref , the voltage command value U generated by the VSG module for the next level of compensation control Rvxref Voltage u' of the power supply arm at the RPC interface xc / 25 as a difference, through the quasi-PR controller T Rvu Output current control command value i Vrx .

[0007] The system also includes a power calculation module for converting the output voltage command value U of the VSG module into RVxref and the converter output current i rx Multiply them to obtain the output active power command value P Rxref and reactive power command value Q Rxref ; The voltage of the power supply arm at the RPC interface u' xc / 25 and the converter output current i rx Multiply them to obtain the active power value P output by the converter Rx And reactive power value Q Rx The power reference values ​​of the basic compensation module and the VSG module are consistent, so as to perform negative sequence compensation on the three-phase grid current and regulate the current on the contact network side.

[0008] The basic compensation module is used to control the DC capacitor voltage; the DC capacitor voltage command value U Rdcref and the DC side voltage U Rdc The instantaneous value of the difference is calculated by PI, and the result is compared with the angle command value θ generated by the VSG module. Rx The generated trigonometric function values ​​of phase a and phase b are multiplied, and the resulting product is added to the current compensation command value i Raref and i Rbref After that, they are respectively related to the output current i rx / 25 instantaneous value difference, obtain the control current instruction of the compensation control module for phase a and phase b; the current control instruction value i generated by the VSG module Vrx The control current command of the basic compensation control module is superimposed and the quasi-PR controller T Ri The PWM modulator sends an action instruction to the switch tube of the converter to control the output current.

[0009] In summary, the beneficial effects of the present invention are as follows:

[0010] 1. The compensation control system of the VSG-based grid-type railway power conditioner proposed in the present invention, when the VSG is connected to the power grid, the output power changes with the change of the command value on the one hand, which plays a role in dispatching the power grid, and on the other hand, it will also change automatically with the fluctuation of the voltage amplitude and frequency of the power grid, which plays a role in improving the inertia of the power grid, thereby enhancing the robustness of the power grid and stabilizing the voltage;

[0011] 2. It has both current compensation function and contact network voltage stabilization function;

[0012] 3. PLL can be omitted, which saves hardware and software resources on the one hand, and avoids the instability caused by PLL under disturbance conditions on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An electric railway structure including RPC in the prior art;

[0014] Figure 2 It is the negative sequence current compensation principle of RPC in the prior art;

[0015] Figure 3 The current detection and compensation principle of the traditional treatment method of electrified railway in the prior art;

[0016] Figure 4 The locomotive power supply structure of the present invention;

[0017] Figure 5 The main circuit and control structure of the locomotive according to the present invention;

[0018] Figure 6 The VSG-based PRC compensation control structure of the present invention;

[0019] Figure 7 It is the three-phase grid current under the remote section and VSG compensation working condition described in the present invention;

[0020] Figure 8 It is the positive and negative sequence amplitude of the three-phase grid current under the remote section and VSG compensation control conditions described in the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] High-speed railways use single-phase power supply. In this scenario, V / v transformers are simpler in design, lower in cost, and easier to install and maintain than Scott transformers, so they are more widely used. Therefore, the existing RPC is introduced based on the traction network with V / v transformers in the main circuit. Figure 1 As shown in the figure, the V / v transformer converts the 220kV three-phase electricity of the power grid into 25kV to 27.5kV single-phase electricity for the power supply arms on the left and right sides of the overhead line (phase a power supply arm and phase b power supply arm respectively). The transformer is an asymmetric transformer. The high-voltage side of each set of windings is connected across two phases of the three-phase line, and the low-voltage side is connected to the single-phase power supply arm. In terms of time, whether there is a train passing through each power supply arm section is random. In terms of space, the terrain and weather of different power supply arms are inconsistent, and the load of each train itself is also inconsistent. Under the influence of many factors, the left and right two-phase power supply of the V / v transformer The arm loads are inconsistent and often vary greatly. Therefore, as long as there is a train running, a large negative sequence current will be injected into the three-phase grid. Each phase power supply arm supplies power to the motor driving the train through a pantograph, a step-down transformer (not shown) and a power electronic device, and the power electronic device includes a locomotive rectifier. Therefore, the harmonics and reactive currents generated by it are injected into the three-phase grid, reducing its power quality. Because the train has the characteristics of high power, intermittent access to a certain phase power supply arm, and a certain degree of random acceleration and braking, the overhead line that supplies energy to the train will also face a large transient power impact. Figure 1 Z gIt represents the sum of line impedance and transformer leakage inductance. The power supply section is generally 20km-40km long, and the traction transformer leakage inductance is as high as more than 5%. Therefore, Z g The value is quite considerable, which is why locomotive load switching can cause large fluctuations in the amplitude and frequency of the contact network current and high distortion rate.

