Control method of alternating current-direct current converter and power equipment

Abstract

The invention relates to a control method for an AC-DC converter, and the method comprises the steps: carrying out the back-stepping calculation of a harmonic current, which mainly affects a bus capacitor, of a DC side according to the output of an AC side, and generating a drive signal according to the harmonic current, so as to drive an idle balance bridge circuit to generate the harmonic current. The balance bridge circuit is used for charging and discharging the bus capacitor by the harmonic current, so that the harmonic current and the bus capacitor are decoupled, the pressure of the bus capacitor during grid-connected operation is greatly reduced, the service life of the bus capacitor is prolonged, a capacitor with a smaller capacitance value or a smaller number of capacitors can be allowed to be used, the cost is reduced, and the size of the circuit can also be reduced.

Description

Technical Field

[0001] The present application belongs to the field of power electronics technology, and in particular, relates to a control method of an AC / DC converter, a power device, and a computer-readable storage medium. Background Art

[0002] T-type three-level inverter circuits can usually be used in power conversion systems (PCS). When the PCS is off-grid and loaded, and the load is a half-wave rectifier (such as low-power appliances, lighting equipment, and battery chargers), the T-type three-level inverter circuit is prone to uneven voltage between the upper and lower half DC buses. At present, the common practice in the industry is to add a balancing bridge circuit on the DC side to control the half DC bus voltage.

[0003] However, when the PCS is connected to the grid, the output is sinusoidal, that is, the output power can show a natural double frequency characteristic. According to the law of energy conservation, the double frequency current on the DC side will cause the DC bus ripple to increase in long-term grid operation, and then increase the heat, affecting the life of the bus capacitor. Summary of the invention

[0004] The purpose of the present application is to provide a control method for an AC / DC converter, an electric power device and a computer-readable storage medium, aiming to solve the problem in the related art that when a PCS is connected to the grid, the DC side double frequency current affects the life of the bus capacitor.

[0005] In a first aspect, an embodiment of the present application provides a control method for an AC-DC converter, wherein the AC-DC converter includes an AC-DC converter and a balancing bridge circuit connected between a positive and negative DC bus of the AC-DC converter, and the control method includes:

[0006] Acquiring an AC side current and an AC side voltage of the AC-DC converter;

[0007] When the AC-DC converter is in grid-connected operation, a harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage;

[0008] A driving signal for driving the balanced bridge circuit is generated according to the harmonic current, and the balanced bridge circuit is driven to output the harmonic current based on the driving signal.

[0009] In one embodiment, obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage includes:

[0010] Obtaining the AC side power of the AC-DC converter according to the AC side current and the AC side voltage;

[0011] Obtaining a DC bus power according to the AC side power, and extracting an AC component from the DC bus power;

[0012] The harmonic current is obtained according to the AC component and the DC bus voltage.

[0013] In one embodiment, generating a driving signal for driving the balanced bridge circuit according to the harmonic current includes:

[0014] configuring the harmonic current to be a given current of the balanced bridge circuit;

[0015] A driving signal of the balanced bridge circuit is generated according to the given current.

[0016] In one embodiment, generating a driving signal of the balanced bridge circuit according to the given current includes:

[0017] Calculating according to the given current to obtain a target duty cycle;

[0018] The drive signal is generated based on the target duty cycle.

[0019] In one embodiment, the balanced bridge circuit includes an upper switch tube and a lower switch tube connected in series between the positive and negative DC bus bars, and an inductor having one end connected between the upper switch tube and the lower switch tube; the calculation according to the given current to obtain the target duty cycle includes:

[0020] Calculating according to the given current to obtain an initial duty cycle;

[0021] Performing a limiting process on the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle;

[0022] Wherein, the driving signal having the target duty cycle is used for:

[0023] During the positive half cycle of the given current, driving the upper switch tube to turn on and the lower switch tube to turn off;

[0024] During the second half cycle of the given current, the upper switch tube is driven to be turned off and the lower switch tube is driven to be turned on.

