Power supply device and control method thereof

Abstract

A power supply device includes a three-phase AC voltage source, a rectifier circuit, and a controller. The rectifying circuit comprises a plurality of switching tubes and a plurality of capacitors. The controller is configured to obtain three-phase sampling current of three-phase alternating current output by the three-phase alternating current voltage source; acquiring sampling voltages of the plurality of capacitors; obtaining a direct current sampling voltage and a midpoint current of the power supply device according to the sampling voltages of the plurality of capacitors; obtaining a three-phase modulation voltage of the power supply device according to the DC sampling voltage and the three-phase sampling current; according to the midpoint current, the three-phase sampling current and the three-phase modulation voltage, a zero-sequence voltage of the power supply device is obtained; and according to the zero sequence voltage and the three-phase modulation voltage, a three-phase synthesis driving control quantity of the power supply device is obtained, and the three-phase synthesis driving control quantity is used for pulse width modulation of the plurality of switch tubes.

Description

Power supply device and control method thereof

[0001] This application claims priority to Chinese patent application No. 202211573840.8 filed on December 8, 2022, and Chinese patent application No. 202310203037.3 filed on March 3, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the technical field of air-conditioning power supplies, and in particular to a power supply device and a control method thereof. Background Art

[0003] Currently, in three-phase AC power supply air conditioning systems, due to cost factors, three-phase AC power supply air conditioning systems generally use an uncontrolled rectifier circuit provided in the three-phase AC power supply circuit as a power input terminal.

[0004] Summary of the Invention

[0005] In one aspect, a power supply device is provided. The power supply device includes a three-phase AC voltage source, a rectifier circuit, and a controller. The three-phase AC voltage source is configured to output three-phase AC power. The rectifier circuit is configured to convert the three-phase AC power into DC power. The rectifier circuit includes multiple switching transistors and multiple capacitors. The controller is connected to the three-phase AC voltage source and the rectifier circuit. The controller is configured to: obtain three-phase sampled data of the three-phase AC power, wherein the three-phase sampled data includes three-phase sampled currents; obtain sampled voltages of the multiple capacitors; obtain a DC sampled voltage and a midpoint current of the power supply device based on the sampled voltages of the multiple capacitors; obtain a three-phase modulation voltage of the power supply device based on the DC sampled voltage and the three-phase sampled currents; obtain a zero-sequence voltage of the power supply device based on the midpoint current, the three-phase sampled currents, and the three-phase modulation voltage; and obtain a three-phase composite drive control variable of the power supply device based on the zero-sequence voltage and the three-phase modulation voltage, wherein the three-phase composite drive control variable is used for pulse width modulation of the multiple switching transistors.

[0006] On the other hand, a control method for a power supply device is provided. The control method for the power supply device is executed at a controller of the power supply device. The power supply device includes: a three-phase AC voltage source, a rectifier circuit, and the controller; the rectifier circuit includes multiple switching tubes and multiple capacitors; and the controller is connected to the three-phase AC voltage source and the rectifier circuit. The control method includes: obtaining three-phase sampling data of the three-phase AC power output by the three-phase AC voltage source, wherein the three-phase sampling data includes three-phase sampling current; obtaining sampling voltages of the multiple capacitors; obtaining a DC sampling voltage and a midpoint current of the power supply device based on the sampling voltages of the multiple capacitors; obtaining a three-phase modulation voltage of the power supply device based on the DC sampling voltage and the three-phase sampling current; obtaining a zero-sequence voltage of the power supply device based on the midpoint current, the three-phase sampling current, and the three-phase modulation voltage; and obtaining a three-phase composite drive control quantity of the power supply device based on the zero-sequence voltage and the three-phase modulation voltage; the three-phase composite drive control quantity is used for pulse width modulation of the multiple switching tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1A is a schematic diagram of an air conditioner according to some embodiments of the present disclosure;

[0008] FIG1B is a schematic diagram of a power supply device according to some embodiments of the present disclosure;

[0009] FIG2 is a schematic diagram of another power supply device according to some embodiments of the present disclosure;

[0010] FIG3 is a curve showing changes in sampled voltages of a plurality of capacitors according to some embodiments of the present disclosure;

[0011] FIG4 is a schematic diagram of another power supply device according to some embodiments of the present disclosure;

[0012] FIG5 is a schematic diagram of a sampling current of a power supply device after steady state according to some embodiments of the present disclosure;

[0013] FIG6 is a schematic diagram of a controller according to some embodiments of the present disclosure;

[0014] FIG7 is a schematic diagram of another controller according to some embodiments of the present disclosure;

[0015] FIG8 is a schematic diagram of yet another controller according to some embodiments of the present disclosure;

[0016] FIG9 is a schematic diagram of a phase-locked loop of a second-order generalized integrator according to some embodiments of the present disclosure;

[0017] FIG10 is a schematic diagram of a second-order generalized integrator according to some embodiments of the present disclosure;

[0018] FIG11 is a Bode plot of a closed-loop transfer function according to some embodiments of the present disclosure;

[0019] FIG12 is a schematic diagram of yet another controller according to some embodiments of the present disclosure;

[0020] FIG13 is a schematic diagram of another power supply device according to some embodiments of the present disclosure;

[0021] FIG14 is a flow chart of a method for controlling a power supply device according to some embodiments of the present disclosure;

[0022] FIG15 is a flowchart of another method for controlling a power supply device according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe some embodiments of the present disclosure in conjunction with the accompanying drawings. However, the described embodiments are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0024] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that the particular features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0025] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0026] When describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. The term "connected" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or a communication between two elements. The term "coupled" is used to indicate that two or more components are in direct physical or electrical contact. However, the term "coupled" or "communicatively coupled" may also refer to two or more components that are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents of this document.

[0027] As used herein, the term "if" is optionally interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined that" or "if [stated condition or event] is detected" are optionally interpreted to mean "upon determining" or "in response to determining" or "upon detecting [stated condition or event]" or "in response to detecting [stated condition or event]," depending on the context.

[0028] The use of "for" or "configured to" herein is intended to be open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

[0029] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0030] In the home appliance sector, electronic devices (such as air conditioners) are typically connected to the power grid through a rectifier. A rectifier is typically a nonlinear circuit consisting of a diode, an inductor, and a capacitor. The inductor is relatively large, and the capacitors are numerous. When the sinusoidal voltage from the grid is applied to the nonlinear circuit, the sinusoidal current becomes non-sinusoidal, generating harmonics that fail to meet standard requirements. Furthermore, the nonlinear circuit generates reactive power pollution, resulting in a low power factor. The power factor here can be understood as the ratio of effective power to apparent power.

[0031] In the air conditioning field, single-phase AC air conditioning systems use power factor correction (PFC) circuits to monitor and control the voltage and current in the circuit, adjust the reactive power in the circuit, improve the power factor of the single-phase air conditioning system, and suppress current harmonics generated in the power grid that do not meet standard requirements.

[0032] Compared to single-phase AC air conditioning systems, three-phase AC air conditioning systems have higher output power and efficiency, lower losses, and better stability, and are therefore in increasing demand in the market. Currently, harmonic content can be reduced by adjusting the parameters of the circuit components in the rectifier of a three-phase AC air conditioning system, for example, by adjusting the inductance of the inductor and the capacitance of the capacitor in the rectifier. However, adjusting the parameters of circuit components to reduce harmonic content carries certain risks. In actual use, it is easily affected by certain factors and cannot completely eliminate the harmonic content. In addition, adjusting the parameters of circuit components will result in a larger circuit inductor and an increased number of capacitors, thereby increasing the occupied space.

[0033] Based on this, an embodiment of the present disclosure provides a power supply device (also referred to as a power supply circuit), which is applied to a three-phase AC air-conditioning system and can efficiently eliminate harmonic content without increasing the occupied space.

[0034] FIG1A is a schematic diagram of the structure of an air conditioner provided by some embodiments of the present disclosure. As shown in FIG1A , the air conditioner 1000 includes an indoor unit 100 and an outdoor unit 200. The indoor unit 100 and the outdoor unit 200 are connected by a pipeline to transmit refrigerant.

[0035] Illustratively, the indoor unit 100 includes an indoor heat exchanger 400 and an indoor fan 600. The outdoor unit 200 includes a compressor 206, a four-way valve 207, an outdoor heat exchanger 208, an outdoor fan 209, and an expansion valve 210. The compressor 206, the outdoor heat exchanger 208, the expansion valve 210, and the indoor heat exchanger 400, connected in sequence, form a refrigerant circuit. Refrigerant circulates in the refrigerant circuit, exchanging heat with air through the outdoor heat exchanger 208 and the indoor heat exchanger 400, respectively, to achieve cooling mode or heating mode for the air conditioner 1000.

