Power converter control method, power converter and chip

Abstract

The invention relates to a power converter control method, a power converter and a chip, the power converter comprises an alternating current side half-bridge circuit and a controller, the provided power converter control method is used in the controller, and the method comprises the following steps: when the alternating current side half-bridge circuit satisfies a zero-crossing switching condition, starting the controller; and switching the control mode of the AC side half-bridge circuit from the first mode to the second mode. Wherein the second mode comprises that all the switching devices located in the same bridge arm circuit are switched on according to a preset time sequence or switched off according to the preset time sequence, the corresponding switching devices in different bridge arm circuits are switched on in a complementary mode, and after the switching device which is switched on in a pilot mode in one bridge arm circuit is switched on for a preset time length, the switching device which is switched off later in the other bridge arm circuit is switched off. By adopting the method, the control reliability of the power converter can be improved.

Description

Technical Field

[0001] This application relates to the field of power control technology, and in particular to a power converter control method, a power converter, and a chip. Background Technology

[0002] In DC-AC converters or AC-DC converters, the AC-side half-bridge circuit connected to the grid needs to switch according to the position of the grid voltage zero-crossing point. However, in practical applications, the controller often has difficulty accurately obtaining the grid voltage zero-crossing point, which leads to the power converter's inability to switch accurately. This can cause problems such as short circuits or overvoltage stress in the AC-side half-bridge circuit connected to the grid, easily resulting in damage to the AC-side switching devices.

[0003] The power converter control method in the related technology controls the switching devices in the same bridge arm of the AC side half-bridge circuit to turn on or off simultaneously near the estimated zero crossing point, and the switching devices in different bridge arms conduct complementaryly.

[0004] However, the above-mentioned power converter control methods have low reliability. Summary of the Invention

[0005] Therefore, it is necessary to provide a power converter control method, power converter, and chip that can improve reliability in response to the above-mentioned technical problems.

[0006] In a first aspect, this application provides a power converter control method, wherein the power converter includes an AC side half-bridge circuit and a controller, and the method is used in the controller, the method comprising:

[0007] When the AC side half-bridge circuit meets the zero-crossing switching condition, the control mode of the AC side half-bridge circuit is switched from the first mode to the second mode. The second mode includes: each switching device in the same bridge arm circuit is turned on or turned off according to a preset timing sequence; corresponding switching devices in different bridge arm circuits are turned on complementaryly; after the switching device that turns on first in one bridge arm circuit is turned on for a preset time, the switching device that turns off later in another bridge arm circuit is turned off.

[0008] In one embodiment, the upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device, wherein the second switching device and the third switching device are respectively connected to the midpoint of the arm of the AC side half-bridge circuit.

[0009] The second mode includes a second positive mode, which includes: the first switching device and the third switching device are complementary in conduction, the second switching device is conducted before the first switching device is conducted, and the fourth switching device is turned off after the third switching device is turned off.

[0010] When the AC-side half-bridge circuit meets the zero-crossing switching condition, the control mode of the AC-side half-bridge circuit is switched from the first mode to the second mode, including:

[0011] When the zero-crossing switching condition is met during the positive half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode.

[0012] In one embodiment, the second positive mode further includes:

[0013] The second switching device is turned on after the third switching device is turned off;

[0014] And / or,

[0015] The fourth switching device is turned off before the first switching device is turned on.

[0016] In one embodiment, the second positive mode further includes:

[0017] The second switching device is turned on at the same time as or before the third switching device is turned off;

[0018] And / or,

[0019] The fourth switching device is turned off at the same time as or after the first switching device is turned on.

[0020] In one embodiment, the second positive mode further includes: the second switching device being turned off after the first switching device is turned off, the fourth switching device being turned on before the third switching device is turned on, and the fourth switching device being turned on before the second switching device is turned off.

[0021] In one embodiment, the second positive mode further includes:

[0022] The fourth switching device turns on after the first switching device turns off;

[0023] And / or,

[0024] The second switching device is turned off before the third switching device is turned on.

[0025] In one embodiment, the second positive mode further includes:

[0026] The fourth switching device is turned on at the same time as or before the first switching device is turned off;

[0027] And / or,

[0028] The second switching device is turned off at the same time as or after the third switching device is turned on.

[0029] In one embodiment, the upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device, wherein the second switching device and the third switching device are respectively connected to the midpoint of the arm of the AC side half-bridge circuit.

[0030] The second mode includes a second negative mode, which includes: the second and fourth switching devices are complementary in conduction, the first switching device is turned off after the second switching device is turned off, the third switching device is turned on before the fourth switching device is turned on, and the first switching device is turned off after the third switching device is turned on.

