Power converter control method, power conversion device, and energy storage apparatus

Abstract

A power converter control method. In a power converter (10), a rectifier bridge arm (101), an inverter bridge arm (102), a common bridge arm (103), and a direct-current bus capacitor (Cbus) are connected in parallel between a positive direct-current bus (BUS+) and a negative direct-current bus (BUS-); the midpoint of the common bridge arm (103) serves as a neutral wire terminal (N); the midpoint of the rectifier bridge arm (101) is connected to a first end of a first inductor (Lf1); a second end of the first inductor (Lf1) is used as a first live wire terminal (L1); the midpoint of the inverter bridge arm (102) is connected to a first end of a second inductor (Lf2); a second end of the second inductor (Lf2) is used as a second live wire terminal (L2); and when an alternating-current power supply is accessed between the first live wire terminal (L1) and the neutral wire terminal (N), and alternating-current loads (R1, R2) are accessed between the first live wire terminal (L1) and the second live wire terminal (L2) or between the second live wire terminal (L2) and the neutral wire terminal (N), the common bridge arm (103) is controlled on the basis of a modulation wave signal of a driving signal of the inverter bridge arm (102).

Description

Power converter control method, power conversion equipment and energy storage device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on February 6, 2024, with application number 202410168730.6 and invention name “Control method of power converter, power conversion equipment and energy storage device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of power electronics technology, and in particular to a control method for a power converter, a power conversion device, and an energy storage device. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute exemplary techniques.

[0005] The three-arm split-phase topology circuit has three bridge arms: a rectifier arm, an inverter arm, and a common arm. The three-arm split-phase topology circuit can achieve rectification by forming a bridge circuit with the rectifier arm and the common arm, or it can achieve inversion by forming a bridge circuit with the inverter arm and the common arm. However, if the three-arm split-phase topology circuit is to achieve both rectification and inversion simultaneously, both the rectification control method and the inverter control method will involve the common arm, resulting in coupling in the control of the common arm. Under this control method, the inverter output waveform will be distorted and have poor sinusoidality. Therefore, how to control the three-arm split-phase topology circuit to achieve both rectification and inversion functions while ensuring the quality of the inverter output is a technical problem that needs to be solved. Summary of the Invention

[0006] According to various embodiments of the present application, a control method for a power converter, a power conversion device, and an energy storage device are provided.

[0007] The first aspect of the present application provides a control method for a power converter, wherein the power converter includes a rectifier bridge arm, an inverter bridge arm, a common bridge arm, a DC bus capacitor, a first inductor, and a second inductor; the rectifier bridge arm, the inverter bridge arm, the common bridge arm, and the DC bus capacitor are connected in parallel between a positive DC bus and a negative DC bus, the midpoint of the common bridge arm serves as a neutral terminal of the power converter, the midpoint of the rectifier bridge arm is connected to a first end of a first inductor, and the second end of the first inductor serves as a first live terminal of the power converter, the midpoint of the inverter bridge arm is connected to a first end of a second inductor, and the second end of the second inductor serves as a second live terminal of the power converter; the control method includes: when an AC power supply is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, the common bridge arm is controlled according to a modulation wave signal of a drive signal of the inverter bridge arm.

[0008] The second aspect of the present application provides a power conversion device, including a power converter and a controller, the power converter including a rectifier bridge arm, an inverter bridge arm, a common bridge arm, a DC bus capacitor, a first inductor and a second inductor; the rectifier bridge arm, the inverter bridge arm, the common bridge arm and the DC bus capacitor are connected in parallel between the positive DC bus and the negative DC bus, the midpoint of the common bridge arm serves as the neutral terminal of the power converter, the midpoint of the rectifier bridge arm is connected to the first end of the first inductor, the second end of the first inductor serves as the first live terminal of the power converter, the midpoint of the inverter bridge arm is connected to the first end of the second inductor, the second end of the second inductor serves as the second live terminal of the power converter; the controller is used to execute the control method of the power converter described in the above-mentioned first aspect or any embodiment of the first aspect.

[0009] A third aspect of the present application provides an energy storage device, comprising a battery pack and the power conversion device described in the second aspect above, wherein the battery pack is used to be connected to a DC bus of the power conversion device.

[0010] The fourth aspect of the present application provides an electronic device, including a processor and a memory, the memory being used to store programs, instructions or codes, and the processor being used to execute the programs, instructions or codes in the memory to complete the control method of the power converter described in the first aspect or any one of the embodiments of the first aspect.

[0011] In a fifth aspect, the present application provides a control device for a power converter, including a common bridge arm control module. The common bridge arm control module is used to control the common bridge arm according to the modulation wave signal of the drive signal of the inverter bridge arm when an AC power supply is connected between a first live terminal and a neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal.

[0012] In a sixth aspect, the present application provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the control method of the power converter described in the first aspect or any one of the embodiments of the first aspect.

[0013] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments or exemplary technologies of the present application, the following briefly introduces the drawings required for use in the description of the embodiments or exemplary technologies. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0015] FIG1A is a circuit diagram of a power converter provided in an embodiment of the present application.

[0016] FIG1B is another circuit diagram of a power converter provided in an embodiment of the present application.

[0017] FIG1C is another circuit diagram of a power converter provided in an embodiment of the present application.

[0018] 2A and 2B are voltage and current waveform diagrams of the power converter when the common bridge arm of the power converter is controlled according to the polarity of the input voltage connected during rectification.

[0019] FIG3A is a flow chart of a method for controlling a power converter according to an embodiment of the present application.

[0020] FIG3B is a timing diagram of the control method shown in FIG3A .

[0021] FIG3C is a schematic diagram of the SPWM modulation principle.

[0022] FIG4 is another flow chart of a method for controlling a power converter provided in an embodiment of the present application.

[0023] FIG5 is a detailed flowchart of step S43 in FIG4 .

[0024] FIG6 is an inverter control block diagram of a power converter provided in an embodiment of the present application.

[0025] FIG. 7 is a detailed flowchart of step S31 in FIG. 3A .

[0026] FIG8 is another flow chart of a method for controlling a power converter provided in an embodiment of the present application.

[0027] FIG9 is a rectification control block diagram of a power converter provided in an embodiment of the present application.

[0028] 10A to 10C are voltage and current waveform diagrams of the power converter when the power converter is controlled using the method according to the embodiment of the present application.

[0029] FIG11A is another flow chart of a method for controlling a power converter provided in an embodiment of the present application.

[0030] FIG. 11B is a timing diagram of the control method shown in FIG. 11A .

[0031] FIG12A is another flow chart of a method for controlling a power converter provided in an embodiment of the present application.

[0032] FIG12B is a timing diagram of the control method shown in FIG12A.

[0033] FIG. 13 is a detailed flowchart of step S121 in FIG. 12A .

[0034] FIG14 is a schematic diagram of a power conversion device provided in an embodiment of the present application.

[0035] FIG15 is a schematic diagram of an energy storage device provided in an embodiment of the present application.

[0036] FIG16 is a schematic diagram of an electronic device provided in an embodiment of the present application.

[0037] FIG17 is a schematic diagram of a control device for a power converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] It should be noted that the terms "first" and "second" in the description, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0039] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0040] The following will describe some embodiments with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0041] Please refer to FIG. 1A , which is a circuit diagram of a power converter provided in an embodiment of the present application.

[0042] As shown in FIG1A , the power converter 10 includes a rectifier bridge arm 101 , an inverter bridge arm 102 , a common bridge arm 103 , a DC bus capacitor Cbus, a first inductor Lf1 , and a second inductor Lf2 .

[0043] The rectifier bridge arm 101, the inverter bridge arm 102, the common bridge arm 103, and the DC bus capacitor Cbus are connected in parallel between the positive DC bus (BUS+) and the negative DC bus (BUS-). It is understood that the DC bus capacitor Cbus, the inverter bridge arm 102, the rectifier bridge arm 101, and the common bridge arm 103 in FIG1A are arranged in sequence. In other embodiments, the position order of the inverter bridge arm 102, the rectifier bridge arm 101, and the common bridge arm 103 can also be adjusted accordingly as needed, which does not constitute a limitation of the present application.

