A control method, system and electronic device of a PWM rectifier

Abstract

This application provides a control method, system, and electronic device for a PWM rectifier. The control method includes: determining the actual current of the PWM rectifier and determining a current error based on the actual current and a reference current; obtaining a first control parameter based on the current error using a preset algorithm; determining an error compensation value based on the current error using a repetitive controller, and compensating the first control parameter with the error compensation value to obtain a second control parameter; determining the fundamental frequency of the modulation wave based on the second control parameter, and obtaining a control signal based on the fundamental frequency of the modulation wave using a discontinuous pulse width modulation (DPWM) method to control the PWM rectifier. This application introduces a repetitive controller into the discontinuous pulse width modulation (DPWM) method, which improves the problem of large current harmonics caused by periodic errors due to periodic entry into clamping state in the DPWM modulation method, thereby improving control accuracy.

Description

Technical Field

[0001] This application relates to the field of rectifier control technology, and in particular to a control method, system and electronic device for a PWM rectifier. Background Technology

[0002] Traditional three-phase rectifiers generally use continuous pulse width modulation methods such as SVPWM (Space Vector Pulse Width Modulation) and discontinuous pulse width modulation methods such as DPWM (Discontinuous Pulse Width Modulation). Continuous pulse width modulation has higher losses, while discontinuous pulse width modulation can improve rectifier efficiency by keeping the switching transistor inactive for 1 / 3 of the cycle. However, discontinuous pulse width modulation can result in sudden changes in the modulation voltage or a sharp increase in the slope of the change, leading to larger current harmonics. Summary of the Invention

[0003] This application mainly provides a control method, system, and electronic device for a PWM rectifier, which helps to improve the problem of large current harmonics caused by discontinuous pulse width modulation.

[0004] To solve the above-mentioned technical problems, the first technical solution adopted in this application is: to provide a control method for a PWM rectifier, including: Determine the actual current of the PWM rectifier, and determine the current error based on the actual current and the reference current; The first control parameter is obtained based on the current error using a preset algorithm; The error compensation value is determined based on the current error using a repetitive controller. The error compensation value is then used to compensate for the first control parameter to obtain the second control parameter. The fundamental frequency of the modulation wave is determined based on the second control parameter, and the control signal is obtained based on the fundamental frequency of the modulation wave using the discontinuous pulse width modulation method to control the PWM rectifier.

[0005] In one embodiment, determining an error compensation value based on current error using a repetitive controller includes: The current error at time m in the N-1th cycle is used to compensate for the current error at time m in the Nth cycle, thereby obtaining the first current cycle error value. The error compensation value is determined based on the error value of the first current cycle.

[0006] In one embodiment, determining the error compensation value based on the first current cycle error value includes: The first current cycle error value is phase-compensated using the current error corresponding to time m+k in the (N-1)th cycle to obtain the second current cycle error value. The error compensation value is determined based on the error value of the second current cycle.

[0007] In one embodiment, after compensating for the current error at time m in the Nth period using the current error at time m in the (N-1)th period to obtain the first current period error value, the method further includes: Gain compensation is applied to the error value of the first current cycle. After using the current error corresponding to time m+k in the (N-1)th period to perform phase compensation on the first current period error value to obtain the second current period error value, the process also includes: Gain compensation is applied to the second current cycle error value; The error compensation value is determined based on the second current cycle error value, including: The error value of the second current cycle is filtered to obtain the error compensation value.

[0008] In one embodiment, determining the fundamental frequency of the modulation wave based on the second control parameter includes: Determine the decoupling parameters and the input voltage of the PWM rectifier; The fundamental frequency of the modulation wave is determined based on the second control parameter, the decoupling parameter, and the input voltage.

[0009] To solve the above-mentioned technical problems, the second technical solution adopted in this application is: to provide a control system for a PWM rectifier, including: a PWM rectifier and a control unit; the control unit is used for: Determine the actual current of the PWM rectifier, and determine the current error based on the actual current and the reference current; The first control parameter is obtained based on the current error using a preset algorithm; The error compensation value is determined based on the current error using a repetitive controller. The error compensation value is then used to compensate for the first control parameter to obtain the second control parameter. The fundamental frequency of the modulation wave is determined based on the second control parameter, and the control signal is obtained based on the fundamental frequency of the modulation wave using the discontinuous pulse width modulation method to control the PWM rectifier.

