Three-phase inverter circuit control method, three-phase inverter circuit, and electric appliance

Abstract

The embodiment of the application relates to a three-phase inverter circuit control method, a three-phase inverter circuit and an electrical appliance, the method comprising: determining an electric energy transmission direction in the three-phase inverter circuit; determining a current direction of input alternating current in the three-phase inverter circuit based on the electric energy transmission direction; sending a control signal to a target switch unit in two switch units on each bridge arm in the three-phase inverter circuit and sending a conduction signal to another switch unit based on a preset inverter control mode corresponding to the electric energy transmission direction, so that the three-phase inverter circuit outputs three-phase alternating current according to the inverter control mode. According to the embodiment of the application, the switch state of the inverter is controlled according to the current direction of the alternating current directly through single-stage conversion, so that the inverter can output expected alternating power and frequency, thereby avoiding energy loss of the power supply caused by direct current energy storage, and improving the utilization rate of the power supply and the energy efficiency of the equipment.

Description

Technical Field

[0001] This application relates to the field of automation control technology, and in particular to a three-phase inverter circuit control method, a three-phase inverter circuit, and electrical equipment. Background Technology

[0002] Conventional inverters (such as those used in air conditioning inverter systems) typically employ AC-DC-AC conversion technology. This involves first rectifying the three-phase AC power into DC power, then inputting the DC power into a second inverter, and finally outputting it to the three-phase motor.

[0003] This circuit architecture involves multiple energy conversions, resulting in low power utilization and significant energy loss. Because it uses converters and diodes or thyristors as the front-end rectification AC-DC-AC conversion devices, it introduces substantial reactive power and harmonic pollution to the power grid, and hinders any substantial improvement in equipment energy efficiency. Summary of the Invention

[0004] In view of this, in order to solve some or all of the above-mentioned technical problems, this application provides a three-phase inverter circuit control method, a three-phase inverter circuit and electrical equipment.

[0005] In a first aspect, embodiments of this application provide a three-phase inverter circuit control method, the method comprising: determining the direction of power transmission in the three-phase inverter circuit; determining the direction of current of input AC power in the three-phase inverter circuit based on the direction of power transmission; and sending a control signal to a target switching unit of two switching units on each arm of the three-phase inverter circuit and sending a conduction signal to another switching unit based on a preset inverter control mode corresponding to the direction of power transmission, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0006] In one possible implementation, based on a preset inverter control mode corresponding to the direction of power transmission, a control signal is sent to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and a conduction signal is sent to the other switching unit. This includes: if the direction of power transmission is from AC power source to load device and the current direction is positive, determining whether the current state is in a first type of positive inverter output stage; if yes, controlling the second switching unit on each arm of the three-phase inverter circuit to conduct and sending a control signal to the first switching unit on each arm; if no, controlling the second switching unit on each arm to turn off; if the direction of power transmission is from AC power source to load device and the current direction is negative, determining whether the current state is in a first type of negative inverter output stage; if yes, controlling the first switching unit on each arm to conduct and sending a control signal to the second switching unit on each arm; if no, controlling the first switching unit on each arm to turn off.

[0007] In one possible implementation, determining whether the current is in a first type of positive inverter output stage includes: if the current direction is positive, acquiring the recorded number of positive voltage half-cycles continuously output by the AC power supply; if the number of positive voltage half-cycles does not reach a preset number, determining that the current is in a first type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, switching the current inverter output stage to a first type of negative inverter output stage, and clearing the recorded number of positive voltage half-cycles to zero; determining whether the current is in a first type of negative inverter output stage includes: if the current direction is negative, acquiring the recorded number of negative voltage half-cycles continuously output by the AC power supply; if the number of negative voltage half-cycles does not reach a preset number, determining that the current is in a first type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, switching the current inverter output stage to a first type of positive inverter output stage, and clearing the recorded number of negative voltage half-cycles to zero.

[0008] In one possible implementation, based on a preset inverter control mode corresponding to the direction of power transmission, a control signal is sent to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and a conduction signal is sent to the other switching unit. This includes: if the direction of power transmission is from the load device to the AC power source and the current direction is positive, determining whether the current state is in a second type of positive inverter output stage; if yes, controlling the first switching unit on each arm to conduct and sending a control signal to the second switching unit on each arm; if no, controlling the first switching unit on each arm to turn off; if the direction of power transmission is from the load device to the AC power source and the current direction is negative, determining whether the current state is in a second type of negative inverter output stage; if yes, controlling the second switching unit on each arm to conduct and sending a control signal to the first switching unit on each arm; if no, controlling the second switching unit on each arm to turn off.

[0009] In one possible implementation, determining whether the current is in a second type of positive inverter output stage includes: if the current direction is positive, acquiring the recorded number of consecutive positive voltage half-cycles output by the load device; if the number of positive voltage half-cycles does not reach a preset number, determining that the current is in a second type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, switching the current inverter output stage to a second type of negative inverter output stage, and clearing the recorded number of positive voltage half-cycles to zero; determining whether the current is in a second type of negative inverter output stage includes: if the current direction is negative, acquiring the recorded number of consecutive negative voltage half-cycles output by the load device; if the number of negative voltage half-cycles does not reach a preset number, determining that the current is in a second type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, switching the current inverter output stage to a second type of positive inverter output stage, and clearing the recorded number of negative voltage half-cycles to zero.

[0010] Secondly, embodiments of this application provide a three-phase inverter circuit, which includes: a controller and three sets of bridge arms. Each set of bridge arms includes an upper bridge arm and a lower bridge arm. The common connection terminal of the upper and lower bridge arms is connected to one phase of the load device. The upper bridge arm is connected to the first output terminal of the AC power supply, and the lower bridge arm is connected to the second output terminal of the AC power supply. Each upper bridge arm and each lower bridge arm are provided with a first switching unit and a second switching unit connected in series. The control terminals of the first and second switching units are connected to the controller. The controller is connected to the AC power supply and / or the load device, and the controller is used to execute the above-described three-phase inverter circuit control method.

