A current control method and device

Abstract

This invention discloses a current control method and apparatus to address the problem in existing three-arm bridge topology circuits where high current generation damages switching transistors and reduces circuit performance. The method, applied to a three-arm bridge topology circuit, first acquires the input voltage information at the AC input terminal and the output voltage information at the AC output terminal of the three-arm bridge topology circuit. Then, based on the input and output voltage information, it determines that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal. Finally, according to a preset current value, it reduces the current values ​​of the second and fifth switching transistors, thereby preventing damage to the switching transistors from high current and improving the reliability of the three-arm bridge topology circuit.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, and in particular to a current control method and apparatus. Background Technology

[0002] In recent years, the three-bridge-arm topology has gained popularity due to the fewer switching transistors required to implement PFC and INV functions. The three-bridge-arm topology is a highly efficient PFC and INV function topology. Its characteristics include a single-bus, five-bridge PFC input circuit and a single-bus, full-bridge INV output; the PFC and INV share the middle bridge arm, and when the input and output operate at the same frequency, the currents in the middle bridge arm almost cancel each other out, resulting in high overall efficiency.

[0003] In a three-arm bridge topology, if the AC input voltage and the AC output voltage are out of phase, the peak voltage will be higher than the bus voltage, damaging the switching transistors in the three-arm bridge topology. Summary of the Invention

[0004] This invention provides a current control method and apparatus to solve the problem in the prior art where large currents in a three-bridge topology circuit damage the switching transistors and reduce circuit performance.

[0005] In a first aspect, embodiments of the present invention provide a current control method applied to a three-bridge-arm topology circuit. The three-bridge-arm topology circuit includes a first bridge arm composed of a first switch and a second switch, a second bridge arm composed of a third switch and a fourth switch, and a third bridge arm composed of a fifth switch and a sixth switch. The three bridge arms are respectively connected in parallel between a positive bus and a negative bus. A bus capacitor is connected in parallel between the positive bus and the negative bus. The midpoint of the first bridge arm is connected to one end of a first inductor, the midpoint of the second bridge arm is connected to one end of a second inductor, and the midpoint of the third bridge arm is connected to one end of a third inductor. The other ends of the first inductor and the second inductor are used as the AC input terminal of the three-bridge-arm topology circuit, and the other ends of the third inductor and the second inductor are used as the AC output terminal of the three-bridge-arm topology circuit. An output capacitor is connected in parallel to the AC output terminal. The method includes:

[0006] Obtain the input voltage information of the AC input terminal and the output voltage information of the AC output terminal;

[0007] Based on the input voltage information and the output voltage information, it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal;

[0008] Based on the preset current value, the current flowing through the second switch and the fifth switch is reduced.

[0009] In one possible implementation, determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal includes:

[0010] Based on the input voltage information and the output current information, determine the phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal;

[0011] If the phase difference is greater than the first threshold, then it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

[0012] In one possible implementation, before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, the method further includes:

[0013] Obtain the input current value at the AC input terminal;

[0014] The input current value is determined to be greater than the second threshold.

[0015] Based on the input voltage information and the output voltage information, it is determined that the voltage at the input terminal is less than the voltage at the output terminal.

[0016] In one possible implementation, before reducing the current flowing through the second and fifth switches, the method further includes:

[0017] Collect the bus voltage between the positive bus and the negative bus;

[0018] The bus voltage is determined to be greater than the third threshold.

[0019] In one possible implementation, after reducing the current flowing through the second switch and the fifth switch, the method further includes:

[0020] The first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch are controlled to disconnect.

[0021] In one possible implementation, after reducing the current flowing through the second switch and the fifth switch, the method further includes:

[0022] Disconnect the first and second switching transistors;

[0023] The path between the DC power supply and the second and third bridge arms is connected to invert the DC power output from the DC power supply and output AC power.

[0024] The DC power supply is connected in parallel between the positive bus and the negative bus.