[0031] When the AC-side half-bridge circuit meets the zero-crossing switching condition, the control mode of the AC-side half-bridge circuit is switched from the first mode to the second mode, including:

[0032] When the zero-crossing switching condition is met during the negative half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second negative mode.

[0033] In one embodiment, the second negative mode further includes:

[0034] The first switching device is turned off before the fourth switching device is turned on;

[0035] And / or,

[0036] The third switching device turns on after the second switching device turns off.

[0037] In one embodiment, the second negative mode further includes:

[0038] The first switching device is turned off at the same time as or after the fourth switching device is turned on;

[0039] And / or,

[0040] The third switching device is turned on at the same time as or before the second switching device is turned off.

[0041] In one embodiment, the second negative mode further includes:

[0042] The first switching device is turned on before the second switching device is turned on, and the third switching device is turned off after the second switching device is turned off, and the third switching device is turned off after the first switching device is turned on.

[0043] In one embodiment, the second negative mode further includes:

[0044] The first switching device is turned on after the fourth switching device is turned off;

[0045] And / or,

[0046] The third switching device is turned off before the second switching device is turned on.

[0047] In one embodiment, the second negative mode further includes:

[0048] The first switching device is turned on at the same time as or before the fourth switching device is turned off;

[0049] And / or,

[0050] The third switching device is turned off at the same time as or after the second switching device is turned on.

[0051] Secondly, this application also provides a power converter, including an AC-side half-bridge circuit and a controller, the controller being used to perform the steps of the method as described in the first aspect above.

[0052] Thirdly, this application also provides a chip including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect above.

[0053] The aforementioned power converter control method, power converter, and chip, wherein the power converter includes an AC-side half-bridge circuit and control, and the provided power converter control method is used in a controller, the method comprising: when the AC-side half-bridge circuit meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from a first mode to a second mode. The second mode includes: each switching device in the same bridge arm circuit is turned on or off according to a preset timing sequence; corresponding switching devices in different bridge arm circuits are complementary in their conduction; after the switching device in one bridge arm circuit is turned on for a preset duration, the switching device in the other bridge arm circuit that is turned off later is turned off. Because a dead time is required during state switching between the upper and lower bridge arm circuits to prevent short circuits in the lower bridge arm circuit, related technologies employ a control method where a group of switching devices on the same bridge arm circuit simultaneously turn on and off within the zero-crossing interval. During the dead time, the leakage inductance current has no discharge path and can only be stored through the parasitic capacitance in the two switching devices near the midpoint of the bridge arm circuit, increasing the risk of breakdown and potentially damaging these two switching devices. However, using the aforementioned method, a second mode is employed to control the AC side half-bridge circuit during the zero-crossing interval. One scenario involves the upper bridge arm circuit switching from off to on, and the lower bridge arm circuit switching from on to off. In this case, the turn-on sequence of the switching devices in the upper bridge arm circuit is as follows: the complementary switching device turns on last, the other switching device turns on first, and so on for the lower bridge arm circuit. The turn-off sequence of the switching devices in the bridge arm circuit is as follows: the switching device in complementary conduction turns off first, followed by the other switching device; there is a preset conduction overlap time between the first conducting switching device in the upper bridge arm circuit and the last turning off switching device in the lower bridge arm circuit; another scenario is: the upper bridge arm circuit switches from the conducting state to the off state, and the lower bridge arm circuit switches from the off state to the conducting state. In this case, the turn-off sequence of the switching devices in the upper bridge arm circuit is as follows: the switching device in complementary conduction turns off first, followed by the other switching device; the conduction sequence of the switching devices in the lower bridge arm circuit is as follows: the switching device in complementary conduction turns on last, followed by the other switching device; the conduction overlap time between the two bridge arm circuits is the conduction overlap time between the last turning off switching device in the upper bridge arm circuit and the first conducting switching device in the lower bridge arm circuit.This is achieved in the following ways: First, it ensures the dead time of the two complementary conducting switches, guaranteeing that the two bridge arm circuits maintain a complementary conducting state overall. Second, the body diode of the later-conducting switch and the earlier-conducting switch provide a freewheeling path for the leakage inductance current, reducing the risk of breakdown of the switch near the midpoint of the bridge arm circuit. Third, because the energy stored in the parasitic capacitance of the switch is equal to the integral of the charging current, the longer the charging time, the greater the possibility of breakdown. In the second mode described above, there is a conduction overlap time between the earlier-conducting switch in the first bridge arm circuit and the later-turn-off switch in the other bridge arm circuit. This maximizes the conduction time of the switch providing the freewheeling path, reducing the charging time of the parasitic capacitance of the switch near the midpoint of the bridge arm circuit and thus reducing the risk of breakdown. In summary, the above method can improve the reliability of power converter control. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is an exemplary circuit topology diagram of a single-stage isolated grid-connected inverter;

