PWM rectifier control method and device, electronic equipment and storage medium

Abstract

The invention provides a control method and device for a three-phase PWM (Pulse Width Modulation) rectifier, electronic equipment and a storage medium. The control method comprises the following steps of obtaining a line current # imgabs0 # in the three-phase PWM rectifier, and obtaining voltages # imgabs1 # of ac sides of all converters; obtaining a reference voltage vector # imgabs4 # based on the line current # imgabs2 # and the voltage # imgabs3 #, and obtaining flux linkage errors # imgabs7 # of all converters based on the line current # imgabs5 # and the voltage # imgabs6 #; and based on the reference voltage vector # imgabs8 # and the flux linkage error # imgabs9 #, the duty ratios of all converters are adjusted. According to the control method, the three-phase PWM rectifier can be controlled.

Description

Technical Field

[0001] The present invention relates to the field of electric power, and in particular to a control method, device, electronic equipment and storage medium for a PWM rectifier. Background Art

[0002] Three-phase PWM rectifiers are simple, robust, and low-cost. However, they generate a large amount of low-order harmonics and require additional equipment to process the remaining energy. Due to this drawback, pulse width modulation (PWM) converters with switching devices are often used to replace diode rectifiers. Figure 1 ) can sinusoidally control the input current, allowing the converter to reduce harmonic components of the input current and control the phase of the input voltage. Furthermore, this converter not only maintains a stable DC bus voltage despite load fluctuations but also regenerates excess power on the load side back into the AC power supply, achieving high efficiency and a high power factor (PF). There are four main control methods for three-phase PWM rectifiers: voltage-oriented vector control (VOC), voltage-based direct power control, virtual field-oriented control (VFOC), and virtual flux-direct power control (VF-DPC). VF-DPC is similar to the direct torque control (DTC) used in motor drives. Because VF-DPC does not require coordinate transformation and can achieve phase locking through virtual flux, its algorithm is relatively simple in practical applications. VF-DPC calculates instantaneous active and reactive power by sensing the input current and combining it with an estimated virtual flux. It then uses a hysteresis comparator and a switching table to achieve instantaneous power control. The key advantages of this method include: fast and excellent power dynamic response (especially during sudden load changes or instantaneous reference changes); low sensitivity to non-ideal supply voltages; and the absence of a pulse-width modulator.

[0003] However, VF-DPC also has some drawbacks: the power ripple amplitude is dependent on the DC bus voltage level; a high sampling frequency is required to digitize the hysteresis comparator; the switching frequency fluctuates with load conditions; achieving extremely short control cycles requires extremely high processor performance, making it extremely difficult to implement; and the limited number of voltage vectors is insufficient for precise power control. To address this, a DPC scheme based on space vector modulation (SVM) has emerged. This scheme calculates the optimal reference voltage vector and applies it to the device using SVM. This approach (generating the reference voltage vector from the active / reactive power error via a proportional-integral regulator (PI) controller) not only effectively suppresses power ripple but also offers the advantage of a fixed switching frequency. However, its dynamic performance in response to sudden load changes is affected by the PI controller gain, requiring fine-tuning of the gain parameter to meet fast response requirements. Furthermore, its dynamic response speed is still slower than that of traditional VF-DPC. Summary of the Invention

[0004] The object of the present invention is to provide a control method, device, electronic device and storage medium for a PWM rectifier.

[0005] In order to achieve one of the above-mentioned objects, an embodiment of the present invention provides a control method for a PWM rectifier, wherein the PWM rectifier is used for three-phase power, comprising the following steps: obtaining the line current in the three-phase PWM rectifier; , get the voltage on the ac side of all converters ; Based on line current and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters ; Based on the reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

[0006] As a further improvement of an embodiment of the present invention, the three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter Respectively electrically connected to phase A, phase B and phase C; the voltage on the ac side of all converters is obtained Specifically include: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter The duty cycle, for of Axis component, for of Axis component.

[0007] As a further improvement of an embodiment of the present invention, the line current-based and voltage Get the flux error of all converters Specifically include: ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

[0008] As a further improvement of an embodiment of the present invention, the line current-based and voltage Get the reference voltage vector Specifically include: , ,in, yes The angular frequency, for of Axis component, for of Axis component, is the instantaneous active power, Q is the reactive power; the amplitude of the reference voltage u* is the three-phase PWM rectifier in the control period The maximum voltage that can be generated, the angle of u* ,in, For a control cycle The rate of change of P in .