[0036] In some examples, the air conditioner 1000 is connected to a power supply device for supplying power to the air conditioner 1000. For example, the power supply device can be connected to the compressor 206 and the outdoor fan 209 in the outdoor unit 200 to supply power to the compressor 206 and the outdoor fan 209.

[0037] FIG1B is a schematic diagram of the structure of a power supply device provided in some embodiments of the present disclosure. The power supply device is applied to the air conditioner 1000 described above. As shown in FIG1B , the power supply device 10 provided in the embodiments of the present disclosure includes a three-phase AC voltage source 1011 and a rectifier circuit 1012.

[0038] Exemplarily, the rectifier circuit 1012 in the power supply device 10 can be disposed inside the air conditioner 1000 , and the three-phase AC voltage source 1011 can be disposed outside the air conditioner 1000 .

[0039] In some embodiments, the three-phase AC voltage source 1011 can be understood as receiving AC power from the power grid and can be considered equivalent to the power grid. The rectifier circuit 1012 can be understood as a rectifier, which is a three-phase rectifier circuit. For example, the three-phase rectifier circuit can be a three-phase Vienna rectifier circuit (also known as a three-phase Vienna topology circuit). It is understood that the air conditioner is connected to the power grid via the rectifier circuit.

[0040] The three-phase AC voltage source 1011 is configured to output three-phase AC power. For example, the three-phase AC power output by the three-phase AC voltage source 1011 consists of three sinusoidal signals with the same frequency, equal potential amplitude, and a phase difference of 120 degrees. This three-phase AC power is used as the power input of the power supply device 10. The rectifier circuit 1012 is configured to convert the three-phase AC power output by the three-phase AC voltage source 1011 into DC power.

[0041] FIG2 is a schematic diagram of the structure of a power supply device 10 provided in some embodiments of the present disclosure. In some embodiments, as shown in FIG2 , the three-phase voltages of the three-phase AC voltage source 1011 are Ea, Eb, and Ec, respectively. The rectifier circuit 1012 includes multiple switching transistors and multiple capacitors. Exemplarily, the rectifier circuit 1012 includes switching transistors Q1, Q2, Q3, Q4, Q5, and Q6, and capacitors C1 and C2 (i.e., a first capacitor C1 and a second capacitor C2). For example, the capacitor can be a DC bus filter capacitor.

[0042] In some embodiments, as shown in FIG2 , the power supply device 10 further includes resistors R1, R2, and R3, inductors L1, L2, and L3, and a load RL. The rectifier circuit 1012 further includes diodes D1, D2, D3, D4, D5, and D6. The load RL can be understood as the variable frequency drive circuit for the compressor and fan in an air conditioner, or as a conventional DC resistive load. The resistors R1, R2, and R3 can be understood as the equivalent resistance of the inductors L1, L2, and L3.

[0043] Illustratively, resistors R1 , R2 and R3 , inductors L1 , L2 and L3 , and capacitors C1 and C2 constitute the passive part of the power supply device 10 ; switches Q1 , Q2 , Q3 , Q4 , Q5 and Q6 constitute the active part of the power supply device 10 .

[0044] As shown in Figure 2, diodes D1, D2, D3, D4, D5, and D6 are connected in pairs to form a three-phase bridge arm. Switching tubes Q1, Q2, Q3, Q4, Q5, and Q6 are connected in pairs to form a three-phase bridge arm. The three-phase voltages Ea, Eb, and Ec are coupled to a node N. Inductor L1 is connected in series between one end of the power supply for providing three-phase voltage Ea and the cathode of diode D1. Inductor L2 is connected in series between one end of the power supply for providing three-phase voltage Eb and the cathode of diode D2. Inductor L3 is connected in series between one end of the power supply for providing three-phase voltage Ec and the cathode of diode D3. The anodes of diodes D1, D2, and D3 are all connected to node P1. The cathodes of diodes D4, D5, and D6 are all connected to node P2. The anode of diode D4 is connected to the cathode of diode D1, the anode of diode D5 is connected to the cathode of diode D2, and the anode of diode D6 is connected to the cathode of diode D3. One end of the switches Q2, Q4, and Q6 is connected to midpoint O. Switches Q1 and Q2 are connected in series, with one end of switch Q1 and the cathode of diode D1 connected to node A. Switches Q3 and Q4 are connected in series, with one end of switch Q3 and the cathode of diode D2 connected to node B. Switches Q5 and Q6 are connected in series, with one end of switch Q5 and the cathode of diode D3 connected to node C. One end of capacitor C1 is connected to node P1, and the other end of capacitor C1 is connected to node S. One end of capacitor C2 is connected to node S, and the other end of capacitor C2 is connected to node P2. Node S between capacitors C1 and C2 and midpoint O can be considered to be the same node.

[0045] It is understood that, based on the operating principle of a rectifier, if the voltage on the DC side of the rectifier is stable, the generated drive pulses are stable and the current harmonic content is low; if the voltage on the DC side of the rectifier is unstable, the generated drive pulses are also unstable and the current harmonic content is high. Therefore, the voltage difference between capacitors C1 and C2 in the rectifier circuit 1012 affects the stability of the DC voltage output by the rectifier circuit 1012 and also affects the harmonic content of the current on the grid side.

[0046] In view of this, by balancing the DC side midpoint voltage between capacitors C1 and C2 through the rectifier circuit 1012, the DC side voltage deviation between the two capacitors C1 and C2 can be reduced, thereby effectively suppressing the midpoint voltage fluctuation and reducing the harmonic content on the AC side.

[0047] The following describes the relationship between various circuit parameters in the power supply device according to the embodiment of the present disclosure.

[0048] The mathematical model of the three-phase voltage of the rectifier circuit in the three-phase stationary coordinate system can be expressed as formula (1-1):

[0049] Among them, L can be understood as the inductance value of inductors L1, L2 and L3; R represents the resistance value of resistors R1, R2 and R3, which can also be equivalent to the resistance value of inductors L1, L2 and L3; V AO It can be understood as the voltage between node A and midpoint O; V BO It can be understood as the voltage between node B and midpoint O; V CO It can be understood as the voltage between the node C and the midpoint O; ia, ib and ic can be understood as the input current of the rectifier circuit 1012.

[0050] Since the three phases of three-phase AC power are symmetrical with each other and there is no neutral line, the voltage relationship between the midpoint O on the DC side and the midpoint N on the AC side of the power supply device 10 can be obtained as follows (1-2):

[0051] When the power supply device 10 is in steady state, without considering the influence of inductance and resistance, the three-phase voltages Ea, Eb and Ec and V can be obtained by combining formula (1-1) and formula (1-2). AO 、V BO and V CO The relationship (1-3) is:

[0052] The relationship between the voltage and current direction controlled by the switch in the rectifier circuit 1012 (1-4) is as follows:

[0053] Among them, the switch tubes Q1 and Q2 control the voltage V AO ; Switch tubes Q3 and Q4 control voltage V BO ; Switch tubes Q5 and Q6 control voltage V CO ;sign() can be understood as a sign function; 1-d a , 1-d b and 1-d c It can be understood as the modulation wave signal before the power supply device 10 is in steady state; V dc It can be understood as the voltage on the DC side of the power supply device 10, that is, the sum of the voltages of the capacitors C1 and C2 (for example, the voltages of the capacitors C1 and C2 can be understood as the sampling voltage V of the capacitors C1 and C2 described below). dcp and V dcn , then V dc =V dcp +V dcn ).

[0054] Since the input voltage and input current of the rectifier circuit 1012 are in phase, the power factor is 1, that is, unity power factor; the equivalent resistance of each phase input of the rectifier circuit 1012 is defined as R e, the relationship between the input voltage and input current of the rectifier circuit 1012 (1-5) is as follows:

[0055] Combining formulas (1-3), (1-4) and (1-5), we can obtain the following formula (1-6):

[0056] Among them, V m is the steady-state output voltage of the DC side of the power supply device 10, and R S is the equivalent input current sampling resistor of the input current of the rectifier circuit 1012.

[0057] According to formula (1-6), the core control equation (1-7) of the rectifier circuit 1012 can be obtained:

[0058] On this basis, in some embodiments of the present disclosure, as shown in FIG1B , the power supply device 10 further includes a controller 102 . The controller 102 is connected to at least the rectifier circuit 1012 , and can control the multiple switches Q1 to Q6 in the rectifier circuit 1012 .