[0025] Secondly, embodiments of the present invention provide a current control device applied to a three-bridge-arm topology circuit. The three-bridge-arm topology circuit includes a first bridge arm composed of a first switch and a second switch, a second bridge arm composed of a third switch and a fourth switch, and a third bridge arm composed of a fifth switch and a sixth switch. The three bridge arms are respectively connected in parallel between a positive bus and a negative bus. A bus capacitor is connected in parallel between the positive bus and the negative bus. The midpoint of the first bridge arm is connected to one end of a first inductor, the midpoint of the second bridge arm is connected to one end of a second inductor, and the midpoint of the third bridge arm is connected to one end of a third inductor. The other ends of the first and second inductors are used as the AC input terminals of the three-bridge-arm topology circuit, and the other ends of the third and second inductors are used as the AC output terminals of the three-bridge-arm topology circuit. An output capacitor is connected in parallel to the AC output terminals. The device includes:

[0026] The acquisition module is used to acquire the input voltage information of the AC input terminal and the output voltage information of the AC output terminal;

[0027] The determining module is used to determine, based on the input voltage information and the output voltage information, that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal;

[0028] The adjustment module is used to reduce the current flowing through the second switch and the fifth switch according to a preset current value.

[0029] In one possible implementation, the determining module is specifically used for:

[0030] Based on the input voltage information and the output current information, determine the phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal;

[0031] If the phase difference is greater than the first threshold, then it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

[0032] In one possible implementation, the determining module is further configured to:

[0033] Before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, the input current value at the AC input terminal is obtained; the input current value is determined to be greater than a second threshold; based on the input voltage information and the output voltage information, the voltage at the input terminal is determined to be less than the voltage at the output terminal.

[0034] In one possible implementation, the determining module is further configured to:

[0035] Collect the bus voltage between the positive bus and the negative bus; determine that the bus voltage is greater than a third threshold.

[0036] In one possible implementation, the device further includes a first control module;

[0037] The first control module is used to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to disconnect.

[0038] In one possible implementation, the device further includes a second control module;

[0039] The second control module is used to control the first and second switching transistors to disconnect; and to connect the DC power supply to the second bridge arm and the third bridge arm to invert the DC power output from the DC power supply and output AC power.

[0040] The DC power supply is connected in parallel between the positive bus and the negative bus.

[0041] The beneficial effects of this invention are as follows:

[0042] In this embodiment of the invention, after determining that the three-arm topology circuit generates a large current, the current values ​​of the second and fifth switching transistors are reduced according to a preset current value, thereby preventing the switching transistors from being damaged by the large current and improving the reliability of the three-arm topology circuit. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a three-arm bridge topology circuit provided in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the current flow direction in a three-arm bridge topology circuit provided by an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the current flow direction in another three-arm bridge topology circuit provided by an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the current flow direction in another three-arm bridge topology circuit provided by an embodiment of the present invention;

[0048] Figure 5 This is a flowchart illustrating a current control method provided in an embodiment of the present invention;

[0049] Figure 6 A schematic diagram of another three-arm bridge topology circuit provided in an embodiment of the present invention;

[0050] Figure 7 This is a complete flowchart of a current control method provided in an embodiment of the present invention;

[0051] Figure 8 This is a schematic diagram of the structure of a current control device provided in an embodiment of the present invention;

[0052] Figure 9 This is a schematic diagram of the structure of a current control device provided in an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0054] The current control method provided in this embodiment of the invention is applied to a three-arm bridge topology circuit, such as... Figure 1 As shown, the circuit includes a first bridge arm consisting of a first switch VT1 and a second switch VT2, a second bridge arm consisting of a third switch VT3 and a fourth switch VT4, and a third bridge arm consisting of a fifth switch VT5 and a sixth switch VT6. The three bridge arms are connected in parallel between the positive bus Vbus+ and the negative bus Vbus-, respectively. A bus capacitor C1 is connected in parallel between the positive bus Vbus+ and the negative bus Vbus-. The midpoint (D) of the first bridge arm is connected to one end of the first inductor L1, the midpoint (E) of the second bridge arm is connected to one end of the second inductor L2, and the midpoint (F) of the third bridge arm is connected to one end of the third inductor L3. The other end (A) of the first inductor L1 and the other end (B) of the second inductor serve as the AC input terminal of the three-bridge-arm topology circuit. The other end (C) of the third inductor L3 and the other end (B) of the second inductor serve as the AC output terminal of the three-bridge-arm topology circuit. An output capacitor C2 is connected in parallel between the AC output terminals (C and B).

[0055] During the positive half-cycle of the AC input voltage, the body diode D2 of VT2 and the body diode D1 of VT1 form a boost circuit to control the bus voltage between the positive bus Vbus+ and the negative bus Vbus-. During the negative half-cycle of the input voltage, the body diode D1 of VT1 and the body diode D2 of VT2 form a boost circuit to control the bus voltage between the positive bus Vbus+ and the negative bus Vbus-. During the positive half-cycle of the inverter voltage, VT4 and VT5 are turned on, and during the negative half-cycle of the inverter voltage, VT6 and VT3 are turned on.