[0010] In one embodiment, the control unit is used to: The current error at time m in the N-1th cycle is used to compensate for the current error at time m in the Nth cycle, thereby obtaining the first current cycle error value; the error compensation value is determined based on the first current cycle error value.

[0011] In one embodiment, the control unit is used to: Phase compensation is performed on the first current cycle error value using the current error corresponding to the m+k time in the N-1th cycle to obtain the second current cycle error value; the error compensation value is determined based on the second current cycle error value.

[0012] In one embodiment, the control unit is further configured to: The fundamental frequency of the modulation wave is determined based on the second control parameter, the decoupling parameter, and the input voltage of the PWM rectifier.

[0013] To solve the above-mentioned technical problems, the third technical solution adopted in this application is: to provide an electronic device for implementing the control method of the PWM rectifier of any of the above-mentioned methods; and / or, the electronic device includes the control system of the PWM rectifier of any of the above-mentioned methods.

[0014] The beneficial effects of this application are as follows: Unlike existing technologies, the control method for a PWM rectifier provided in this application includes: determining the actual current of the PWM rectifier and determining the current error based on the actual current and a reference current; obtaining a first control parameter based on the current error using a preset algorithm; determining an error compensation value based on the current error using a repetitive controller, and compensating the first control parameter with the error compensation value to obtain a second control parameter; determining the fundamental frequency of the modulation wave based on the second control parameter, and obtaining a control signal based on the fundamental frequency of the modulation wave using discontinuous pulse width modulation (DPWM) to control the PWM rectifier. This application introduces a repetitive controller into the discontinuous pulse width modulation (DPWM) method, improving the problem of large current harmonics caused by periodic errors due to periodic entry into clamping state in DPWM modulation, thereby improving control accuracy. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating an embodiment of the control method for the PWM rectifier of this application; Figure 2 This is a schematic diagram of the structure of an embodiment of the control system of the PWM rectifier of this application; Figure 3 This is a schematic diagram of another embodiment of the control system of the PWM rectifier of this application. Detailed Implementation

[0017] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0018] In the following description, specific details such as particular system architectures, interfaces, and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0019] In this article, the term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, "more" in this article means two or more objects.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0021] Before providing a further detailed description of the embodiments of this application, the nouns and terms involved in the embodiments of this application will be explained, and the nouns and terms involved in the embodiments of this application shall be interpreted as follows.

[0022] It should be noted that the PWM rectifier in this application is a three-phase PWM rectifier. A three-phase PWM rectifier is a high-performance power electronic device that can achieve four-quadrant operation. By controlling the three-phase bridge arm switches through high-frequency PWM modulation, it can efficiently rectify AC power into DC power. At the same time, it can achieve unity power factor, low harmonic current, and bidirectional energy flow. It is widely used in new energy grid connection, motor drive, UPS and other fields.

[0023] Traditional three-phase PWM rectifiers generally use continuous pulse width modulation methods such as SVPWM (Space Vector Pulse Width Modulation) and discontinuous pulse width modulation methods such as DPWM (Discontinuous Pulse Width Modulation). Continuous pulse width modulation has higher losses, while discontinuous pulse width modulation can improve rectifier efficiency by keeping the switching transistor inactive for 1 / 3 of the cycle. However, discontinuous pulse width modulation can result in sudden changes in the modulation voltage or a sharp increase in the slope of the change, leading to larger current harmonics.

[0024] Based on this, this application provides a control method for a PWM rectifier. The method includes: determining the actual current of the PWM rectifier and determining a current error based on the actual current and a reference current; obtaining a first control parameter based on the current error using a preset algorithm; determining an error compensation value based on the current error using a repetitive controller, and compensating the first control parameter with the error compensation value to obtain a second control parameter; determining the fundamental frequency of the modulation wave based on the second control parameter, and obtaining a control signal based on the fundamental frequency of the modulation wave using discontinuous pulse width modulation to control the PWM rectifier. This helps to improve the problem of large current harmonics caused by discontinuous pulse width modulation.