[0059] In some examples, the controller 102 can be a processing device or chip capable of processing data or running program instructions, such as a central processing unit (CPU), a microcontroller unit (MCU), an application specific integrated circuit (ASIC), a programmable logic device (PLD), etc.

[0060] The controller 102 is configured to: obtain three-phase sampling data of the three-phase alternating current output by the three-phase alternating current voltage source 1011 , the three-phase sampling data including three-phase sampling current; and obtain sampling voltages of multiple capacitors in the rectifier circuit.

[0061] It can be understood that the three-phase sampling currents are ia, ib and ic. In the case where the plurality of capacitors include a first capacitor C1 and a second capacitor C2, the sampling voltages of the plurality of capacitors may include the sampling voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor C2 dcn .

[0062] Exemplarily, the power supply device includes a sampling circuit configured to sample three-phase AC power to obtain three-phase sampled data, and to sample multiple capacitors to obtain sampled voltages of the multiple capacitors. For example, the sampling circuit may be composed of circuit elements such as capacitors, resistors, and operational amplifiers, although this is not limited in the embodiments of the present disclosure.

[0063] The controller 102 is further configured to obtain a DC sampling voltage and a mid-point current of the power supply device 10 according to the sampling voltages of the plurality of capacitors.

[0064] The DC sampling voltage of the power supply device 10 can be understood as the sampling voltage of the DC side of the power supply device 10, that is, the above-mentioned V m For example, the sampling voltages of the first capacitor C1 and the second capacitor C2 are V dcp and V dcn At this time, the DC sampling voltage V m It can be expressed as V m =KⅹV dc =K×(V dcp +V dcn ), where K is a fixed constant (i.e. ).

[0065] In some embodiments, the controller 102 is further configured to obtain a DC sampling voltage of the power supply device 10 according to a preset voltage reference value and the sampling voltages of the plurality of capacitors.

[0066] In the case where the plurality of capacitors include a first capacitor C1 and a second capacitor C2, the controller 102 generates a voltage signal based on a preset voltage reference value, a sampling voltage V of the first capacitor C1, and a voltage signal V dcp and the sampling voltage V of the second capacitor C2 dcn , get the DC sampling voltage V of the power supply device 10 m .

[0067] For example, the controller 102 determines the preset voltage reference value V dc ' and the sampling voltage V of the first capacitor C1 dcp and the sampling voltage V of the second capacitor C2 dcn The sum V dc The difference between the DC sampling voltage V of the power supply device 10 is determined. m The preset voltage reference value may refer to the third voltage reference value described below, which has a value range of 600V to 800V. Those skilled in the art may set the preset voltage reference value according to the working principle and actual conditions.

[0068] The midpoint current of the power supply device 10 can be understood as the current at the midpoint O between the first capacitor C1 and the second capacitor C2. In some embodiments, the controller 102 is further configured to obtain the midpoint current of the power supply device 10 based on the capacitance of one of the multiple capacitors, the sampled voltages of the multiple capacitors, and the sampling period of the power supply device 10. For example, the sampling period can range from 1 kHz to 100 kHz.

[0069] In the case where the plurality of capacitors include a first capacitor C1 and a second capacitor C2, the controller 102 generates a voltage signal based on the capacitance value of the first capacitor C1 or the capacitance value of the second capacitor C2, the sampling voltage V dcp and the sampling voltage V of the second capacitor C2 dcn , and the sampling period of the power supply device 10, and obtain the midpoint current of the power supply device 10.

[0070] For example, the midpoint current is expressed as Among them, I npcon represents the midpoint current, C represents the capacitance value of the first capacitor C1 or the capacitance value of the second capacitor C2, T s Indicates the sampling period of the power supply device 10 .

[0071] In some embodiments, the midpoint current is used to balance the sampling voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor C2 dcn The deviation can be controlled to be within the permissible range. That is, by using the midpoint current, the deviation can be kept small, or even zero. This can avoid the generation of current harmonics on the AC side of the circuit.

[0072] The controller 102 is further configured to: m And the three-phase sampling current ia, ib and ic are used to obtain the three-phase modulation voltage of the power supply device 10.

[0073] The three-phase modulation voltage of the power supply device 10 can be understood as the 1-d a , 1-d b and 1-d c For example, 1-d a , 1-d b and 1-d c It can be a sine wave signal.

[0074] For example, according to the above formula (1-7), the three-phase modulation voltage 1-d a , 1-d b and 1-d c Respectively expressed as:

[0075] In some embodiments, the controller 102 is further configured to npcon , three-phase sampling current ia, ib and ic, and three-phase modulation voltage 1-d a , 1-d b and 1-d c , and obtain the zero-sequence voltage of the power supply device 10.

[0076] For example, the zero-sequence voltage V0 is expressed as:

[0077] Among them, V ral 、V rbl and V rcl Represents the three-phase modulation voltage 1-d respectively a , 1-d b and 1-d c .

[0078] Since the three-phase modulation voltage is constantly changing when the power supply device 10 has not reached a steady state, in the embodiment of the present disclosure, the zero-sequence voltage V0 is superimposed on the three-phase modulation voltage 1-d. a , 1-d b and 1-d c In the process, the modulated three-phase modulation voltage is obtained. In this way, when the power supply device 10 reaches a steady state, the modulated three-phase modulation voltage will change stably.

[0079] Superimpose the zero-sequence voltage V0 on the three-phase modulation voltage 1-d a , 1-d b and 1-d c It can be understood as a balanced control of the midpoint voltage in the power supply device 10. The midpoint voltage here can be understood as the sampling voltage V of the second capacitor C2. dcn .

[0080] The controller 102 is further configured to obtain a three-phase composite drive control variable of the power supply device 10 according to the zero-sequence voltage and the three-phase modulation voltage. The three-phase composite drive control variable is used for pulse width modulation of multiple switching tubes in the rectifier circuit 1012.

[0081] For example, the three-phase composite drive control quantity V ra 、V rb and V rc Respectively expressed as: V ra =V ral +V0,V rb =V rbl +V0,V rc =V rcl +V0.

[0082] Among them, the three-phase composite drive control quantity V ra、V rb and V rc It can be understood as the three-phase modulation voltage 1-d a , 1-d b and 1-d c (i.e. V ral 、V rbl and V rcl ) is modulated by the zero-sequence voltage V0 to obtain a new sinusoidal signal. It can be understood that by modulating the three-phase modulation voltage 1-d according to the zero-sequence voltage V0 a , 1-d b and 1-d c The sine wave signal is modulated to obtain a new sine wave signal. According to the new sine wave signal, the pulse width modulation of the multiple switch tubes in the rectifier circuit 1012 can be performed, so as to control the sampling voltage V dcp and the sampling voltage V of the second capacitor C2 dcn Therefore, by balancing the midpoint voltage in the power supply device 10, the sampling voltage V of the first capacitor C1 can be reduced. dcp And the sampling voltage V of the second capacitor C2 dcn The voltage deviation is reduced, thereby reducing the current harmonic content on the three-phase AC voltage source side.

[0083] In some embodiments, FIG3 shows a curve showing a change in the sampling voltage of the capacitor in the rectifier circuit 1012 provided by some embodiments of the present disclosure. Curve X1 represents the sampling voltage V of the first capacitor C1. dcp , curve X2 represents the sampling voltage V of the second capacitor C2 dcn As shown in FIG3 , the rectifier circuit 1012 starts at 0.5s; at 1s, the zero-sequence voltage V0 is superimposed on the three-phase modulation voltage V ral 、V rbl and V rcl Before the power supply device 10 performs modulation (for example, in the time period of 0.5s to 1s in FIG3 ), the sampling voltage V dcp and the sampling voltage V of the second capacitor C2 dcn The deviation between them is large, and the current harmonic content of the three-phase AC voltage source side (i.e., the AC side of the power supply device) is high. After the power supply device 10 is modulated (for example, after 1s in Figure 3), the sampling voltage V dcp and the sampling voltage V of the second capacitor C2 dcn The deviation between them is reduced, and the current harmonic content on the three-phase AC voltage source side is reduced.

[0084] In some embodiments, the three-phase synthetic drive control quantity is modulated by the zero-sequence voltage to obtain a sinusoidal wave signal, which is compared with the carrier signal output by the controller 102 to output a square wave signal. The square wave signal is used to perform pulse width modulation on the switches Q1, Q2, Q3, Q4, Q5 and Q6 in the rectifier circuit 1012, thereby driving the switches Q1, Q2, Q3, Q4, Q5 and Q6 in the rectifier circuit 1012 to open and close, so as to achieve balanced control of the midpoint voltage of the first capacitor C1 and the second capacitor C2.