[0011] In one possible implementation, the first switching unit and the second switching unit are of the same type, and the electrodes to which the first switching unit and the second switching unit are connected are of the same type.

[0012] Thirdly, embodiments of this application provide a three-phase inverter circuit control device, which includes: a first determining module for determining the direction of power transmission in the three-phase inverter circuit; a second determining module for determining the direction of current of input AC power in the three-phase inverter circuit based on the direction of power transmission; and a control module for sending a control signal to a target switching unit of two switching units on each bridge arm of the three-phase inverter circuit and sending a conduction signal to another switching unit based on a preset inverter control mode corresponding to the direction of power transmission, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0013] Fourthly, embodiments of this application provide an electrical device, including: the aforementioned three-phase inverter circuit, and also including a motor.

[0014] Fifthly, embodiments of this application provide a controller, comprising: a memory for storing a computer program; and a processor for executing the computer program stored in the memory, wherein when the computer program is executed, it implements the method of any embodiment of the three-phase inverter circuit control method of the first aspect of this application described above.

[0015] In a sixth aspect, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method of any embodiment of the three-phase inverter circuit control method of the first aspect described above.

[0016] In a seventh aspect, embodiments of this application provide a computer program including computer-readable code that, when executed on a device, causes a processor in the device to implement the method of any embodiment of the three-phase inverter circuit control method of the first aspect described above.

[0017] The three-phase inverter circuit control method, three-phase inverter circuit, and electrical equipment provided in this application determine the direction of power transmission in the three-phase inverter circuit; based on the direction of power transmission, determine the direction of the input AC current in the three-phase inverter circuit; and based on a preset inverter control mode corresponding to the direction of power transmission, send a control signal to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and send a conduction signal to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode. This application embodiment eliminates the need to convert the AC power output from the AC power source to DC power and then back to AC power. Instead, it directly controls the switching state of the inverter according to the direction of the AC current through a single-stage conversion, enabling the inverter to output the desired AC power and frequency. This avoids power loss caused by DC energy storage and improves power utilization and equipment energy efficiency. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 A flowchart illustrating a three-phase inverter circuit control method provided in an embodiment of this application;

[0022] Figure 2 A flowchart illustrating another three-phase inverter circuit control method provided in an embodiment of this application;

[0023] Figure 3 A schematic diagram of AC voltage waveforms for the positive inverter output stage and the negative inverter output stage provided in the embodiments of this application;

[0024] Figure 4 A flowchart illustrating another three-phase inverter circuit control method provided in this application embodiment;

[0025] Figure 5 This is a schematic diagram of the structure of a three-phase inverter circuit provided in an embodiment of this application;

[0026] Figure 6 An equivalent circuit diagram provided for an embodiment of this application;

[0027] Figure 7 Another equivalent circuit diagram provided for embodiments of this application;

[0028] Figure 8 A schematic diagram of the structure of a three-phase inverter circuit control device provided in an embodiment of this application;

[0029] Figure 9 This is a schematic diagram of the structure of an electrical device provided in an embodiment of this application;

[0030] Figure 10 This is a schematic diagram of the structure of a controller provided in an embodiment of this application. Detailed Implementation

[0031] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0032] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of this application are only used to distinguish different steps, devices or modules, and do not represent any specific technical meaning, nor do they indicate the logical order between them.

[0033] It should also be understood that in this embodiment, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0034] It should also be understood that any component, data or structure mentioned in the embodiments of this application can generally be understood as one or more unless explicitly defined or given contrary guidance in the context.

[0035] Furthermore, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "or" relationship.

[0036] It should also be understood that the description of the various embodiments in this application emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0037] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0038] Techniques, circuits, and devices known to a person skilled in the art may not be discussed in detail, but where appropriate, such techniques, circuits, and devices should be considered part of the specification.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. To facilitate understanding of the embodiments of this application, the application will be described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0041] To address the technical problem of low energy efficiency in electrical equipment caused by the need for AC-DC-AC conversion in existing inverters, this application provides a three-phase inverter circuit control method that can directly convert AC power to AC power with the desired power and frequency through a single-stage conversion, thereby avoiding power loss caused by DC energy storage and improving power utilization and equipment energy efficiency.

[0042] Figure 1 This is a flowchart illustrating a three-phase inverter circuit control method provided in an embodiment of this application. This method can be applied to various electrical appliances with three-phase inverters (e.g., air conditioners, refrigerators, etc.), and can be executed by the controller of the electrical appliance. Furthermore, the executing entity of this method can be hardware or software. When the executing entity is hardware, it can be one or more of the aforementioned electronic devices. For example, a single electronic device can execute this method, or multiple electronic devices can cooperate with each other to execute this method. When the executing entity is software, this method can be implemented as multiple software programs or software modules, or as a single software program or software module. No specific limitations are made here.

[0043] like Figure 1 As shown, the method specifically includes:

[0044] Step 101: Determine the direction of power transmission in the three-phase inverter circuit.

[0045] In some embodiments, the two ends of the three-phase inverter circuit can be connected to an AC power source and a load device, respectively. The direction of power transmission can be from the AC power source to the load device, that is, the power provided by the AC power source drives the operation of the load device. Alternatively, the direction of transmission can be from the load device to the AC power source, that is, the load device generates power in the direction of the AC power source.

[0046] Step 102: Determine the direction of the input AC current in the three-phase inverter circuit based on the direction of power transmission.

[0047] In some embodiments, the input AC power is the AC power input to the three-phase inverter circuit, and the source of this input AC power varies depending on the direction of power transmission. That is, if the direction of power transmission is from the AC power source to the load device, the input AC power is the AC power output from the AC power source; if the direction of power transmission is from the load device to the AC power source, the input AC power is the AC power output from the load device, which acts as a generator, towards the AC power source.