[0025] To enable those skilled in the art to better understand the technical solutions of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] See Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the control method for the PWM rectifier of this application. Specifically, it includes: Step S11: Determine the actual current of the PWM rectifier and determine the current error based on the actual current and the reference current.

[0027] Combination Figure 2 , Figure 2 This is a schematic diagram of the control system of the PWM rectifier according to an embodiment of this application. The PWM rectifier 11 includes inductors Lfl1, Lfl2, Lfl3, Lf1, Lf2, and Lf3. Inductors Lfl1 and Lf1 are connected in series between the A-phase input and node m1; inductors Lfl2 and Lf2 are connected in series between the B-phase input and node m2; and inductors Lfl3 and Lf3 are connected in series between the C-phase input and node m3.

[0028] The PWM rectifier 11 also includes switches Q1 to Q6, wherein the first terminals of switches Q1, Q3, and Q5 are interconnected, and the second terminals of switches Q2, Q4, and Q6 are interconnected; the second terminals of switches Q1 and Q2 are connected to node m1, the second terminals of switches Q3 and Q4 are connected to node m2, and the second terminals of switches Q5 and Q6 are connected to node m3. The control terminals of switches Q1 to Q6 are connected to control unit 12.

[0029] Furthermore, Figure 2 The PWM rectifier 11 shown also includes capacitors Cf1, Cf2, Cf3, C1, and C2. Cf1 is connected between node n1 (the node between inductors Lf1 and Lf2) and ground; Cf2 is connected between node n2 (the node between inductors Lf2 and Lf2) and ground; and Cf3 is connected between node n3 (the node between inductors Lf3 and Lf3) and ground. Capacitors C1 and C2 are connected in series between the first terminal of switch Q1 and the second terminal of switch Q2.

[0030] It should be noted that in the control process of the PWM rectifier 11, the current and / or voltage of the direct axis d and the quadrature axis q need to be introduced. The control method of this application has the same calculation method for the quadrature axis q and the direct axis d. The following describes the control method of this application in detail using the calculation of the quadrature axis q and the direct axis d respectively.

[0031] Specifically, the three-phase input currents Ia, Ib, and Ic of the PWM rectifier 11 are collected. A coordinate transformation is then performed on the collected three-phase input currents Ia, Ib, and Ic to obtain the direct-axis actual current Id and the quadrature-axis actual current Iq. It can be understood that the direct-axis actual current Id and the quadrature-axis actual current Iq represent the actual currents of the PWM rectifier 11.

[0032] The output voltage Uo of the PWM rectifier 11 is further acquired, and the difference between the output voltage Uo and the reference voltage Uref is calculated to obtain the voltage difference. Based on this voltage difference, the direct-axis reference current Idref and the quadrature-axis reference current Iqref are obtained using a PI controller. It can be understood that the direct-axis reference current Idref and the quadrature-axis reference current Iqref are reference currents.

[0033] The difference between the actual direct-axis current Id and the direct-axis reference current Idref is calculated to obtain the current error, which is the direct-axis current error. The difference between the actual quadrature-axis current Iq and the quadrature-axis reference current Iqref is also calculated to obtain the current error, which is the quadrature-axis current error.

[0034] Step S12: Obtain the first control parameter based on the current error using a preset algorithm.

[0035] Specifically, the preset algorithm is, for example, a PI (proportional-integral) algorithm or a PID (proportional-integral-derivative) algorithm. Taking the PI algorithm as an example, for the direct axis, the PI algorithm is used to obtain the first control parameter based on the direct axis current error, and this first control parameter is the first direct axis control parameter. For the quadrature axis, the PI algorithm is used to obtain the first control parameter based on the quadrature axis current error, and this first control parameter is the first quadrature axis control parameter.

[0036] Step S13: Determine the error compensation value based on the current error using the repetitive controller, and use the error compensation value to compensate the first control parameter to obtain the second control parameter.

[0037] Specifically, the error compensation value is determined based on the direct-axis current error using a repetitive controller; this error compensation value is then determined based on the quadrature-axis current error; this error compensation value is then determined based on the quadrature-axis error. The direct-axis error compensation value is used to compensate for the first direct-axis control parameter, resulting in a second direct-axis control parameter, which is then used as the second control parameter. Similarly, the quadrature-axis error compensation value is used to compensate for the first quadrature-axis control parameter, resulting in a second quadrature-axis control parameter, which is then used as the second control parameter.