[0056] When the input and output voltages are in phase, decoupled control can be achieved between the input and output, and it is unrelated to the second bridge arm. When the input and output voltages are out of phase, the inverter output requires the second bridge arm to generate a waveform, causing uncontrolled rectification at the input, resulting in uncontrolled bus voltage and damage to the switching transistors.

[0057] Due to the phase-locked loop (PLL) mechanism, there will inevitably be situations where the input and output are out of phase. If there is a phase deviation, with the input voltage in the negative half-cycle and the inverter voltage in the positive half-cycle, then when VT1 and VT4 are simultaneously turned on, there will be a loop where the input voltage is superimposed on the DC bus, causing inductor saturation and a large current that will damage the switching transistors.

[0058] The current solution is to control the second bridge arm to conduct at high frequency near the zero-crossing point. During control, it is necessary to ensure that VT1 and VT4, and VT2 and VT3 cannot conduct simultaneously. However, before the high-frequency waveform switching from the second switch VT2 in the first bridge arm to the first switch VT2 in the first bridge arm, there is a problem such as... Figure 2 The circuit shown is as follows: the current flows out from the AC output terminal C, passes through the body diode D5 of the fifth switch VT5, the bus capacitor C1, and the body diode D2 of the second switch VT2, and returns to the AC input terminal A. The current flows from the AC input terminal B to the AC output terminal B.

[0059] Figure 2 The direction of the medium current flow will cause the input voltage to be superimposed on the DC bus, resulting in a large current. Since the diode cannot limit the current, the diode D5 of the fifth switch VT5 and the body diode D2 of the second switch VT2 may be damaged. If diode D5 is damaged, since the fifth switch VT5 and the sixth switch VT6 will generate complementary waveforms, the waveform generated by the sixth switch VT6 will short-circuit the bus capacitor C1. Figure 3 As shown, the sixth switch VT6 is also at risk of being damaged by overcurrent.

[0060] The above describes the situation when the input voltage is in the negative half-cycle. After a period of time, the input voltage changes from the negative half-cycle to the positive half-cycle, while the output voltage is in the negative half-cycle. At this time, if the input relay is not disconnected, the third switch VT3 will conduct when the inverter voltage is in the negative half-cycle. The input voltage will then form a circuit through the body diode D1 of the first switch VT1, the body of the third switch VT3, and the second inductor L2. Figure 4 As shown, due to the large current, diode D1 and the third switching transistor VT3 are also at risk of being damaged.

[0061] The inverter voltage mentioned above is the voltage between points E and F in the diagram.

[0062] The input relay is connected between the AC input terminal and the AC power supply. Disconnecting the input relay disconnects the AC input.

[0063] In summary, when the AC input voltage of the three-arm bridge circuit undergoes a phase change, causing the input voltage and output voltage to be out of phase, a large current path may exist in the three-arm bridge circuit, and the first switch VT1, the second switch VT2, the third switch VT3, and the fifth switch VT5 are at risk of being damaged by the large current.

[0064] To address the aforementioned problems, embodiments of the present invention provide a current control method applied to a three-arm bridge topology circuit, such as... Figure 5 As shown, the method includes the following steps:

[0065] S501. Obtain the input voltage information of the AC input terminal and the output voltage information of the AC output terminal;

[0066] S502. Based on the input voltage information and the output voltage information, determine that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal;

[0067] S503. Based on the preset current value, reduce the current value flowing through the first switch, the second switch, the third switch, and the fifth switch.

[0068] In this embodiment of the invention, the input voltage information of the AC input terminal and the output voltage information of the AC output terminal of the three-arm topology circuit are first obtained. Then, based on the input voltage information and the output voltage information, it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal. Finally, according to the preset current value, the current values ​​of the second and fifth switching transistors are reduced, thereby preventing the switching transistors from being damaged by large currents and improving the reliability of the three-arm topology circuit.

[0069] The execution subject of this invention embodiment can be a controller, such as a DSP (Digital Signal Processor) chip.

[0070] The embodiments of the present invention can be applied in parallel scenarios, that is, multiple three-bridge-arm topologies are used in parallel. Due to the phase-locked loop factor in parallel operation, there may be a situation where the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal due to the phase change of the input voltage, thereby generating a large current.