[0024] Large power grid line voltage vector u AC 、u BC and phase voltage vector u A 、u B 、u C The vector relationship is as follows Figure 2 Before RPC is put into operation, the locomotive load current i La 、i Lb The angle is equal to u AC 、u BC Assuming that the current of the locomotive on phase a is much greater than the current of the locomotive on phase b, the current of the three-phase grid will be unbalanced, and the harmonic current generated by the locomotive will also be injected into the three-phase grid. To compensate for the negative sequence and harmonic current, Figure 2 Calculate the reactive current i Ra_r 、i Rb_r and fundamental current i af 、i bf 、i cf The sum of the two is the total compensation command current i Ra 、i Rb . Figure 3 The current detection and compensation principle of the traditional governance method is demonstrated, and its calculation process is shown in formula (1):

[0025]

[0026] At this time, i Ra 、i Rb The difference is calculated by the PR controller, and the calculated value is used as the modulation wave to generate the converter switch action command, so that the instantaneous value of the converter output current tracks the command value, thereby compensating for the negative sequence and harmonic current injected into the three-phase power grid by the overhead contact network. RPC can effectively reduce the imbalance of the power grid (there may be a small three-phase imbalance as compensation when the load power has a large transient), but under extremely long-distance conditions, the operation of RPC will aggravate system instability.

[0027] Embodiment 1

[0028] In view of the problems existing in the prior art, this embodiment provides a compensation control system of a grid-type railway power conditioner based on VSG. The present invention is described in detail below in conjunction with the accompanying drawings.

[0029] like Figure 4 The locomotive power supply structure of the present invention is shown. The electric energy of the overhead line is transmitted to the locomotive through the pantograph on the top of the locomotive, and then the 25kV AC is reduced to 1kV through the step-down transformer, and then the traction motor is powered by the back-to-back converter. In order to simplify the mathematical model, it is assumed that the parameters of the locomotives on both sides of the power supply arm are the same. When the locomotive is running stably, the inverter and the motor can be replaced by resistors. The main circuit and control structure after approximation are as follows Figure 5 As shown, the DC capacitor voltage command value is U Ldcref , for the instantaneous value of DC capacitor voltage U Ldc Sampling is performed, and then the difference between the two is calculated by PI. The calculated value obtained under steady-state conditions is a DC value that gradually decreases and finally approaches 0. The voltage and current on the low-voltage side of the step-down transformer are then sampled and transmitted, and the electrical angle is obtained through PLL, and the corresponding sine value is further calculated. The sine value is multiplied by the aforementioned DC value, and the product is subtracted from the current of the input rectifier. The difference is sequentially subjected to quasi-PR calculation and PWM modulation to obtain the action instruction of the switch tube, forming a closed-loop control of the rectifier and keeping the voltage across the load near the rated voltage. The mathematical model of this part is shown in the following formula:

[0030]

[0031] Among them, i L Filter inductor current, U L The voltage of the overhead line that supplies power to the locomotive load after the voltage is stepped down. L is the voltage of the converter bridge arm, L t is the filter inductor at the rectifier end of the locomotive, i RLdc Equivalent current supplied to the locomotive, T Lu (s), k Lui , k Lup They are Figure 5 The voltage loop PI controller and its integral coefficient and proportional coefficient, T Li (s), k Lir , k Lip ,ω Lc They are Figure 5 The current loop quasi-PR controller and its resonant gain, proportional gain and cut-off frequency are shown in the figure. ω0 is the resonant frequency; m is the modulation ratio, θ is the rectifier electrical angle; s is the Laplace operator, C is the locomotive DC capacitor, R L is the line impedance on the locomotive load side.