[0056] Figure 2 This is a schematic diagram of the zero-crossing interval in one embodiment;

[0057] Figure 3 This is an exemplary schematic diagram of the control timing corresponding to the second positive mode in one embodiment;

[0058] Figure 4 This is an exemplary control timing diagram corresponding to the second positive mode in another embodiment;

[0059] Figure 5 This is an exemplary control timing diagram corresponding to the second positive mode in yet another embodiment;

[0060] Figure 6 This is a schematic diagram of the freewheeling path of the leakage inductor current when the leakage inductor current flows from the leakage inductor Lr to point C, using the control timing corresponding to the second positive mode.

[0061] Figure 7 This is a schematic diagram of the freewheeling path of the leakage inductance current when the leakage inductance current flows from point C to the leakage inductance Lr, using the control timing corresponding to the second positive mode.

[0062] Figure 8 This is an exemplary control timing diagram corresponding to the second negative mode in one embodiment;

[0063] Figure 9 This is an exemplary schematic diagram of the control timing corresponding to the second negative mode in another embodiment;

[0064] Figure 10 This is an exemplary schematic diagram of the control timing corresponding to the second negative mode in yet another embodiment;

[0065] Figure 11 This is a schematic diagram of the freewheeling path of the leakage inductor current when the leakage inductor current flows from the leakage inductor Lr to point C, using the control timing corresponding to the second negative mode.

[0066] Figure 12 This is a schematic diagram of the freewheeling path of the leakage inductor current when the leakage inductor current flows from point C to the leakage inductor Lr, using the control timing corresponding to the second negative mode.

[0067] Figure 13 This is a flowchart illustrating a power converter control method in one embodiment;

[0068] Figure 14 This is an exemplary control timing diagram corresponding to the second mode in one embodiment;

[0069] Figure 15 A schematic diagram of the circuit topology of the power converter in another embodiment is provided.

[0070] Figure 16 To adopt Figure 15 The circuit topology of the power converter shown is illustrated in the diagram of the freewheeling path of the leakage inductor current when the leakage inductor current flows from the leakage inductor Lr to point C, using the control timing corresponding to the second positive mode.

[0071] Figure 17 To adopt Figure 15 The circuit topology of the power converter shown is illustrated in the diagram of the freewheeling path of the leakage inductor current when the leakage inductor current flows from the leakage inductor Lr to point C, using the control timing corresponding to the second positive mode.

[0072] Figure 18 This is an exemplary schematic diagram of the circuit topology of the power converter in yet another embodiment;

[0073] Figure 19 To adopt Figure 18 The circuit topology of the power converter shown is illustrated in the diagram of the leakage inductor current freewheeling path corresponding to the control timing of the second negative mode when the leakage inductor current flows from the leakage inductor Lr to point C.

[0074] Figure 20 To adopt Figure 18 The circuit topology of the power converter shown is illustrated in the diagram of the leakage inductor current freewheeling path corresponding to the control timing of the second negative mode when the leakage inductor current flows from the leakage inductor Lr to point C.

[0075] Figure 21 This is an exemplary circuit topology diagram of a power converter in another embodiment. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0077] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0078] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0079] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0080] It is understood that the term "based on" as used in this application is used to describe one or more factors that influence the determination, but does not exclude other factors that may influence the determination. For example, the phrase "determine A based on B" means that the determination of A can be based entirely or at least partially on factor B. That is, B is a factor that influences the determination of A, but does not exclude the fact that the determination of A is also based on C.

[0081] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0082] The power converter control method provided in this application can be used in the controller of a power converter employing a half-bridge circuit structure on the AC side. The upper and lower arms of the half-bridge circuit are both implemented by bidirectional switches. The controller is connected to at least each switching device in the power converter to control the switching frequency, duty cycle, and phase shift of each switching device. The power converter can be a DC-AC converter, such as a single-stage isolated grid-connected inverter, or an AC-DC converter, such as a single-stage isolated rectifier.