[0048] Because the voltage of alternating current changes in a sinusoidal waveform, the direction of the current also changes in a sinusoidal waveform; that is, the current direction may be positive or negative. Typically, the current direction can be determined by installing a voltage sensor or current sensor on the line between the AC power source and the inverter.

[0049] Step 103: Based on the preset inverter control mode corresponding to the direction of power transmission, a control signal is sent to the target switching unit of the two switching units on each bridge arm of the three-phase inverter circuit, and a conduction signal is sent to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0050] In some embodiments, different power transmission directions correspond to different inverter control methods, that is, different control methods are applied to the two switching units on each bridge arm. The two switching units on each bridge arm are connected in series (as described below). Figure 5 As shown, Q11-Q61 are the first switching units, and Q12-Q62 are the second switching units. When the current direction is positive, a control signal can be sent to the first switching unit (i.e., the target switching unit) and a conduction signal can be sent to the second switching unit to turn it on. The three-phase inverter circuit is equivalent to one type of inverter. When the current direction is negative, a control signal can be sent to the second switching unit (i.e., the target switching unit) and a conduction signal can be sent to the first switching unit to turn it on. The three-phase inverter circuit is equivalent to another type of inverter, such as the following... Figure 6 and Figure 7 As shown. The two types of inverters described above convert the positive and negative voltages into DC current, respectively, and perform voltage inversion operation to generate AC current of the desired frequency.

[0051] The three-phase inverter circuit control method provided in this application determines the direction of power transmission in the three-phase inverter circuit; based on the direction of power transmission, it determines the direction of the input AC current in the three-phase inverter circuit; based on a preset inverter control mode corresponding to the direction of power transmission, it sends a control signal to the target switching unit of the two switching units on each arm of the three-phase inverter circuit and sends a conduction signal to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode. This application embodiment eliminates the need to convert the AC power output from the AC power source to DC power and then back to AC power. Instead, it directly controls the switching state of the inverter according to the direction of the AC current through a single-stage conversion, enabling the inverter to output the desired AC power and frequency. This avoids power loss caused by DC energy storage and improves power utilization and equipment energy efficiency.

[0052] In some alternative implementations, such as Figure 2 As shown, step 103 includes:

[0053] Step 10301: If the direction of power transmission is from AC power source to load device and the current direction is positive, determine whether the current is in the first type of positive inverter output stage.

[0054] In some embodiments, the load device is a device connected to the inverter, typically a three-phase motor. The direction of power transmission can be from the AC power source to the load device, meaning the AC power source drives the load device. Alternatively, the transmission direction can be from the load device to the AC power source, meaning the load device generates power in the direction of the AC power source.

[0055] Because the voltage of an AC power source varies in a sinusoidal wave pattern, the direction of the current also varies in a sinusoidal wave pattern. That is, the current direction may be positive (current flows from the AC power source to the load device) or negative (current flows from the load device to the AC power source). Typically, the current direction can be determined by installing a voltage sensor or current sensor on the line between the AC power source and the inverter.

[0056] When the current direction is positive, the alternating current can be treated as positive direct current, and it can be determined whether the current is in the first type of positive inverter output stage. The determination criteria for the first type of positive inverter output stage can be set according to requirements. For example, each positive half-cycle of the AC voltage can be used as the first type of positive inverter output stage, or a preset number of consecutive positive half-cycles can be used as the first type of positive inverter output stage.

[0057] The first type of positive inverter output stage and the following first type of negative inverter output stage correspond to the situation where the AC power supply outputs AC power.

[0058] If the current stage is the first type of forward inverter output stage, proceed to step 10302; if the current stage is not the first type of forward inverter output stage, proceed to step 10303.

[0059] Step 10302: Control the second switching unit on each bridge arm of the three-phase inverter circuit to turn on, and send a control signal to the first switching unit on each bridge arm.

[0060] Each arm of the three-phase inverter circuit is equipped with two sets of switching units connected in series (as follows) Figure 5 As shown below, if the current phase is the positive half-cycle of the AC voltage and in the first type of forward inverter output stage, the second switching unit on each bridge arm can be turned on. At this time, according to the inverter control mode of forward DC to AC conversion, a PWM signal is sent to the first switching unit on each bridge arm to realize the inverter function. As follows Figure 6 As shown, it is the equivalent circuit diagram when the second switching unit on each bridge arm is turned on.

[0061] Step 10303: Control the second switch unit on each bridge arm to turn off.

[0062] In some embodiments, if the current period is a positive half-cycle of the AC voltage but not a first-type forward inverter output phase, the second switching unit on each bridge arm is turned off, and the inverter output function is no longer executed. For example, if the positive half-cycles of two consecutive AC power cycles are defined as a first-type forward inverter output phase, and the negative half-cycles of the following two consecutive cycles are defined as a first-type negative inverter output phase, then after the first-type forward inverter output phase, the first-type negative inverter output phase begins. During the first-type negative inverter output phase, the positive half-cycle of the AC power is blocked by the second switching unit, prohibiting the execution of the forward inverter output function.

[0063] Step 10304: If the direction of power transmission is from AC power source to load device and the current direction is negative, determine whether the current is in the first type of negative inverter output stage.

[0064] When the current direction is negative, the alternating current can be treated as negative direct current, and it can be determined whether the current is in the first type of negative inverter output stage. The judgment condition for the first type of negative inverter output stage can correspond to the judgment condition for the first type of positive inverter output stage.

[0065] If the current stage is the first type of negative inverter output stage, proceed to step 10305; if the current stage is not the first type of negative inverter output stage, proceed to step 10306.

[0066] Step 10305: Control the first switch unit on each bridge arm to turn on, and send a control signal to the second switch unit on each bridge arm.

[0067] If the current phase is the negative half-cycle of the AC voltage and is in the first type of negative inverter output stage, the first switching unit on each bridge arm can be turned on. At this time, according to the inverter control mode of converting negative DC to AC, a PWM signal is sent to the second switching unit on each bridge arm to realize the inverter function.