[0044] The rectifier bridge arm 101 includes an upper switch L1_H and a lower switch L1_L connected in series. The inverter bridge arm 102 includes an upper switch L2_H and a lower switch L2_L connected in series. The common bridge arm 103 includes an upper switch N_H and a lower switch N_L connected in series. Specifically, the first connection ends of the upper switches L1_H, L2_H, and N_H are all connected to the positive DC bus BUS+, and the second connection ends of the lower switches L1_L, L2_L, and N_H are all connected to the negative DC bus BUS-. The second connection end of the upper switch L1_H is connected to the first connection end of the lower switch L1_L, and the connection point is the midpoint a of the rectifier bridge arm 101. Midpoint a is connected to the first end of the first inductor Lf1, and the second end of the first inductor Lf1 serves as the first live terminal L1 of the power converter 10. The second connection end of the upper switch L2_H is connected to the first connection end of the lower switch L2_L. The connection point is the midpoint b of the inverter bridge arm 102. Midpoint b is connected to the first end of the second inductor Lf2. The second end of the second inductor Lf2 serves as the second live terminal L2 of the power converter 10. The second connection end of the upper switch N_H is connected to the first connection end of the lower switch N_L. The connection point is the midpoint of the common bridge arm 103. The midpoint of the common bridge arm 103 serves as the neutral terminal N of the power converter 10.

[0045] It is understood that the upper and lower switching tubes of each bridge arm can adopt corresponding semiconductor switching devices according to actual conditions, such as triodes, silicon controlled rectifiers (SCRs), metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), or gallium nitride high electron mobility transistors (GaN HEMTs). Among them, triodes, SCRs, MOSFETs, IGBTs, and GaN HEMTs can all include a reverse-connected body diode (also known as a parasitic diode). Of course, in one embodiment, the switching tube can also be formed by connecting a triode, SCR, MOSFET, IGBT, or GaN HEMT in parallel with a reverse-connected diode. For ease of description, the embodiments of the present application are described as an example in which both the upper and lower switching tubes are IGBTs containing body diodes. Among them, the base of the IGBT tube is the control terminal, the collector of the IGBT tube is the first connection terminal, and the emitter of the IGBT tube is the second connection terminal.

[0046] The control end of each switch tube in the rectifier bridge arm 101, the inverter bridge arm 102 and the common bridge arm 103 is also used to be connected to a controller (not shown), and the on-off state is controlled by the driving signal of the controller.

[0047] The DC bus capacitor Cbus may include a single capacitor element, or multiple capacitor elements connected in parallel, in series, or in series-parallel, which does not constitute a limitation of the present application. The first inductor Lf1 and the second inductor Lf2 may each include a single inductor element, or multiple inductor elements connected in parallel, in series, or in series-parallel.

[0048] In some embodiments, as shown in FIG1A , the power converter 10 may further include a first capacitor Cf1 and a second capacitor Cf2 . The first capacitor Cf1 is connected between the first live terminal L1 and the neutral terminal N, and the second capacitor Cf2 is connected between the first live terminal L1 and the second live terminal L2 . The first capacitor Cf1 and the second capacitor Cf2 may function as voltage stabilizers.

[0049] In the embodiment of the present application, an AC power source is connected between the first live terminal L1 and the neutral terminal N. For ease of description, FIG1A illustrates the AC power source by its real-time input voltage Vin. The AC power source can be selected as needed and is not limited herein. For example, the AC power source can be a 110V grid, a 120V grid, or a grid with other voltage levels, including a municipal grid, a local grid, a microgrid, and the like. The AC power source can also be an AC motor or other device capable of outputting AC power.

[0050] An AC load can be connected between the second live terminal L2 and the neutral terminal N. For ease of description and distinction, this AC load is represented by R1 in FIG1A . Of course, in other embodiments, please refer to FIG1B , an AC load can also be connected between the first live terminal L1 and the second live terminal L2. For ease of description and distinction, this AC load is represented by R2 in FIG1B . Please refer to FIG1C , a corresponding AC load can also be connected between the first live terminal L1 and the second live terminal L2, and between the second live terminal L2 and the neutral terminal N. The AC loads R1 and R2 can be resistive loads, inductive loads, capacitive loads, RCD loads, or other nonlinear loads. As a further example, the AC load R1 can be, for example, a household single-phase load, and the AC load R2 can be, for example, a household two-phase load, which is not limited here.

[0051] In addition, in one embodiment, as shown in FIG1C , a DC load may be connected between the positive DC bus and the negative DC bus. For ease of description, this DC load is represented by R3 , which may be, for example, a battery pack.

[0052] Based on this design, the rectifier bridge arm 101, the common bridge arm 103, and the first inductor can collectively form a bridge rectifier circuit. The first live terminal L1 and the neutral terminal N can serve as the input ports of the rectifier circuit for connecting to the AC power supply, and the positive and negative DC busbars can serve as the output ports of the rectifier circuit. The rectifier bridge arm 101 and the common bridge arm 103 can achieve a rectification function by switching the switches L1_H, L1_L, N_H, and N_L on and off. This rectifies the input voltage of the AC power supply and charges the DC bus capacitor Cbus between the positive and negative DC busbars. If a DC load R3 is connected between the positive and negative DC busbars, this can also power the DC load R3. In this case, energy flows from the first live terminal L1 to the positive and negative DC busbars. Therefore, the rectifier bridge arm 101 can also be referred to as the charging bridge arm.

[0053] The inverter bridge arm 102, the common bridge arm 103, and the second inductor can collectively constitute a bridge inverter circuit. The positive and negative DC busbars can serve as input ports of the inverter circuit, the second live terminal L2 and the neutral terminal N can serve as output ports of the inverter circuit, and the second live terminal L2 and the first live terminal L1 can serve as another output port of the inverter circuit. The inverter bridge arm 102 and the common bridge arm 103 can implement an inverter function by switching the switches L2_H, L2_L, N_H, and N_L on and off, thereby inverting the voltage of the DC bus capacitor Cbus and then supplying power to the AC load R1 and / or the AC load R2. At this time, energy flows from the positive and negative DC busbars to the second live terminal L2. Therefore, the inverter bridge arm 102 can also be referred to as a discharge bridge arm.

[0054] Thus, the power converter 10 can achieve bidirectional energy flow. In this embodiment of the present application, the direction in which energy flows from the first live terminal L1 to the positive and negative DC busbars is defined as the forward direction, and the direction in which energy flows from the positive and negative DC busbars to the second live terminal L2 is defined as the reverse direction. Of course, in other embodiments, the definitions of forward and reverse directions may be reversed.

[0055] In general, the power converter 10 can operate in a rectification mode, that is, a separate rectification function is realized through the rectification bridge arm 101 and the common bridge arm 103. The power converter 10 can also operate in an inversion mode, and a separate inversion function is realized through the inversion bridge arm 102 and the common bridge arm 103. The power converter 10 can also operate in a rectification and inversion mode, that is, simultaneous rectification and inversion are realized through the rectification bridge arm 101, the inversion bridge arm 102 and the common bridge arm 103. In addition, the power converter 10 can realize the division of one input into two outputs, that is, split-phase output. Therefore, the topology of the power converter 10 can be called a three-bridge-arm split-phase topology. Among them, the voltage value between the first live terminal L1 and the neutral terminal N is equal to the voltage value between the second live terminal L2 and the first live terminal L1. Therefore, the voltage value between the second live terminal L2 and the neutral terminal N is actually the sum of the voltage value between the first live terminal L1 and the neutral terminal N, and the voltage value between the second live terminal L2 and the first live terminal L1, that is, equal to twice the voltage value between the first live terminal L1 and the neutral terminal N. In other words, in this embodiment of the present application, the phase voltage of the second live terminal L2 is twice the phase voltage of the first live terminal L1.

[0056] However, if the power converter 10 is to achieve rectification and inversion at the same time, both the rectification control mode and the inversion control mode will involve the common bridge arm 103, resulting in coupling in the control of the common bridge arm 103. The inverter output waveform under this control mode will be distorted and the sinusoidality is poor. In this regard, in the related art, a decoupling control mode is proposed to control the common bridge arm 103 according to the polarity of the input voltage connected during rectification. Figure 2A shows the input voltage waveform and input current waveform of the AC power supply in the power converter 10 under this decoupling control mode, as well as the inverter output voltage waveform (that is, the voltage between the second live terminal L2 and the neutral terminal N) and the inverter output current waveform. For better display, Figure 2A is partially enlarged to obtain Figure 2B. It should be noted that in Figures 2A and 2B, one grid corresponding to the input voltage waveform curve represents 100V, and one grid corresponding to the inverter output voltage waveform curve represents 250V, that is, the ratio of the input voltage waveform curve and the inverter output voltage waveform in the figure is not a 1:1 ratio. Each grid cell in the input current waveform and inverter output current curves in the figure represents 50A. However, as can be seen in Figures 2A and 2B, the inverter output voltage waveform is still distorted, indicating that the output waveform at the second live terminal L2 is still distorted. Therefore, how to control the three-leg split-phase topology circuit to achieve both rectification and inversion while ensuring inverter output quality remains a technical challenge.