[0083] Please refer to Figure 1 This is an exemplary schematic diagram of a circuit topology for a single-stage isolated grid-connected inverter. Wherein, V dc This represents the DC-side power supply voltage, V. ac The AC side is the mains voltage. A half-bridge circuit is used on the AC side. The upper arm of the AC half-bridge circuit is implemented using a bidirectional switch composed of switching devices Q5 and Q6, and the lower arm is implemented using a bidirectional switch composed of switching devices Q7 and Q8. The midpoint C of the arm is connected to the leakage inductance Lr of the power converter. The upper arm circuit corresponds to capacitor Cp, and the lower arm circuit corresponds to capacitor Cn. Capacitors Cp and Cn are connected in series. Capacitor Co and resistor Zg form a filter circuit. For example, the leakage inductance Lr, along with capacitors Cp and Cn, constitutes the resonant circuit of the power converter.

[0084] Among them, the controller is Figure 1 As not shown, the controller can be implemented using an MCU (Microcontroller Unit) chip; it can also be implemented based on a DSP (Digital Signal Processor) chip, an FPGA (Field-Programmable Gate Array), or a custom controller chip; the embodiments of this application do not limit the specific hardware implementation of the controller.

[0085] Please refer to Figure 1For example, the method provided in this application embodiment can be implemented on the DC side of the power converter using an H-bridge circuit. The first arm of the DC-side H-bridge circuit includes switching devices Q1 and Q2, and the second arm includes switching devices Q3 and Q4. Points A and B are the load interfaces of the DC-side H-bridge circuit, and Tr is the transformer.

[0086] It should be noted that the embodiments of this application do not limit the specific circuit structure used on the DC side. Figure 1 This is merely an illustrative example. In some embodiments, the DC side of the power converter may also be implemented using a half-bridge circuit.

[0087] In this application, the switching device involved in the embodiments can also be referred to as a power switching transistor. For example, the switching device can be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). This application does not limit the specific type and model of the switching device.

[0088] In an exemplary embodiment, the power converter includes an AC-side half-bridge circuit and a control system. A power converter control method is provided in the controller. The method includes: when the AC-side half-bridge circuit meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from a first mode to a second mode. The second mode includes: each switching device in the same bridge arm circuit is turned on or off according to a preset timing sequence; corresponding switching devices in different bridge arm circuits are complementary in their conduction; and after a preset duration of conduction by the first switching device in one bridge arm circuit, the last switching device in the other bridge arm circuit is turned off.

[0089] The first mode refers to the operating mode of the power converter in the non-zero-crossing region. For an example, please refer to [reference needed]. Figure 1 and Figure 2 When the AC grid voltage is in the positive half-cycle, switching devices Q5 and Q7 conduct complementaryly (vertical box part), while switching devices Q6 and Q8 are always on. When the AC grid voltage is in the negative half-cycle, switching devices Q6 and Q8 conduct complementaryly (vertical box part), while switching devices Q5 and Q7 are always on.

[0090] The zero-crossing switching condition is a moment when the AC grid voltage is about to drop from the positive half-cycle to zero or about to increase from the negative half-cycle to zero. The zero-crossing switching condition can be understood as the condition for entering the zero-crossing interval; please refer to [reference needed]. Figure 2The zero-crossing interval corresponds to Figure 2 The dotted box portion of the control timing described herein.

[0091] In one possible implementation, the zero-crossing interval is determined based on the voltage amplitude of the AC-side power grid. Correspondingly, the zero-crossing switching condition includes: the absolute value of the AC voltage on the AC-side power grid decreasing from above a voltage threshold to below a voltage threshold. Specifically, during the positive half-cycle, the zero-crossing switching condition corresponds to the AC voltage decreasing from above the voltage threshold to below the voltage threshold until reaching zero voltage; during the negative half-cycle, the zero-crossing switching condition corresponds to the AC voltage increasing from below a negative voltage threshold to above a negative voltage threshold until reaching zero voltage.

[0092] In one possible implementation, the zero-crossing interval is determined based on the voltage phase of the AC-side power grid. Correspondingly, the zero-crossing switching conditions include a preset zero-crossing initiation phase. It is understood that the AC-side power grid voltage is a periodically changing sine wave, therefore the zero-crossing initiation phase also changes periodically, i.e., the controller's zero-crossing switching conditions include a set of zero-crossing initiation phases.

[0093] In one possible implementation, the zero-crossing interval is determined based on a preset switching time. The zero-crossing switching condition includes a preset zero-crossing start time. The zero-crossing start time includes the zero-crossing start time corresponding to the positive half-cycle and the zero-crossing time corresponding to the negative half-cycle.