[0068] As follows Figure 7 As shown, it is the equivalent circuit diagram when the first switching unit on each bridge arm is turned on.

[0069] Step 10306: Control the first switch unit on each bridge arm to turn off.

[0070] In some embodiments, if the current period is the negative half-cycle of the AC voltage but not the first type of negative inverter output stage, the first switching unit on each bridge arm is turned off, and the inverter output function is no longer executed. For example, if the positive half-cycles of two consecutive AC power cycles are defined as the first type of positive inverter output stage, and the negative half-cycles of the next two consecutive cycles are defined as the first type of negative inverter output stage, and so on, then the first type of positive inverter output stage follows the first type of negative inverter output stage. During the first type of positive inverter output stage, the negative half-cycle of the AC power is blocked by the first switching unit, prohibiting the execution of the negative inverter output function.

[0071] This embodiment can provide opposite currents to the load device during the positive and negative inverter output stages. When this embodiment is applied to a frequency converter, it can enable the frequency converter to operate in the first and third quadrants.

[0072] This embodiment achieves smooth switching of the circuit structure corresponding to the positive and negative half-cycles of AC power on the same inverter circuit by controlling the state of the two switching units on each bridge arm. This effectively suppresses voltage and current surges and energy losses, thereby improving the energy efficiency of the equipment.

[0073] In some alternative implementations, step 10301 includes:

[0074] First, if the current direction is positive, obtain the number of positive voltage half-cycles continuously output by the AC power supply.

[0075] like Figure 3 As shown, the voltage output by the AC power supply is a sine wave. In each cycle, the half-cycle in which the voltage is greater than zero is the positive half-cycle, and the half-cycle in which the voltage is less than zero is the negative half-cycle.

[0076] Then, if the number of positive voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of negative inverter output stage, and the recorded number of positive voltage half-cycles is cleared to zero.

[0077] As an example, the preset quantity is three, such as Figure 3 As shown, the first type of forward inverter output stage includes three positive voltage half-cycles (as shown by P1, P2, and P3 in the figure) and two negative voltage half-cycles. During the negative voltage half-cycle, referring to step 10306, since it is in the first type of forward inverter output stage, not the first type of negative inverter output stage, the first switching unit on each bridge arm is turned off, blocking the transmission of current. During each positive voltage half-cycle, the first switching unit on each bridge arm performs the inverter function under the action of the control signal.

[0078] like Figure 3 As shown, after the third positive half-cycle ends, the current inverter output stage is switched to the first type of negative inverter output stage, and the subsequent steps are executed.

[0079] Step 10304 includes:

[0080] First, if the current direction is negative, obtain the number of negative voltage half-cycles continuously output by the AC power supply.

[0081] Then, if the number of negative voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of positive inverter output stage, and the recorded number of negative voltage half-cycles is cleared to zero.

[0082] Continuing with the example above, such as Figure 3 As shown, the first type of negative inverter output stage includes three negative voltage half-cycles (as shown by N1, N2, and N3 in the figure) and two positive voltage half-cycles. During the positive voltage half-cycle, referring to step 10303, since this is the first type of negative inverter output stage, not the first type of positive inverter output stage, the second switching unit on each bridge arm is turned off, blocking current transmission. During each negative voltage half-cycle, the second switching unit on each bridge arm performs the inverter function under the action of the control signal.

[0083] This embodiment achieves flexible control over the voltage frequency output to the load device by setting the number of positive and negative voltage half-cycles included in the first type of positive inverter output stage and the first type of negative inverter output stage, thereby facilitating the adjustment of the inverter output power and frequency and expanding the application scenarios of the device.

[0084] In some alternative implementations, such as Figure 4 As shown, step 103 includes:

[0085] Step 10307: If the direction of power transmission is from the load device to the AC power source and the current direction is positive, determine whether the current is in the second type of positive inverter output stage.

[0086] Specifically, when the current is transmitted from the load device to the AC power source, the load device generates electricity in the direction of the AC power source.

[0087] When the current direction is positive, the AC output from the load device can be treated as positive DC, and it can be determined whether the current state is in the second type of positive inverter output stage. The determination criteria for the second type of positive inverter output stage can be set according to requirements. For example, each positive half-cycle of the AC voltage can be used as the second type of positive inverter output stage, or a preset number of consecutive positive half-cycles can be used as the second type of positive inverter output stage. The second type of positive inverter output stage and the second type of negative inverter output stage described below correspond to the situation where the load device outputs AC power.

[0088] If the current stage is the second type of forward inverter output stage, proceed to step 10308; if the current stage is not the second type of forward inverter output stage, proceed to step 10309.

[0089] Step 10308: Control the first switch unit on each bridge arm to turn on, and send a control signal to the second switch unit on each bridge arm.

[0090] As follows Figure 5 As shown, if the current period is the positive half-cycle of the AC voltage output by the load device and is in the second type of forward inverter output stage, the first switching unit on each bridge arm can be turned on. At this time, according to the inverter control mode of forward DC to AC, a PWM signal is sent to the second switching unit on each bridge arm to realize the inverter function.

[0091] Because the energy transfer direction is the same as above Figure 1 The energy transmission direction is reversed in the corresponding embodiments. Therefore, the equivalent circuit of the second type of positive inverter output stage is the same as that of the second type of negative inverter output stage described above, and is as follows: Figure 7 The circuit diagram shown is shown.

[0092] Step 10309: Control the first switch unit on each bridge arm to turn off.

[0093] If the current phase is within the positive half-cycle of the AC voltage but not within the second type of forward inverter output phase, the first switching unit on each bridge arm is turned off, and the inverter output function is no longer executed. For example, if the positive half-cycles of two consecutive cycles of the load device's output are defined as the second type of forward inverter output phase, and the negative half-cycles of the following two consecutive cycles are defined as the second type of negative inverter output phase, then after the second type of forward inverter output phase, the second type of negative inverter output phase will begin. During the second type of negative inverter output phase, the positive half-cycle of the AC voltage is blocked by the first switching unit, prohibiting the execution of the forward inverter output (i.e., output to AC power) function.