[0071] Taking the parallel operation of two three-bridge topology circuits as an example, the determination of phase change of AC input voltage can include phase changes such as uninterrupted input voltage from 90 degrees to 270 degrees, uninterrupted input voltage from 90 degrees to 0 degrees, and double wavefronts of input voltage.

[0072] Specifically, based on the input voltage information and the output voltage information, it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal. The phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal can be determined according to the input voltage information and the output voltage information. Then, this phase difference is compared with a first threshold. If the phase difference is greater than the first threshold, it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

[0073] The input voltage information may include the phase value of the input voltage, and the output voltage information may include the phase value of the output voltage. Based on the phase values ​​of the input voltage and the output voltage, the phase difference between the AC input voltage and the AC output voltage is determined.

[0074] Before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, this embodiment of the invention can also obtain the input current value at the AC input terminal, and then determine that the input current value is greater than a second threshold; based on the input voltage information and the output voltage information, it can be determined that the voltage value at the input terminal is less than the voltage value at the output terminal.

[0075] If the voltage at the AC input terminal and the voltage at the AC output terminal are out of phase, the current value at the input terminal will become very large. Therefore, a second threshold is set, and the input current value is compared with the second threshold. If the input current value is greater than the second threshold, it can be further determined that the voltage at the AC input terminal and the voltage at the AC output terminal are out of phase.

[0076] Determining that the input voltage is less than the output voltage is to ensure that the three-arm bridge topology is not in maintenance bypass mode. Maintenance bypass mode refers to the input voltage being higher than the output voltage. When the three-arm bridge topology triggers maintenance bypass mode, the output power is negative. Since the output power of the three-arm bridge topology is at least 0 under no-load conditions when it is working normally.

[0077] When the three-arm bridge topology circuit triggers maintenance bypass, the voltage at the AC input terminal and the voltage at the AC output terminal will be out of phase. However, this state will not generate a large current. Therefore, to make the judgment more accurate, it can be determined first that the three-arm bridge topology circuit is not in maintenance bypass state.

[0078] Furthermore, since the large current in the three-arm topology circuit is caused by the bus voltage being superimposed on the input voltage, meaning the bus voltage will increase, this embodiment of the invention can also determine whether there is a large current in the three-arm topology circuit based on the bus voltage value.

[0079] Specifically, the bus voltage between the positive bus Vbus+ and the negative bus Vbus- is collected to determine if the bus voltage is greater than the third threshold.

[0080] It should be noted that the first threshold, the second threshold, and the third threshold in the embodiments of the present invention can all be set according to actual needs.

[0081] In this embodiment of the invention, a sudden change in voltage at the AC input terminal indicates an abnormal AC power supply. Therefore, to prevent damage to the switching transistors from large currents, the current flowing through the second switching transistor VT2 and the fifth switching transistor VT5 is reduced. To prevent damage to the switching transistors from the abnormal AC power supply, the first switching transistor VT1, the second switching transistor VT2, the third switching transistor VT3, the fourth switching transistor VT4, the fifth switching transistor VT5, and the sixth switching transistor VT6 can be disconnected. This means preventing the transmission of drive voltages to these transistors, such as by performing a shutdown process. Alternatively, to ensure continued power supply to the load, the first switching transistor VT1 and the second switching transistor VT2 can be disconnected, cutting off the path between the AC input and AC output terminals. Then, a DC power supply 601 can be connected in parallel between the positive bus Vbus+ and the negative bus Vbus-. Figure 6 As shown, the path between the DC power supply and the second and third bridge arms is controlled to invert the DC power output from the DC power supply to generate AC power, which is then output through the AC output terminal to continuously power the load and improve the reliability of the three-bridge topology circuit.

[0082] like Figure 7 The diagram shown is a complete flowchart of a current control method provided in an embodiment of the present invention.

[0083] S701, Acquire input current;

[0084] S702. Determine whether the input current is greater than the first threshold. If yes, execute S703; otherwise, return to S701.

[0085] S703: Acquires input voltage information and output voltage information;

[0086] S704. Determine if the input voltage is less than the output voltage. If yes, execute S705; otherwise, return to S703.

[0087] S705. Determine the phase difference between the input voltage and the output voltage based on the input voltage information and the output voltage information;

[0088] S706. Determine if the phase difference is greater than the second threshold. If yes, execute S706; otherwise, return to S704.

[0089] S707, Collect bus voltage;

[0090] S708. Determine whether the bus voltage is greater than the third threshold. If yes, execute S709; otherwise, return to S707.