[0025] In one embodiment, generating a driving signal of the balanced bridge circuit according to the given current includes:

[0026] Obtaining the inductor current of the balanced bridge circuit;

[0027] Calculating a target duty cycle according to a difference between the given current and the inductor current;

[0028] The drive signal is generated based on the target duty cycle.

[0029] In one embodiment, the calculating according to the difference between the given current and the inductor current to obtain the target duty cycle includes:

[0030] Calculating according to the difference between the given current and the inductor current to obtain an initial duty cycle;

[0031] The initial duty cycle is limited according to a preset duty cycle range to obtain the target duty cycle.

[0032] In one of the embodiments, when the AC-DC converter is in grid-connected operation, obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage includes:

[0033] When the AC-DC converter is in grid-connected operation and the load is an unbalanced load, the harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage.

[0034] In a second aspect, an embodiment of the present application further provides an electric power device, comprising an AC-DC converter, a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the AC-DC converter comprises an AC-DC converter and a balancing bridge circuit connected between the positive and negative DC bus bars of the AC-DC converter, wherein the balancing bridge circuit is also connected to the processor, and when the processor executes the computer program, the steps of the control method of the AC-DC converter as described above are implemented.

[0035] In a third aspect, an embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a controller, the steps of the control method of the AC / DC converter as described above can be implemented.

[0036] Compared with the related art, the embodiments of the present application have the following beneficial effects:

[0037] According to the technical solution of the embodiment of the present application, when the AC / DC converter is connected to the grid, the harmonic current that mainly affects the bus capacitor on the DC side (i.e., at the positive and negative DC bus) is calculated based on the output of the AC side, and a driving signal is generated based on the harmonic current to drive an idle balancing bridge circuit to generate the harmonic current. The balancing bridge circuit is responsible for charging and discharging the bus capacitor by the harmonic current, so that the harmonic current is decoupled from the bus capacitor, which greatly reduces the pressure on the bus capacitor during grid-connected operation, increases the life of the bus capacitor, and allows the use of capacitors with smaller capacitance or fewer capacitors, thereby reducing costs and reducing the size of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of an AC / DC converter provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of the structure of an AC / DC converter provided in an embodiment of the present application;

[0040] Figure 3 A flow chart of a control method for an AC / DC converter provided in one embodiment of the present application;

[0041] Figure 4 A control loop diagram of a control method for an AC / DC converter provided in an embodiment of the present application;

[0042] Figure 5 A harmonic current waveform diagram of an AC / DC converter provided in one embodiment of the present application;

[0043] Figure 6 for Figure 5 The circuit control diagram shown is during the rising period of the positive half cycle of the harmonic current;

[0044] Figure 7 for Figure 5 The circuit control diagram shown is during the rising period of the positive half cycle of the harmonic current;

[0045] Figure 8 for Figure 5 The circuit control diagram shown is during the rising period of the positive half cycle of the harmonic current;

[0046] Fig. 9 for Figure 5 The circuit control diagram shown is during the rising period of the positive half cycle of the harmonic current;

[0047] Fig.10 A control loop diagram of a control method for an AC / DC converter provided in an embodiment of the present application;

[0048] Fig.11 A schematic diagram of a module of a control device for an AC / DC converter provided in an embodiment of the present application;

[0049] Fig.12 A schematic diagram of the structure of an electric power device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0053] Power equipment such as energy storage converters are equipped with AC / DC converters. Figure 1 The example is a T-type three-level inverter topology. The AC-DC converter includes an AC-DC converter and a balanced bridge circuit (such as Figure 2 As shown in Figure 2 As shown, the first bus capacitor C1 and the second bus capacitor C2 are connected in series and connected between the positive and negative DC buses, and the inductor L4 of the balancing bridge circuit is connected to the first series node of the first bus capacitor C1 and the second bus capacitor C2. The DC side of the AC-DC converter is connected to the positive and negative DC buses; the AC side of the AC / DC converter is used to connect the power grid and the load.