[0094] Step 10310: If the direction of power transmission is from the load device to the AC power source and the current direction is negative, determine whether the current is in the second type of negative inverter output stage.

[0095] When the current direction is negative, the alternating current can be treated as negative direct current, and it can be determined whether the current is in the second type of negative inverter output stage. The judgment conditions for the second type of negative inverter output stage can correspond to the judgment conditions for the second type of positive inverter output stage.

[0096] If the current stage is the second type of negative inverter output stage, proceed to step 10311; if the current stage is not the second type of negative inverter output stage, proceed to step 10312.

[0097] Step 10311: Control the second switch unit on each bridge arm to turn on, and send a control signal to the first switch unit on each bridge arm.

[0098] If the current phase is the negative half-cycle of the AC voltage and is in the second type of negative inverter output stage, the second switching unit on each bridge arm can be turned on. At this time, according to the inverter control mode of converting negative DC to AC, a PWM signal is sent to the first switching unit on each bridge arm to realize the inverter function.

[0099] Because the energy transfer direction is the same as above Figure 2 The energy transmission direction is reversed in the corresponding embodiments. Therefore, the equivalent circuit of the second type of negative inverter output stage is the same as that of the first type of positive inverter output stage, and both are as follows: Figure 6 The circuit diagram shown is shown.

[0100] Step 10312: Control the second switch unit on each bridge arm to turn off.

[0101] If the current phase is in the negative half-cycle of the AC voltage but not in the second type of negative inverter output phase, the second switching unit on each bridge arm is turned off, and the inverter output function is no longer executed. For example, if the negative half-cycles of two consecutive cycles of the load device output are set as the second type of negative inverter output phase, and the next two consecutive positive half-cycles are set as the second type of positive inverter output phase, then after the second type of negative inverter output phase, the second type of positive inverter output phase will begin. In the second type of positive inverter output phase, the negative half-cycle of the AC voltage is blocked by the second switching unit, prohibiting the execution of the negative inverter output (i.e., output to AC power) function.

[0102] This embodiment achieves reverse energy transfer on the same inverter circuit by controlling the state of the two switching units on each bridge arm. The circuit structure corresponding to the positive and negative half-cycles of AC current can be smoothly switched, effectively suppressing voltage and current surges and energy losses, thus improving the energy efficiency of the equipment. When this method is applied to a frequency converter, it can enable the frequency converter to operate in the second and fourth quadrants. Combined with the above embodiment, it enables the frequency converter to operate in all four quadrants.

[0103] In some alternative implementations, step 10307 includes:

[0104] First, if the current direction is positive, obtain the number of consecutive positive voltage half-cycles output by the load device.

[0105] Then, if the number of positive voltage half-cycles does not reach the preset number, it is determined that the current stage is the second type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of negative inverter output stage, and the recorded number of positive voltage half-cycles is cleared to zero.

[0106] As an example, the preset quantity is three, as described above. Figure 3 As shown, the second type of forward inverter output stage includes three positive voltage half-cycles and two negative voltage half-cycles. During the negative voltage half-cycle, referring to step 10312, since it is in the second type of forward inverter output stage rather than the second type of negative inverter output stage, the second switching unit on each bridge arm is turned off, blocking the transmission of current. During each positive voltage half-cycle, the second switching unit on each bridge arm performs the inverter function under the action of the control signal.

[0107] like Figure 3 As shown, after the third positive half-cycle ends, the current inverter output stage is switched to the second type of negative inverter output stage, and the subsequent steps are executed.

[0108] Step 10310 includes:

[0109] First, if the current direction is negative, obtain the number of consecutive negative voltage half-cycles output by the load device.

[0110] Then, if the number of negative voltage half-cycles does not reach the preset number, it is determined that the current stage is the second type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of positive inverter output stage, and the recorded number of negative voltage half-cycles is cleared to zero.

[0111] Continuing with the example above, such as Figure 3As shown, the second type of negative inverter output stage includes three negative voltage half-cycles and two positive voltage half-cycles. During the positive voltage half-cycle, referring to step 10309, since this is the second type of negative inverter output stage, not the second type of positive inverter output stage, the first switching unit on each bridge arm is turned off, blocking current transmission. During each negative voltage half-cycle, the first switching unit on each bridge arm performs the inverter function under the action of the control signal.

[0112] This embodiment achieves flexible control over the voltage frequency of AC power generation by setting the number of positive and negative voltage half-cycles included in the second type of positive inverter output stage and the second type of negative inverter output stage, thereby facilitating the adjustment of the inverter output power and frequency and expanding the application scenarios of the equipment.

[0113] Figure 5 This is a schematic diagram of a three-phase inverter circuit 500 provided in an embodiment of this application. The circuit 500 specifically includes: a controller 501 and three sets of bridge arms 502.

[0114] Each of the three bridge arms 502 includes an upper bridge arm and a lower bridge arm. The common connection terminal of the upper and lower bridge arms is connected to one phase of the load device. The upper bridge arm is connected to the first output terminal of the AC power supply, and the lower bridge arm is connected to the second output terminal of the AC power supply. For example... Figure 5 As shown, U, V, and W are the three-phase output terminals of the three-phase inverter circuit. The common connection terminal of each pair of upper and lower bridge arms is connected to U, V, and W respectively. Figure 5 As shown, the load device is usually a three-phase motor.

[0115] Each upper bridge arm and each lower bridge arm are equipped with a first switch unit and a second switch unit connected in series. The control terminals of the first switch unit and the second switch unit are connected to the controller 501.

[0116] The types of the first and second switching units mentioned above can be set according to actual needs. For example... Figure 5 As shown, the first and second switching units are combinations of IGBTs and parallel diodes. The gate of the IGBT serves as the control terminal and is connected to the controller 501. As an example, Figure 5 Q11 and D11 form a first switching unit, and Q12 and D12 form a second switching unit. The two switching units are located in the upper bridge arm corresponding to U. Q41 and D41 form a first switching unit, and Q42 and D42 form a second switching unit. The two switching units are located in the lower bridge arm corresponding to U.