[0038] In one embodiment, the current error at time m in the Nth period is compensated using the current error at time m in the N-1th period to obtain a first current period error value; and an error compensation value is determined based on the first current period error value.

[0039] Specifically, for the direct axis, the direct axis current error at time m in the Nth period is compensated using the direct axis current error at time m in the N-1th period to obtain the first direct axis current cycle error value as the first current cycle error value; further, the direct axis error compensation value is determined based on the first direct axis current cycle error value. For the quadrature axis, the quadrature axis current error at time m in the N-1th period is compensated using the quadrature axis current error at time m in the Nth period to obtain the first quadrature axis current cycle error value as the first current cycle error value; further, the quadrature axis error compensation value is determined based on the first quadrature axis current cycle error value.

[0040] It should be noted that the above period refers to the switching period in the PWM rectifier.

[0041] In another embodiment, determining the error compensation value based on the first current cycle error value includes: using the current error corresponding to the m+k time in the N-1th cycle to perform phase compensation on the first current cycle error value to obtain a second current cycle error value; and determining the error compensation value based on the second current cycle error value.

[0042] Specifically, for the direct axis, the phase compensation of the first direct axis current periodic error value is performed using the direct axis current error corresponding to time m+k in the (N-1)th period to obtain the second direct axis current periodic error value; the direct axis error compensation value is then determined based on the second direct axis current periodic error value. For the quadrature axis, the phase compensation of the first quadrature axis current periodic error value is performed using the quadrature axis current error corresponding to time m+k in the (N-1)th period to obtain the second quadrature axis current periodic error value; the quadrature axis error compensation value is then determined based on the second quadrature axis current periodic error value.

[0043] In one specific embodiment, after compensating for the current error at time m in the Nth period using the current error at time m in the (N-1)th period to obtain the first current period error value, the method further includes: performing gain compensation on the first current period error value. Specifically, gain compensation is performed on the first direct-axis current period error value and the first quadrature-axis current period error value, respectively.

[0044] In one specific embodiment, after phase compensation is performed on the first current cycle error value using the current error corresponding to time m+k in the (N-1)th cycle to obtain the second current cycle error value, the method further includes: performing gain compensation on the second current cycle error value. Specifically, gain compensation is performed on the second direct-axis current cycle error value and the second quadrature-axis current cycle error value, respectively.

[0045] In one specific embodiment, determining the error compensation value based on the second current cycle error value includes: filtering the second current cycle error value to obtain the error compensation value. Specifically, the second direct-axis current cycle error value and the second quadrature-axis current cycle error value are filtered respectively to obtain the direct-axis error compensation value and the quadrature-axis error compensation value.

[0046] The first direct axis control parameter is compensated using the direct axis error compensation value to obtain the second direct axis control parameter, which is then used as the second control parameter; the first quadrature axis control parameter is compensated using the quadrature axis error compensation value to obtain the second quadrature axis control parameter, which is then used as the second control parameter.

[0047] Step S14: Determine the fundamental frequency of the modulation wave based on the second control parameter, and obtain the control signal based on the fundamental frequency of the modulation wave using the discontinuous pulse width modulation method to control the PWM rectifier.

[0048] In one specific embodiment, decoupling parameters and the input voltage of the PWM rectifier are determined. The input voltage of the PWM rectifier is the mapping value of the input voltage along the quadrature axis q and the direct axis d, denoted as the quadrature axis voltage Vq and the direct axis voltage Vd.

[0049] The fundamental frequency of the modulation wave is determined based on the second control parameter, the decoupling parameter, and the input voltage. Specifically, the decoupling parameter includes direct-axis decoupling parameters and quadrature-axis decoupling parameters. In one specific embodiment, the direct-axis voltage signal Ud is determined based on the second direct-axis control parameter, the direct-axis decoupling parameter, and the direct-axis voltage; the quadrature-axis voltage signal Uq is determined based on the second quadrature-axis control parameter, the quadrature-axis decoupling parameter, and the quadrature-axis voltage.