[0054] When the energy storage converter is off-grid and loaded, and the load is a half-wave rectifier type (such as low-power appliances, lighting equipment, battery chargers), it is easy for the positive and negative DC bus voltages to be uneven. In this case, a balancing bridge circuit is generally added to control the positive and negative DC bus voltages. Figure 2 As shown, the balanced bridge circuit includes an upper switch tube M1 and a lower switch tube M2 connected in series between the positive and negative DC busbars, and an inductor L4 having one end connected to a second series node between the upper switch tube M1 and the lower switch tube M2. The other end of the inductor L4 is connected to the first series node between the first busbar capacitor C1 and the second busbar capacitor C2.

[0055] In most cases, the energy storage converter works in the grid-connected state. The balanced bridge circuit is usually triggered when the half-wave load is off the grid, and it is idle the rest of the time. When the energy storage converter is connected to the grid, since the output voltage U and current I are both sinusoidal fluctuations, the output power can be obtained to show a natural double frequency characteristic. The double frequency current on the DC (bus) side will increase the bus ripple in the long-term grid-connected operation, and then the heat will increase, affecting the life of the bus capacitor.

[0056] Based on this, the embodiment of the present application provides a control method for an AC-DC converter that can increase the life of a bus capacitor. Figure 3 , a control method of an AC / DC converter provided in an embodiment of the present application includes:

[0057] Step S110, obtaining the AC side current and AC side voltage of the AC-DC converter.

[0058] The AC side current and the AC side voltage of the AC-DC converter can be detected respectively by setting a current detection circuit and a voltage detection circuit, such as a current sensor, a voltage sensor or a Hall sensor.

[0059] Step S120, when the AC-DC converter is in grid-connected operation, the harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage.

[0060] Among them, the AC power measurement of the AC-DC converter can be obtained according to the AC side current and the AC side voltage. According to the principle of energy conservation, the AC power measurement of the AC-DC converter comes from the DC side power. Therefore, the AC component can be extracted according to the AC side power of the AC-DC converter. For the DC side of the AC-DC converter, the AC component can be considered as the main cause of the harmonic current. Therefore, the harmonic current of the AC-DC converter can be obtained according to the AC component.

[0061] Step S130: generating a driving signal for driving the balanced bridge circuit according to the harmonic current, and driving the balanced bridge circuit to output the harmonic current based on the driving signal.

[0062] In the case of grid-connected operation of the AC-DC converter, the balanced bridge circuit is generally in an idle state, and the harmonic current on the DC side of the AC-DC converter (all or most of it) is formed based on the first bus capacitor C1 and the second bus capacitor C2. Figure 2 At the first bus capacitor C1, according to Kirchhoff's law, there exists I1+I3=I2( Figure 2 The current flows shown in are exemplary only, and the present application does not limit the actual current direction). Since the output of the AC-DC converter is a sine wave, there is a naturally doubled frequency component in its power, so it is inevitable that there are harmonic currents in I2. Assuming that I2 = DC current + harmonic current, when the balanced bridge circuit is not working, I1 comes from the current I0 of the DC source, and the AC component in the current I0 is extremely small. Therefore, the harmonic current in I2 must be borne or generated by the two bus capacitors C1 / C2, that is, there is a large harmonic current in I3.

[0063] In the embodiment of the present application, the harmonic current of the AC-DC converter is calculated based on the AC power measurement of the AC-DC converter, and a driving signal is generated based on the harmonic current to drive the balanced bridge circuit to generate the harmonic current, so that all or most of the harmonic current of the AC-DC converter is decoupled from the first bus capacitor C1 and the second bus capacitor C2, reducing the harmonic current on the bus capacitor, greatly reducing the pressure on the bus capacitor C1 / C2 when the AC-DC converter is connected to the grid, and increasing the life of the bus capacitor C1 / C2. At the same time, it can also allow the use of capacitors with smaller capacitance or fewer capacitors, reducing costs and reducing the size of the circuit.

[0064] In some embodiments, step S120 includes:

[0065] Step 1: Obtain the AC side power of the AC-DC converter according to the AC side current and the AC side voltage.

[0066] Wherein, AC side power: Pac = Uac*sin( ω t)Iac*sin( ω t), where Uac is the AC side voltage, Iac is the AC side current, ω t is the phase of AC power.