[0057] To this end, an embodiment of the present application provides a control method for a power converter, which can control a three-bridge-arm split-phase topology circuit to simultaneously realize rectification and inversion functions, and ensure the quality of the inverter output.

[0058] As shown in FIG3A , the control method of the power converter includes:

[0059] When an AC power supply is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, the common bridge arm is controlled according to the modulated wave signal of the drive signal of the inverter bridge arm (corresponding to step S31 in Figure 3A).

[0060] It can be understood that when an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, since the bridge arms connected to the AC power source are the rectifier bridge arm 101 and the common bridge arm 103, and the bridge arms connected to the AC load are the inverter bridge arm 102 and the common bridge arm 103, the input voltage of the AC power source needs to be rectified and then inverted before it can be supplied to the AC load. In other words, the power converter 10 is now operating in a rectification and inversion mode, and the common bridge arm 103 is used to realize both the rectification function together with the rectifier bridge arm 101 and the inversion function together with the inverter bridge arm 102.

[0061] As shown in Figure 3C (Figure 3C is a simple illustration of the modulation principle and does not constitute a specific limitation on the modulation signal, fundamental signal and drive signal, and the actual modulation is not limited to that shown in Figure 3C), since the drive signal of the inverter bridge arm 102 is obtained by modulating the preset fundamental signal with the modulation wave signal, the modulation wave signal will not lag behind the drive signal of the inverter bridge arm 102, and the drive signal of the inverter bridge arm 102 can follow the polarity of the modulation wave signal. In other words, the common bridge arm 103 can follow the operation of the upper inverter bridge arm, so that the inverter output waveform can be presented as a sine waveform, without distortion, and with good sinusoidality. Moreover, such a control method also eliminates the control coupling of the common bridge arm 103, and the control of the common bridge arm 103 can be relatively independent. Therefore, through the control method of the power converter 10 of the present application, the decoupling control of the common bridge arm 103 in the power converter 10 can be achieved, so that the common bridge arm 103 can participate in rectification and inversion at the same time, and the power converter 10 can have better inverter output quality.

[0062] In the embodiment of the present application, for ease of description, the drive signal of the common bridge arm 103 may be referred to as the first drive signal, and the drive signal of the inverter bridge arm 102 may be referred to as the second drive signal. The modulated wave signal of the second drive signal may be referred to as the first modulated wave signal. The fundamental wave signal of the second drive signal may be referred to as the first preset fundamental wave signal. In this embodiment, as shown in FIG. 3C , the first preset fundamental wave signal may be a preset triangular wave signal.

[0063] Referring to FIG4 , the method may generate the first modulated wave signal through the following process:

[0064] Step S41: obtaining the input voltage of the AC power supply, the real-time output voltage of the power converter to the AC load, the real-time DC bus voltage, and the second inductor current.

[0065] The input voltage of the AC power supply is the effective value of the voltage of the AC power supply, which can be calculated based on the real-time input voltage Vin of the AC power supply. For example, the real-time input voltage Vin of the AC power supply over at least one AC cycle can be calculated by performing a root mean square (RMS) calculation (i.e., integrating the square of the real-time input voltage Vin over at least one AC cycle, dividing it by the AC cycle, and then taking the square root of the square root) to obtain the effective value of the voltage. In one embodiment, the effective value of the voltage of the AC power supply can be obtained by dividing the obtained peak voltage by the square root of 2.

[0066] The real-time output voltage output by the power converter 10 to the AC load R1 refers to the real-time voltage between the second live terminal L2 and the neutral terminal N. The real-time output voltage output by the power converter 10 to the AC load R2 refers to the real-time voltage between the second live terminal L2 and the first live terminal L1. Since the AC loads R1 and R2 are both connected to the second live terminal L2, it is only necessary to control the real-time voltage between the first live terminal L1 and the second live terminal L2 to control the real-time voltage between the second live terminal L2 and the neutral terminal N. Alternatively, by controlling the voltage between the second live terminal L2 and the neutral terminal N, it is possible to control the real-time voltage between the first live terminal L1 and the second live terminal L2. Therefore, in this embodiment, the real-time voltage between the second live terminal L2 and the neutral terminal N is used as the real-time output voltage. In other embodiments, the real-time output voltage can also be determined based on the location where the AC load is connected.

[0067] The real-time DC bus voltage Vdc refers to the real-time voltage between the positive and negative DC buses, that is, the voltage of the DC bus capacitor. The second inductor current ILf2 refers to the current flowing through the second inductor Lf2.

[0068] It is understandable that the real-time input voltage of the AC power supply, the real-time output voltage of the second live terminal L2, and the real-time DC bus voltage can all be detected by corresponding voltage detection circuits. The second inductor current can be detected by current detection circuits.

[0069] Step S42: determining a target output voltage for the AC load according to the input voltage.

[0070] It can be understood that the target output voltage for the AC load R1 refers to the target voltage (also referred to as the demand voltage) required by the AC load R1, that is, the target voltage between the second live terminal L2 and the neutral terminal N. The target output voltage for the AC load R2 refers to the target voltage (also referred to as the demand voltage) required by the AC load R2, that is, the target voltage between the second live terminal L2 and the first live terminal L1. Since the AC loads R1 and R2 are both connected to the second live terminal L2, when the phase voltage of the first live terminal L1 is determined, the demand voltage for both the AC load R1 and R2 is related to the phase voltage of the second live terminal L2. Therefore, the target output voltage Vo_ref output to the AC load at this time needs to correspond to the real-time output voltage obtained in step S41. In this embodiment, the real-time output voltage obtained is the real-time voltage between the second live terminal L2 and the neutral terminal N.

[0071] As previously mentioned, the voltage between the first live terminal L1 and the neutral terminal N is equal to the voltage between the second live terminal L2 and the first live terminal L1. Therefore, the voltage between the second live terminal L2 and the neutral terminal N (i.e., the phase voltage of the second live terminal L2) is equal to twice the voltage between the first live terminal L1 and the neutral terminal (i.e., the phase voltage of the first live terminal L1). Therefore, twice the input voltage of the AC power supply can be used as the target output voltage Vo_ref.

[0072] Step S43: generating a modulation wave signal according to the target output voltage, the real-time output voltage, the real-time DC bus voltage and the second inductor current.

[0073] It can be understood that since step S43 generates the first modulation wave signal based on relevant parameters such as the target output voltage, the real-time output voltage, the real-time DC bus voltage and the second inductor current, the second drive signal of the inverter bridge arm 102 modulated by the first modulation wave signal is applicable to the inverter bridge arm 102, and the real-time output voltage Vo can be accurately adjusted to be close to or equal to the target output voltage value Vo_ref.

[0074] In an embodiment of the present application, in step S43, the first modulation wave signal can be obtained by performing closed-loop control on the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current.

[0075] For example, referring to FIG5 , the process of generating a modulation wave signal according to the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current may include:

[0076] Step S51: Calculate the voltage difference between the target output voltage value and the real-time output voltage.

[0077] That is, a voltage difference value obtained by subtracting the real-time output voltage Vo from the target output voltage value Vo_ref is calculated.

[0078] Step S52: performing deviation adjustment on the voltage difference to obtain a first current reference value.

[0079] The deviation adjustment may be PI adjustment (Proportional Integral adjustment). In other embodiments, the deviation adjustment may also be PID adjustment (Proportional Integral Derivative adjustment) or other adjustment methods, which are not limited here. After the input voltage difference is deviation adjusted, the first current reference value ILf2_ref can be obtained.

[0080] Step S53 : Obtaining a first current deviation value according to the first current reference value and the second inductor current.

