A Control Method, Device, Equipment and Storage Medium for a Three-Phase Four-Wire PWM Rectifier

Abstract

The present invention relates to a control method, device, equipment and storage medium for a three-phase four-wire PWM rectifier. The method includes: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer loop; based on the current inner loop, determining a current difference according to the inductor current on the AC side of the three-phase four-wire PWM rectifier and the current reference value; setting an initial bias amount, and inputting the initial bias amount and the current difference into a PID controller to calculate a duty cycle for controlling the three-phase four-wire PWM rectifier. The present invention first determines the current reference value by controlling the designed voltage outer loop, then based on the designed current inner loop, determines the current difference according to the current reference value and the inductor current on the AC side, then sets the initial bias amount to determine the current bias value, and finally, the inductor current on the AC side and the output voltage of the three-phase four-wire PWM rectifier can be adjusted only by one PID controller. The control algorithm is simple, the analysis process is concise, and it is suitable for engineering practice.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular, to a control method, device, equipment and storage medium for a three-phase four-wire PWM rectifier. Background Art

[0002] The three-phase PWM rectifier is a common power electronic device. Compared with the three-phase three-wire PWM rectifier, the three-phase four-wire PWM rectifier can better suppress the DC component of the input current, greatly improve the waveform quality of the input current, and further improve the power factor of the rectifier. Therefore, the three-phase four-wire PWM rectifier is put into use more and more.

[0003] Currently, there are many control strategies for the three-phase four-wire PWM rectifier, such as single-cycle control, using the virtual orthogonal transformation method to achieve zero-static error control of the input current, using fractional-order repetitive control to suppress grid-side current harmonics, etc. These control strategies generally require two PID controllers, or even three PID controllers to complete the control, and can produce good control results for a certain aspect of the PWM rectifier.

[0004] However, the current control strategy of the three-phase four-wire PWM rectifier needs to be completed by multiple PID controllers, its control algorithm is relatively complex, the analysis process is cumbersome, and it cannot control the three-phase four-wire PWM rectifier in a timely manner, which is not conducive to engineering practice. Summary of the Invention

[0005] In view of this, it is necessary to provide a control method, device, equipment and storage medium for a three-phase four-wire PWM rectifier to solve the problem in the prior art that the control of the three-phase four-wire PWM rectifier needs to be completed by multiple PID controllers, resulting in a relatively complex control algorithm, a cumbersome analysis process, and the inability to control the three-phase four-wire PWM rectifier in a timely manner, which is not conducive to engineering practice.

[0006] To achieve the above technical purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a control method for a three-phase four-wire PWM rectifier, including:

[0008] Determine a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer-loop circuit;

[0009] Based on the current inner-loop circuit, determine a current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value;

[0010] Set an initial bias, and input the initial bias and the current difference into a PID controller to calculate the duty cycle for controlling the three-phase four-wire PWM rectifier.

[0011] In some possible implementation manners, based on the voltage outer loop, determining a current reference value according to the output voltage of a three-phase four-wire PWM rectifier includes:

[0012] Generating a duty ratio wave table according to a duty ratio expression and an initial value of an auto-reload register of a microcontroller timer;

[0013] Setting a phase offset, and determining a current standard value according to the phase offset and the duty ratio wave table;

[0014] Performing a step adjustment on the output voltage according to a wave table coefficient and the current standard value to determine the current reference value.

[0015] In some possible implementation manners, generating a duty ratio wave table according to a duty ratio expression and an initial value of an auto-reload register of a microcontroller timer includes:

[0016] The duty ratio expression is:

[0017]

[0018] where D is the duty ratio value, N is the number of values in the wave table, k is a specific value from 0 to N, and m is the modulation degree;

[0019] Determining the values in the wave table according to the initial value of the auto-reload register of the microcontroller timer;

[0020] Generating a duty ratio wave table according to the values in the wave table and the duty ratio expression.