[0085] When the power supply device 10 is in a steady state, the three-phase sampled currents ia, ib, and ic change steadily, and their waveforms can be seen in FIG5 . It is understood that, as shown in FIG5 , the signal of the sampled current of each phase is ideally a sinusoidal wave, but in practice it changes steadily with the sub-ripple fluctuation of the switching frequency.

[0086] Therefore, in the embodiment of the present disclosure, the rectifier circuit 1012 in the power supply device 10 can balance the midpoint voltage of the DC side of the power supply device 10. Based on the method of zero-sequence voltage injection, a single-cycle control strategy is used to control the midpoint current to balance the voltage of the first capacitor C1 and the second capacitor C2. The single-cycle control strategy controls the midpoint current by superimposing the zero-sequence voltage on the three-phase modulation voltage 1-d after obtaining the midpoint current and the zero-sequence voltage. a , 1-d b and 1-d c , and obtain the three-phase composite drive control quantity of the power supply device 10. That is, through simple addition and subtraction operations, six drive signals for simultaneously switching the three-phase circuit (for example, six drive signals for controlling the six switches Q1 to Q6) can be obtained to achieve a balanced DC side midpoint voltage of the power supply device 10.

[0087] If the midpoint voltage is not superimposed, the voltage deviation between the first capacitor C1 and the second capacitor C2 is large, and the harmonic content of the AC side current is high. Therefore, the embodiment of the present disclosure can effectively suppress the fluctuation of the DC side midpoint voltage of the power supply device 10 and reduce the current harmonic content generated on the grid side.

[0088] Moreover, the algorithm adopted in the embodiment of the present disclosure is simple, low-cost, and occupies little controller memory. At the same time, it adds midpoint voltage balance control based on zero-sequence components, which can effectively stabilize the bus voltage and reduce current harmonics on the grid side to meet standard requirements.

[0089] In some embodiments, as shown in FIG. 4 , the controller 102 includes a first control subcircuit 701 , a second control subcircuit 702 , a third control subcircuit 703 , and a pulse width modulation subcircuit 704 .

[0090] The controller 102 samples the three-phase AC voltage source 1011 to obtain the three-phase sampled currents ia, ib and ic, and samples the first capacitor C1 and the second capacitor C2 to obtain the sampled voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor C2 dcn .

[0091] The first control subcircuit 701 (which may be referred to as a voltage loop control loop) is configured to: dcp and the sampling voltage V of the second capacitor C2 dcn The sampled voltage V on the DC side of the power supply device is obtained m For example, in the first control subcircuit 701, the preset voltage reference value V dc 'Subtract the sampling voltage V of the first capacitor C1 dcp and the sampling voltage V of the second capacitor C2 dcn The sum of V dc The difference is processed by the voltage controller to obtain the sampling voltage V on the DC side of the power supply device. m .

[0092] The third control subcircuit 703 (which may be referred to as a single-cycle control loop) is configured to: m The three-phase modulation voltage V of the power supply device is obtained by combining the three-phase sampling current ia, ib and ic ral 、V rbl and V rcl .

[0093] The second control subcircuit 702 (which may be referred to as a balance loop control loop) is configured to: dcp and the sampling voltage V of the second capacitor C2 dcn Get the midpoint current I of the power supply device npcon ; According to the midpoint current I npcon , three-phase sampling current ia, ib and ic, and three-phase modulation voltage V ral 、V rbl and V rcl The zero-sequence voltage V0 of the power supply device is obtained. For example, in the second control subcircuit 702, the sampling voltage V dcp , the sampling voltage V of the second capacitor C2 dcn The three-phase sampling currents ia, ib and ic are balanced by a balancing controller.

[0094] The third control subcircuit 703 is further configured to superimpose the zero-sequence voltage V0 on the three-phase modulation voltage V ral 、V rbl and V rcl, get the three-phase synthetic drive control quantity V of the power supply device ra 、V rb and V rc .

[0095] The pulse width modulation sub-circuit 704 is configured to synthesize the three-phase drive control quantity V ra 、V rb and V rc After comparison with the carrier signal provided by the controller 102, a square wave signal is outputted for pulse width modulation of the switches Q1, Q2, Q3, Q4, Q5 and Q6 of the rectifier circuit 1012. The carrier signal here may be a triangular wave signal.

[0096] It should be noted that the specific implementation process of each function of the first control subcircuit 701, the second control subcircuit 702, the third control subcircuit 703 and the pulse width modulation subcircuit 704 can be referred to the above description and will not be repeated here.

[0097] In some embodiments, the voltage and current of a three-phase AC voltage source can be represented by a vector in the complex plane, which is a space vector. In field-oriented control (FOC), there are two coordinate transformations: one from a stationary abc coordinate system to a stationary αβ coordinate system, and the other from a stationary αβ coordinate system to a rotating dq coordinate system. The directions of the spatial voltage vectors of the three-phase voltages Ea, Eb, and Ec can be described using the vector reference directions of the stationary abc coordinate system. By summing the spatial voltage vectors of the three-phase voltages Ea, Eb, and Ec, a spatial composite voltage vector with constant magnitude and uniform rotation is synthesized. Because the spatial composite voltage vector is a rotating vector, it is difficult to describe it using the three-phase stationary abc coordinate system. Therefore, a two-phase stationary αβ coordinate system is introduced, in which the α and β axes are orthogonal, and the α axis of the two-phase stationary αβ coordinate system is selected to coincide with the a direction of the three-phase stationary abc coordinate system. It is understood that the spatial composite voltage vector still rotates in the two-phase stationary αβ coordinate system.

[0098] The rotating dq coordinate system can rotate synchronously with the spatial composite voltage vector. The coordinate axes are the d-axis and q-axis, where the d-axis and q-axis are orthogonal. Decomposing the components of the spatial composite voltage vector on the d-axis and q-axis into the α-axis and β-axis yields a transformation from the two-phase stationary αβ coordinate system to the rotating dq coordinate system. Furthermore, the components of the spatial composite voltage vector in the rotating dq coordinate system are constant.

[0099] Because the current of rectifier circuit 1012 (i.e., a three-phase Vienna rectifier circuit or a three-phase Vienna topology circuit) is AC in the stationary abc coordinate system, the proportional-integral (PI) controller in rectifier circuit 1012 has difficulty eliminating steady-state errors. Furthermore, in the stationary abc coordinate system, rectifier circuit 1012 is not very effective in suppressing harmonics. Therefore, in the embodiments of the present disclosure, the implementation of rectifier circuit 1012 is primarily based on a rotating dq coordinate system.

[0100] In the embodiment of the present disclosure, the controller 102 can receive the three-phase AC voltage source sampling voltage (Ea, Eb and Ec) and the three-phase AC voltage source sampling current (ia, ib and ic) and the sampling capacitor voltage (V dcp and V dcn ) is converted into the three-phase AC voltage source sampling voltage (Ed and Eq), the three-phase AC voltage source sampling current (id and iq) and the sampling capacitor voltage (V dcp and V dcn ). The controller 102 calculates the three-phase AC voltage source sampling voltage (Ed and Eq), the three-phase AC voltage source sampling current (id and iq) and the sampling capacitor voltage (V dcp and V dcn ) is calculated to obtain the voltage control quantity, which controls the duty cycle of the switch tubes Q1, Q2, Q3, Q4, Q5 and Q6 in the three-phase Vienna topology circuit. The three-phase AC voltage source sampling voltage (Ed and Eq) and the three-phase AC voltage source sampling current (id and iq) in the rotated dq coordinate system after coordinate transformation are DC quantities. The duty cycle here can be understood as the proportion of the high level in a pulse cycle to the entire cycle, which can be used to control the conduction time of the switch tube. For example, 1 second of high level and 1 second of low level, the duty cycle is 50%.

[0101] Therefore, in the embodiment of the present disclosure, the three-phase AC voltage source in the power supply device 10 is rectified using a three-phase Vienna topology circuit, and the sampled three-phase AC voltage source sampled voltages (Ea, Eb, and Ec) and three-phase AC voltage source sampled currents (ia, ib, and ic) in the stationary abc coordinate system are converted into three-phase AC voltage source sampled voltages (Ed and Eq) and three-phase AC voltage source sampled currents (id and iq) in the rotating dq coordinate system. This converts the AC quantity in the three-phase Vienna topology circuit into a DC quantity, thereby better filtering out the harmonics generated in the three-phase Vienna topology circuit and improving the power factor of the three-phase Vienna topology circuit.