[0081] For example, the difference between the first current reference value ILf2_ref and the second inductor current ILf2 may be calculated to obtain the first current deviation value ILf2_ref-ILf2.

[0082] Step S54: performing deviation adjustment on the first current deviation value to obtain a deviation adjustment amount.

[0083] The deviation adjustment amount ΔV1 can be understood as a compensation value for the real-time output voltage, which can be used to compensate the real-time output voltage to be closer to or reach the target output voltage value. It is understood that the deviation adjustment method in step S54 is the same or similar to the deviation adjustment method in step S52, and therefore will not be further described here.

[0084] Step S55: obtaining the current target voltage according to the deviation adjustment amount and the real-time output voltage.

[0085] For example, the sum of the deviation adjustment amount ΔV1 and the real-time output voltage Vo may be calculated to obtain the current target voltage ΔV1+Vo.

[0086] Step S56: Generate a modulation wave signal according to the current target voltage and the real-time DC bus voltage.

[0087] In this embodiment, the ratio between the current target voltage and the real-time DC bus voltage is used to determine the first target duty cycle information used to control the switches of the inverter bridge arm 102, thereby outputting a first modulated wave signal carrying the first target duty cycle information. This first modulated wave signal can be used to modulate the first fundamental wave signal into the second drive signal for the inverter bridge arm 102.

[0088] In this embodiment, the second drive signals for the upper switch L2_H and the lower switch L2_L of the inverter bridge arm 102 can be obtained by using the first modulated wave signal and the first preset fundamental wave signal using SPWM (sinusoidal pulse width modulation) modulation, thereby causing the upper switch L2_H and the lower switch L2_L of the inverter bridge arm 102 to conduct at a high frequency and complementarily, thereby outputting alternating positive and negative alternating current on the second live terminal L2. In other words, the switching states of the upper switch L2_H and the lower switch L2_L of the inverter bridge arm 102 are controlled by the first modulated wave signal and remain consistent with the first modulated wave signal. When the first modulation wave signal is greater than zero, the output first modulation wave signal corresponds to the high-frequency duty cycle of the upper switch tube L2_H, and the upper switch tube L2_H and the lower switch tube L2_L are high-frequency complementary and conductive; when the first modulation wave signal is less than zero, the output first modulation wave signal corresponds to the high-frequency duty cycle of the lower switch tube L2_L, and the upper switch tube L2_H and the lower switch tube L2_L are high-frequency complementary and conductive.

[0089] In summary, in steps S51-S56, the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current form an outer voltage loop and an inner current loop, which are used to calculate the first modulated wave signal. The use of an offset adjustment algorithm in this process helps improve control accuracy and speed, facilitating the rapid generation of a matching first modulated wave signal.

[0090] In the embodiment of the present application, the controller can also implement the steps shown in Figure 5 through the inverter control loop of Figure 6. As shown in Figure 6, the controller includes a first subtractor 201, a first deviation regulator 202, a second subtractor 203, a second deviation regulator 204, a first adder 205, a first divider 206, and a first modulator 207.

[0091] Specifically, the real-time output voltage Vo of the power converter 10 to the AC load and the target output voltage Vo_ref to the AC load are both input to a first subtractor 201. First subtractor 201 subtracts Vo_ref from Vo and outputs the subtraction result, Vo_ref-Vo, to a first offset regulator 202. First offset regulator 202 then performs an offset calculation on Vo_ref-Vo and outputs ILf2_ref to a second subtractor 203. Second inductor current ILf2 is also input to second subtractor 203. Second subtractor 203 further subtracts ILf2_ref from ILf2 and outputs the subtraction result, ILf2_ref-ILf2, to a second offset regulator 204. Second offset regulator 204 performs an offset calculation on ILf2_ref-ILf2 and outputs an offset adjustment value, ΔV1, to a first adder 205. The real-time output voltage Vo is also input to the first adder 205. Furthermore, the first adder 205 adds ΔV1 and Vo to obtain the current target voltage ΔV1+Vo, and outputs the current target voltage ΔV1+Vo to the first divider 206. The real-time DC bus voltage Vdc is also input to the first divider 206. The first divider 206 divides ΔV1+Vo by Vdc to obtain a first modulated wave signal carrying the first target duty cycle information. It is understood that the first modulated wave signal can be input to the first modulator 207, which then uses the first modulated wave signal to modulate the corresponding second drive signal for the inverter bridge arm 102.

[0092] It should be understood that the inverter control loop described above is only an illustrative example provided in this application. The control logic shown in Figure 5 and the specific composition of the inverter control loop shown in Figure 6 can be adjusted accordingly according to actual conditions and are not limited to the implementation method mentioned in this application.

[0093] It should be noted that the target output voltage Vo_ref and the real-time output voltage Vo are both AC voltages with positive and negative polarities. Therefore, the first modulation wave signal generated according to the target output voltage, the real-time output voltage, the real-time DC bus voltage and the second inductor current also has positive and negative polarities accordingly.

[0094] Therefore, referring to FIG7 , when an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, a process of controlling the common bridge arm according to the modulated wave signal of the drive signal of the inverter bridge arm (corresponding to step S31 in FIG3A ) may include:

[0095] Step S71A: When the modulated wave signal is positive, the upper switch tube of the common bridge arm is controlled to be turned off and the lower switch tube of the common bridge arm is controlled to be turned on.

[0096] Step S71B: When the modulated wave signal is of negative polarity, the upper switch tube of the common bridge arm is controlled to be turned on and the lower switch tube of the common bridge arm is controlled to be turned off.

[0097] In this embodiment, when the first modulation wave signal is in positive polarity, the upper switch tube N_H of the common bridge arm 103 is controlled to be turned off and the lower switch tube N_L of the common bridge arm 103 is controlled to be turned on; when the first modulation wave signal is in negative polarity, the upper switch tube N_H of the common bridge arm 103 is controlled to be turned on and the lower switch tube N_L of the common bridge arm 103 is controlled to be turned off, thereby combining the inverter bridge arm 102 to realize the inverter split phase output control.

[0098] For ease of understanding, Figure 3B shows the control logic of the first drive signal of the switch tubes N_H and N_L. Among them, the high level in the signal waveform represents that the switch tube is in the on state, and the low level in the waveform represents that the switch tube is in the off state. As can be seen from Figure 3B, the first drive signal of the switch tubes N_H and N_L is a PWM (Pulse Width Modulation) drive signal. The polarity of the first drive signal of the switch tubes N_H and N_L changes synchronously with the polarity of the first modulation wave signal, wherein the first drive signal of the switch tube N_L has the same polarity as the first modulation wave signal, and the first drive signal of the switch tube N_H has the opposite polarity to the first modulation wave signal.

[0099] Specifically, when the first modulated wave signal is of positive polarity and the upper switch tube L2_H of the inverter bridge arm 102 is turned on and the lower switch tube L2_L is turned off, at this time, driven by the first drive signal, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, and the DC power provided on the DC bus capacitor Cbus flows back to the neutral terminal N through the upper switch tube L2_H, the second inductor Lf2, and the load R1, thereby forming a current on the second inductor Lf2, thereby realizing output control of the second live terminal L2.

[0100] When the first modulated wave signal is positive, and the upper switch tube L2_H of the inverter bridge arm 102 is turned off and the lower switch tube L2_L is turned on, at this time, driven by the first drive signal, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, and the energy stored on the second inductor Lf2 forms a freewheeling loop through the load R1, the lower switch tube N_L and the lower switch tube L2_L, thereby outputting a voltage at the second live wire terminal L2.

[0101] When the first modulation wave signal is negative, the control logic is similar to the control logic when the first modulation wave signal is positive, so it is not described in detail. The specific control timing can be seen in Figure 3B.

[0102] In summary and referring to FIG3B , the controller can be a first drive signal for generating the common bridge arm 103 based on the first modulation wave signal, and the polarity of the first drive signal and the first modulation wave signal change synchronously, so that when the polarity of the first modulation wave signal is positive, the first drive signal can control the upper switch tube N_H of the common bridge arm 103 to be turned off and the lower switch tube N_L to be turned on. When the polarity of the first modulation wave signal is negative, the first drive signal can be switched to control the lower switch tube N_L of the common bridge arm 103 to be turned on and the upper switch tube N_H to be turned off. As a result, the zero crossing point of the first modulation wave signal and the first drive signal of the common bridge arm 103 in FIG3B is completely coincident, thereby avoiding the problem that the inverter output waveform cannot be presented as a sine wave due to the polarity of the first drive signal of the common bridge arm not following the polarity of the first modulation wave signal.