[0117] The controller 501 is connected to an AC power supply and / or a load device, and the controller 501 is used to execute the three-phase inverter circuit control method of any one of claims 1-5.

[0118] The controller 501 can be connected to the AC power supply and / or load device via a voltage sensor or current sensor to determine the voltage phase of the input three-phase inverter circuit at the current moment, that is, to determine the current direction and magnitude. Based on the collected current direction and magnitude, the controller 501 can control the state of the corresponding switching unit to realize the corresponding voltage inversion function.

[0119] In conjunction with the above method embodiments, when the power transmission direction is from AC power source to load device, if it is currently in the first type of forward inverter output stage, the second switching unit on each bridge arm is turned on (i.e., Q12-Q62 are turned on), and the equivalent circuit diagram is as follows. Figure 6 As shown; if the current stage is the first type of negative inverter output stage, the first switching unit (i.e., Q11-Q61) on each bridge arm is turned on, and the equivalent circuit diagram is as follows. Figure 7 As shown.

[0120] When the direction of power transmission is from the load device to the AC power source, and if the current stage is the second type of forward inverter output, the first switching unit on each bridge arm is turned on, and the equivalent circuit diagram is as follows. Figure 7 As shown; if currently in the second type of negative inverter output stage, the second switching unit on each bridge arm is turned on, and the equivalent circuit diagram is as follows. Figure 6 As shown.

[0121] The three-phase inverter circuit provided in this embodiment, by setting two switching units connected in series on each bridge arm, can control different switching units to perform inverter functions, or directly turn them on or off, according to the current direction. Therefore, it can be applied in four-quadrant frequency inverters. Furthermore, it eliminates the need to convert AC to DC and then back to AC; instead, it directly controls the inverter's switching state according to the AC current direction through a single-stage conversion. This allows the inverter to output the desired AC power and frequency, thereby avoiding power loss caused by DC energy storage and improving power utilization and equipment energy efficiency.

[0122] In some alternative implementations, the first switching unit and the second switching unit are of the same type, and the electrodes to which the first switching unit and the second switching unit are connected are of the same type.

[0123] like Figure 5 As shown, both the first and second switching units are IGBTs composed of N-type MOS transistors and NPN transistors, and the emitter of one IGBT on the same bridge arm is connected to the collector of the other IGBT.

[0124] This embodiment connects two switching units on each bridge arm in reverse series, which allows different input current directions to automatically adapt to the output current direction of the inverter, further improving the scenario adaptability of the inverter circuit.

[0125] Figure 8 This is a schematic diagram of a three-phase inverter circuit control device provided in an embodiment of this application. Specifically, it includes:

[0126] The first determining module 801 is used to determine the direction of power transmission in the three-phase inverter circuit;

[0127] The second determining module 802 is used to determine the current direction of the input AC power in the three-phase inverter circuit based on the direction of power transmission.

[0128] The control module 803 is used to send control signals to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and send a conduction signal to the other switching unit, based on the preset inverter control mode corresponding to the direction of power transmission, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0129] In some optional implementations, the control module includes: a first determining unit, configured to determine whether the current state is in a first type of positive inverter output stage if the power transmission direction is from AC power source to load device and the current direction is positive; a first controlling unit, configured to control the second switching unit on each bridge arm of the three-phase inverter circuit to conduct if yes, and send a control signal to the first switching unit on each bridge arm; otherwise, control the second switching unit on each bridge arm to cut off; a second determining unit, configured to determine whether the current state is in a first type of negative inverter output stage if the power transmission direction is from AC power source to load device and the current direction is negative; a second controlling unit, configured to control the first switching unit on each bridge arm to conduct if yes, and send a control signal to the second switching unit on each bridge arm; otherwise, control the first switching unit on each bridge arm to cut off.

[0130] In some optional implementations, the first determining unit includes: a first acquiring subunit, configured to acquire, if the current direction is positive, the number of recorded positive voltage half-cycles continuously output by the AC power supply; the first determining subunit, configured to determine, if the number of positive voltage half-cycles does not reach a preset number, that the current is in a first type of positive inverter output stage; and if the number of positive voltage half-cycles reaches the preset number, switch the current inverter output stage to a first type of negative inverter output stage and clear the recorded number of positive voltage half-cycles; the second determining unit includes: a second acquiring subunit, configured to acquire, if the current direction is negative, the number of recorded negative voltage half-cycles continuously output by the AC power supply; the second determining subunit, configured to determine, if the number of negative voltage half-cycles does not reach a preset number, that the current is in a first type of negative inverter output stage; and if the number of negative voltage half-cycles reaches the preset number, switch the current inverter output stage to a first type of positive inverter output stage and clear the recorded number of negative voltage half-cycles.

[0131] In some optional implementations, the control module includes: a third determining unit, configured to determine whether the current state is in the second type of positive inverter output stage if the power transmission direction is from the load device to the AC power source and the current direction is positive; a third controlling unit, configured to control the first switching unit on each bridge arm to turn on and send a control signal to the second switching unit on each bridge arm if yes; otherwise, control the first switching unit on each bridge arm to turn off; a fourth determining unit, configured to determine whether the current state is in the second type of negative inverter output stage if the power transmission direction is from the load device to the AC power source and the current direction is negative; a fourth controlling unit, configured to control the second switching unit on each bridge arm to turn on and send a control signal to the first switching unit on each bridge arm if yes; otherwise, control the second switching unit on each bridge arm to turn off.