[0021] In some possible implementation manners, determining a current standard value according to a phase offset and a duty ratio wave table includes:

[0022] Judging the half cycle in which the phase voltage is located;

[0023] Determining a wave table index value according to the half cycle in which the phase voltage is located and the duty ratio wave table;

[0024] Determining the current standard value according to the wave table index value and the phase offset.

[0025] In some possible implementation manners, performing a step adjustment on the output voltage according to a wave table coefficient and a current standard value to determine a current reference value includes:

[0026] Setting an initial wave table coefficient;

[0027] If the initial wave table coefficient does not meet a preset condition, adjusting the initial wave table coefficient until the output voltage meets a preset voltage reference value to obtain a target wave table coefficient;

[0028] Multiplying the target wave table coefficient and the current standard value to obtain the current reference value.

[0029] In some possible implementation manners, inputting an initial bias amount and a current difference into a PID controller to calculate a duty cycle for controlling a three-phase four-wire PWM rectifier, including:

[0030] Determining a plurality of consecutive current bias values according to the initial bias amount and the current difference;

[0031] After based on the discrete expression of the PID controller, calculating a duty cycle according to the plurality of current bias values;

[0032] Adjusting the AC-side inductor current and the output voltage of the three-phase four-wire PWM rectifier according to the duty cycle.

[0033] In some possible implementation manners, the discrete expression of the PID controller is as follows:

[0034] Δu(k) = K p [e r (k) - e r (k - 1)] + K i e r (k) + K d [e r (k) - 2e r (k - 1) + e r (k - 2)];

[0035] Wherein, Δu(k) represents the duty cycle output by the controller, K p , K i , K d respectively represent the gain coefficients of proportional, integral and differential, e r (k), e r (k - 1), e r (k - 2) respectively represent the current bias value at the k-th time, the current bias value at the (k - 1)-th time and the current bias value at the (k - 2)-th time.

[0036] In a second aspect, the present invention further provides a control device for a three-phase four-wire PWM rectifier, including:

[0037] A voltage loop module, configured to determine a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and voltage outer loop circuit parameters;

[0038] A current loop module, configured to determine a current difference based on the current inner loop, according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value;

[0039] A control module, configured to set an initial bias amount, and input the initial bias amount and the current difference into a PID controller to calculate a duty cycle for controlling the three-phase four-wire PWM rectifier.

[0040] Third aspect, the present invention further provides a three-phase four-wire PWM rectifier control device, including a memory and a processor, wherein,

[0041] The memory is used for storing programs;

[0042] The processor is coupled to the memory and is used for executing the programs stored in the memory to implement the steps in the three-phase four-wire PWM rectifier control method in any of the above implementation manners.

[0043] Fourth aspect, the present invention further provides a computer-readable storage medium for storing computer-readable programs or instructions. When the programs or instructions are executed by a processor, the steps in the three-phase four-wire PWM rectifier control method in any of the above implementation manners can be implemented.

[0044] The beneficial effects of adopting the above embodiments are as follows: The present invention relates to a three-phase four-wire PWM rectifier control method, device, equipment and storage medium. The method includes: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer loop; based on the current inner loop, determining a current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value; setting an initial bias amount, and inputting the initial bias amount and the current difference into a PID controller to calculate a duty cycle for controlling the three-phase four-wire PWM rectifier. The present invention first determines the current reference value through the designed voltage outer loop, then determines the current difference based on the designed current inner loop according to the current reference value and the AC-side inductor current, and then determines the current bias value by setting the initial bias amount. Through the double-loop closed-loop control of the voltage outer loop and the current inner loop in sequence, finally, the AC-side inductor current and the output voltage of the three-phase four-wire PWM rectifier can be adjusted only by one PID controller, reducing the number of PID controllers, making the control algorithm simpler and the analysis process more concise. Therefore, it can be better applied to engineering practice. Description of the Drawings

[0045] Figure 1 It is a schematic flow chart of an embodiment of the three-phase four-wire PWM rectifier control method provided by the present invention;

[0046] Figure 2 It is a schematic structural diagram of an embodiment of the three-phase four-wire PWM rectifier control system provided by the present invention;