[0103] In addition, since the target output voltage and the real-time output voltage Vo are AC voltages and are sinusoidal signals, as shown in FIG3B , the first modulation wave signal generated according to the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current is also a sinusoidal signal and changes in a sinusoidal pattern.

[0104] Therefore, when an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, please refer to FIG. 3A again. The control process of the inverter bridge arm 102 may include:

[0105] Step S32: generating a drive signal for the inverter bridge arm according to the modulated wave signal and the preset fundamental wave signal.

[0106] Specifically, as shown in FIG3C , the first modulated wave signal can be compared with the first preset fundamental wave signal. If the first modulated wave signal is greater than the first preset fundamental wave signal, a first level is generated. If the first modulated wave signal is less than the first preset fundamental wave signal, a second level different from the first level is generated. This modulates the first preset fundamental wave signal into an SPWM drive signal consisting of a series of pulses of varying widths. The first and second levels can be set accordingly based on practical needs and are not limited herein. The first preset fundamental wave signal can be determined based on practical needs, for example, a triangular wave signal can be used. It is understood that in FIG6 , the first preset fundamental wave signal can be input into or pre-stored in the first modulator, so that the first modulator can use the first modulated wave signal to modulate the first preset fundamental wave signal to obtain a drive signal for the inverter bridge arm 102 (for ease of description, this drive signal can be referred to as the second drive signal).

[0107] It is understood that either the upper switch L2_H or the lower switch L2_L of the inverter bridge arm 102 needs to be turned on, otherwise a short circuit will occur. Therefore, the second drive signal of the upper switch L2_H and the second drive signal of the lower switch L2_L are complementary, as shown in FIG3B .

[0108] Step S33: controlling the inverter bridge arm according to the driving signal to control the on and off of the upper switch tube and the lower switch tube of the inverter bridge arm.

[0109] Specifically, regardless of whether the real-time input voltage Vin is greater than 0 or not greater than 0 and what its polarity is, under the drive of the second drive signal, the upper switch tube L2_H and the lower switch tube L2_L of the inverter bridge arm 102 are always complementary and turned on at high frequency, and the power frequency polarity of the common bridge arm follows the polarity of the first modulation wave signal, thereby ensuring that the inverted output sinusoidal wave signal can be output.

[0110] In addition, when an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, the rectifier bridge arm 101 also performs corresponding on-off control of the switch tube. Therefore, please continue to refer to Figure 3A. The control method of the embodiment of the present application may also include:

[0111] Step S34: Generate a driving signal for the rectifier bridge arm according to the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage and the first inductor current to control the on and off of the upper switch tube and the lower switch tube of the rectifier bridge arm.

[0112] The first inductor current ILf1 refers to the current flowing through the first inductor Lf1 and can be detected by a current detection circuit.

[0113] It can be understood that since the drive signal of the rectifier bridge arm 101 (for the convenience of description, this drive signal can be referred to as the third drive signal) is generated based on the relevant parameters such as the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage and the first inductor current, the third drive signal is applicable to the rectifier bridge arm 101.

[0114] In an embodiment of the present application, in step S34, the driving signal of the rectifier bridge arm 101 can be obtained by performing closed-loop control on the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage and the first inductor current.

[0115] For example, referring to FIG8 , the process of generating a driving signal for a rectifier bridge arm according to the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage, and the first inductor current may include:

[0116] Step S81: Calculate the voltage difference between the reference DC bus voltage and the real-time DC bus voltage.

[0117] That is, the voltage difference between the reference DC bus voltage Vdc_ref and the real-time DC bus voltage Vdc is calculated.

[0118] The reference DC bus voltage may be set according to actual conditions (eg, specification parameters of the DC bus capacitor, required voltage of the DC load, etc.), and is not limited here.

[0119] Step S82: performing deviation adjustment on the voltage difference to obtain a second current reference value.

[0120] The deviation adjustment may be PI adjustment (Proportional Integral adjustment). In other embodiments, the deviation adjustment may also be PID adjustment (Proportional Integral Derivative adjustment) or other adjustment methods, which are not limited here. After the input voltage difference is deviation adjusted, the second current reference value ILf1_ref can be obtained.

[0121] Step S83: Obtain a second current deviation value according to the second current reference value and the first inductor current.

[0122] For example, the difference between the second current reference value ILf1_ref and the first inductor current ILf1 may be calculated to obtain the second current deviation value ILf1_ref-ILf1.

[0123] Step S84: performing deviation adjustment on the second current deviation value to obtain a deviation compensation amount.

[0124] It is understandable that the deviation adjustment method of step S84 is the same as or similar to the deviation adjustment method of step S82, so it will not be repeated here.

[0125] Step S85: obtaining a current reference voltage according to the deviation compensation amount and the real-time DC bus voltage.

[0126] For example, the sum of the deviation compensation amount and the real-time DC bus voltage may be calculated to obtain the current reference voltage ΔV2+Vdc.

[0127] Step S86: Generate a second modulated wave signal according to the current reference voltage and the real-time input voltage of the AC power supply.

[0128] In this embodiment, the ratio between the current reference voltage and the real-time input voltage is used to determine the second target duty cycle information used to control the switch of the rectifier bridge arm 101, thereby outputting a second modulated wave signal carrying the second target duty cycle information. The second modulated wave signal can be used to modulate the third drive signal for the rectifier bridge arm 101.

[0129] Step S87: generating a driving signal for the rectifier bridge arm according to the second modulated wave signal and the second preset fundamental wave signal.

[0130] The second preset fundamental wave signal can be set accordingly according to actual needs and is not limited here.

[0131] Similar to or identical to step S32, step S87 can generate a third drive signal for the rectifier bridge arm 101 by comparing the second modulated wave signal with the second preset fundamental wave signal. In this embodiment, the third drive signal is obtained by PWM modulation.

[0132] In this embodiment, the upper switch L1_H and the lower switch L1_L are complementary to each other in conduction. Therefore, the third drive signal of the upper switch L1_H and the third drive signal of the lower switch L1_L are complementary, as shown in Figure 3B. The order in which the upper switch L1_H and the lower switch L1_L are turned on depends on the polarity of the current input voltage Vin. The specific control process of this part can be implemented using existing drive logic in the art and is not detailed here.

[0133] In summary, in steps S81-S87, the AC power supply input voltage, the reference DC bus voltage, the real-time DC bus voltage, and the first inductor current form an outer voltage loop and an inner current loop. These loops are used to calculate the third drive signal for rectifier bridge arm 101. The use of an offset adjustment algorithm in this process improves control accuracy and speed, facilitating the rapid generation of a matching third drive signal.

[0134] In the embodiment of the present application, the controller can also implement the steps shown in Figure 8 through the rectification control loop of Figure 9. As shown in Figure 9, the controller includes a third subtractor 208, a third deviation regulator 209, a fourth subtractor 210, a fourth deviation regulator 211, a second adder 212, a second divider 213, and a second modulator 214.

[0135] Specifically, both the reference DC bus voltage Vdc_ref and the real-time DC bus voltage Vdc are input to the third subtractor 208. The third subtractor 208 subtracts Vdc_ref from Vdc and outputs the subtraction result, Vdc_ref-Vdc, to the third offset regulator 209. The third offset regulator 209 performs an offset operation on Vdc_ref-Vdc and outputs ILf1_ref to the fourth subtractor 210. The first inductor current ILf1 is also input to the fourth subtractor 210. The fourth subtractor 210 further subtracts ILf1_ref from ILf1 and outputs the subtraction result, ILf1_ref-ILf1, to the fourth offset regulator 211. The fourth offset regulator 211 performs an offset operation on ILf1_ref-ILf1 and outputs an offset compensation value, ΔV2, to the second adder 212. The real-time DC bus voltage Vdc is also input to the second adder 212. Furthermore, the second adder 212 adds △V2 and Vdc to obtain the current reference voltage △V2+Vdc, and outputs the current reference voltage △V2+Vdc to the second divider 213. The real-time input voltage Vin is also input to the second divider 213. After the second divider 213 divides △V2+Vdc by Vin, it obtains a second modulated wave signal carrying the second target duty cycle information. The second modulated wave signal can be input to the second modulator 214. The second modulator 214 then uses the second modulated wave signal to modulate the second preset fundamental signal (to simplify Figure 9, the second preset fundamental signal is not shown) to output the corresponding third drive signal of the rectifier bridge arm 101. The second preset fundamental signal can be pre-stored in the second modulator 214, of course, it can also be input to the second modulator 214, which is not limited here.