[0067] Step 2: Obtain the DC bus power according to the AC side power, and extract the AC component from the DC bus power.

[0068] Among them, according to the principle of conservation of energy, ignoring the conversion loss, under ideal conditions, the DC bus power = AC side power Pac.

[0069] Decompose the DC bus power into DC component and AC component: Uac*sin( ω t+φ)Iac*sin( ω t+φ)=1 / 2*Uac*Iac[1-cos(2 ω t+2φ)], where Uac*Iac / 2 is the DC component and Uac*Iac(cos2ωt+2φ) / 2 is the AC component.

[0070] Step three, obtaining harmonic current according to the AC component and the DC bus voltage.

[0071] The harmonic current can be calculated according to the formula: (Uac*Iac(cos2 ω t+2φ) / 2) / Vdc, where Vdc is the DC bus voltage.

[0072] In some embodiments, generating a driving signal for driving a balanced bridge circuit according to the harmonic current in step S130 includes:

[0073] Step a, configuring the harmonic current to be a given current of a balanced bridge circuit.

[0074] The purpose is to use the harmonic current as the target current of the balanced bridge circuit, and to generate the harmonic current by the balanced bridge circuit. Figure 2 As shown in the figure, at this time, since the target current of the balanced bridge circuit is a harmonic current, at this time, in addition to I0, I1 will also include the current from the balanced bridge circuit and the current is a harmonic current, so the harmonic current in I2 does not need to be generated by the bus capacitors C1 and C2. That is, the bus capacitor is decoupled from the harmonic current, reducing the working pressure of the bus capacitor, thereby reducing the cost of the bus capacitor.

[0075] Step b: generating a driving signal for the balanced bridge circuit according to a given current.

[0076] Among them, a current control loop of open-loop control or closed-loop control can be used to generate a driving signal for the balanced bridge circuit according to a given current.

[0077] In some embodiments, an open-loop current control loop is used to generate a drive signal for driving a balanced bridge circuit. Figure 4 , step b includes: calculating according to a given current to obtain a target duty cycle; and generating a drive signal based on the target duty cycle.

[0078] A PI (proportional integral) controller is used to calculate a given current to obtain a target duty cycle, and a PWM controller is used to generate a PWM drive signal for driving a balanced bridge circuit according to the target duty cycle.

[0079] Compared with the closed-loop control current control loop, the open-loop control current control loop is simpler, more stable and reliable for the output control of harmonic current, and the cost is relatively low.

[0080] In some embodiments, calculating according to a given current to obtain a target duty cycle includes: calculating according to the given current to obtain an initial duty cycle; and limiting the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle.

[0081] Among them, the PI controller calculates the initial duty cycle according to the given current, and the initial duty cycle passes through the limiter to obtain the final effective target duty cycle. The parameter configuration of the limiter for the preset duty cycle range can be set according to the critical value of the input / output current of the balanced bridge circuit. The limiter is to configure the maximum / minimum duty cycle of the balanced bridge circuit to ensure that the input / output current of the balanced bridge circuit does not exceed its maximum / minimum output / input capacity during loop control.

[0082] The driving signal with the target duty cycle is used to drive the upper switch tube M1 to turn on and the lower switch tube M2 to turn off during the positive half cycle of the given current.

[0083] The inductor current of the balanced bridge circuit is as follows Figure 5 As shown, in the positive half cycle, the inductor current is controlled during the given current rise period as follows Figure 6 As shown in Figure 1, at this time, the inductor L4 is in a state of discharging energy, releasing energy to the DC bus side. Given the current drop period, the inductor L4 current is controlled as follows: Figure 7 As shown, at this time, the inductor L4 is in an energy storage state and absorbs energy from the DC bus side.

[0084] The driving signal with the target duty cycle is used to drive the upper switch tube M1 to turn off and the lower switch tube M2 to turn on during the second half cycle of a given current.

[0085] When the given current is in the negative half cycle, the rising period controls the inductor current flow direction as follows Figure 8 As shown in Figure 1, at this time, the inductor L4 is in a state of discharging energy, releasing energy to the DC bus side. Given the current drop period, the current flow direction of the inductor L4 is controlled as follows: Fig. 9 As shown, at this time, the inductor L4 is in an energy storage state and absorbs energy from the DC bus side.