[0047] Figure 3 Provided by the present invention Figure 1 It is a schematic flow chart of an embodiment of step S101 in the above;

[0048] Figure 4 It is a partial schematic diagram of an embodiment of the duty cycle look-up table provided by the present invention;

[0049] Figure 5 provided by the present invention Figure 2 A schematic flow chart of an embodiment of step S202 in

[0050] Figure 6 provided by the present invention Figure 2 A schematic flow chart of an embodiment of step S203 in

[0051] Figure 7 A schematic flow chart of an embodiment of controlling a three-phase four-wire PWM rectifier provided by the present invention;

[0052] Figure 8 A schematic structural diagram of an embodiment of a three-phase four-wire PWM rectifier control device provided by the present invention;

[0053] Figure 9 A schematic structural diagram of a three-phase four-wire PWM rectifier control device provided by an embodiment of the present invention. Specific embodiments

[0054] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0055] In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0056] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0057] The present invention provides a three-phase four-wire PWM rectifier control method, device, equipment, and storage medium, which will be described separately below.

[0058] Please refer to Figure 1 , Figure 1 A schematic flow chart of an embodiment of the three-phase four-wire PWM rectifier control method provided by the present invention. A specific embodiment of the present invention discloses a three-phase four-wire PWM rectifier control method, including:

[0059] S101. Determine a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer loop;

[0060] S102. Based on the current inner loop, determine the current difference according to the AC-side inductor current and the current reference value of the three-phase four-wire PWM rectifier;

[0061] S103. Set an initial bias, and input the initial bias and the current difference into the PID controller to calculate the duty cycle for controlling the three-phase four-wire PWM rectifier.

[0062] In the above embodiment, the three-phase four-wire PWM rectifier is a unified circuit, and its control needs to be implemented in the overall control system. Please refer to Figure 2 , Figure 2 which is a schematic structural diagram of an embodiment of the three-phase four-wire PWM rectifier control system provided by the present invention. The output voltage of the three-phase four-wire PWM rectifier first passes through the voltage outer loop, is compared with the preset reference voltage and adjusted, so that the output voltage gradually approaches the preset reference voltage, achieving the effect of the output voltage tracking the reference voltage. At this time, the current corresponding to the output voltage is the current reference value.

[0063] It should be noted that Figure 2 in the loop where the output voltage of the three-phase four-wire PWM rectifier in [[ ]] passes through the filter, is compared with the voltage reference value to obtain the changing voltage, and then passes through the voltage regulator to obtain the current reference value, this is the voltage outer loop; Figure 2 in the loop where the AC-side inductor current of the three-phase four-wire PWM rectifier in [[ ]] passes through the filter, is compared with the current reference value, and passes through the overcurrent protection to reach the discrete PID controller, this is the current inner loop.

[0064] The current inner loop can control the AC-side inductor current to keep it constant, control the AC-side inductor current of the three-phase four-wire PWM rectifier according to the current reference value output by the voltage outer loop, determine the current difference between the AC-side inductor current and the current reference value, and transmit this difference as an input to the PID controller.

[0065] The initial bias can be adjusted subsequently and input to the PID controller through the capacitor voltage equalizer. It is to control the current difference and the bias, adjust the duty cycle of the three-phase four-wire PWM rectifier, so as to realize the control of the output voltage and the AC-side inductor current of the three-phase four-wire PWM rectifier, make the actual AC-side inductor current follow the current reference value in the wave table, and realize the sinusoidalization of the input current.

[0066] It should be noted that, since the three-phase four-wire PWM rectifier has multiple phases, in order to control the three-phase four-wire PWM rectifier, it is necessary to be able to control a single phase. Therefore, the present invention needs to determine the relationship between the phases by constructing an average equivalent model of the three-phase four-wire PWM rectifier, determine the relationship between the bridge arm voltage and the DC side voltage according to the topological structure and switching mode of the three-phase four-wire PWM rectifier, and then determine the state equation of the three-phase four-wire PWM rectifier and the average duty cycle of the three bridge arms, and further derive the average equivalent model of the three-phase four-wire PWM rectifier according to the switching cycle averaging method, thereby determining that each phase of the three-phase four-wire PWM rectifier circuit is independent of each other, and there is no coupling relationship between them, and the three-phase four-wire PWM rectifier circuit can be decomposed into three independent unidirectional full-bridge rectifiers.