[0094] For ease of description, this embodiment is based on... Figure 2 The process of transitioning from the positive half-cycle to the negative half-cycle is illustrated to explain the determination of the zero-crossing interval. It is understandable that a corresponding zero-crossing interval is also set for the AC grid voltage as it transitions from the negative half-cycle to the positive half-cycle. Those skilled in the art will understand this. Figure 2 The zero-crossing intervals shown clearly illustrate how to set the zero-crossing intervals corresponding to the change from a negative half-cycle to a positive half-cycle.

[0095] In this embodiment, the AC-side half-bridge circuit is controlled to operate in the second mode during the zero-crossing interval. For an example, please refer to... Figure 2 The zero-crossing interval corresponding to the second mode is as follows: Figure 2 The dotted box in the figure represents time t. p up to time t n The control timing of the switching devices between them. Specifically, in the zero-crossing interval, each switching device in the same bridge arm circuit is turned on or off according to a preset timing sequence. Corresponding switching devices in different bridge arm circuits are turned on complementaryly. After the switching device that turns on first in one bridge arm circuit is turned on for a preset time, the switching device that turns off later in another bridge arm circuit is turned off.

[0096] In this embodiment, the AC-side half-bridge circuit includes two bridge arm circuits: an upper bridge arm circuit and a lower bridge arm circuit. Each bridge arm circuit includes two switching devices. The body diodes of the two switching devices on the same bridge arm circuit have opposite conduction directions, while the body diodes of corresponding switching devices in different bridge arm circuits have the same conduction direction. In this embodiment, the corresponding switching devices in different bridge arm circuits refer to two switching devices that are in a complementary conduction state in the first mode. That is, two switching devices that are complementary in conduction in the first mode are also complementary in conduction in the second mode. Please refer to... Figure 1 During the positive half-cycle of the AC side voltage, the switching devices Q5 and Q7 in different bridge arm circuits maintain complementary conduction. During the negative half-cycle of the AC side voltage, the switching devices Q6 and Q8 in different bridge arm circuits maintain complementary conduction. In this embodiment, during the zero-crossing interval, the different bridge arm circuits are complementary in conduction. During the dead time of complementary conduction, there is a preset conduction overlap time between the switching device that turns on first in one bridge arm circuit and the switching device that turns off later in another bridge arm circuit, providing a freewheeling path for the leakage inductance current. For an example, please refer to... Figure 1 During the dead time of the complementary conduction switching of switching devices Q5 and Q7, there is a preset duration of overlapping conduction time between switching devices Q6 and Q8, providing a freewheeling path for leakage inductance energy during the dead time; during the dead time of the complementary conduction switching of switching devices Q6 and Q8, there is a preset duration of overlapping conduction time between switching devices Q5 and Q7, providing a freewheeling path for leakage inductance energy during the dead time.

[0097] Assuming the upper bridge arm circuit switches from the off state to the on state, and the switching device in the lower bridge arm circuit switches from the on state to the off state, the complementary switching devices in the two bridge arm circuits are the switching device that turns on later in the upper bridge arm circuit and the switching device that turns off earlier in the lower bridge arm circuit. This ensures the overall conduction dead time between the two bridge arm circuits, avoiding short circuits in the AC side half-bridge circuit. There is a preset conduction overlap time between the switching device that turns on earlier in the upper bridge arm circuit and the switching device that turns off later in the lower bridge arm circuit.

[0098] Because a dead time is required during state switching between the upper and lower bridge arm circuits to prevent short circuits in the lower bridge arm circuit, related technologies employ a control method where a group of switching devices on the same bridge arm circuit simultaneously turn on and off within the zero-crossing interval. During the dead time, the leakage inductance current has no discharge path and can only be stored through the parasitic capacitance in the two switching devices near the midpoint of the bridge arm circuit, increasing the risk of breakdown and potentially damaging these two switching devices. However, the method provided in this embodiment uses a second mode to control the AC side half-bridge circuit during the zero-crossing interval. One scenario involves the upper bridge arm circuit switching from off to on, and the lower bridge arm circuit switching from on to off. In this case, the turn-on sequence of the switching devices in the upper bridge arm circuit is: the complementary switching device turns on last, and the other switching device turns on first. The turn-off sequence of the switching devices in the lower bridge arm circuit is: the complementary switching device turns off first, and the other switching device turns off last. There is a preset time interval between the first-turning switching device in the upper bridge arm circuit and the last-turning switching device in the lower bridge arm circuit. The conduction overlap time is as follows: In one scenario, the upper bridge arm circuit switches from the on state to the off state, and the lower bridge arm circuit switches from the off state to the on state. In this case, the turn-off sequence of the switching devices in the upper bridge arm circuit is: the complementary conducting switching device turns off first, followed by the other switching device; the conduction sequence of the switching devices in the lower bridge arm circuit is: the complementary conducting switching device turns on later, followed by the other switching device; the conduction overlap time between the two bridge arm circuits is the conduction overlap time between the switching device that turns off later in the upper bridge arm circuit and the switching device that turns on first in the lower bridge arm circuit. This is achieved in the following ways: First, it ensures the dead time of the two complementary conducting switching devices, so that the two bridge arm circuits as a whole maintain a complementary conducting state. Second, the body diode of the later-conducting switching device and the earlier-conducting switching device can provide a freewheeling path for the leakage inductance current, reducing the risk of breakdown of the switching device near the midpoint of the bridge arm circuit. Third, because the energy stored in the parasitic capacitance of the switching device is equal to the integral of the charging current, the longer the charging time, the greater the possibility of breakdown. In this embodiment, there is a conduction overlap time between the earlier-conducting switching device in one bridge arm circuit and the later-turn-off switching device in the other bridge arm circuit. This maximizes the conduction time of the switching device providing the freewheeling path, reducing the charging time of the parasitic capacitance of the switching device near the midpoint of the bridge arm circuit, and reducing the risk of breakdown. In summary, the method provided in this embodiment can improve the reliability of power converter control.