[0136] It should be understood that the rectifier control loop described above is only an illustrative example provided in this application. The control logic shown in Figure 8 and the specific composition of the rectifier control loop shown in Figure 9 can be adjusted accordingly according to actual conditions and are not limited to the implementation method mentioned in this application.

[0137] It should be noted that, as shown in FIG3B , although the first modulation wave signal and the real-time input voltage Vin are both sinusoidal signals, the zero crossing points of the two sinusoidal signals do not completely overlap. This is mainly because the real-time input voltage Vin is an existing signal, and the first modulation wave signal is a signal that needs to be regulated by the inverter control loop. Therefore, at the beginning, there is a certain time difference between the real-time input voltage Vin and the first modulation wave signal, and thus the zero crossing points of the two waveforms will not completely overlap. This is also the reason why the common bridge arm 103 is controlled according to the polarity of the real-time input voltage Vin in the related art to achieve simultaneous rectification and inversion, but the common bridge arm 103 cannot completely follow the operation of the upper inverter bridge arm 102, causing the inverter output waveform to be distorted at the zero crossing point. Therefore, the embodiment of the present application controls the common bridge arm 103 according to the first modulation wave signal. Under this control mode, the first drive signal of the common bridge arm 103 follows the polarity of the first modulation wave signal, and the first modulation wave signal and the first drive signal of the common bridge arm 103 can completely coincide with each other at the zero crossing point, that is, the common bridge arm 103 can follow the operation of the upper inverter bridge arm 102, thereby avoiding distortion of the inverter output waveform at the zero crossing point, so the inverter output waveform can be a sinusoidal waveform.

[0138] Moreover, the common bridge arm 103 is controlled according to the first modulation wave signal and does not affect the rectification process. Specifically, when the first modulation wave signal and the real-time input voltage Vin of the AC power supply are both positive, and when the upper switch tube L1_H of the rectifier bridge arm 101 is turned on and the lower switch tube L1_L is turned off, at this time, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, and the AC power provided by the AC power supply flows back to the neutral terminal N after passing through the first live terminal L1, the first inductor Lf1, the upper switch tube L1_H, the DC bus capacitor Cbus between the DC bus bars BUS+ and BUS-, and the lower switch tube N_L, thereby forming a current in the first inductor Lf1 (the flow direction is positive at this time, flowing from the first live terminal L1 to point a), thereby charging the DC bus capacitor Cbus.

[0139] When the first modulated wave signal and the real-time input voltage Vin of the AC power supply are both positive, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned off and the lower switch tube L1_L is turned on, at this time, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, the AC power provided by the AC power supply and the stored energy on the first inductor Lf1 form a freewheeling loop through the first live wire terminal L1, the first inductor Lf1, the lower switch tube L1_L, and the lower switch tube N_L.

[0140] When the first modulated wave signal is positive and the real-time input voltage Vin of the AC power supply is negative, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned on and the lower switch tube L1_L is turned off, the drive signal of the common bridge arm 103 is synchronized with the first modulated wave signal. That is, at this time, the upper switch tube N_H of the common bridge arm is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on. The AC power provided by the AC power supply flows through the neutral terminal N, the lower switch tube N_L, the DC bus capacitor Cbus between the DC buses BUS+ and BUS-, and the upper switch tube L1_H to the first inductor Lf1, thereby forming a current in the first inductor Lf1 (the flow direction at this time is reverse, that is, flowing from point a to the first live terminal L1), thereby charging the DC bus capacitor Cbus.

[0141] When the first modulated wave signal is positive and the real-time input voltage Vin of the AC power supply is negative, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned off and the lower switch tube L1_L is turned on, at this time, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, the AC power provided by the AC power supply and the stored energy on the first inductor Lf1 pass through the neutral terminal N, the lower switch tube N_H, the lower switch tube L1_L and flow to the first live terminal L1 to form a freewheeling loop.

[0142] When the first modulated wave signal has a negative polarity and the real-time input voltage Vin of the AC power supply has a positive polarity, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned on and the lower switch tube L1_L is turned off, at this time, the upper switch tube N_H of the common bridge arm 103 is turned on and the lower switch tube N_L of the common bridge arm 103 is turned off, and the AC power provided by the AC power supply flows back to the neutral terminal after passing through the first live terminal L1, the first inductor Lf1, the upper switch tube L1_H, the DC bus capacitor Cbus, and the body diode of the lower switch tube N_L.

[0143] When the first modulated wave signal has a negative polarity and the real-time input voltage Vin of the AC power supply has a positive polarity, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned off and the lower switch tube L1_L is turned on, at this time, the upper switch tube N_H of the common bridge arm 103 is turned on and the lower switch tube N_L of the common bridge arm 103 is turned off, the AC power provided by the AC power supply and the stored energy of the first inductor Lf1 flow back to the neutral terminal through the lower switch tube L1_L and the body diode of the lower switch tube N_L to form a freewheeling loop.

[0144] It can be understood that when the first modulated wave signal and the real-time input voltage Vin of the AC power supply are both negative polarity, or when the first modulated wave signal and the real-time input voltage Vin of the AC power supply are different polarities, the control logic is similar to the above control logic, so it is not repeated. The specific control timing can be seen in Figure 3B.

[0145] That is, when the common bridge arm 103 participates in both rectification and inversion, although the common bridge arm 103 switches the upper and lower switches N_H and N_L to conduct following the first modulation wave signal of the inverter bridge arm 102, in the rectification mode, the common bridge arm 103 can use its own body diode for freewheeling, and thus will not affect the rectification function of the power converter 10. Therefore, based on the embodiment method of the present application, it is possible to achieve both rectification and inversion without affecting the inverter output of the power converter 10.

[0146] To verify the method shown in FIG3A , a simulation experiment was also conducted in the embodiment of the present application.

[0147] Please refer to FIG. 10A to FIG. 10C , which are voltage and current waveform diagrams of the power converter 10 when the power converter 10 is controlled by the method shown in FIG. 3A .

[0148] 10A shows the input voltage waveform, input current waveform, output voltage waveform, and output current waveform of the power converter 10 when a 120V AC power supply is connected between the first live terminal L1 and the neutral terminal N, and a resistive load (full load at this time) with a required voltage of 240V is connected between the second live terminal L2 and the neutral terminal N. The unit V / DIV of the output voltage waveform is twice the unit V / DIV of the input voltage waveform. In this embodiment, one grid corresponding to the output voltage waveform represents 100V, and one grid corresponding to the input voltage waveform represents 200V.

[0149] FIG10B shows the input voltage waveform, input current waveform, output voltage waveform, and output current waveform of the power converter 10 when a 120V AC power supply is connected between the first live terminal L1 and the neutral terminal N, and an RCD load (fully loaded at this time) with a demand voltage of 240V is connected between the second live terminal L2 and the neutral terminal N. The unit V / DIV of the output voltage waveform is twice the unit V / DIV of the input voltage waveform. In this embodiment, one grid corresponding to the output voltage waveform represents 100V, and one grid corresponding to the input voltage waveform represents 200V.

[0150] FIG10C shows the input voltage waveform, input current waveform, output voltage waveform, and output current waveform of the power converter 10 when a 120V AC power supply is connected between the first live terminal L1 and the neutral terminal N, and an inductive load (full load at this time) with a demand voltage of 240V is connected between the second live terminal L2 and the neutral terminal N. The unit V / DIV of the output voltage waveform is twice the unit V / DIV of the input voltage waveform. In this embodiment, one grid corresponding to the output voltage waveform represents 100V, and one grid corresponding to the input voltage waveform represents 200V.

[0151] As can be seen from Figures 10A to 10C, regardless of the type of AC load connected to the power converter 10, the output voltage waveform and output current waveform of the power converter 10 are not distorted and have good sinusoidal properties. Furthermore, the output voltage can reach twice the input voltage, which verifies that when the power converter is controlled using the method of the embodiment of the present application, the power converter 10 is able to achieve a phase voltage outputted from the second live terminal L2 that is twice the phase voltage of the first live terminal L1. Therefore, the output voltage can meet the requirements of the AC load.