[0032] The PRC compensation control structure based on VSG described in the present invention is as follows: Figure 6As shown, the compensation control system specifically includes a-phase contact network and b-phase contact network, which are used to convert the three-phase power grid into single-phase electricity through a V / V transformer; the electric energy of the contact network is transmitted to the locomotive through the pantograph on the top of the locomotive, and then the 25kV AC power is reduced to 1kV through a step-down transformer, and then the traction motor is powered by a back-to-back converter.

[0033] There are two step-down transformers, which are used to convert the voltage of the single-phase electricity of the a-phase contact network and the b-phase contact network and output them to the RPC module. Because the converter uses a fully controlled switching device, excessive voltage may damage the switch tube, so the 25kV voltage of the power supply arm must be stepped down to 1kV by the transformer before being connected to the AC side of the converter.

[0034] The RPC module includes two back-to-back converters, which are used to adjust the output current i by providing action instructions to the switch tubes of the converters. ra and i rb , to regulate the current on the contact network side; the RPC module specifically includes an a-phase converter, a b-phase converter and a DC capacitor, and the a-phase and b-phase converters each include two parallel switch tube groups, each switch tube group includes two series switch tube components, and each switch tube component includes a diode and a switch in parallel, wherein the diode and the power semiconductor are anti-parallel. The a-phase converter and the b-phase converter are respectively connected in parallel on both sides of the DC capacitor, and the output current i ra and i rb .

[0035] The same VSG module is used in the two back-to-back converters of the RPC module. The control structure diagram does not repeat the same control module. x represents the parameter with the same meaning that appears in both phases a and b. The power calculation module converts the output voltage command value U RVxref and the converter output current i rx Multiply them to obtain the output active power command value P Rxref and reactive power command value Q Rxref ; The voltage of the power supply arm at the RPC interface u' xc / 25 and the converter output current i rx Multiply them to obtain the active power value P output by the converter Rx And reactive power value Q Rx The power reference values ​​of the basic compensation module and VSG are consistent, so as to perform negative sequence compensation on the three-phase grid current and regulate the current on the contact network side.

[0036] The VSG module specifically controls the VSG voltage command value U Rxref Voltage amplitude of the power supply arm at the interface with RPC U′ xcm / 25 difference, after droop coefficient K RVuAfter that, with the reactive power command value Q Vxref and the instantaneous value of the converter reactive power Q Rx The difference between the two values ​​is summed and the result is integrated and then added to the VSG voltage control command value U Rxref The result is superimposed with the angle command value θ generated by the VSG module. Rx The corresponding trigonometric function values ​​are multiplied to obtain the voltage command value U generated by VSG for the next level of compensation control RVxref The VSG module generates a voltage command value U for the next level of compensation control. Rvxref Voltage u' of the power supply arm at the RPC interface xc / 25 as a difference, through the quasi-PR controller T Rvu Output current control command value i Vrx .

[0037] Under steady-state conditions, the output voltage command value U of the VSG module is RVxref The amplitude is close to the VSG voltage control command value U Rxref , whose angular frequency is close to ω Rxref .

[0038] The compensation control system of the present invention has an RPC module near the power supply station, so the electrical angle output by the RPC module is close to the electrical angle of the V / V transformer, so the electrical angle θ generated by the VSG itself can be used. Rx All the required electrical angles can be inferred in reverse, so that the PLL can be omitted. On the one hand, this saves hardware and software resources, and on the other hand, it can avoid the instability caused by the PLL under disturbed conditions.