[0067] It is understandable that the preset reference voltage and initial bias can be adjusted according to the actual use needs, and the present invention does not impose further restrictions on this. As a preferred embodiment, the initial bias is artificially set to a constant (about 200), and the PID controller will adjust on this basis during operation to reduce the voltage difference between the upper and lower tubes.

[0068] Compared with the prior art, the present embodiment provides a three-phase four-wire PWM rectifier control method, the method comprising: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop parameter; determining a current difference according to the AC side inductor current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner loop; setting an initial bias, and inputting the initial bias and the current difference into a PID controller to calculate the duty cycle to control the three-phase four-wire PWM rectifier. The present invention first determines the current reference value by controlling the designed voltage outer loop, and then determines the current difference according to the current reference value and the AC side inductor current based on the designed current inner loop, and then determines the current bias value by setting the initial bias, successively through the double-loop closed control of the voltage outer loop and the current inner loop, and finally only through a PID controller to adjust the AC side inductor current and output voltage of the three-phase four-wire PWM rectifier, reducing the number of PID controllers, making the control algorithm simpler, and the analysis process more concise, so it can be better put into engineering practice.

[0069] In order to achieve precise control of the three-phase four-wire PWM rectifier, the first step of control is to design a voltage outer loop. Figure 3 , Figure 3 The present invention provides Figure 1 In some embodiments of the present invention, the current reference value is determined according to the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer loop, including:

[0070] S301. Generate a duty cycle wave table based on the duty cycle expression and the initial value of the auto - reload register of the microcontroller timer;

[0071] S302. Set the phase offset, and determine the current standard value according to the phase offset and the duty cycle wave table;

[0072] S303. Perform a step - by - step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine the current reference value.

[0073] In the above - mentioned embodiment, first, the initial value of the auto - reload register of the microcontroller timer is set. The initial value of the auto - reload register of the microcontroller timer is related to the duty cycle. The duty cycle wave table can be determined through the initial value of the auto - reload register of the microcontroller timer, realizing the adjustment of the current reference value output by the voltage outer loop, which is beneficial to the subsequent control of the current inner loop.

[0074] The phase offset Phase means that there will be a certain deviation in the current of different phases. By setting the phase offset Phase, an accurate current standard value can be determined, which is beneficial to the adjustment and control of the voltage outer loop, and thus the current reference value can be accurately determined. It can be understood that the phase offset Phase can be adjusted according to the actual situation, and the present invention does not make further limitations in this regard. As a preferred embodiment, the initially set value of the phase offset Phase is 0, and it can be adjusted according to the need of the power factor.

[0075] An initial value also needs to be set for the wave table coefficient in advance. By multiplying the wave table coefficient by the current standard value, a step - by - step adjustment of the voltage outer loop can be performed in advance. Through subsequent adjustment of the wave table coefficient, the output voltage of the three - phase four - wire PWM rectifier gradually approaches the preset reference voltage, and finally the voltage outer loop outputs the current reference value.

[0076] In some embodiments of the present invention, generating a duty cycle wave table based on the duty cycle expression and the initial value of the auto - reload register of the microcontroller timer includes:

[0077] The duty cycle expression is:

[0078]

[0079] where D is the duty cycle value, N is the number of values in the wave table, k is a specific value from 0 to N, and m is the modulation degree;

[0080] Determine the values in the wave table according to the initial value of the auto - reload register of the microcontroller timer;

[0081] Generate a duty cycle wave table according to the values in the wave table and the duty cycle expression.