[0152] It can be seen that through the method of the embodiment of the present application, the power converter 10 can realize simultaneous rectification and inversion, and also has better inverter output quality under the condition of simultaneous rectification and inversion, and can meet the power supply requirements of the AC load.

[0153] In addition, when the AC power supply is cut off (such as the power grid is out of power), the power converter 10 is equivalent to the first live terminal and the neutral terminal being disconnected from the AC power supply, and the rectifier bridge arm 101 has no input, so the power converter 10 needs to exit the rectifier mode. Therefore, referring to FIG. 11A , the control method of the embodiment of the present application may further include:

[0154] When no AC power is connected between the first live terminal and the neutral terminal, the output of the driving signal of the rectifier bridge arm is stopped to control the rectifier bridge arm to stop working (see step S114 in FIG. 11A ).

[0155] Understandably, at this time, an AC load is still connected between the first live terminal L1 and the second live terminal L2 or between the second live terminal L2 and the neutral terminal N of the power converter 10. Although the rectifier bridge arm 101 stops working, a certain amount of electrical energy is pre-stored in the DC bus capacitor Cbus (in some cases, a DC power supply such as a battery pack can be connected between the positive and negative DC bus BUS+ and BUS- to supplement the electrical energy). Therefore, when no AC power supply is connected between the first live terminal L1 and the neutral terminal N, and an AC load is connected between the first live terminal L1 and the second live terminal L2 or between the second live terminal L2 and the neutral terminal N, the controller can still control the common bridge arm 103 and the inverter bridge arm 102 according to the control logic shown in Figure 3A (see steps S111 to S113 in Figure 11A, corresponding to steps S31 to S33 in Figure 3A), so that the power converter 10 can still operate in the inverter mode. The control logic can be specifically referred to the relevant description above and will not be repeated here.

[0156] Correspondingly, as shown in Figure 11B, the switch tube of the rectifier bridge arm 101 is wave-sealed. The wave generation of the inverter bridge arm 102 and the common bridge arm 103 is the same as that of Figure 3B, so it will not be repeated here.

[0157] In addition, when the load condition of the power converter 10 changes, such as when no AC load is connected between the first live terminal L1 and the second live terminal L2, and between the second live terminal L2 and the neutral terminal N, and a DC load is connected between the positive DC bus BUS+ and the negative DC bus BUS-, the inverter bridge arm 102 does not need to work at this time, and the second live terminal L2 does not need to output, so the power converter 10 needs to exit the inverter mode. Therefore, referring to FIG. 12A , the control method of the embodiment of the present application may further include:

[0158] When an AC power supply is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus but no AC load is connected, the output of the drive signal of the inverter bridge arm is stopped to control the inverter bridge arm to stop working (see step S122 in Figure 12A).

[0159] Since the power converter 10 needs to supply power to a DC load at this time, the power converter 10 operates in a rectification mode, and the controller needs to control the rectification bridge arm 101 and the common bridge arm 103 .

[0160] The control logic of the rectifier bridge arm 101 is similar to step S34 in FIG. 3A , specifically:

[0161] When an AC power supply is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus, but no AC load is connected, a drive signal for the rectifier bridge arm is generated according to the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage, and the first inductor current to control the on and off of the upper switch tube and the lower switch tube of the rectifier bridge arm (see step S123 in Figure 12A, corresponding to step S34 in Figure 3A).

[0162] It is understandable that the control process of the rectifier bridge arm 101 can be specifically referred to the relevant description of the aforementioned step S34, which will not be repeated here.

[0163] At this time, the common bridge arm 103 does not need to cooperate with the inverter bridge arm 102 to achieve the inverter function, and the inverter bridge arm 102 does not need to work at this time, and the controller does not need to generate the first modulation wave signal of the inverter bridge arm 102. Therefore, the common bridge arm 103 adopts a control strategy different from the control logic of Figure 3A. Specifically, please continue to refer to Figure 12A. The control method of the embodiment of the present application may also include:

[0164] When an AC power supply is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus, but no AC load is connected, the common bridge arm is controlled according to the real-time input voltage of the AC power supply (see step S121 in Figure 12A).

[0165] Understandably, the voltage between the midpoint of the common bridge arm 103 and the second end of the first inductor Lf1 on the rectifier bridge arm 101, that is, the voltage between the neutral terminal N and the first live terminal L1, is clamped by the AC power supply. Therefore, the voltage polarity of the neutral terminal N changes with the polarity of the real-time input voltage of the AC power supply. Therefore, in step S111, it is necessary to control the switching of the upper and lower switches N_H and N_L of the common bridge arm 103 based on the real-time input voltage Vin, so that the common bridge arm 103 can, through the switching of the upper and lower switches N_H and N_L, work together with the rectifier bridge arm 101 to rectify the real-time input voltage Vin of both positive and negative polarities into positive direct current.

[0166] Further, referring to FIG13 , when an AC power source is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus, but no AC load is connected, the process of controlling the common bridge arm according to the real-time input voltage of the AC power source can be specifically as follows:

[0167] Step S131A: When the real-time input voltage is positive, the upper switch tube of the common bridge arm is controlled to be turned off and the lower switch tube of the common bridge arm is controlled to be turned on.

[0168] Step S131B: When the real-time input voltage is negative, the upper switch tube of the common bridge arm is controlled to be turned on and the lower switch tube of the common bridge arm is controlled to be turned off.

[0169] In this embodiment, when the real-time input voltage is in positive polarity, the upper switch tube N_H of the common bridge arm 103 is controlled to be turned off and the lower switch tube N_L of the common bridge arm 103 is controlled to be turned on; when the modulation wave signal is in negative polarity, the upper switch tube N_H of the common bridge arm 103 is controlled to be turned on and the lower switch tube N_L of the common bridge arm 103 is controlled to be turned off, thereby realizing the rectification function in combination with the rectifier bridge arm 101.

[0170] Specifically, when the real-time input voltage Vin is positive, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned on and the lower switch tube L1_L is turned off, at this time, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on, and the AC power provided by the AC power supply passes through the first live terminal L1, the first inductor Lf1, the upper switch tube L1_H, the DC bus capacitor Cbus between the DC bus BUS+ and BUS-, and the lower switch tube N_L and flows back to the neutral terminal N, thereby forming a current on the first inductor Lf1 (at this time the flow direction is from the first live terminal L1 to point a), thereby charging the DC bus capacitor Cbus.

[0171] When the real-time input voltage Vin is positive, and the upper switch tube L1_H of the rectifier bridge arm 101 is turned off and the lower switch tube L1_L is turned on, the upper switch tube N_H of the common bridge arm 103 is turned off and the lower switch tube N_L of the common bridge arm 103 is turned on. The AC power provided by the AC power supply and the energy stored in the first inductor Lf1 form a freewheeling loop through the first live wire terminal L1, the first inductor Lf1, the lower switch tube L1_L, and the lower switch tube N_L.

[0172] When the real-time input voltage Vin is negative, the control logic is similar to the control logic when the real-time input voltage Vin is positive, so it is not described in detail. The specific control timing can be seen in Figure 12B.

[0173] Correspondingly, as shown in FIG12B , the switch tube of the inverter bridge arm 102 is wave-sealed. The wave generation situation of the rectifier bridge arm 101 is the same as that of FIG3B . The first drive signal of the switch tubes N_H and N_L of the common bridge arm 103 is a PWM (Pulse Width Modulation) drive signal. The polarity of the first drive signal of the common bridge arm 103 changes synchronously with the polarity of the real-time input voltage Vin, wherein the first drive signal of the switch tube N_L has the same polarity as the real-time input voltage Vin, and the first drive signal of the switch tube N_H has the opposite polarity to the real-time input voltage Vin. The first drive signals of the switch tubes N_H and N_L coincide with the zero-crossing point of the real-time input voltage Vin.

[0174] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should know that this application is not limited to the described order of actions, because according to this application, certain steps can be performed in other orders or simultaneously.

[0175] Please refer to FIG14 , which shows a schematic diagram of a power conversion device provided in an embodiment of the present application.