[0099] In an exemplary embodiment, the upper arm circuit of the AC-side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC-side half-bridge circuit includes a third switching device and a fourth switching device. The second and third switching devices are respectively connected to the midpoint of the arms of the AC-side half-bridge circuit. The second mode includes a second positive mode, which includes: the first and third switching devices are complementary in conduction, the second switching device is turned on before the first switching device is turned on, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned off after the second switching device is turned on. In this embodiment, when the AC-side half-bridge circuit meets the zero-crossing switching condition, the process of switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode includes: when the positive half-cycle of the AC-side voltage meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from the first mode to the second positive mode.

[0100] Please refer to Figure 3 , Figure 4 and Figure 5 This is an exemplary schematic diagram of the control timing corresponding to the second positive mode provided in this embodiment; wherein, Figure 1 , Figure 3 , Figure 4 and Figure 5 In the diagram, the first switching device corresponds to switching device Q5, the second switching device corresponds to switching device Q6, the third switching device corresponds to switching device Q7, and the fourth switching device corresponds to switching device Q8.

[0101] In the second positive mode, switching devices Q5 and Q7 operate in a high-frequency complementary state. Switching device Q6 is turned on before switching device Q5 is turned on, and switching device Q8 is turned off after switching device Q7 is turned off, and switching device Q8 is turned off after switching device Q6 is turned on. To clearly represent the overlap conduction duration between switching devices Q6 and Q8, the following is used: Figure 3 , Figure 4 and Figure 5 The illustration is outlined in gray.

[0102] Among them, Figure 3 , Figure 4 and Figure 5 In the middle, at time t p1 up to time t p8 In the corresponding switching cycle, at time t p1 Switching device Q7 is turned off at time t p3 Switching device Q8 is turned off at time t. p2 Switching device Q6 is turned on at time t p4 Switching device Q5 is turned on. Where, t p3 -t p2 >0, t p4 -tp2 >0, t p3 -t p1 >0. The preset duration of overlapping conduction between switching devices Q8 and Q6 is t. p3 -t p2 The dead time between switching devices Q7 and Q5 is t. p4 -t p1 .

[0103] Please refer to Figure 6 When the leakage inductance current flows from the leakage inductance Lr to point C, this embodiment provides a schematic diagram of the leakage inductance current freewheeling path corresponding to the control timing. The body diode of switching device Q5 and switching device Q6 provide a freewheeling path for the leakage inductance current, reducing the risk of overvoltage breakdown of switching devices Q7 and Q6. In the lower bridge arm circuit, switching devices Q7 are turned off first and then Q8 is turned off to ensure the dead time of switching devices Q5 and Q7.

[0104] Please refer to Figure 7 This embodiment provides a schematic diagram of the freewheeling path in the second positive mode when the leakage inductance current flows from point C to the leakage inductance Lr. Switching device Q7 is turned off first, followed by switching device Q8. The body diode of switching device Q7 and switching device Q8 provide a freewheeling path for the leakage inductance current, reducing the risk of overvoltage damage to switching devices Q7 and Q6. The upper bridge arm circuit is turned on in the order of switching device Q6 turning on first, followed by switching device Q5, ensuring the dead time of switching devices Q5 and Q7.