[0132] In some optional implementations, the third determining unit includes: a third acquiring subunit, used to acquire the number of continuously output positive voltage half-cycles of the load device if the current direction is positive; the third determining subunit is used to determine that the current is in the second type of positive inverter output stage if the number of positive voltage half-cycles does not reach a preset number; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of negative inverter output stage, and the number of recorded positive voltage half-cycles is cleared to zero; determining whether the current is in the second type of negative inverter output stage includes: a fourth acquiring subunit, used to acquire the number of continuously output negative voltage half-cycles of the load device if the current direction is negative; the fourth determining subunit is used to determine that the current is in the second type of negative inverter output stage if the number of negative voltage half-cycles does not reach a preset number; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of positive inverter output stage, and the number of recorded negative voltage half-cycles is cleared to zero.

[0133] The three-phase inverter circuit control device provided in this embodiment can be as follows: Figure 8 The three-phase inverter circuit control device shown can execute all the steps of the above three-phase inverter circuit control methods, thereby achieving the technical effects of the above three-phase inverter circuit control methods. For details, please refer to the relevant descriptions above. For the sake of brevity, it will not be elaborated here.

[0134] Figure 9 This is a schematic diagram of the structure of an electrical device provided in an embodiment of this application. The electrical device 900 includes: the above-mentioned three-phase inverter circuit 500 and a motor 901. The three-phase input terminal of the motor 901 is connected to the three-phase output terminal of the three-phase inverter circuit 500.

[0135] The electrical appliance can be any device that requires driving an AC motor, such as an air conditioner or a refrigerator. In one scenario, the electrical appliance is an air conditioner, with the aforementioned three-phase inverter circuit housed in the frequency converter and the motor housed in the compressor.

[0136] The electrical equipment provided in this application embodiment, by applying the above-described three-phase inverter circuit, can avoid power energy loss caused by DC energy storage, thereby improving power utilization and equipment energy efficiency.

[0137] Figure 10 This is a schematic diagram of the structure of a controller provided in an embodiment of this application. Figure 10 The controller 1000 shown includes at least one processor 1001, a memory 1002, at least one network interface 1004, and other user interfaces 1003. The various components in the controller 1000 are coupled together via a bus system 1005. It is understood that the bus system 1005 is used to implement communication between these components. In addition to a data bus, the bus system 1005 also includes a power bus, a control bus, and a status signal bus. However, for clarity, ... Figure 10 The general labeled all buses as Bus System 1005.

[0138] The user interface 1003 may include a display, keyboard, or clicking device (e.g., mouse, trackball, touchpad, or touchscreen).

[0139] It is understood that the memory 1002 in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate Synchronous DRAM (DDRSDRAM), Enhanced Synchronous DRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). The memory 1002 described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0140] In some implementations, memory 1002 stores elements, executable units or data structures, or subsets thereof, or extended sets thereof: operating system 10021 and application programs 10022.

[0141] The operating system 10021 includes various system programs, such as the framework layer, core library layer, and driver layer, used to implement various basic business functions and handle hardware-based tasks. The application program 10022 includes various applications, such as a media player and a browser, used to implement various application functions. The program implementing the method of this application embodiment can be included in the application program 10022.

[0142] In this embodiment, by calling the program or instructions stored in memory 1002, specifically the program or instructions stored in application program 10022, processor 1001 executes the method steps provided in each method embodiment, including, for example:

[0143] Determine the direction of power transmission in the three-phase inverter circuit; based on the direction of power transmission, determine the direction of input AC current in the three-phase inverter circuit; based on the preset inverter control mode corresponding to the direction of power transmission, send control signals to the target switching unit of the two switching units on each bridge arm of the three-phase inverter circuit, and send a conduction signal to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0144] The methods disclosed in the embodiments of this application can be applied to or implemented by the processor 1001. The processor 1001 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware or by instructions in the form of software in the processor 1001. The processor 1001 may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or can be executed by a combination of hardware and software units in the decoding processor. The software units may be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in memory 1002. Processor 1001 reads the information in memory 1002 and, in conjunction with its hardware, completes the steps of the above method.

[0145] It is understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described above in this application, or combinations thereof.

[0146] For software implementation, the techniques described herein can be implemented by units that perform the functions described above. The software code can be stored in memory and executed by a processor. The memory can be implemented within the processor or external to the processor.

[0147] The controller provided in this embodiment can be as follows: Figure 10 The controller shown can execute all the steps of the three-phase inverter circuit control methods described above, thereby achieving the technical effects of the three-phase inverter circuit control methods described above. For details, please refer to the relevant descriptions above. For the sake of brevity, it will not be elaborated here.

[0148] This application also provides a storage medium (computer-readable storage medium). This storage medium stores one or more programs. The storage medium may include volatile memory, such as random access memory; it may also include non-volatile memory, such as read-only memory, flash memory, hard disk, or solid-state drive; and it may also include combinations of the above types of memory.

[0149] One or more programs in the storage medium can be executed by one or more processors to implement the above-mentioned three-phase inverter circuit control method.

[0150] The processor described above is used to execute the program stored in the memory to implement the following steps of the three-phase inverter circuit control method:

[0151] Determine the direction of power transmission in the three-phase inverter circuit; based on the direction of power transmission, determine the direction of input AC current in the three-phase inverter circuit; based on the preset inverter control mode corresponding to the direction of power transmission, send control signals to the target switching unit of the two switching units on each bridge arm of the three-phase inverter circuit, and send a conduction signal to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode.

[0152] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different circuits to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0153] The steps of the circuits or algorithms described in connection with the embodiments disclosed herein can be implemented in hardware, software modules executed by a processor, or a combination of both. The software modules can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art.