[0009] As a further improvement of an embodiment of the present invention, the reference voltage vector and flux linkage error , the duty cycle of all converters is adjusted specifically including: , reference voltage vector In polar coordinates it is , For a control cycle in The rate of change, j is the imaginary unit, is the voltage vector magnitude, is the angle between the α-axis and the d-axis, where for The d-axis component of for The q-axis component of the voltage vector And SVM algorithm to adjust the duty cycle of all converters.

[0010] The embodiment of the present invention further provides a control device for a PWM rectifier, wherein the PWM rectifier is used for three-phase power, and comprises the following modules: an information acquisition module for obtaining the line current in the three-phase PWM rectifier; , get the voltage on the ac side of all converters Processing module for line current based and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters Control module for reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

[0011] As a further improvement of an embodiment of the present invention, the three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter Electrically connected to phase A, phase B and phase C respectively The information acquisition module is also used for: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter The duty cycle, for of Axis component, for of Axis component.

[0012] As a further improvement of one embodiment of the present invention, ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

[0013] An embodiment of the present invention further provides an electronic device comprising a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction implements the steps of the above-mentioned control method when executed by the processor.

[0014] An embodiment of the present invention further provides a storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the above-mentioned control method are implemented.

[0015] Compared with the prior art, the technical effect of the present invention is that: the embodiment of the present invention provides a control method, device, electronic device and storage medium for a PWM rectifier, the control method includes the following steps: obtaining the line current in the three-phase PWM rectifier , get the voltage on the ac side of all converters ; Based on line current and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters ; Based on the reference voltage vector and flux linkage error , and adjust the duty cycle of all converters. This control method can control the three-phase PWM rectifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a topological diagram of a three-phase PWM rectifier in an embodiment of the present invention; Figure 2 is a schematic diagram of a control method in an embodiment of the present invention; Figure 3 is a schematic diagram including reference coordinates and vectors in an embodiment of the present invention; Figure 4 is a schematic diagram of a power ripple suppression strategy in an embodiment of the present invention; Figure 5 is a schematic diagram of the low-pass filter compensation in an embodiment of the present invention; Figure 6 is a schematic diagram of phase plane division in an embodiment of the present invention; Figure 7 is a schematic diagram of converter flux control in an embodiment of the present invention; Figure 8 It is a flow chart of a control method for a PWM rectifier in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0018] As used herein, terms indicating spatial relative positions, such as "upper," "above," "lower," and "below," are used for ease of explanation to describe the relationship of one element or feature relative to another element or feature as shown in the accompanying drawings. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in the drawings were turned over, elements described as being "below" or "beneath" other elements or features would then be "above" the other elements or features. Thus, the exemplary term "below" encompasses both above and below. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0019] A first embodiment of the present invention provides a control method for a PWM rectifier, wherein the PWM rectifier is used for three-phase power, such as Figure 2 and Figure 8 As shown, the following steps are included: Step 801: Obtain the line current in the three-phase PWM rectifier , get the voltage on the ac side of all converters .

[0020] Step 802: Based on line current and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters .

[0021] Step 803: Based on the reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

[0022] This control method eliminates the need for a PI controller and switching lookup table. By thoroughly analyzing the coupling relationship between grid voltage, virtual flux, power, and converter voltage, it selects the optimal voltage vector and ultimately switches the converter's duty cycle. This method eliminates the need for adjusting PI gain parameters, as required by traditional DPC-SVM. By applying voltage through precise mathematical calculations, this method accurately implements VF-DPC while avoiding overshoot, resulting in superior dynamic performance.

[0023] In this embodiment, the three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter Electrically connected to phase A, phase B and phase C respectively.

[0024] The voltage on the AC side of all converters is obtained Specifically include: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter The duty cycle, for of Axis component, for of Axis component.

[0025] Virtual flux and power estimation: Figure 3 As shown, is a stationary reference frame, and the dq reference frame is connected to the virtual magnetic flux Synchronous rotating system. Grid voltage and virtual magnet links The expression in the stationary reference frame is: , ,in, is the converter ac side voltage, is the line current, R is the line resistance, L is the line inductance, of The components can be derived from the DC bus voltage , converter Duty cycle , converter Duty cycle and converter Duty cycle Obtain, that is: .

[0026] In this embodiment, the line current and voltage Get the flux error of all converters Specifically include: ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

[0027] Under the condition of sinusoidal balanced voltage, ignoring R=0, the instantaneous active power in the stationary coordinate system is and reactive power The expression is as follows: , ,in, yes angular frequency. for of Axis component, for of Axis component, for of Axis component, for of Axis component.