[0105] Meanwhile, switch Q8 turns off after switch Q6 turns on, so there is an overlap in the conduction time between switch Q6 and switch Q8. This makes the conduction time of the switch providing the freewheeling path as long as possible, avoiding the risk of overvoltage breakdown of switch Q6 and switch Q7 during the dead time of switch Q7 and switch Q5.

[0106] In related technologies, after switching device Q8 is turned off, switching device Q6 is turned on again. This only guarantees one [function / function]. Figure 6 or Figure 7In the illustrated freewheeling path, one freewheeling path has a relatively long freewheeling time. If a large power disturbance occurs during the operation of the power converter, the direction of the leakage inductance current during the switching of the bridge arm circuit's conduction state cannot be accurately determined, which may result in a short freewheeling time. Switching devices Q6 and Q7 still have a significant risk of breakdown. Using the method provided in this application embodiment, switching device Q8 is turned off after switching device Q6 is turned on, ensuring that both freewheeling paths have a long freewheeling time. Regardless of whether the leakage inductance current flows towards point C or towards the leakage inductance Lr during the switching of the bridge arm circuit's conduction state, a longer freewheeling time can be provided for the leakage inductance current, improving the reliability of circuit operation.

[0107] In an exemplary embodiment, the provided power converter control method further includes a second positive mode in which a second switching device turns on after a third switching device turns off, and / or a fourth switching device turns off before a first switching device turns on.

[0108] In one possible implementation, please refer to Figure 3 Switching device Q6 is turned on after switching device Q7 is turned off, such as Figure 3 As shown, t p2 -t p1 >0.

[0109] In one possible implementation, please refer to Figure 3 Switching device Q8 is turned off before switching device Q5 is turned on; for example Figure 3 As shown, t p4 -t p3 >0.

[0110] In one possible implementation, please refer to Figure 3 Switch Q6 turns on after switch Q7 turns off, and switch Q8 turns off before switch Q5 turns on; for example Figure 3 As shown in this embodiment, t p2 -t p1 >0, t p3 -t p2 >0, t p4 -t p3 >0.

[0111] In other embodiments, the provided power converter control method includes a second positive mode comprising: a second switching device being turned on at the same time as or before a third switching device is turned off; and / or, a fourth switching device being turned off at the same time as or after a first switching device is turned on.

[0112] In one exemplary embodiment, the second positive mode includes: the second switching device being turned on simultaneously with or before the third switching device is turned off. In one possible implementation, please refer to... Figure 4 Switching device Q6 is turned on at the same time as switching device Q7 is turned off; for example Figure 4 As shown, t p2 =t p1 In one possible implementation, please refer to... Figure 5 Switching device Q6 is turned on before switching device Q7 is turned off; for example Figure 5 As shown, t p2 <t p1 .

[0113] In one exemplary embodiment, the second positive mode includes: the fourth switching device being turned off simultaneously with or after the first switching device is turned on. In one possible implementation, please refer to... Figure 4 Switching device Q8 is turned off at the same time as switching device Q5 is turned on; for example Figure 4 As shown, t p4 =t p3 In one possible implementation, please refer to... Figure 5 Switching device Q8 is turned off after switching device Q5 is turned on; for example Figure 5 As shown, t p4 <t p3 .

[0114] In one exemplary embodiment, the second positive mode includes: the second switching device being turned on simultaneously with or before the third switching device being turned off, and the fourth switching device being turned off simultaneously with or after the first switching device being turned on. In one possible implementation, please refer to... Figure 4 and Figure 5 Switching device Q6 is turned on at the same time as or before switching device Q7 is turned off, and switching device Q8 is turned off at the same time as or after switching device Q5 is turned on; where t p2 ≤t p1 , t p4 ≤t p3 , t p4 -t p1 >0. Thus, a freewheeling path is formed for the entire time period during the dead time of switching devices Q5 and Q7.

[0115] In an exemplary embodiment, the provided power converter control method further includes the following in the second positive mode: the second switching device turns off after the first switching device turns off, the fourth switching device turns on before the third switching device turns on, and the fourth switching device turns on before the second switching device turns off.

[0116] Please continue to refer to this. Figure 3 At time tp1 up to time t p8 In the corresponding switching cycle, at time t p5 Switching device Q5 is turned off at time t. p6 Switching device Q8 is turned on at time t p7 Switching device Q6 is turned off at time t p8 Switching device Q7 is turned on. Where, t p7 -t p6 >0, t p7 -t p5 >0, t p8 -t p6 >0; where the preset duration of the overlapping conduction between switching device Q8 and switching device Q6 is t. p7 -t p6 The dead time between switching devices Q7 and Q5 is t. p8 -t p5 .