[0050] It should be noted that the direct-axis decoupling parameter is the actual quadrature-axis current Iq*K, and the quadrature-axis decoupling parameter is the actual direct-axis current Id*K, where K= , The input voltage angular frequency is represented by L, and the inductance value in the PWM rectifier is represented by L.

[0051] After obtaining the direct-axis voltage signal Ud and the quadrature-axis voltage signal Uq, coordinate transformation is performed on the direct-axis voltage signal Ud and the quadrature-axis voltage signal Uq to obtain the three-phase modulation wave fundamentals Ua, Ub, and Uc. Discontinuous pulse width modulation (PWM) is used to process the three-phase modulation wave fundamentals Ua, Ub, and Uc to obtain three modulation waves Umodda, Umodb, and Umodc. The three modulation waves Umodda, Umodb, and Umodc are compared with a triangular carrier wave to obtain a control signal. This control signal is used to control the power switching transistors of the PWM rectifier, for example... Figure 2 Switches Q1 to Q6 in the middle.

[0052] The PWM rectification control method of this application improves the control accuracy by setting a repetitive controller, which addresses the problem of large current harmonics caused by periodic errors due to periodic clamping in DPWM modulation. Specifically, the PWM rectification control method of this application achieves high efficiency while maintaining a low total harmonic distortion rate in the input current.

[0053] Understandably, the PWM rectification control method of this application can be applied to three-level rectifiers and multi-level rectifiers such as three-phase two-level rectifiers, three-phase flying capacitor rectifiers, three-phase NPC rectifiers, three-phase ANPC rectifiers, and three-phase T-type rectifiers.

[0054] See also Figure 2 The control system of the PWM rectifier of this application includes a PWM rectifier 11 and a control unit 12. The control unit 12 is used to determine the actual current of the PWM rectifier and determine the current error based on the actual current and a reference current; obtain a first control parameter based on the current error using a preset algorithm; determine an error compensation value based on the current error using a repetitive controller, and compensate the first control parameter using the error compensation value to obtain a second control parameter; determine the fundamental frequency of the modulation wave based on the second control parameter, and obtain a control signal based on the fundamental frequency of the modulation wave using a discontinuous pulse width modulation method to control the PWM rectifier.

[0055] Combination Figure 3 The control unit 12 acquires the three-phase input currents Ia, Ib, and Ic of the PWM rectifier 11. A coordinate transformation is performed on the acquired three-phase input currents Ia, Ib, and Ic to obtain the direct-axis actual current Id and the quadrature-axis actual current Iq. Understandably, the direct-axis actual current Id and the quadrature-axis actual current Iq are the actual currents of the PWM rectifier. Further, the output voltage Uo of the PWM rectifier 11 is acquired. The difference between the output voltage Uo and the reference voltage Uref is calculated using adder a, obtaining the voltage difference. The PI controller f then uses this voltage difference to obtain the direct-axis reference current Idref and the quadrature-axis reference current Iqref. Understandably, the direct-axis reference current Idref and the quadrature-axis reference current Iqref are the reference currents.

[0056] The difference between the actual direct-axis current Id and the direct-axis reference current Idref is calculated using adder b, thus obtaining the direct-axis current error Id_a; the difference between the actual quadrature-axis current Iq and the quadrature-axis reference current Iqref is calculated using adder c, thus obtaining the quadrature-axis current error Iq_a.

[0057] Furthermore, the first direct-axis control parameter Pd1 is obtained using PI controller g based on the direct-axis current error Id_a. The first quadrature-axis control parameter Pq1 is obtained using PI controller h based on the quadrature-axis current error Iq_a.

[0058] Specifically, repetitive controller 1 determines the direct-axis error compensation value Pd2 based on the direct-axis current error Id_a; repetitive controller 2 determines the quadrature-axis error compensation value Pq2 based on the quadrature-axis current error Iq_a. The direct-axis error compensation value Pd2 is used to compensate the first direct-axis control parameter Pd1 to obtain the second direct-axis control parameter, which is then used as the second control parameter. Similarly, the quadrature-axis error compensation value Pq2 is used to compensate the first quadrature-axis control parameter Pq1 to obtain the second quadrature-axis control parameter, which is then used as the second control parameter.