[0028] Relationship between voltage vector and active power: Based on the time-varying instantaneous power, the differential formula of active power can be obtained as follows: .

[0029] and and The rate of change over time is as follows: , , , ,in, for of Axis component, for of Axis component.

[0030] Substituting the above formula into the active power differential formula, we get: , by determining 、 and The value of the control voltage Control the active power to the desired value.

[0031] In this embodiment, the line current and voltage Get the reference voltage vector Specifically include: , ,in, yes The angular frequency, for of Axis component, for of Axis component, is the instantaneous active power, Q is the reactive power; the amplitude of the reference voltage u* is the three-phase PWM rectifier in the control period The maximum voltage that can be generated, the angle of u* ,in, For a control cycle The rate of change of P in .

[0032] Calculate the reference voltage vector based on the error of active and reactive power It has two main advantages: fixed sampling period and realization of continuous voltage vector. However, since the traditional DPC-SVM method uses PI controller to calculate the control The angle and amplitude of the voltage vector are determined by the PI controller, so if the PI controller is not adjusted properly, power overshoot will occur. However, this control method does not select the voltage vector through the PI controller, but analyzes the 、 、 、 and The relationship between the two, based on the mathematical equations constructed, is calculated To precisely control the active power.

[0033] Power prediction control strategy, assuming the converter flux is , ignoring the line resistance voltage drop, the increment can be calculated as follows: , .

[0034] Substituting the above formula into the active power differential formula, we get: , assuming that in one DSP control cycle Based on the above formula, it can be deduced that the rate of change of P is affected by The impact is as follows: .

[0035] Assume that the amplitude of the reference voltage u* is The maximum voltage that the converter can generate during this period can be inferred from the above formula as the angle of u*: The purpose of this angle is to determine the correct direction of u* so that the power error is zero.

[0036] In this embodiment, the reference voltage vector and flux linkage error , the duty cycle of all converters is adjusted specifically including: , reference voltage vector In polar coordinates it is , For a control cycle in The rate of change, j is the imaginary unit, is the voltage vector magnitude, is the angle between the α-axis and the d-axis, where for The d-axis component of for The q-axis component of the voltage vector And SVM algorithm to adjust the duty cycle of all converters.

[0037] The power ripple reduction method is a two-step design. The first step is as follows: Figure 4 As shown, according to the converter flux error To determine the reference voltage in the d-axis The magnitude of the voltage vector is used to apply the non-zero voltage required for converter control. The second step is to calculate Active power errors of the same magnitude within the amplitude The predicted voltage The angle and magnitude of the voltage are used to correct the voltage previously predicted by Determine the voltage vector magnitude The prediction algorithm calculates the active power error by applying each voltage vector and selecting the voltage vector that minimizes the error. Ignoring the voltage drop across the line resistance, the voltage vector magnitude required for flux control can be obtained from the following equation: , the converter flux error can be defined as: , the obtained The amplitude of and Determined together. The predicted voltage obtained previously and converter flux error , based on the following trigonometric function equation, we can get the same active power change The magnitude and angle of: , Thus, the voltage vector that ensures the minimum power ripple can be obtained.

[0038] In actual digital implementation of virtual flux estimation, a high-pass filter is added after the pure integrator, which is equivalent to a low-pass filter. Although this eliminates DC drift, it also causes amplitude and phase deviations. Under a stable sine wave, the error can be expressed as: , ,in, yes The synchronization frequency, is the cutoff frequency of the low-pass filter. In order to eliminate the steady-state error caused by the low-pass filter, a compensation term is required, namely: .

[0039] To improve performance, the cut-off frequency should vary with the grid frequency, i.e. , where k is usually chosen to be 0.1-0.5. If k is small, the transient behavior is good, but the higher the k value, the larger the DC offset in the measurement. Pure integration is achieved when k=0. Synchronous frequency Can be based on calculate: ,in Is the differential operator. The compensator structure is shown in the figure below. Figure 5 shown.

[0040] The d-axis represents , the q-axis represents , the dq reference system can be divided into four quadrants, each of which has the following characteristics: and Symbols such as Figure 6 As shown, the area where the voltage vector is located can be selected as needed. 、 and The relationship between Figure 7 As shown. When decreasing, Ahead angle ,when When increasing, Hysteresis angle . And when and If the phase difference between them is within ±90°, The amplitude increases, otherwise it decreases. of The angle can be determined by: 1) The magnitude must be increased, 2) The magnitude must be reduced, .