[0102] In some embodiments, the controller 102 acquires three-phase sampled data of three-phase AC power, including three-phase sampled currents and three-phase sampled voltages. For example, the three-phase sampled currents are ia, ib, and ic; and the three-phase sampled voltages are Ea, Eb, and Ec. For example, a sampling circuit in a power supply device samples the three-phase AC power to obtain three-phase sampled currents and three-phase sampled voltages. The sampling circuit may be composed of circuit elements such as resistors, capacitors, or operational amplifiers.

[0103] The controller 102 (eg, the phase locking module in the controller 102 shown in FIG. 7 ) is configured to lock the phase θ1 of the voltage of the grid used to supply power to the power supply device 10 .

[0104] For example, the controller 102 uses a phase-locked loop (PLL) based on a second-order general integrator (SOGI) to lock the phase of the grid voltage. When the grid voltage is unbalanced, harmonics are typically generated. The SOGI can shift the input voltage of the power supply device 10 by 90 degrees and filter out higher-order harmonics generated by the unbalanced grid. Therefore, even when the grid voltage is unbalanced, the PLL can stably lock the phase θ1 of the grid voltage.

[0105] Grid voltage is alternating current, and its magnitude and direction vary with time. For example, the trigonometric expression for a sinusoidal AC voltage is u = Usin2πft, where 2πft corresponds to the angle and can be referred to as the voltage phase.

[0106] It is understood that locking the grid voltage phase ensures a fixed relationship between the three-phase AC phase and the grid voltage phase, thereby achieving a unity power factor. For example, after locking the grid voltage phase, the current phase can follow the grid voltage phase to achieve a unity power factor.

[0107] In some embodiments, as shown in FIG8 , the controller 102 (eg, a phase-locked module in the controller 102 ) includes a phase-locked loop and a second-order generalized integrator.

[0108] The phase-locked loop is configured to obtain the angular frequency of the voltage output by the grid.

[0109] The second-order generalized integrator is configured to extract a positive sequence component of the voltage of the grid according to an angular frequency of the voltage output by the grid.

[0110] The phase-locked loop is further configured to lock the phase of the voltage of the grid according to the positive sequence component of the voltage of the three-phase alternating current.

[0111] For example, the phase-locked loop may be the PPL described above, and the second-order generalized integrator may be the SOGI described above.

[0112] In some embodiments, Figure 9 is a schematic diagram of a phase-locked loop (PLL) for a second-order generalized integrator provided in an embodiment of the present disclosure. Figure 10 is a schematic diagram of a second-order generalized integrator provided in an embodiment of the present disclosure. k represents the damping coefficient; ω0 represents the resonant frequency of the second-order generalized integrator, which can also be understood as the angular frequency of the grid output voltage obtained by the PLL. It is understood that the angular frequency of the grid output voltage changes in real time.

[0113] Exemplarily, the closed-loop transfer functions D(s) and Q(s) are as follows (2-3):

[0114] Here, s refers to the independent variable of the function after Laplace transformation.

[0115] Figure 11 shows the Bode plot of the closed-loop transfer functions of D(s) and Q(s). D(s) refers to bandpass filtering, and Q(s) refers to lowpass filtering. A second-order generalized integrator generates Eα', which is then phase-shifted by 90 degrees to obtain qEα. Therefore, SOGI exhibits certain filtering characteristics.

[0116] The controller 102 (eg, the coordinate conversion module in the controller 103 ) is configured to perform coordinate conversion on the three-phase sampled voltages and the three-phase sampled currents according to the phase of the locked voltage of the power grid.

[0117] For example, the controller 102 performs coordinate transformation on the three-phase sampled voltages Ea, Eb, and Ec and the three-phase sampled currents ia, ib, and ic in the abc coordinate system according to the phase of the locked grid voltage, and obtains the three-phase sampled voltages Ed and Eq and the three-phase sampled currents id and iq after coordinate transformation in the dq coordinate system.

[0118] The mathematical model of the three-phase voltages Ed and Eq in the rotating dq coordinate system obtained by changing the coordinates of the three-phase voltages Ea, Eb, and Ec of the power supply device 10 in the stationary abc coordinate system (i.e., the three-phase sampled voltages) is as follows:

[0119] Similarly, the mathematical model of the three-phase currents ia, ib and ic of the power supply device 10 in the stationary abc coordinate system (i.e., the three-phase sampled currents) is obtained by coordinate transformation to obtain the three-phase currents id and iq in the rotating dq coordinate system as shown below:

[0120] Among them, θ in formulas (2-1) and (2-2) is the angle between the d-axis of the rotating dq coordinate system during the rotation process and the α-axis in the two-phase stationary αβ coordinate system.

[0121] In some embodiments, referring to FIG9 , the controller samples the three-phase AC voltage (Ea, Eb, and Ec) in the stationary abc coordinate system and converts it to the two-phase stationary αβ coordinate system to obtain orthogonal output signals Eα and Eβ. The orthogonal output signals Eα and Eβ are linearly combined by SOGI to obtain the positive sequence components Eα+ and Eβ+ of the grid voltage. The positive sequence components Eα+ and Eβ+ are then subjected to single synchronous phase locking to obtain the locked grid voltage phase θ1. Even when the grid voltage is distorted, the SOGI system still has good steady-state and dynamic performance and can also filter the input signal. It can be understood that the grid voltage phase θ1 is the same as the angle of θ in Equation (2-1).

[0122] In some embodiments, the controller 102 (eg, the voltage loop calculation module in the controller 102 shown in FIG. 6 to FIG. 8 ) is configured to sample the voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor C2 dcn Perform voltage following control to obtain the first current reference value id' corresponding to the d-axis in the dq coordinate system. For example, the sampling voltage V dcp and the sampling voltage V of the second capacitor C2 dcn The first current reference value may be obtained by a PI controller.

[0123] The controller 102 (for example, the current loop calculation module in the controller 102 shown in Figures 6 to 8) is configured to: perform current following control according to a first current reference value to obtain a first voltage reference value corresponding to the d-axis in the dq coordinate system; and perform current following control according to a second current reference value corresponding to a preset q-axis in the dq coordinate system to obtain a second voltage reference value corresponding to the q-axis in the dq coordinate system.

[0124] In some embodiments, the voltage loop calculation module controls the output voltage of the rectifier circuit to be stable and outputs a first current reference value to the current loop calculation device. The first current reference value can be used as a reference value of the active component of the current loop calculation module.

[0125] In some embodiments, the current loop calculation module can control the amplitude and phase of the three-phase alternating current, thereby correcting the input power factor of the rectifier circuit. For example, when factoring the input power of the rectifier circuit, the d-axis input component of the current loop calculation module is a first current reference value, and the q-axis input component is generally 0. After the current loop calculation module controls the calculation, a first voltage reference value and a second voltage reference value are obtained.

[0126] Exemplarily, the controller 102 (e.g., the voltage loop calculation module in the controller 102 shown in FIG6 to FIG8 ) is configured to: obtain a third voltage reference value in the dq coordinate system, and obtain the accumulated value of the sampled voltage of the first capacitor and the sampled voltage of the second capacitor; and obtain the first current reference value through the PI controller according to the difference between the third voltage reference value and the accumulated value. That is, the first current reference value is expressed as: id'=(V dc '-((V dcp +V dcn ))ⅹ(kp+ki / s)), where id' represents the first current reference value, V dc ' represents the third voltage reference value, kp represents the proportional adjustment parameter of the PI controller, ki represents the integral adjustment parameter of the PI controller, and s is the independent variable of the Laplace transform.

[0127] For example, the third voltage reference value V dc ' refers to the reference value of the DC voltage, which ranges from 600V to 800V, for example, it can be 600V, 700V or 800V, and those skilled in the art can set it according to the working principle and actual situation.

[0128] The controller 102 is further configured to obtain a voltage control variable based on the three-phase sampled voltage and three-phase sampled current after coordinate conversion, and the sampled voltages of multiple capacitors, wherein the voltage control variable is used to control the duty cycle of multiple switching tubes in the rectifier circuit 1012.

[0129] In some embodiments, the controller 102 (e.g., the pulse width modulation module in the controller 102 shown in FIG6 to FIG8 ) is configured to generate a pulse width modulation signal according to the first voltage reference value, the second voltage reference value, and the sampled voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor C2 dcn For example, the pulse width modulation module performs coordinate transformation using the coordinate transformation module based on the received first voltage reference value, the second voltage reference value, and the voltage deviation of the capacitor to obtain the voltage control value, so that the duty cycle of the switch in the rectifier circuit can be controlled according to the voltage control value.