[0091] S709. Based on the preset current value, reduce the current value flowing through the second and fifth switching transistors, and execute S710 or S711.

[0092] S710, disconnect the first switch transistor, the second switch transistor, the third switch transistor, the fourth switch transistor, the fifth switch transistor, and the sixth switch transistor;

[0093] S711: Connect the DC power supply to the second and third bridge arms to invert the DC power output from the DC power supply and output AC power.

[0094] Based on the same inventive concept, this embodiment of the invention also provides a current control device applied to a three-arm bridge topology circuit. The three-arm bridge topology circuit includes a first arm composed of a first switch and a second switch, a second arm composed of a third switch and a fourth switch, and a third arm composed of a fifth switch and a sixth switch. The three arms are connected in parallel between a positive bus and a negative bus, respectively. A bus capacitor is connected in parallel between the positive bus and the negative bus. The midpoint of the first arm is connected to one end of a first inductor, the midpoint of the second arm is connected to one end of a second inductor, and the midpoint of the third arm is connected to one end of a third inductor. The other ends of the first and second inductors are used as the AC input terminals of the three-arm bridge topology circuit, and the other ends of the third and second inductors are used as the AC output terminals of the three-arm bridge topology circuit. An output capacitor is connected in parallel to the AC output terminals. Figure 8 As shown, the device includes:

[0095] The acquisition module 801 is used to acquire the input voltage information of the AC input terminal and the output voltage information of the AC output terminal;

[0096] The determining module 802 is used to determine, based on the input voltage information and the output voltage information, that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal;

[0097] The adjustment module 803 is used to reduce the current flowing through the second switch and the fifth switch according to a preset current value.

[0098] In one possible implementation, the determining module 802 is specifically used for:

[0099] Based on the input voltage information and the output current information, determine the phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal;

[0100] If the phase difference is greater than the first threshold, then it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

[0101] In one possible implementation, the determining module 802 is further configured to:

[0102] Before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, the input current value at the AC input terminal is obtained; the input current value is determined to be greater than a second threshold; based on the input voltage information and the output voltage information, the voltage at the input terminal is determined to be less than the voltage at the output terminal.

[0103] In one possible implementation, the determining module 802 is further configured to:

[0104] Collect the bus voltage between the positive bus and the negative bus; determine that the bus voltage is greater than a third threshold.

[0105] In one possible implementation, the device further includes a first control module;

[0106] The first control module is used to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to disconnect.

[0107] In one possible implementation, the device further includes a second control module;

[0108] The second control module is used to control the first and second switching transistors to disconnect; and to connect the DC power supply to the second bridge arm and the third bridge arm to invert the DC power output from the DC power supply and output AC power.

[0109] The DC power supply is connected in parallel between the positive bus and the negative bus.

[0110] Based on the same inventive concept, embodiments of the present invention also provide a current control device, such as... Figure 9As shown, the device includes a processor 901, such as a central processing unit (CPU), and a memory 902.

[0111] The memory 902 may include a read-only memory (ROM) and a random access memory (RAM), and provides the processor 901 with program instructions and data stored in the memory 902. In this embodiment of the invention, the memory 902 may be used to store a program for executing a current control method.

[0112] The processor 901 can execute the following according to the program instructions stored in the memory 902: obtain the input voltage information of the AC input terminal and the output voltage information of the AC output terminal; determine that the voltage of the AC input terminal is out of phase with the voltage of the AC output terminal based on the input voltage information and the output voltage information; and reduce the current value flowing through the second switch and the fifth switch according to a preset current value.

[0113] Based on the same inventive concept, embodiments of the present invention also provide a computer-readable storage medium for storing computer program instructions for use in the above-described computing device, which includes a program for performing the above-described current control method.

[0114] The computer storage medium can be any available medium or data storage device that a computer can access, including but not limited to magnetic storage (e.g., floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (e.g., CDs, DVDs, BDs, HVDs, etc.), and semiconductor storage (e.g., ROMs, EPROMs, EEPROMs, non-volatile memory (NAND flash), solid-state drives (SSDs)).

[0115] Furthermore, the number of any elements in the accompanying drawings and specifications is for illustrative purposes only and not for limitation, and any naming is for distinction only and has no limiting meaning.