[0039] The basic compensation module is used to control the DC capacitor voltage; the DC capacitor voltage command value U Rdcref and the DC side voltage U Rdc The instantaneous value of the difference is calculated by PI, and the result is compared with the angle command value θ generated by the VSG module. Rx The generated trigonometric function values ​​of phase a and phase b are multiplied, and the resulting product is added to the current compensation command value i Raref and i Rbref After that, they are respectively related to the output current i rx / 25 instantaneous value difference, and obtain the control current instruction of the compensation control module for phase a and phase b. Vrx The control current command of the basic compensation control module is superimposed and the quasi-PR controller T Ri The PWM modulator sends an action instruction to the switch tube of the converter to control the output current.

[0040] Because the output of the quasi-PR controller is also a co-frequency AC value, the instruction output by the VSG module does not need to be converted into a co-frequency AC value through a trigonometric function like the PI output value of the DC voltage. Whether it is a quasi-PR controller or a PI controller, when the system reaches a steady state, the value on its input side approaches 0. Therefore, the control system described in the present invention can be stable and have both the current compensation function and the contact network voltage stabilization function.

[0041] Embodiment 2

[0042] Based on the embodiment, this embodiment provides a compensation control system of a VSG-based grid-type railway power conditioner. Figure 6 The structure is used to build a simulation model in Matlab / Simulink. The total impedance from the power supply station to the train increases with the distance between the two. The total inductive reactance from the train to the RPC access point is generally between 5mH and 40mH, and can reach 45mH in a few working conditions. The total resistance is generally between 0Ω and 1.5Ω, and can reach 2Ω in a few working conditions. The DC side of the rectifier uses a parallel connection of resistance and capacitance to replace the train load.

[0043] The proportional gain and cutoff frequency of the train end are set to 10 and 2 respectively to reduce its response speed. If the train runs well in the section far away from the power supply station, the system will not be unstable in the section close to the power supply station. The design of future high-speed railways usually avoids the extremely far section working condition. In order to highlight the key results and avoid redundancy, the present invention omits the near, medium and extremely far section working conditions and directly compares the performance of the traditional compensation under the far section working condition close to the critical stable state.

[0044] The three-phase current of the power grid is Figure 7 As shown in the figure, in the two stages after the RPC was put into operation, there was a high degree of imbalance and high harmonic content. Under the VSG compensation condition, there was no obvious current imbalance and the harmonic reduction was more obvious. In the final stage, the a-phase train suffered a power surge beyond the rated range, and its maximum instantaneous current was 76.2A, which was much smaller than the maximum instantaneous current under the traditional compensation control condition. It can be clearly seen from the overall waveform that the current stability is better when using VSG compensation.

[0045] from Figure 8The positive and negative sequence current amplitudes can be used to more intuitively compare the compensation effect. The positive sequence amplitudes of the three stages from left to right during steady-state operation are 33.2A, 32.7A, and 44.9A, respectively, which are almost equal to the positive sequence amplitudes of 33.3A, 33.7A, and 44.6A under the remote section and traditional compensation conditions. The negative sequence amplitudes are 18.4A, 1.7A, and 1.8A, respectively, and the negative sequence amplitudes of the traditional compensation are 19A, 1.6A, and 2.5A, respectively. It can be seen that the first two stages are also relatively close, indicating that the added VSG compensation does not affect the accuracy of the RPC current compensation function. The negative sequence compensation effect of the VSG compensation in the third stage is better, and is close to the negative sequence amplitude of its own second stage, while the negative sequence amplitude of the third stage of the traditional compensation is significantly larger than the negative sequence amplitude of its own second stage, which confirms that the compensation control system of the VSG-based grid-type railway power conditioner described in the present invention has played the advantage of the grid-type converter in improving the robustness of the power grid. When the disturbance occurred at the 7th second, the negative-sequence amplitude overshoot of VSG compensation was only 1.9A, which was much smaller than the overshoot of 6.64A corresponding to the traditional control. At the 11th second, the positive-sequence overshoot of VSG compensation was about 62.8A, and the corresponding value of the traditional compensation was 68.3A, indicating that the proposed VSG compensation control, as a network-forming control, also has the effect of suppressing disturbances on the contact network.

[0046] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When the use is implemented in whole or in part in the form of a computer program product, the computer program product includes one or more computer instructions. When the computer program instructions are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL) or wireless (e.g., infrared, wireless, microwave, etc.) mode) to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk Solid State Disk (SSD)), etc.