[0130] In some embodiments, as shown in FIG12 , the current loop calculation module in the controller 102 includes: a first PI control circuit, a first decoupling circuit, a second PI control circuit, and a second decoupling circuit.

[0131] For example, the first PI control circuit and the second PI control circuit may be PI controllers.

[0132] The first PI control circuit is configured to perform current balancing control according to the first current reference value and the sampled current of the three-phase AC voltage source corresponding to the d-axis in the dq coordinate system to obtain a fourth voltage reference value corresponding to the d-axis in the dq coordinate system.

[0133] For example, the difference between the first current reference value and the sampled current of the three-phase AC voltage source corresponding to the d-axis in the dq coordinate system is processed by the first PI control circuit to obtain a fourth voltage reference value corresponding to the d-axis in the dq coordinate system. The fourth voltage reference value is input to the first decoupling circuit.

[0134] The first decoupling circuit is configured to perform a decoupling calculation based on the fourth voltage reference value, a sampled current iq of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system, and a sampled voltage of the three-phase AC voltage source corresponding to the d-axis (as a feedforward), to obtain a first voltage reference value. The first voltage reference value is transmitted to the coordinate conversion module for coordinate conversion.

[0135] For example, the first voltage reference value can be obtained according to the formula Ed-(Vd'+iq×ωL)=Vd", wherein Ed represents the sampled voltage of the three-phase AC voltage source corresponding to the d-axis in the dq coordinate system, Vd' represents the fourth voltage reference value, iq represents the sampled current of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system, Vd" represents the first voltage reference value, L represents the inductance value of inductors L1, L2 and L3, and ω can be understood as a constant (for example, ω is 2π×50 or 2π×60), which can be determined according to actual conditions.

[0136] The second PI control circuit is configured to perform current balancing control according to the second current reference value and the sampled current of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system to obtain a fifth voltage reference value corresponding to the q-axis in the dq coordinate system.

[0137] For example, the difference between the second current reference value iq' and the sampled current iq of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system is processed by the second PI control circuit to obtain a fifth voltage reference value Vq' corresponding to the q-axis. The fifth voltage reference value Vq' is input to the second decoupling circuit.

[0138] The second decoupling circuit is configured to perform a decoupling calculation based on the fifth voltage reference value Vq', the sampled current id of the three-phase AC voltage source corresponding to the d-axis in the dq coordinate system, and the sampled voltage Eq of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system (as feedforward) to obtain a second voltage reference value Vq". The second voltage reference value Vq" is transmitted to the coordinate conversion module for coordinate conversion.

[0139] For example, according to the formula Eq-(Vq'+id×ω)=Vq", the second voltage reference value is obtained, where Eq represents the sampled voltage of the three-phase AC voltage source corresponding to the q-axis in the dq coordinate system, Vq' represents the fifth voltage reference value, id represents the sampled current of the three-phase AC voltage source corresponding to the d-axis in the dq coordinate system, and Vq" represents the second voltage reference value.

[0140] In some embodiments, inconsistent parasitic parameters of capacitors (e.g., first capacitor C1 and second capacitor C2) and unbalanced input voltages can lead to unbalanced voltages at the outputs of the capacitors. This unbalanced voltage at the outputs of the capacitors can cause different stresses on capacitors C1 and C2, thereby increasing the stress on the switches (e.g., switches Q1, Q2, Q3, Q4, Q5, and Q6). When the stress on the switches exceeds a certain range, the switches in the rectifier circuit may fail.

[0141] In some embodiments, the controller 102 (eg, the voltage balancing module in the controller 102 in FIG. 12 ) is configured to: calculate the sampled voltage V of the first capacitor C1 in the abc coordinate system. dcp and the sampling voltage V of the second capacitor C2 dcn , obtain the voltage deviation between the sampling voltage of the first capacitor and the sampling voltage of the second capacitor in the abc coordinate system; perform voltage balancing correction on the voltage deviation between the sampling voltage of the first capacitor and the sampling voltage of the second capacitor in the abc coordinate system to obtain a voltage adjustment value, and the voltage adjustment value is used to obtain the voltage control amount.

[0142] For example, the controller (such as the voltage balancing module in FIG. 12 and FIG. 13 ) performs linear calculations through a PI controller to calculate the sampled voltage V of the first capacitor C1. dcp and the sampling voltage V of the second capacitor dcn Perform equalization correction to make the sampling voltage V dcp and the sampling voltage V of the second capacitor dcn The voltage deviation (for example, the difference V dcp -V dcn ) is within a normal range (e.g., -50V to +50V), thereby obtaining a voltage adjustment value V T ; Voltage adjustment value V T Transmit to the coordinate transformation module for coordinate inverse transformation.

[0143] In some embodiments, the coordinate conversion module is further configured to: perform inverse coordinate transformation based on the first voltage reference value, the second voltage reference value and the voltage adjustment value; and convert the voltage AC quantity based on the result of the inverse coordinate transformation, and output the voltage AC quantity as the voltage control quantity to the pulse width modulation module.

[0144] The inverse coordinate transformation refers to the transformation from the dq coordinate system to the αβ coordinate system, thereby converting the DC voltage into the AC voltage.

[0145] For example, the first voltage reference value and the second voltage reference value are output to the coordinate conversion module 304. The coordinate conversion module 304 performs an inverse coordinate transformation based on the received first voltage reference value, the second voltage reference value, and the difference between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor. The first voltage reference value, the second voltage reference value, and the difference between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor in the dq coordinate system are converted into a reference voltage in the two-phase stationary αβ coordinate system. The coordinate conversion module 304 transmits the reference voltage in the two-phase stationary αβ coordinate system to the pulse width modulation module 305.

[0146] For example, the voltage can be transformed from the dq coordinate system to the αβ coordinate system by performing an inverse coordinate transformation using the mathematical model formula (2-4) shown below.

[0147] FIG13 is a schematic diagram of the internal structure of a controller 102 provided in some embodiments of the present disclosure.

[0148] In some embodiments, the pulse width modulation module is further configured to determine the duty cycle of the switch tube in the three-phase Vienna topology circuit based on the voltage control quantity (Vα and Vβ), and send a pulse width modulation signal to the three-phase Vienna topology circuit based on the duty cycle to control the switch tube in the three-phase Vienna topology circuit.

[0149] In some embodiments, the pulse width modulation module can be understood as space vector pulse width modulation (SVPWM). The pulse width modulation signal can be understood as a high and low level drive signal. The duty cycle of the switch tube can be understood as the ratio of the switch tube conduction time to the duty cycle.

[0150] Exemplarily, the pulse width modulation module sends drive signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6 to the switch tubes Q1, Q2, Q3, Q4, Q5 and Q6 in the three-phase Vienna topology circuit according to the received voltage control quantities Vα and Vβ, so as to control the switching and closing of the switch tubes Q1, Q2, Q3, Q4, Q5 and Q6. When the drive signal is at a high level, the switch tube is turned on, and when the drive signal is at a low level, the switch tube is closed.

[0151] Therefore, in the embodiments of the present disclosure, during the rectification of the three-phase AC voltage source in a three-phase air conditioning power supply system through a rectifier circuit, the three-phase sampled data obtained by sampling in a stationary abc coordinate system is converted into three-phase sampled data in a rotating dq coordinate system, thereby converting the AC quantity in the rectifier circuit into a DC quantity. Using the DC quantity to control the circuit components, harmonics generated in the power supply device are filtered out, the power factor of the rectifier circuit is improved, and the control difficulty is reduced. Furthermore, after the control is completed, the DC quantity can be converted back to an AC quantity to facilitate subsequent processing.

[0152] Embodiments of the present disclosure also provide a control method for a power supply device. This control method is applied to the power supply device described above. Referring to FIG1B , the power supply device 10 includes: a three-phase AC voltage source 1011, a rectifier circuit 1012, and a controller 102; the controller 102 is connected to the three-phase AC voltage source 1011 and the rectifier circuit 1012. The control method is executed at the controller 102 of the power supply device 10. In some embodiments, referring to FIG2 , the rectifier circuit 1012 includes a plurality of switching transistors Q1 to Q6 and a plurality of capacitors C1 and C2.

[0153] As shown in FIG14 , the control method includes the following steps.

[0154] S101: Acquire three-phase sampling data of three-phase alternating current output by a three-phase alternating current voltage source, wherein the three-phase sampling data includes three-phase sampling current.