[0082] In the above embodiment, the duty cycle expression of the SPWM wave is derived according to the symmetric rule sampling method. In this embodiment, please refer to Figure 4 , Figure 4 which is a partial schematic diagram of an embodiment of the duty cycle wave table provided by the present invention. The initial value of the automatic reload register of the single-chip microcomputer timer is set to 4000 (that is, when the value in the wave table is 4000, the corresponding duty cycle at this time is 1). However, when initially adjusting, in order to leave a margin for up and down adjustment, the present invention takes the register values corresponding to the median and peak values of the duty cycle to be around 2000, and then a duty cycle wave table of a certain number of switching devices can be generated through the duty cycle expression (the number generated by the present invention is 400, which can be set by itself according to the accuracy requirements).

[0083] Please refer to Figure 5 , Figure 5 which is a schematic flowchart of an embodiment of step S202 provided by the present invention. In some embodiments of the present invention, determining the current standard value according to the phase offset and the duty cycle wave table includes: Figure 2

[0084] S501. Determine the half cycle in which the phase voltage is located;

[0085] S502. Determine the wave table index value according to the half cycle in which the phase voltage is located and the duty cycle wave table;

[0086] S503. Determine the current standard value according to the wave table index value and the phase offset.

[0087] In the above embodiment, the state of the phase voltage is divided into a positive half cycle and a negative half cycle. First, a zero-crossing detection circuit is set up, the zero-crossing detection circuit is connected to the I / O interface of the single-chip microcomputer, and the timer interrupt is set to the rising / falling edge trigger mode. This design can judge whether the phase voltage is in the positive half cycle or the negative half cycle, so that the corresponding value in the duty cycle wave table is used as a reference value and input into the PID controller, that is, which reference value will be input into the PID for processing, and then the initial value of the phase offset can be set. The positive and negative half cycles of the phase voltage where it is located will affect the determined current standard value.

[0088] In the present invention, taking the phase voltage in the positive half cycle as an example for illustration, the following is the wave table index value when the single-chip microcomputer detects the falling edge, that is, when the AC voltage is about to be in the positive half cycle:

[0089]

[0090] Among them, i u_index , i v_index , i w_index respectively represent the wave table index values of different three-phase currents.

[0091] ​In order to achieve the phase shift of the AC - side current, generate the phase difference between the AC - side voltage and current, and further adjust the power factor of the rectifier, in the present invention, while passing through the zero - crossing point, a phase - offset value Phase (the initial set value of Phase is 0 and can be adjusted according to the need of the power factor) is added simultaneously after the three - phase index value. That is, when the AC voltage is about to enter the positive half - cycle, there is:

[0092]

[0093] That is, the current standard value is obtained.

[0094] Please refer to Figure 6 , Figure 6 which is a schematic flow diagram of an embodiment of step S203 provided by the present invention. In some embodiments of the present invention, the output voltage is step - adjusted according to the wavetable coefficient and the current standard value to determine the current reference value, including: Figure 2 Figure 2

[0095] S601. Set the initial wavetable coefficient;

[0096] S602. If the initial wavetable coefficient does not meet the preset conditions, adjust the initial wavetable coefficient until the output voltage meets the preset voltage reference value to obtain the target wavetable coefficient;

[0097] S603. Multiply the target wavetable coefficient by the current standard value to obtain the current reference value.

[0098] In the above - mentioned embodiment, the present invention uses the introduction of the wavetable coefficient M multiplied by the current reference value, that is, multiplying the current standard value by M to achieve the step - adjustment of the voltage and obtain the current reference value. The specific method is as follows: The DC - side output voltage of the three - phase four - wire PWM rectifier is collected through the direct memory access mode of the ADC. After digital filtering, the result is compared with the reference value. If the actual voltage is greater than the reference value, the value of M will be reduced; conversely, the value of M will be increased. After continuous step - adjustment, the output voltage can be stabilized near the reference value, that is, ΔU approaches 0.