[0086] In some embodiments, a current control loop of closed-loop control is used to generate a drive signal for driving a balanced bridge circuit. Fig.10 , step b includes: obtaining the current of the inductor L4 of the balanced bridge circuit; calculating according to the difference between the given current and the current of the inductor L4 to obtain the target duty cycle; and generating a driving signal based on the target duty cycle.

[0087] Among them, the current of the inductor L4 of the balanced bridge circuit can be detected by the current detection circuit. In the closed-loop control process, the current of the inductor L4 of the balanced bridge circuit is used as a feedback signal, and compared with the given current to obtain the current deviation. The PI controller is used to calculate the output target duty cycle according to the current deviation, and the PWM controller is used to generate a PWM drive signal for driving the balanced bridge circuit according to the target duty cycle. Compared with the current control loop of open-loop control, the current control loop of closed-loop control is more precise in output control of harmonic current and has higher control accuracy.

[0088] In some embodiments, the target duty cycle is obtained by calculating based on the difference between the given current and the current of the inductor L4, including: obtaining an initial duty cycle by calculating based on the difference between the given current and the current of the inductor L4; and limiting the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle.

[0089] Among them, the PI controller calculates the initial duty cycle according to the difference between the given current and the current of the inductor L4, and the initial duty cycle passes through the limiter to obtain the final effective target duty cycle. The parameter configuration of the limiter for the preset duty cycle range can be set according to the critical value of the input / output current of the balanced bridge circuit. The limiter is to configure the maximum / minimum duty cycle of the balanced bridge circuit to ensure that the input / output current of the balanced bridge circuit does not exceed its maximum / minimum output / input capacity during loop control.

[0090] Specifically, the process of driving the balanced bridge circuit to output harmonic current using a driving signal with a target duty cycle is described in detail. Figures 5 to 9 and their corresponding instructions.

[0091] In some embodiments, step S120 includes: when the AC-DC converter is grid-connected and the load is an unbalanced load, obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage.

[0092] Among them, when the load is an unbalanced load, the harmonic current of the bus capacitor is much greater than that of other working conditions. Therefore, the control method provided by the embodiment of the present application is more effective under such working conditions. For example, when the load is an unbalanced load, the AC-DC converter operates in a single-phase anti-reverse current mode. In the single-phase anti-reverse current mode, when the AC-DC converter is in the grid-connected anti-reverse current mode, the three-phase output power of the AC-DC converter A / B / C is not equal, only one of the phases outputs, and the other two phases do not output, or two phases have output and one of the phases has no output.

[0093] See also Fig.11 , an embodiment of the present application further provides a control device for an AC / DC converter, the control device comprising:

[0094] An acquisition module, used for acquiring the AC side current and the AC side voltage of the AC-DC converter;

[0095] A calculation module, used for obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage when the AC-DC converter is in grid-connected operation;

[0096] A control module is used to generate a driving signal for driving the balanced bridge circuit according to the harmonic current, and drive the balanced bridge circuit to output the harmonic current based on the driving signal.

[0097] In one embodiment, the computing module includes:

[0098] The first calculation unit is used to obtain the AC side power of the AC-DC converter according to the AC side current and the AC side voltage.

[0099] The second calculation unit is used to obtain the DC bus power according to the AC side power and extract the AC component from the DC bus power.

[0100] The third calculation unit is used to obtain the harmonic current according to the AC component and the DC bus voltage.

[0101] In one embodiment, the control module includes:

[0102] A configuration unit is used to configure the harmonic current to be a given current of the balanced bridge circuit.

[0103] A control unit is used to generate a driving signal for the balanced bridge circuit according to the given current.

[0104] In one embodiment, the control unit comprises:

[0105] The control circuit is used to calculate according to the given current to obtain a target duty cycle.

[0106] A PWM controller is used to generate the driving signal based on the target duty cycle.

[0107] In one embodiment, the control circuit comprises:

[0108] The PI controller is used to calculate according to the given current to obtain an initial duty cycle.