[0155] S102 : Obtain sampled voltages of multiple capacitors.

[0156] S103 : Obtain a DC sampling voltage and a midpoint current of the power supply device according to the sampling voltages of the plurality of capacitors.

[0157] In some embodiments, a DC sampling voltage of the power supply device is obtained according to a preset voltage reference value and sampling voltages of a plurality of capacitors.

[0158] In some embodiments, the midpoint current of the power supply device is obtained according to the capacitance value of one of the plurality of capacitors, the sampled voltages of the plurality of capacitors, and the sampling period of the power supply device.

[0159] S104 : Obtain a three-phase modulation voltage of the power supply device according to the DC sampling voltage and the three-phase sampling current.

[0160] S105 , obtaining a zero-sequence voltage of the power supply device according to the midpoint current, the three-phase sampled current, and the three-phase modulated voltage.

[0161] S106: Obtain a three-phase composite drive control quantity of the power supply device according to the zero-sequence voltage and the three-phase modulation voltage. The three-phase composite drive control quantity is used for pulse width modulation of multiple switching tubes.

[0162] In some embodiments, the three-phase sampled data obtained by sampling the three-phase AC power output by the three-phase AC voltage source includes the three-phase sampled current and three-phase sampled voltage mentioned above. As shown in FIG15 , the control method further includes the following steps.

[0163] S201 : Lock the phase of the voltage of a power grid used to supply power to a power supply device.

[0164] In some embodiments, the angular frequency of the voltage output by the power grid is obtained; the positive sequence component of the voltage of the power grid is extracted according to the angular frequency; and the phase of the voltage of the power grid is locked according to the positive sequence component of the voltage of the power grid.

[0165] S202 : performing coordinate transformation on the three-phase sampled voltage and the three-phase sampled current according to the locked phase of the grid voltage.

[0166] In some embodiments, the three-phase sampled voltages and the three-phase sampled currents are transformed from the abc coordinate system to the dq coordinate system according to the phase of the locked voltage of the power grid.

[0167] S203: Obtain a voltage control variable based on the three-phase sampled voltages and three-phase sampled currents after coordinate conversion and the sampled voltages of the plurality of capacitors, wherein the voltage control variable is used to control the duty cycle of the plurality of switching tubes.

[0168] In some embodiments, the plurality of capacitors includes a first capacitor and a second capacitor. In this case, voltage following control is performed on the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a first current reference value corresponding to the d-axis in a dq coordinate system; current following control is performed based on the first current reference value to obtain a first voltage reference value corresponding to the d-axis in the dq coordinate system; current following control is performed based on a second current reference value corresponding to a preset q-axis in the dq coordinate system to obtain a second voltage reference value corresponding to the q-axis in the dq coordinate system; and a voltage control amount is obtained based on the first voltage reference value, the second voltage reference value, and a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor.

[0169] For example, a third voltage reference value in the dq coordinate system is obtained, the accumulated value of the sampled voltage of the first capacitor and the sampled voltage of the second capacitor is obtained, and the first current reference value is obtained according to the difference between the third voltage reference value and the accumulated value.

[0170] For example, current following control is performed based on the first current reference value and the three-phase sampled current to obtain a fourth voltage reference value corresponding to the d-axis in the dq coordinate system; and decoupling calculation is performed based on the fourth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the first voltage reference value.

[0171] For example, current following control is performed based on the second current reference value and the three-phase sampled current to obtain a fifth voltage reference value corresponding to the q-axis in the dq coordinate system; and decoupling calculation is performed based on the fifth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the second voltage reference value.

[0172] In some embodiments, a voltage deviation between the sampled voltages of the first capacitor and the second capacitor is obtained based on the sampled voltages of the first capacitor and the second capacitor. Voltage balancing correction is performed on the voltage deviation between the sampled voltages of the first capacitor and the second capacitor to obtain a voltage adjustment value. An inverse coordinate transformation is performed based on the first voltage reference value, the second voltage reference value, and the voltage adjustment value. The result of the inverse coordinate transformation is converted into a voltage alternating current variable, wherein the voltage alternating current variable serves as the voltage control variable.

[0173] In some embodiments, the control method further includes: determining the duty cycle of multiple switching tubes in the rectifier circuit based on the voltage control amount; and sending a pulse width modulation signal to the rectifier circuit based on the duty cycle of the multiple switching tubes to control the multiple switching tubes in the rectifier circuit.

[0174] The coordinate transformation includes the transformation from the abc coordinate system to the αβ coordinate system, and then the transformation from the αβ coordinate system to the dq coordinate system; the inverse coordinate transformation includes the inverse transformation from the dq coordinate system to the αβ coordinate system.

[0175] It should be noted that for the details of each step of the control method of the power supply device, reference can be made to the description of the corresponding part of the power supply device described in the above embodiment, and will not be repeated here. In addition, the beneficial effects of the control method of the power supply device are the same as the beneficial effects of the power supply device described in the above embodiment, and will not be repeated here.

[0176] Those skilled in the art will understand that the disclosure scope of this application is not limited to the above specific embodiments, and certain elements of the embodiments may be modified and replaced without departing from the spirit of this application. The scope of this application is limited by the appended claims.

Claims

1. A power supply device, comprising: A three-phase AC voltage source configured to output three-phase AC power; and A rectifier circuit configured to convert the three-phase alternating current into direct current; wherein the rectifier circuit includes a plurality of switching tubes and a plurality of capacitors; and a controller connected to the three-phase AC voltage source and the rectifier circuit; Wherein, the controller is configured as follows: Acquiring three-phase sampling data of the three-phase alternating current, wherein the three-phase sampling data includes three-phase sampling current; obtaining sampled voltages of the plurality of capacitors; Obtaining a DC sampling voltage and a midpoint current of the power supply device according to the sampling voltages of the plurality of capacitors; Obtaining a three-phase modulation voltage of the power supply device according to the DC sampling voltage and the three-phase sampling current; Obtaining a zero-sequence voltage of the power supply device according to the midpoint current, the three-phase sampling current, and the three-phase modulation voltage; A three-phase composite drive control quantity of the power supply device is obtained according to the zero-sequence voltage and the three-phase modulation voltage, wherein the three-phase composite drive control quantity is used for pulse width modulation of the multiple switching tubes.

2. The power supply device according to claim 1, wherein The controller is configured to obtain a DC sampling voltage of the power supply device according to a preset voltage reference value and the sampling voltages of the plurality of capacitors.

3. The power supply device according to claim 1 or 2, wherein: The controller is configured to obtain a midpoint current of the power supply device according to a capacitance value of one of the plurality of capacitors, sampled voltages of the plurality of capacitors, and a sampling period of the power supply device.

4. The power supply device according to any one of claims 1 to 3, wherein: The plurality of capacitors includes a first capacitor and a second capacitor; The midpoint current is expressed as: Among them, I npcon represents the midpoint current, C represents the capacitance value of the first capacitor or the capacitance value of the second capacitor, V dcp represents the sampling voltage of the first capacitor, V dcn represents the sampling voltage of the second capacitor, T s Indicates the sampling period of the power supply device.

5. The power supply device according to any one of claims 1 to 4, wherein: The zero-sequence voltage is expressed as: Wherein, V0 represents the zero sequence voltage, V ral 、V rbl and V rcl represents the three-phase modulation voltage, i a 、i b and i c Represents the three-phase sampling current.

6. The power supply device according to claim 5, wherein: The three-phase composite drive control quantity is expressed as: V ra =V ral +V0,V rb =V rbl +V0,V rc =V rcl +V0; Among them, V ra 、V rb and V rc Represents the three-phase composite drive control quantity.

7. The power supply device according to claim 1, wherein: The three-phase sampling data also includes three-phase sampling voltage; The controller is further configured to: locking a phase of a voltage of a power grid used to supply power to the power supply device; performing coordinate transformation on the three-phase sampled voltage and the three-phase sampled current according to the locked phase of the voltage of the power grid; A voltage control variable is obtained according to the three-phase sampled voltages and three-phase sampled currents after coordinate conversion, and the sampled voltages of the multiple capacitors, wherein the voltage control variable is used to control the duty cycle of the multiple switching tubes.