[0047] Although the present disclosure has been described in conjunction with the specific embodiments of the present disclosure, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description. Therefore, any omissions, modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the embodiments of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A compensation control system for a grid-type railway power conditioner based on VSG, characterized in that: The control system includes a phase A contact network and a phase B contact network, which are used to convert the three-phase power grid into single-phase electricity through a V / V transformer; a step-down transformer, which is used to convert the voltage of the single-phase electricity of the contact network and output it to the RPC module, and at the same time convert the voltage level of the train power supply; The RPC module includes two back-to-back converters, which are used to adjust the output current i according to the action instructions of the converter switch tube. ra and i rb , thereby achieving the effect of negative sequence compensation for the three-phase grid current and balancing the energy flowing through the power supply arms on both sides; the VSG module is used to control the a-phase and b-phase converters respectively, according to the voltage control command value U Rxref , the voltage amplitude of the power supply arm at the RPC module interface U′ xcm , where x = a or b, and the current i ra and i rb Get the current control command value i Vrx ; Basic compensation module, used to adjust the output current command according to the current difference between the power supply arms on both sides; The current control command value i generated by the VSG module Vrx The control current command of the basic compensation control module is superimposed and the quasi-PR controller T Ri The PWM modulator sends an action instruction to the switch tube of the converter to control the output current.

2. The compensation control system of the VSG-based grid-type railway power conditioner according to claim 1 is characterized in that: The RPC module specifically includes an a-phase converter, a b-phase converter and a DC capacitor. The a-phase and b-phase converters each include two switch tube groups connected in parallel, each switch tube group includes two switch tube components connected in series, each switch tube component includes a diode and a switch connected in parallel, wherein the diode and the power semiconductor are connected in anti-parallel; the a-phase converter and the b-phase converter are respectively connected in parallel on both sides of the DC capacitor, and the output current i ra and i rb .

3. The compensation control system of the VSG-based grid-type railway power conditioner according to claim 2 is characterized in that: The VSG module specifically controls the VSG voltage command value U Rxref Voltage amplitude of the power supply arm at the interface with RPC U′ xcm / 25 difference, after droop coefficient K RVu After that, with the reactive power command value Q Vxref and the instantaneous value of the converter reactive power Q Rx The difference between the two values ​​is summed and the result is integrated and then added to the VSG voltage control command value U Rxref The result is superimposed with the angle command value θ generated by the VSG module. Rx The corresponding trigonometric function values ​​are multiplied to obtain the voltage command value U generated by VSG for the next level of compensation control RVxref ; The voltage command value U generated by the VSG module for the next level of compensation control Rvxref Voltage u' of the power supply arm at the RPC interface xc / 25 as a difference, through the quasi-PR controller T Rvu Output current control command value i Vrx .

4. The compensation control system of the VSG-based grid-type railway power conditioner according to claim 3 is characterized in that: The system also includes a power calculation module for converting the output voltage command value U of the VSG module into RVxref and the converter output current i rx Multiply them to obtain the output active power command value P Rxref and reactive power command value Q Rxref ; The voltage of the power supply arm at the RPC interface u' xc / 25 and the converter output current i rx Multiply them to obtain the active power value P output by the converter Rx And reactive power value Q Rx ; The power reference values ​​of the basic compensation module and the VSG module are consistent, so as to perform negative sequence compensation on the three-phase grid current and regulate the current on the contact network side.

5. The compensation control system of the VSG-based grid-type railway power conditioner according to claim 4 is characterized in that: The basic compensation module is used to control the DC capacitor voltage; the DC capacitor voltage command value U Rdcref and the DC side voltage U Rdc The instantaneous value of the difference is calculated by PI, and the result is compared with the angle command value θ generated by the VSG module. Rx The generated trigonometric function values ​​of phase a and phase b are multiplied, and the resulting product is added to the current compensation command value i Raref and i Rbref After that, they are respectively related to the output current i rx The instantaneous value difference of / 25 is used to obtain the control current instructions for phase a and phase b by the compensation control module.

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