[0041] After obtaining the angle increment, the reference voltage vector is output In polar coordinates it is: ,Predictive power control modular scheme, first, detect the output current to calculate the stationary reference frame Alternatively, we can first obtain Then, in the virtual flux and power estimation block, we estimate 、 and In the predictive control block, the calculation will Set to zero Angle, where 、 、 and Get the maximum duty cycle. This angle is and According to the ripple minimization controller, by and Determine the magnitude of the modified reference voltage vector and recalculate The amplitude and angle are used to correct The converter flux controller uses the calculated 、 and The hysteresis control technology obtains the final Finally, SVM is used to control the switches of the converter. Under control, if The reference value and When the values ​​of are the same, control On the other hand, by changing Reference value to increase or decrease .

[0042] A second embodiment of the present invention provides a control device for a PWM rectifier, wherein the PWM rectifier is used for three-phase power and includes the following modules: An information acquisition module is used to obtain the line current in the three-phase PWM rectifier , get the voltage on the ac side of all converters .

[0043] Processing module for line current based and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters .

[0044] Control module for reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

[0045] In this embodiment, the three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter Electrically connected to phase A, phase B and phase C respectively The information acquisition module is also used for: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter The duty cycle, for of Axis component, for of Axis component.

[0046] In this embodiment, the processing module is further configured to: ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

[0047] Embodiment 3 of the present invention provides an electronic device, including a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction, when executed by the processor, implements the steps of the control method in embodiment 1.

[0048] A fourth embodiment of the present invention provides a storage medium storing a program or instruction. When the program or instruction is executed by a processor, the steps of the control method in the first embodiment are implemented.

[0049] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0050] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for a PWM rectifier, wherein the PWM rectifier is used for three-phase power, characterized in that: The following steps are involved: Obtain the line current in the three-phase PWM rectifier , get the voltage on the ac side of all converters ; Based on line current and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters ; Based on the reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

2. The control method according to claim 1, characterized in that: The three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter electrically connected to phase A, phase B and phase C respectively; The voltage on the AC side of all converters is obtained Specifically include: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter Duty cycle , for of Axis component, for of Axis component.

3. The control method according to claim 2, characterized in that: The line current and voltage Get the flux error of all converters Specifically include: ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

4. The control method according to claim 3, characterized in that: The line current and voltage Get the reference voltage vector Specifically include: , ,in, yes The angular frequency, for of Axis component, for of Axis component, is the instantaneous active power, Q is the reactive power; The amplitude of the reference voltage u* is the value of the three-phase PWM rectifier in the control cycle The maximum voltage that can be generated, the angle of u* ,in, For a control cycle The rate of change of P in .

5. The control method according to claim 4, characterized in that: The reference voltage vector and flux linkage error , the duty cycle of all converters is adjusted specifically including: , reference voltage vector In polar coordinates it is , For a control cycle in The rate of change, j is the imaginary unit, is the voltage vector magnitude, is the angle between the α-axis and the d-axis, where for The d-axis component of for The q-axis component of After that, give the voltage vector And SVM algorithm to adjust the duty cycle of all converters.

6. A control device for a PWM rectifier, wherein the PWM rectifier is used for three-phase power, characterized in that: Includes the following modules: An information acquisition module is used to obtain the line current in the three-phase PWM rectifier , get the voltage on the ac side of all converters ; Processing module for line current based and voltage Get the reference voltage vector , based on line current and voltage Get the flux error of all converters ; Control module for reference voltage vector and flux linkage error , and adjust the duty cycle of all converters.

7. The control device according to claim 6, characterized in that The three-phase PWM rectifier is provided with a converter , converter and converter , the converter , converter and converter electrically connected to phase A, phase B and phase C respectively; The information acquisition module is also used for: ,in, is the DC bus voltage in the three-phase PWM rectifier, For converter The duty cycle, For converter The duty cycle, For converter Duty cycle , for of Axis component, for of Axis component.

8. The control device according to claim 7, characterized in that: The processing module is further configured to: ,in, is the line current, R is the line resistance, and L is the line inductance, where is the virtual magnetic link, is the grid voltage; , , ,in, is the grid voltage of Axis component, is the grid voltage of Axis component, is the flux linkage of the converter, for of Axis component, for of Axis component, for of Axis component, for of Axis component; , ,in, is the absolute value of the virtual magnetic flux.

9. An electronic device, characterized in that: The method comprises a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction, when executed by the processor, implements the steps of the control method according to any one of claims 1 to 5.

10. A storage medium, characterized in that: The storage medium stores a program or instruction, and when the program or instruction is executed by the processor, the steps of the control method according to any one of claims 1 to 5 are implemented.

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