[0099] Please refer to Figure 7 , Figure 7 which is a schematic flow diagram of an embodiment of controlling the three - phase four - wire PWM rectifier provided by the present invention. In some embodiments of the present invention, the initial bias and the current difference are input into the PID controller to calculate the duty cycle to control the three - phase four - wire PWM rectifier, including:

[0100] S701. Determine a series of continuous current bias values according to the initial bias and the current difference;

[0101] S702. Based on the discrete expression of the PID controller, calculate the duty cycle according to the multiple current bias values;

[0102] S703. Adjust the AC-side inductor current and output voltage of the three-phase four-wire PWM rectifier according to the duty cycle.

[0103] In some embodiments of the present invention, the discrete expression of the PID controller is as follows:

[0104] Δu(k) = K p [e r (k) - e r (k - 1)] + K i e r (k) + K d [e r (k) - 2e r (k - 1) + e r (k - 2)];

[0105] where Δu(k) represents the duty cycle output by the controller, and K p , K i , K d represent the proportional, integral, and differential gain coefficients respectively, and e r (k), e r (k - 1), e r (k - 2) represent the current bias value at the k-th time, the current bias value at the (k - 1)-th time, and the current bias value at the (k - 2)-th time respectively.

[0106] In the above embodiments, to achieve the DC-side capacitor voltage equalization control, the present invention adds a bias amount DC_Bias to the input end of the PID controller, that is, the input of the PID controller is:

[0107] e r (k) = I ADC (k) - I ref (k) + DC_Bias;

[0108] where I ADC (k) represents the AC-side inductor current of the three-phase four-wire PWM rectifier collected at the k-th time through the ADC, and I ref (k) represents the k-th current reference value output by the voltage outer loop.

[0109] The PID controller adjusts and controls according to the register, and the output is the increment of the duty cycle to be set this time, so as to make the actual AC-side inductor current follow the current reference value calculated by the voltage outer loop, thereby realizing the sinusoidalization of the input current.

[0110] The single-chip microcomputer detects the total DC voltage on the DC side of the three-phase four-wire PWM rectifier and the capacitor voltage of the lower switch. If the total voltage is greater than twice the voltage of the lower switch, the bias amount DC_Bias is increased; otherwise, the bias amount DC_Bias is decreased. Since the DC component of the current in the neutral line is equal to the sum of the DC components of the three-phase currents and is also equal to the difference between the DC components of the capacitor currents of the upper and lower groups, the difference between the capacitor voltages of the upper and lower switches can be adjusted by simultaneously increasing or decreasing the DC component of the three-phase four-wire PWM rectifier, thereby realizing the control of the three-phase four-wire PWM rectifier. It should be noted that the PID controller in this embodiment is an incremental discrete PID controller.

[0111] To better implement the three-phase four-wire PWM rectifier control method in the embodiments of the present invention, based on the three-phase four-wire PWM rectifier control method, correspondingly, please refer to Figure 8 , Figure 8 FIG. is a schematic structural diagram of an embodiment of a three-phase four-wire PWM rectifier control device provided by the present invention. The embodiments of the present invention provide a three-phase four-wire PWM rectifier control device 800, including:

[0112] A voltage loop module 810, configured to determine a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer loop circuit parameters;

[0113] A current loop module 820, configured to determine a current difference based on the current inner loop, according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value;

[0114] A control module 830, configured to set an initial bias amount, and input the initial bias amount and the current difference into a PID controller to calculate a duty ratio for controlling the three-phase four-wire PWM rectifier.

[0115] It should be noted here that: the device 800 provided in the above embodiment can implement the technical solutions described in the above method embodiments. The specific implementation principles of the above modules or units can be referred to the corresponding content in the above method embodiments, and will not be elaborated here.