[0176] As shown in Figure 14, the power conversion device 100 includes a power converter 10 and a controller 20. The power converter 10 and the controller 20 may be integrated into one body or may be provided separately, which is not limited here.

[0177] The power converter 10 is the power converter shown in Figures 1A to 1C. The controller 20 can be a microcontroller unit (MCU) or other control circuit. The controller 20 can be used to execute the above-mentioned power converter control method to control the power conversion of the power converter. The specific implementation can refer to the relevant description in the above-mentioned method embodiment, which will not be repeated here.

[0178] Please refer to FIG15 , which shows a schematic diagram of an energy storage device provided in an embodiment of the present application.

[0179] As shown in Figure 15, the energy storage device 1000 includes a battery pack 200 and the above-mentioned power conversion device 100. The battery pack 200 and the power conversion device 100 can be integrated into one body or can be separately provided, which is not limited here.

[0180] The battery pack 200 is used to connect to the DC bus (BUS+, BUS-) in the power conversion device 100. In this way, the battery pack 200 can be charged by the power conversion device 100 and / or discharged through the power conversion device 100. In one embodiment, the battery pack 200 can be directly connected to the DC bus of the power conversion device 100 or connected to the DC bus of the power conversion device 100 through a DC conversion circuit.

[0181] Please refer to FIG16 , which shows a schematic diagram of an electronic device provided in an embodiment of the present application.

[0182] As shown in FIG. 16 , the electronic device 300 includes a processor 301 and a memory 302 .

[0183] The processor 301 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0184] The memory 302 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 302 may exist independently and be connected to the processor 301 via a bus. The memory 302 may also be integrated with the processor 301.

[0185] The memory 302 is used to store programs, instructions, or codes for executing the above power converter control method. The processor 301 is used to execute the programs, instructions, or codes stored in the memory 302. The programs, instructions, or codes stored in the memory 302 can execute some or all of the steps of the power converter control method in the embodiments shown in Figures 3A to 12.

[0186] 17 , which shows a schematic diagram of a control device for a power converter according to an embodiment of the present application. The control device 400 for a DC converter can be used to implement the above-mentioned control method for a power converter.

[0187] Specifically, as shown in FIG17 , the control device 400 of the power converter includes a common bridge arm control module 401 .

[0188] The common bridge arm control module 401 can be used to control the common bridge arm according to the modulated wave signal of the drive signal of the inverter bridge arm when an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal. The specific implementation can correspond to the corresponding description of the control method embodiment of the power converter shown in Figures 3A to 13, and will not be described in detail here.

[0189] In addition, the control device 400 of the power converter may further include a rectifier bridge arm control module 402 and an inverter bridge arm control module 403. The rectifier bridge control module may be used to control the rectifier bridge arm, and the inverter bridge arm control module 403 may be used to control the inverter bridge arm. For details, please refer to the corresponding description of the control method embodiment of the power converter shown in Figures 3A to 13, which will not be described in detail here.

[0190] It can be understood that the division of the various modules in the control device 400 of the above-mentioned power converter is only for illustration. In other embodiments, the control device 400 of the power converter can be divided into different modules as needed to complete all or part of the functions of the control device 400 of the above-mentioned power converter.

[0191] The functional modules in the embodiments of the present application may all be integrated into one processing module / unit, or each module may be a separate module, or two or more modules may be integrated into one module; the above-mentioned integrated modules may be implemented in the form of hardware or in the form of hardware plus software functional modules.

[0192] If the above-mentioned integrated module of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0193] The present application embodiment also provides a computer-readable storage medium for storing a computer program or code, which, when loaded and executed by a processor, implements all or part of the steps in the control method embodiment of the power converter shown in Figures 3A to 13. Wherein, the computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). The specific implementation of the computer-readable storage medium can be found in the description of the memory 302 in Figure 16, which will not be repeated here.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A control method for a power converter, the power converter comprising a rectifier bridge arm, an inverter bridge arm, a common bridge arm, a DC bus capacitor, a first inductor, and a second inductor; the rectifier bridge arm, the inverter bridge arm, the common bridge arm, and the DC bus capacitor are connected in parallel between a positive DC bus and a negative DC bus, the midpoint of the common bridge arm serves as a neutral terminal of the power converter, the midpoint of the rectifier bridge arm is connected to a first end of a first inductor, the second end of the first inductor serves as a first live terminal of the power converter, the midpoint of the inverter bridge arm is connected to a first end of a second inductor, the second end of the second inductor serves as a second live terminal of the power converter; the control method comprising: When an AC power source is connected between the first live terminal and the neutral terminal, and an AC load is connected between the first live terminal and the second live terminal or between the second live terminal and the neutral terminal, the common bridge arm is controlled according to the modulation wave signal of the drive signal of the inverter bridge arm.

2. The control method according to claim 1, wherein: The controlling the common bridge arm according to the modulation wave signal of the drive signal of the inverter bridge arm includes: When the modulated wave signal is positive, the upper switch tube of the common bridge arm is controlled to be turned off and the lower switch tube of the common bridge arm is controlled to be turned on; When the modulated wave signal is of negative polarity, the upper switch tube of the common bridge arm is controlled to be turned on and the lower switch tube of the common bridge arm is controlled to be turned off.

3. The control method according to claim 1 or 2, wherein: The control method further includes: Acquire the input voltage of the AC power supply, the real-time output voltage output by the power converter to the AC load, the real-time DC bus voltage, and the second inductor current; determining a target output voltage for the AC load according to the input voltage; The modulation wave signal is generated according to the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current.

4. The control method according to claim 3, wherein: Generating the modulated wave signal according to the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current includes generating a modulated wave signal that changes in a sinusoidal pattern according to the target output voltage, the real-time output voltage, the real-time DC bus voltage, and the second inductor current; The method further comprises: generating a drive signal for the inverter bridge arm according to the modulated wave signal and a preset fundamental wave signal; The inverter bridge arm is controlled according to the driving signal to control the on and off of the upper switch tube and the lower switch tube of the inverter bridge arm.

5. The control method according to any one of claims 1 to 4, wherein: The control method further includes: A drive signal for the rectifier bridge arm is generated according to the input voltage of the AC power supply, the reference DC bus voltage, the real-time DC bus voltage and the first inductor current to control the on and off of the upper switch tube and the lower switch tube of the rectifier bridge arm.

6. The control method according to claim 1, wherein: The control method further includes: When the AC power supply is not connected between the first live terminal and the neutral terminal, the output of the driving signal of the rectifier bridge arm is stopped to control the rectifier bridge arm to stop working.

7. The control method according to claim 1, wherein: The control method further includes: When an AC power supply is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus, but the AC load is not connected, the common bridge arm is controlled according to the real-time input voltage of the AC power supply.

8. The control method according to claim 1, wherein: The control method further includes: When an AC power source is connected between the first live terminal and the neutral terminal, and a DC load is connected between the positive DC bus and the negative DC bus, but the AC load is not connected, outputting the drive signal of the inverter bridge arm is stopped to control the inverter bridge arm to stop working.

9. The control method according to claim 7, wherein: The controlling the common bridge arm according to the real-time input voltage of the AC power supply includes: When the real-time input voltage is positive, controlling the upper switch tube of the common bridge arm to be turned off and controlling the lower switch tube of the common bridge arm to be turned on; When the real-time input voltage is negative, the upper switch tube of the common bridge arm is controlled to be turned on and the lower switch tube of the common bridge arm is controlled to be turned off.

10. A power conversion device, comprising a power converter and a controller, wherein the power converter comprises a rectifier bridge arm, an inverter bridge arm, a common bridge arm, a DC bus capacitor, a first inductor and a second inductor; the rectifier bridge arm, the inverter bridge arm, the common bridge arm and the DC bus capacitor are connected in parallel between a positive DC bus and a negative DC bus, the midpoint of the common bridge arm serves as a neutral terminal of the power converter, the midpoint of the rectifier bridge arm is connected to a first end of a first inductor, the second end of the first inductor serves as a first live terminal of the power converter, the midpoint of the inverter bridge arm is connected to a first end of a second inductor, the second end of the second inductor serves as a second live terminal of the power converter; the controller is used to execute the control method of the power converter as described in any one of claims 1 to 9.

11. An energy storage device comprising a battery pack and the power conversion device according to claim 10, wherein the battery pack is configured to be connected to the DC bus of the power conversion device.

Images