[0059] In one embodiment, the control unit 12 is configured to: compensate for the current error corresponding to the m-th time in the N-th period using the current error corresponding to the m-th time in the N-1-th period, thereby obtaining a first current period error value; and determine an error compensation value based on the first current period error value.

[0060] Specifically, for the direct axis, the direct axis current error Id_a corresponding to time m in the (N-1)th period is used. N-1（m） The direct-axis current error Id_a at time m in the Nth period N（m） Compensation is performed to obtain the first direct-axis current period error value as the first current period error value; further, the direct-axis error compensation value Pd2 is determined based on the first direct-axis current period error value. For the quadrature axis, the quadrature axis current error Iq_a corresponding to the m-th time in the (N-1)-th period is used. N-1（m） The quadrature-axis current error Iq_a at time m in the Nth period N（m） Compensation is performed to obtain the first cross-axis current period error value as the first current period error value; further, the cross-axis error compensation value Pq2 is determined based on the first cross-axis current period error value.

[0061] Furthermore, the control unit 12 is also used to: use the current error corresponding to the m+k time in the N-1th cycle to perform phase compensation on the first current cycle error value to obtain the second current cycle error value; and determine the error compensation value based on the second current cycle error value.

[0062] Specifically, for the direct axis, the direct axis current error Id_a corresponding to time m+k in the (N-1)th period is used. N-1（m+k） Phase compensation is performed on the first direct-axis current periodic error value to obtain the second direct-axis current periodic error value, which is then used as the second current periodic error value. The direct-axis error compensation value Pd2 is determined based on this second direct-axis current periodic error value. For the quadrature axis, the quadrature axis current error Iq_a corresponding to the m+k time in the (N-1)th period is used. N-1（m+k） Phase compensation is performed on the first quadrature-axis current period error value to obtain the second quadrature-axis current period error value as the second current period error value; the quadrature-axis error compensation value Pq2 is determined based on the second quadrature-axis current period error value.

[0063] In one embodiment, the control unit 12 is further configured to perform gain compensation on the first direct-axis current period error value and the first quadrature-axis current period error value, respectively.

[0064] In one embodiment, the control unit 12 is further configured to perform gain compensation on the second direct-axis current period error value and the second quadrature-axis current period error value, respectively.

[0065] In one embodiment, the control unit 12 filters the second direct-axis current period error value and the second quadrature-axis current period error value respectively to obtain the direct-axis error compensation value Pd2 and the quadrature-axis error compensation value Pq2.

[0066] The control unit 12 is also used to determine the fundamental frequency of the modulation wave based on the second control parameters, the decoupling parameters, and the input voltage of the PWM rectifier.

[0067] Specifically, the decoupling parameters and the input voltage of the PWM rectifier are determined. The input voltage of the PWM rectifier is the mapping value of the input voltage on the quadrature axis q and the direct axis d, denoted as the quadrature axis voltage Vq and the direct axis voltage Vd. The decoupling parameters include direct axis decoupling parameters and quadrature axis decoupling parameters. In one specific embodiment, adder d is used to determine the direct axis voltage signal Ud based on the second direct axis control parameters, the direct axis decoupling parameters, and the direct axis voltage Vd; adder e is used to determine the quadrature axis voltage signal Uq based on the second quadrature axis control parameters, the quadrature axis decoupling parameters, and the quadrature axis voltage Vq.

[0068] It should be noted that the direct-axis decoupling parameter is the actual quadrature-axis current Iq*K, and the quadrature-axis decoupling parameter is the actual direct-axis current Id*K, where K= , The input voltage angular frequency is represented by L, and the inductance value in the PWM rectifier is represented by L.

[0069] After performing coordinate transformation on the direct-axis voltage signal Ud and the quadrature-axis voltage signal Uq, the three-phase modulation fundamental waves Ua, Ub, and Uc are obtained. Using a DPWM modulation module with discontinuous pulse width modulation, the three-phase modulation fundamental waves Ua, Ub, and Uc are processed to obtain three modulation waves Umodda, Umodb, and Umodc. These three modulation waves Umodda, Umodb, and Umodc are compared with a triangular carrier wave to obtain a control signal. This control signal is used to control the power switching transistors of the PWM rectifier, for example... Figure 2 Switches Q1 to Q6 in the middle.