[0116] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus (devices), or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0117] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0118] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0119] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0120] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0121] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A current control method applied to a three-arm bridge topology circuit, the three-arm bridge topology circuit comprising a first bridge arm composed of a first switch and a second switch, a second bridge arm composed of a third switch and a fourth switch, and a third bridge arm composed of a fifth switch and a sixth switch, the three bridge arms being connected in parallel between a positive bus and a negative bus, a bus capacitor being connected in parallel between the positive bus and the negative bus; the midpoint of the first bridge arm being connected to one end of a first inductor, the midpoint of the second bridge arm being connected to one end of a second inductor, the midpoint of the third bridge arm being connected to one end of a third inductor, the other ends of the first inductor and the other ends of the second inductor being used as the AC input terminal of the three-arm bridge topology circuit, the other ends of the third inductor and the other ends of the second inductor being used as the AC output terminal of the three-arm bridge topology circuit, an output capacitor being connected in parallel between the AC output terminal; characterized in that, The method includes: Obtain the input voltage information of the AC input terminal and the output voltage information of the AC output terminal; Based on the input voltage information and the output voltage information, it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal; Based on the preset current value, reduce the current flowing through the second switch and the fifth switch; The method of reducing the current flowing through the second and fifth switching transistors further includes: Disconnect the first and second switching transistors; The path between the DC power supply and the second and third bridge arms is connected to invert the DC power output from the DC power supply and output AC power. The DC power supply is connected in parallel between the positive bus and the negative bus.

2. The method as described in claim 1, characterized in that, Determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal includes: Based on the input voltage information and the output voltage information, determine the phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal; If the phase difference is greater than the first threshold, then it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

3. The method as described in claim 1, characterized in that, Before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, the method further includes: Obtain the input current value at the AC input terminal; The input current value is determined to be greater than the second threshold. Based on the input voltage information and the output voltage information, it is determined that the voltage at the input terminal is less than the voltage at the output terminal.

4. The method as described in claim 1, characterized in that, Before reducing the current flowing through the second and fifth switching transistors, the method further includes: Collect the bus voltage between the positive bus and the negative bus; It is determined that the bus voltage is greater than the third threshold.

5. The method as described in claim 1, characterized in that, After reducing the current flowing through the second and fifth switching transistors, the method further includes: The first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch are controlled to disconnect.

6. A current control device applied to a three-arm bridge topology circuit, the three-arm bridge topology circuit comprising a first bridge arm composed of a first switch and a second switch, a second bridge arm composed of a third switch and a fourth switch, and a third bridge arm composed of a fifth switch and a sixth switch, the three bridge arms being connected in parallel between a positive bus and a negative bus, a bus capacitor being connected in parallel between the positive bus and the negative bus; the midpoint of the first bridge arm being connected to one end of a first inductor, the midpoint of the second bridge arm being connected to one end of a second inductor, the midpoint of the third bridge arm being connected to one end of a third inductor, the other ends of the first inductor and the other ends of the second inductor being used as the AC input terminal of the three-arm bridge topology circuit, the other ends of the third inductor and the other ends of the second inductor being used as the AC output terminal of the three-arm bridge topology circuit, an output capacitor being connected in parallel between the AC output terminal; characterized in that, The device includes: The acquisition module is used to acquire the input voltage information of the AC input terminal and the output voltage information of the AC output terminal; The determining module is used to determine, based on the input voltage information and the output voltage information, that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal; The adjustment module is used to reduce the current flowing through the second switch and the fifth switch according to a preset current value; The device also includes a second control module; The second control module is used to control the first and second switching transistors to disconnect; and to connect the DC power supply to the second bridge arm and the third bridge arm to invert the DC power output from the DC power supply and output AC power. The DC power supply is connected in parallel between the positive bus and the negative bus.

7. The apparatus as claimed in claim 6, characterized in that, The determining module is specifically used for: Based on the input voltage information and the output voltage information, determine the phase difference between the voltage at the AC input terminal and the voltage at the AC output terminal; If the phase difference is greater than the first threshold, then it is determined that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal.

8. The apparatus as claimed in claim 6, characterized in that, The determining module is also used for: Before determining that the voltage at the AC input terminal is out of phase with the voltage at the AC output terminal, the input current value at the AC input terminal is obtained; the input current value is determined to be greater than a second threshold; based on the input voltage information and the output voltage information, the voltage at the input terminal is determined to be less than the voltage at the output terminal.

9. The apparatus as claimed in claim 6, characterized in that, The determining module is also used for: Collect the bus voltage between the positive bus and the negative bus; determine that the bus voltage is greater than a third threshold.

10. The apparatus as claimed in claim 6, characterized in that, The device also includes a first control module; The first control module is used to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to disconnect.

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