[0116] Please refer to Figure 9 , Figure 9 FIG. is a schematic structural diagram of a three-phase four-wire PWM rectifier control device provided by an embodiment of the present invention. Based on the above three-phase four-wire PWM rectifier control method, the present invention also correspondingly provides a three-phase four-wire PWM rectifier control device. The three-phase four-wire PWM rectifier control device may be a computing device such as a mobile terminal, a desktop computer, a notebook, a palm computer, and a server. The three-phase four-wire PWM rectifier control device includes a processor 910, a memory 920, and a display 930. Figure 9Only some components of the three-phase four-wire PWM rectifier control device are shown, but it should be understood that it is not required to implement all the shown components, and more or fewer components can be implemented alternatively.

[0117] The memory 920 may be an internal storage unit of the three-phase four-wire PWM rectifier bridge control device in some embodiments, such as the hard disk or memory of the three-phase four-wire PWM rectifier bridge control device. The memory 920 may also be an external storage device of the three-phase four-wire PWM rectifier bridge control device in other embodiments, such as a plug-in hard disk equipped on the three-phase four-wire PWM rectifier bridge control device, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory 920 may also include both an internal storage unit and an external storage device of the three-phase four-wire PWM rectifier bridge control device. The memory 920 is used to store application software installed on the three-phase four-wire PWM rectifier bridge control device and various types of data, such as program codes for installing the three-phase four-wire PWM rectifier bridge control device. The memory 920 may also be used to temporarily store data that has been output or will be output. In one embodiment, a three-phase four-wire PWM rectifier bridge control program 940 is stored on the memory 920, and the three-phase four-wire PWM rectifier bridge control program 940 can be executed by the processor 910, thereby implementing the three-phase four-wire PWM rectifier bridge control method of various embodiments of the present application.

[0118] The processor 910 may be a central processing unit (CPU), a microprocessor, or other data processing chips in some embodiments, and is used to run the program codes stored in the memory 920 or process data, such as executing the three-phase four-wire PWM rectifier bridge control method.

[0119] The display 930 may be an LED display, a liquid crystal display, a touch liquid crystal display, and an OLED (Organic Light-Emitting Diode) toucher, etc. in some embodiments. The display 930 is used to display information on the three-phase four-wire PWM rectifier bridge control device and to display a visual user interface. The components 910-930 of the three-phase four-wire PWM rectifier bridge control device communicate with each other through the system bus.

[0120] In one embodiment, when the processor 910 executes the three-phase four-wire PWM rectifier bridge control program 940 in the memory 920, the steps in the above three-phase four-wire PWM rectifier bridge control method are implemented.

[0121] This embodiment also provides a computer-readable storage medium, on which a three-phase four-wire PWM rectifier control program is stored. When the three-phase four-wire PWM rectifier control program is executed by a processor, the following steps are implemented:

[0122] Determine a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer-loop circuit parameters;

[0123] Based on the current inner-loop circuit, determine a current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value;

[0124] Set an initial bias amount, and input the initial bias amount and the current difference into a PID controller to calculate a duty ratio for controlling the three-phase four-wire PWM rectifier.

[0125] In summary, a three-phase four-wire PWM rectifier control method, device, equipment, and storage medium provided in this embodiment. The method includes: determining a current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the voltage outer-loop circuit parameters; based on the current inner-loop circuit, determining a current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value; setting an initial bias amount, and inputting the initial bias amount and the current difference into a PID controller to calculate a duty ratio for controlling the three-phase four-wire PWM rectifier. The present invention first determines a current reference value through the designed voltage outer loop, then based on the designed current inner loop, determines a current difference according to the current reference value and the AC-side inductor current, and then determines a current bias value by setting an initial bias amount. Through the double-loop closed-loop control of the voltage outer loop and the current inner loop in sequence, finally, only one PID controller can be used to adjust the AC-side inductor current and the output voltage of the three-phase four-wire PWM rectifier, reducing the number of PID controllers, making the control algorithm simpler, and the analysis process more concise. Therefore, it can be better applied to engineering practice.