[0070] The PWM rectification control system of this application improves the problem of large current harmonics caused by periodic errors due to periodic clamping in DPWM modulation by setting a repetitive controller, thereby improving control accuracy. Specifically, the PWM rectification control method of this application has high efficiency while achieving a low total harmonic distortion rate of the input current.

[0071] This application also provides a schematic diagram of an electronic device, which includes a control system for the PWM rectifier of any of the above embodiments, and / or a control method for implementing the PWM rectifier of any of the above embodiments.

[0072] The above are merely embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A control method for a PWM rectifier, characterized in that, include: Determine the actual current of the PWM rectifier, and determine the current error based on the actual current and the reference current; The first control parameter is obtained based on the current error using a preset algorithm; The error compensation value is determined based on the current error using a repetitive controller, and the error compensation value is used to compensate the first control parameter to obtain the second control parameter; The fundamental frequency of the modulation wave is determined based on the second control parameter, and a control signal is obtained based on the fundamental frequency of the modulation wave using a discontinuous pulse width modulation method to control the PWM rectifier.

2. The control method according to claim 1, characterized in that, Determining the error compensation value based on the current error using a repetitive controller includes: The current error at time m in the N-1th period is used to compensate for the current error at time m in the Nth period, thereby obtaining the first current period error value. The error compensation value is determined based on the first current cycle error value.

3. The control method according to claim 2, characterized in that, Determining the error compensation value based on the first current cycle error value includes: The first current period error value is phase-compensated using the current error corresponding to the m+k time in the N-1th period to obtain the second current period error value; The error compensation value is determined based on the second current cycle error value.

4. The control method according to claim 3, characterized in that, After compensating for the current error at time m in the Nth period using the current error at time m in the (N-1)th period to obtain the first current period error value, the process further includes: Gain compensation is applied to the first current cycle error value; After using the current error corresponding to time m+k in the (N-1)th period to perform phase compensation on the first current period error value to obtain the second current period error value, the method further includes: Gain compensation is applied to the second current cycle error value; Determining the error compensation value based on the second current cycle error value includes: The second current cycle error value is filtered to obtain the error compensation value.

5. The control method according to any one of claims 1 to 4, characterized in that, Determining the fundamental frequency of the modulation wave based on the second control parameter includes: Determine the decoupling parameters and the input voltage of the PWM rectifier; The fundamental frequency of the modulation wave is determined based on the second control parameter, the decoupling parameter, and the input voltage.

6. A control system for a PWM rectifier, characterized in that, include: PWM rectifier and control unit; the control unit is used for: Determine the actual current of the PWM rectifier, and determine the current error based on the actual current and the reference current; The first control parameter is obtained based on the current error using a preset algorithm; The error compensation value is determined based on the current error using a repetitive controller, and the error compensation value is used to compensate the first control parameter to obtain the second control parameter; The fundamental frequency of the modulation wave is determined based on the second control parameter, and a control signal is obtained based on the fundamental frequency of the modulation wave using a discontinuous pulse width modulation method to control the PWM rectifier.

7. The system according to claim 6, characterized in that, The control unit is used for: The current error at time m in the N-1th cycle is compensated by the current error at time m in the Nth cycle to obtain a first current cycle error value; the error compensation value is determined based on the first current cycle error value.

8. The system according to claim 7, characterized in that, The control unit is used for: The first current cycle error value is phase-compensated using the current error corresponding to the m+k time in the (N-1)th cycle to obtain the second current cycle error value; the error compensation value is determined based on the second current cycle error value.

9. The system according to claim 6, characterized in that, The control unit is also used for: The fundamental frequency of the modulation wave is determined based on the second control parameter, the decoupling parameter, and the input voltage of the PWM rectifier.

10. An electronic device, characterized in that, The electronic device is used to implement the control method of the PWM rectifier according to any one of claims 1 to 5; and / or, the electronic device includes the control system of the PWM rectifier according to any one of claims 6 to 9.

Images