[0109] A limiter is used to limit the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle.

[0110] Wherein, the driving signal having the target duty cycle is used for:

[0111] During the positive half cycle of the given current, driving the upper switch tube to turn on and the lower switch tube to turn off;

[0112] During the second half cycle of the given current, the upper switch tube is driven to be turned off and the lower switch tube is driven to be turned on.

[0113] In one embodiment:

[0114] The acquisition module is also used to acquire the inductor current of the balanced bridge circuit.

[0115] The control circuit is further used to calculate the target duty cycle according to the difference between the given current and the inductor current.

[0116] The PWM controller is further configured to generate the driving signal based on the target duty cycle.

[0117] In one embodiment, the calculating according to the difference between the given current and the inductor current to obtain the target duty cycle includes:

[0118] The PI controller is further used to calculate the initial duty cycle according to the difference between the given current and the inductor current.

[0119] The limiter is further used to limit the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle.

[0120] In one embodiment, the computing module is specifically used for:

[0121] When the AC-DC converter is in grid-connected operation and the load is an unbalanced load, the harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage.

[0122] For the specific implementation of the control device and the description of the related beneficial effects, please refer to the description of the specific embodiment of the control method of the AC / DC converter mentioned above, which will not be repeated here.

[0123] See also Figure 1 , 2 12, an electric power device 120, comprising an AC-DC converter 121, a memory 122, a processor 123, and a computer program 1221 stored in the memory 122 and executable on the processor 123, wherein the AC-DC converter 121 comprises an AC-DC converter, a first bus capacitor C1, a second bus capacitor C2, and a balancing bridge circuit (see Figure 2 ), the first bus capacitor C1 and the second bus capacitor C2 are connected in series and connected between the positive and negative DC buses of the AC-DC converter, the balancing bridge circuit is connected between the positive and negative DC buses and the inductor L4 of the balancing bridge circuit is connected to the series node of the first bus capacitor C1 and the second bus capacitor C2, the DC side of the AC-DC converter is connected to the positive and negative DC buses, the AC side of the AC / DC converter is used to connect to the power grid and / or the load, the balancing bridge circuit is also connected to the processor 123, and when the processor 123 executes the computer program 1221, the steps of the control method of the AC / DC converter 121 as described above are implemented.

[0124] It is understandable that the power device 120 may be a separate power device, or may be a mobile energy storage device having a battery module, or may include a plurality of energy storage systems having battery modules.

[0125] Those skilled in the art will understand that Fig.12This is merely an example of the power device 120 and does not constitute a limitation on the power device 120 . The power device 120 may include more or fewer components than shown in the figure, or a combination of certain components, or different components, such as input and output devices, network access devices, etc.

[0126] The processor 123 may be a central processing unit (CPU), or may be other general controllers, 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. The general controller may be a microcontroller or any conventional controller.

[0127] In some embodiments, the memory 122 may be an internal storage unit of the power device 120 or the energy storage device, such as a hard disk or memory of the power device 120 or the energy storage device. In other embodiments, the memory 122 may also be an external storage device of the power device 120 or the energy storage device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the power device 120 or the energy storage device. Further, the memory 122 may also include both an internal storage unit of the power device 120 or the energy storage device and an external storage device. The memory 122 is used to store an operating system, an application program, a boot loader (Boot Loader), data, and other programs. The memory 122 may also be used to temporarily store data that has been output or is to be output.

[0128] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program 1221 . When the computer program 1221 is executed by the processor 123 , the steps in the above-mentioned method embodiments can be implemented.

[0129] The embodiment of the present application provides a computer program 1221 product, which, when executed on a computer, enables the computer to execute the steps in the above-mentioned various method embodiments.