[0154] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0155] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A three-phase inverter circuit control method, characterized in that, The method includes: Determine the direction of power transmission in the three-phase inverter circuit; Based on the direction of electrical energy transmission, the direction of the input AC current in the three-phase inverter circuit is determined; Based on the preset inverter control mode corresponding to the direction of power transmission, a control signal is sent to the target switching unit of the two switching units on each bridge arm of the three-phase inverter circuit, and a conduction signal is sent to the other switching unit, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode. The inverter control method, based on a preset direction corresponding to the power transmission direction, sends control signals to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and sends an on signal to the other switching unit, including: If the direction of power transmission is from AC power source to load device, and the direction of current is positive, determine whether the current is in the first type of positive inverter output stage; If yes, turn on the second switching unit on each bridge arm of the three-phase inverter circuit and send a control signal to the first switching unit on each bridge arm; if no, turn off the second switching unit on each bridge arm. If the direction of power transmission is from AC power source to load device, and the direction of current is negative, determine whether the current is in the first type of negative inverter output stage; If yes, control the first switch unit on each bridge arm to turn on and send a control signal to the second switch unit on each bridge arm; if no, control the first switch unit on each bridge arm to turn off. Determining whether the current stage is the first type of forward inverter output stage includes: If the current direction is positive, obtain the number of positive voltage half-cycles continuously output by the AC power supply; If the number of positive voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of negative inverter output stage, and the recorded number of positive voltage half-cycles is cleared to zero. Determining whether the current stage is the first type of negative inverter output stage includes: If the current direction is negative, obtain the number of negative voltage half-cycles continuously output by the AC power supply; If the number of negative voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of positive inverter output stage, and the recorded number of negative voltage half-cycles is cleared to zero.

2. The method according to claim 1, characterized in that, The inverter control method, based on a preset direction corresponding to the power transmission direction, sends control signals to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and sends an on signal to the other switching unit, including: If the direction of power transmission is from the load device to the AC power source, and the direction of current is positive, determine whether the current is in the second type of positive inverter output stage; If yes, control the first switch unit on each bridge arm to turn on and send a control signal to the second switch unit on each bridge arm; if no, control the first switch unit on each bridge arm to turn off. If the direction of power transmission is from the load device to the AC power source, and the direction of current is negative, determine whether the current is in the second type of negative inverter output stage; If yes, control the second switch unit on each bridge arm to turn on and send a control signal to the first switch unit on each bridge arm; if no, control the second switch unit on each bridge arm to turn off.

3. The method according to claim 2, characterized in that, Determining whether the current stage is the second type of forward inverter output stage includes: If the current direction is positive, obtain the number of consecutive positive voltage half-cycles output by the load device; If the number of positive voltage half-cycles does not reach the preset number, it is determined that the current stage is the second type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of negative inverter output stage, and the recorded number of positive voltage half-cycles is cleared to zero. Determining whether the current stage is the second type of negative inverter output stage includes: If the current direction is negative, obtain the number of consecutive negative voltage half-cycles output by the load device; If the number of negative voltage half-cycles does not reach the preset number, it is determined that the current stage is the second type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the second type of positive inverter output stage, and the recorded number of negative voltage half-cycles is cleared to zero.

4. A three-phase inverter circuit, characterized in that, The circuit includes: a controller and three sets of bridge arms. Each set of bridge arms includes an upper bridge arm and a lower bridge arm. The common connection terminal of the upper bridge arm and the lower bridge arm is connected to one phase of the load device. The upper bridge arm is connected to the first output terminal of the AC power supply, and the lower bridge arm is connected to the second output terminal of the AC power supply. Each of the upper bridge arms and each of the lower bridge arms is provided with a first switch unit and a second switch unit connected in series, and the control terminals of the first switch unit and the second switch unit are connected to the controller. The controller is connected to the AC power supply and / or the load device, and the controller is used to execute the three-phase inverter circuit control method according to any one of claims 1-3.

5. The circuit according to claim 4, characterized in that, The first switching unit and the second switching unit are of the same type, and the electrodes connected to the first switching unit and the second switching unit are of the same type.

6. A three-phase inverter circuit control device, characterized in that, The device includes: The first determining module is used to determine the direction of power transmission in the three-phase inverter circuit; The second determining module is used to determine the current direction of the input AC power in the three-phase inverter circuit based on the direction of power transmission. The control module is used to send control signals to the target switching unit of the two switching units on each bridge arm of the three-phase inverter circuit, and send a conduction signal to the other switching unit, based on the preset inverter control mode corresponding to the direction of power transmission, so that the three-phase inverter circuit outputs three-phase AC power according to the inverter control mode. The inverter control method, based on a preset direction corresponding to the power transmission direction, sends control signals to the target switching unit of the two switching units on each arm of the three-phase inverter circuit, and sends an on signal to the other switching unit, including: If the direction of power transmission is from AC power source to load device, and the direction of current is positive, determine whether the current is in the first type of positive inverter output stage; If yes, turn on the second switching unit on each bridge arm of the three-phase inverter circuit and send a control signal to the first switching unit on each bridge arm; if no, turn off the second switching unit on each bridge arm. If the direction of power transmission is from AC power source to load device, and the direction of current is negative, determine whether the current is in the first type of negative inverter output stage; If yes, control the first switch unit on each bridge arm to turn on and send a control signal to the second switch unit on each bridge arm; if no, control the first switch unit on each bridge arm to turn off. Determining whether the current stage is the first type of forward inverter output stage includes: If the current direction is positive, obtain the number of positive voltage half-cycles continuously output by the AC power supply; If the number of positive voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of positive inverter output stage; if the number of positive voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of negative inverter output stage, and the recorded number of positive voltage half-cycles is cleared to zero. Determining whether the current stage is the first type of negative inverter output stage includes: If the current direction is negative, obtain the number of negative voltage half-cycles continuously output by the AC power supply; If the number of negative voltage half-cycles does not reach the preset number, it is determined that the current stage is the first type of negative inverter output stage; if the number of negative voltage half-cycles reaches the preset number, the current inverter output stage is switched to the first type of positive inverter output stage, and the recorded number of negative voltage half-cycles is cleared to zero.

7. An electrical appliance, characterized in that, The system includes the three-phase inverter circuit as described in claim 4 or 5, and also includes a motor.

8. A controller, characterized in that, include: Memory, used to store computer programs; A processor is configured to execute a computer program stored in the memory, wherein when the computer program is executed, it implements the three-phase inverter circuit control method according to any one of claims 1-3.

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