8. The power supply device according to claim 7, wherein: The plurality of capacitors includes a first capacitor and a second capacitor; The controller is configured to: According to the phase of the locked power grid voltage, the three-phase sampled voltage and the three-phase sampled current are transformed from the abc coordinate system to the dq coordinate system; performing voltage following control on the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a first current reference value corresponding to the d-axis in the dq coordinate system; Performing current following control according to the first current reference value to obtain a first voltage reference value corresponding to the d-axis in the dq coordinate system; Performing current following control according to a second current reference value corresponding to the q-axis preset in the dq coordinate system to obtain a second voltage reference value corresponding to the q-axis in the dq coordinate system; The voltage control amount is obtained according to the first voltage reference value, the second voltage reference value, and a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor.

9. The power supply device according to claim 8, wherein: The controller is configured to: Obtaining a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor according to the sampled voltage of the first capacitor and the sampled voltage of the second capacitor; A voltage balance correction is performed on a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a voltage adjustment value, and the voltage adjustment value is used to obtain the voltage control amount.

10. The power supply device according to any one of claims 7 to 9, wherein: The controller includes: a phase-locked loop configured to obtain an angular frequency of a voltage output by the power grid; and a second-order generalized integrator configured to extract a positive sequence component of the voltage of the power grid according to the angular frequency; The phase-locked loop is further configured to lock the phase of the voltage of the power grid according to the positive sequence component of the voltage of the power grid.

11. The power supply device according to claim 8 or 9, wherein: The controller is configured to: Obtaining a third voltage reference value in the dq coordinate system; Obtaining a cumulative value of a sampled voltage of the first capacitor and a sampled voltage of the second capacitor; The first current reference value is obtained according to the difference between the third voltage reference value and the accumulated value.

12. The power supply device according to claim 9, wherein: The controller is configured to: Performing current following control according to the first current reference value and the three-phase sampled current to obtain a fourth voltage reference value corresponding to the d-axis in the dq coordinate system; Performing a decoupling calculation according to the fourth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the first voltage reference value; performing current following control according to the second current reference value and the three-phase sampled current to obtain a fifth voltage reference value corresponding to the q-axis in the dq coordinate system; A decoupling calculation is performed according to the fifth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the second voltage reference value.

13. The power supply device according to claim 9, wherein: The controller is further configured to: Performing an inverse coordinate transformation based on the first voltage reference value, the second voltage reference value, and the voltage adjustment value; wherein the coordinate transformation includes transforming from the abc coordinate system to an αβ coordinate system, and then transforming from the αβ coordinate system to a dq coordinate system, and the inverse coordinate transformation includes transforming from the dq coordinate system to an αβ coordinate system; Converting the result of the coordinate inverse transformation into a voltage AC quantity, wherein the voltage AC quantity serves as the voltage control quantity; determining duty cycles of the plurality of switching tubes in the flow circuit according to the voltage control amount; According to the duty cycles of the multiple switching tubes, a pulse width modulation signal is sent to the rectifier circuit to control the multiple switching tubes in the rectifier circuit.

14. A method for controlling a power supply device, executed at a controller of the power supply device, wherein: The power supply device includes: a three-phase AC voltage source, a rectifier circuit and the controller; the rectifier circuit includes multiple switching tubes and multiple capacitors; the controller is connected to the three-phase AC voltage source and the rectifier circuit; The control method includes: Acquire three-phase sampling data of the three-phase alternating current output by the three-phase alternating current voltage source, wherein the three-phase sampling data includes three-phase sampling current; obtaining sampled voltages of the plurality of capacitors; Obtaining a DC sampling voltage and a midpoint current of the power supply device according to the sampling voltages of the plurality of capacitors; Obtaining a three-phase modulation voltage of the power supply device according to the DC sampling voltage and the three-phase sampling current; Obtaining a zero-sequence voltage of the power supply device according to the midpoint current, the three-phase sampling current, and the three-phase modulation voltage; A three-phase synthetic drive control quantity of the power supply device is obtained according to the zero-sequence voltage and the three-phase modulation voltage; the three-phase synthetic drive control quantity is used for pulse width modulation of the multiple switching tubes.

15. The control method according to claim 14, wherein: Obtaining a DC sampling voltage of the power supply device according to the sampling voltages of the plurality of capacitors, comprising: A DC sampling voltage of the power supply device is obtained according to a preset voltage reference value and the sampling voltages of the plurality of capacitors.

16. The control method according to claim 14 or 15, wherein: Obtaining a midpoint current of the power supply device according to the sampled voltages of the plurality of capacitors, comprising: A midpoint current of the power supply device is obtained according to a capacitance value of one of the plurality of capacitors, sampled voltages of the plurality of capacitors, and a sampling period of the power supply device.

17. The control method according to claim 14, wherein: The three-phase sampling data also includes three-phase sampling voltage; the control method also includes: locking a phase of a voltage of a power grid used to supply power to the power supply device; performing coordinate transformation on the three-phase sampled voltage and the three-phase sampled current according to the locked phase of the voltage of the power grid; A voltage control variable is obtained according to the three-phase sampled voltages and three-phase sampled currents after coordinate conversion, and the sampled voltages of the multiple capacitors. The voltage control variable is used to control the duty cycle of the multiple switching tubes.

18. The control method according to claim 17, wherein: Performing coordinate transformation on the three-phase sampled voltage and the three-phase sampled current according to the locked phase of the voltage of the power grid, including: According to the phase of the locked power grid voltage, the three-phase sampled voltage and the three-phase sampled current are transformed from the abc coordinate system to the dq coordinate system; The plurality of capacitors include a first capacitor and a second capacitor; and the voltage control amount is obtained according to the three-phase sampled voltages and three-phase sampled currents after coordinate conversion and the sampled voltages of the plurality of capacitors, including: performing voltage following control on the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a first current reference value corresponding to the d-axis in the dq coordinate system; Performing current following control according to the first current reference value to obtain a first voltage reference value corresponding to the d-axis in the dq coordinate system; Performing current following control according to a second current reference value corresponding to the q-axis preset in the dq coordinate system to obtain a second voltage reference value corresponding to the q-axis in the dq coordinate system; The voltage control amount is obtained according to the first voltage reference value, the second voltage reference value, and a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor.

19. The control method according to claim 17 or 18, wherein: Locking the phase of the voltage of the power grid used to supply power to the power supply device, comprising: Obtaining the angular frequency of the voltage output by the power grid; extracting a positive sequence component of the voltage of the power grid according to the angular frequency; The phase of the voltage of the power grid is locked according to the positive sequence component of the voltage of the power grid.

20. The control method according to claim 18, wherein: Performing voltage following control on the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a first current reference value corresponding to the d-axis in the dq coordinate system includes: Obtaining a third voltage reference value in the dq coordinate system; Obtaining a cumulative value of a sampled voltage of the first capacitor and a sampled voltage of the second capacitor; Obtaining the first current reference value according to a difference between the third voltage reference value and the accumulated value; Performing current following control according to the first current reference value to obtain a first voltage reference value corresponding to the d-axis in the dq coordinate system includes: Performing current following control according to the first current reference value and the three-phase sampled current to obtain a fourth voltage reference value corresponding to the d-axis in the dq coordinate system; Performing a decoupling calculation according to the fourth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the first voltage reference value; Performing current following control according to a second current reference value corresponding to the q-axis preset in the dq coordinate system to obtain a second voltage reference value corresponding to the q-axis in the dq coordinate system includes: performing current following control according to the second current reference value and the three-phase sampled current to obtain a fifth voltage reference value corresponding to the q-axis in the dq coordinate system; A decoupling calculation is performed according to the fifth voltage reference value, the three-phase sampled current, and the three-phase sampled voltage to obtain the second voltage reference value.

21. The control method according to claim 18, wherein: Obtaining the voltage control amount according to the first voltage reference value, the second voltage reference value, and a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor includes: Obtaining a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor according to the sampled voltage of the first capacitor and the sampled voltage of the second capacitor; performing voltage balancing correction on a voltage deviation between the sampled voltage of the first capacitor and the sampled voltage of the second capacitor to obtain a voltage adjustment value; Performing an inverse coordinate transformation based on the first voltage reference value, the second voltage reference value, and the voltage adjustment value; wherein the coordinate transformation includes transforming from the abc coordinate system to an αβ coordinate system, and then transforming from the αβ coordinate system to a dq coordinate system, and the inverse coordinate transformation includes transforming from the dq coordinate system to an αβ coordinate system; Converting the result of the coordinate inverse transformation into a voltage AC quantity, wherein the voltage AC quantity serves as the voltage control quantity; The control method further includes: determining duty cycles of the plurality of switching tubes in the rectifier circuit according to the voltage control amount; According to the duty cycles of the multiple switching tubes, a pulse width modulation signal is sent to the rectifier circuit to control the multiple switching tubes in the rectifier circuit.

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