[0130] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above method embodiments, which can be completed by instructing the relevant hardware through a computer program 1221. The computer program 1221 can be stored in a computer-readable storage medium. When the computer program 1221 is executed by the processor 123, the steps of the above method embodiments can be implemented. Among them, the computer program 1221 includes a computer program 1221 code, and the computer program 1221 code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program 1221 code to the camera device / terminal device, a recording medium, a computer memory 122, a ROM (Read-Only Memory, read-only memory 122), a RAM (Random Access Memory, random access memory 122), a CD-ROM (Compact Disc Read-Only Memory, read-only optical disc), a magnetic tape, a floppy disk and an optical data storage device. The computer-readable storage medium mentioned in the present application may be a non-volatile storage medium, in other words, a non-transitory storage medium.

[0131] It should be understood that all or part of the steps to implement the above embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program 1221 product. The computer program 1221 product includes one or more computer instructions. The computer instructions can be stored in the above-mentioned computer readable storage medium.

[0132] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0133] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0134] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0135] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0136] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A control method for an AC / DC converter, characterized in that: The AC-DC converter includes an AC-DC converter and a balancing bridge circuit connected between the positive and negative DC bus bars of the AC-DC converter, and the control method includes: Acquiring an AC side current and an AC side voltage of the AC-DC converter; When the AC-DC converter is in grid-connected operation, a harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage; A driving signal for driving the balanced bridge circuit is generated according to the harmonic current, and the balanced bridge circuit is driven to output the harmonic current based on the driving signal.

2. The control method according to claim 1, characterized in that: The step of obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage comprises: Obtaining the AC side power of the AC-DC converter according to the AC side current and the AC side voltage; Obtaining a DC bus power according to the AC side power, and extracting an AC component from the DC bus power; The harmonic current is obtained according to the AC component and the DC bus voltage.

3. The control method according to claim 1, characterized in that: The step of generating a driving signal for driving the balanced bridge circuit according to the harmonic current comprises: configuring the harmonic current to be a given current of the balanced bridge circuit; A driving signal of the balanced bridge circuit is generated according to the given current.

4. The control method according to claim 3, characterized in that: The step of generating a driving signal for the balanced bridge circuit according to the given current comprises: Calculating according to the given current to obtain a target duty cycle; The drive signal is generated based on the target duty cycle.

5. The control method according to claim 4, characterized in that: The balanced bridge circuit includes an upper switch tube and a lower switch tube connected in series between the positive and negative DC bus bars, and an inductor having one end connected between the upper switch tube and the lower switch tube; The step of calculating according to the given current to obtain a target duty cycle includes: Calculating according to the given current to obtain an initial duty cycle; Performing a limiting process on the initial duty cycle according to a preset duty cycle range to obtain the target duty cycle; Wherein, the driving signal having the target duty cycle is used for: During the positive half cycle of the given current, driving the upper switch tube to turn on and the lower switch tube to turn off; During the second half cycle of the given current, the upper switch tube is driven to be turned off and the lower switch tube is driven to be turned on.

6. The control method according to claim 3, characterized in that: The step of generating a driving signal for the balanced bridge circuit according to the given current comprises: Obtaining the inductor current of the balanced bridge circuit; Calculating a target duty cycle according to a difference between the given current and the inductor current; The drive signal is generated based on the target duty cycle.

7. The control method according to claim 6, characterized in that: The calculating according to the difference between the given current and the inductor current to obtain the target duty cycle includes: Calculating according to the difference between the given current and the inductor current to obtain an initial duty cycle; The initial duty cycle is limited according to a preset duty cycle range to obtain the target duty cycle.

8. The control method according to any one of claims 1 to 7, characterized in that: In the case where the AC-DC converter is grid-connected, obtaining the harmonic current of the AC-DC converter according to the AC side current and the AC side voltage includes: When the AC-DC converter is in grid-connected operation and the load is an unbalanced load, the harmonic current of the AC-DC converter is obtained according to the AC side current and the AC side voltage.

9. An electric power device, characterized in that: The invention comprises an AC-DC converter, a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the AC-DC converter comprises an AC-DC converter and a balancing bridge circuit connected between the positive and negative DC buses of the AC-DC converter, and the balancing bridge circuit is also connected to the processor, and when the processor executes the computer program, the steps of the control method of the AC-DC converter according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by the controller, the steps of the control method of the AC-DC converter according to any one of claims 1 to 8 can be implemented.

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