[0126] As described above, only the specific preferred embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A control method for a three-phase four-wire PWM rectifier, characterized in that, Including: Determine the current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer-loop circuit; Based on the current inner-loop circuit, determine the current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value; Set an initial bias and input the initial bias and the current difference into a PID controller to calculate the duty cycle for controlling the three-phase four-wire PWM rectifier; The determining the current reference value according to the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer-loop includes: Generate a duty-cycle wave table according to the duty-cycle expression and the initial value of the auto-reload register of the microcontroller timer; Set a phase offset and determine the current standard value according to the phase offset and the duty-cycle wave table; Perform a step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine the current reference value.

2. The three-phase four-wire PWM rectifier control method according to claim 1, wherein, The generating a duty-cycle wave table according to the duty-cycle expression and the initial value of the auto-reload register of the microcontroller timer includes: The duty-cycle expression is: ； Among them, is the duty ratio, is the number of median values in the wave table, is from 0 to a specific value among them, is the modulation degree; Determine the value in the wave table according to the initial value of the auto-reload register of the microcontroller timer; Generate a duty-cycle wave table according to the value in the wave table and the duty-cycle expression.

3. The three-phase four-wire PWM rectifier control method according to claim 1, wherein The determining the current standard value according to the phase offset and the duty-cycle wave table includes: Judge the half-cycle in which the phase voltage is located; Determine the wave table index value according to the half-cycle in which the phase voltage is located and the duty-cycle wave table; Determine the current standard value according to the wave table index value and the phase offset.

4. The three-phase four-wire PWM rectifier control method according to claim 1, characterized in that The performing a step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine the current reference value includes: Set an initial wave table coefficient; If the initial wave table coefficient does not meet the preset condition, adjust the initial wave table coefficient until the output voltage meets the preset voltage reference value to obtain the target wave table coefficient; Multiply the target wave table coefficient and the current standard value to obtain the current reference value.

5. The three-phase four-wire PWM rectifier control method according to claim 1, characterized in that, The inputting the initial bias and the current difference into a PID controller to calculate the duty cycle for controlling the three-phase four-wire PWM rectifier includes: Determine a plurality of consecutive current bias values according to the initial bias and the current difference; Based on the discrete expression of the PID controller, calculate the duty cycle according to the plurality of current bias values; Adjust the AC-side inductor current and the output voltage of the three-phase four-wire PWM rectifier according to the duty cycle.

6. The three-phase four-wire PWM rectifier control method according to claim 5, characterized in that The discrete expression of the PID controller is as follows: ； Among them, represents the duty cycle output by the controller, , , respectively represent the gain coefficients of proportional, integral, and derivative, , , respectively represent the k -th current bias value, the k-1 -th current bias value, and the k-2 -th current bias value.

7. A three-phase four-wire PWM rectifier control device, characterized in that, Including: A voltage-loop module for determining the current reference value according to the output voltage of the three-phase four-wire PWM rectifier and the parameters of the voltage outer-loop circuit; A current-loop module for determining the current difference according to the AC-side inductor current of the three-phase four-wire PWM rectifier and the current reference value based on the current inner-loop circuit; A control module for setting an initial bias and inputting the initial bias and the current difference into a PID controller to calculate the duty cycle for controlling the three-phase four-wire PWM rectifier; The determining the current reference value according to the output voltage of the three-phase four-wire PWM rectifier based on the voltage outer-loop includes: Generate a duty-cycle wave table according to the duty-cycle expression and the initial value of the auto-reload register of the microcontroller timer; Set a phase offset and determine a current standard value according to the phase offset and the duty cycle wave table; Perform a step adjustment on the output voltage according to the wave table coefficient and the current standard value to determine the current reference value.

8. A three-phase four-wire PWM rectifier control device, characterized in that, It includes a memory and a processor, wherein, The memory is used to store programs; The processor is coupled to the memory and is used to execute the program stored in the memory to implement the steps in the three-phase four-wire PWM rectifier control method described in any one of claims 1 to 6 above.

9. A computer-readable storage medium, characterized in that, It is used to store computer-readable programs or instructions, and when the programs or instructions are executed by a processor, the steps in the three-phase four-wire PWM rectifier control method described in any one of claims 1 to 6 above can be implemented.

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