[0117] In one exemplary embodiment, the second positive mode further includes: a fourth switching device being turned on after the first switching device is turned off; and / or, the second switching device being turned off before the third switching device is turned on.

[0118] In one possible implementation, please refer to Figure 3 Switching device Q8 is turned on after switching device Q5 is turned off; for example Figure 3 As shown, t p6 -t p5 >0.

[0119] In one possible implementation, please refer to Figure 3 Switching device Q6 is turned off before switching device Q7 is turned on; for example Figure 3 As shown, t p8 -t p7 >0.

[0120] In one possible implementation, please refer to Figure 3 Switch Q8 turns on after switch Q5 turns off, and switch Q6 turns off before switch Q7 turns on. Figure 3 As shown in this embodiment, t p6 -t p5 >0, t p7 -t p6 >0, t p8 -t p7 >0.

[0121] In some other embodiments, the provided power converter control method includes a second positive mode comprising: a fourth switching device being turned on at the same time as or before the first switching device is turned off; and / or, a second switching device being turned off at the same time as or after the third switching device is turned on.

[0122] In one exemplary embodiment, the second positive mode includes: the fourth switching device being turned on simultaneously with or before the first switching device is turned off. In one possible implementation, please refer to... Figure 4 Switching device Q8 is turned on at the same time as switching device Q5 is turned off; for example Figure 4 As shown, t p6 =t p5 In one possible implementation, please refer to... Figure 5 Switching device Q8 is turned on before switching device Q5 is turned off; for example Figure 5 As shown, t p6 <t p5 .

[0123] In one exemplary embodiment, the second positive mode includes: the second switching device being turned off simultaneously with or after the third switching device is turned on. In one possible implementation, please refer to... Figure 4 Switching device Q6 is turned off at the same time that switching device Q7 is turned on; for example Figure 4 As shown, t p8 =t p7 In one possible implementation, please refer to... Figure 5 Switching device Q6 is turned off after switching device Q7 is turned on; for example Figure 5 As shown, t p8 <t p7 .

[0124] In one exemplary embodiment, the second positive mode includes: the fourth switching device being turned on simultaneously with or before the first switching device being turned off, and the second switching device being turned off simultaneously with or after the third switching device being turned on. In one possible implementation, please refer to... Figure 4 and Figure 5 Switching device Q8 is turned on at the same time as or before switching device Q5 is turned off, and switching device Q6 is turned off at the same time as or after switching device Q7 is turned on; where t p6 ≤t p5 , t p8 ≤t p7 , t p8 -t p5 >0. Thus, a freewheeling path is formed for the entire time period during the dead time of switching devices Q5 and Q7.

[0125] In an exemplary embodiment, the upper arm circuit of the AC-side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC-side half-bridge circuit includes a third switching device and a fourth switching device. The second and third switching devices are respectively connected to the midpoint of the arms of the AC-side half-bridge circuit. The second mode includes a second negative mode, in which the second and fourth switching devices are complementaryly turned on, the first switching device is turned off after the second switching device is turned off, the third switching device is turned on before the fourth switching device is turned on, and the first switching device is turned off after the third switching device is turned on. In this embodiment, when the AC-side half-bridge circuit meets the zero-crossing switching condition, the process of switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode includes: when the negative half-cycle of the AC-side voltage meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from the first mode to the second negative mode.

[0126] Please refer to Figure 8 , Figure 9 and Figure 10 This is an exemplary schematic diagram of the control timing corresponding to the second negative mode provided in this embodiment; wherein, Figure 1 , Figure 8 , Figure 9 and Figure 10 In the diagram, the first switching device corresponds to switching device Q5, the second switching device corresponds to switching device Q6, the third switching device corresponds to switching device Q7, and the fourth switching device corresponds to switching device Q8.

[0127] In the second negative mode, switching devices Q6 and Q8 operate in a high-frequency complementary state. Switching device Q5 turns off after Q6 turns off, and switching device Q7 turns on before Q8 turns on. Switching device Q5 turns off after Q7 turns on. To clearly represent the overlap conduction duration between switching devices Q6 and Q8, [the following is a simplified explanation]. Figure 7 and Figure 8 The illustration is outlined in gray.

[0128] like Figure 7 and Figure 8 As shown, at time t n1 up to time t n8 In the corresponding switching cycle, at time t n1 Switching device Q6 is turned off at time t n2 Switching device Q7 is turned on at time t n3 Switching device Q5 is turned off at time t. n4 Switching device Q8 is turned on. Where, t n3 -t n2 >0, t n4 -t n2 >0, t n3 -tn1 >0. The preset duration of overlapping conduction between switching devices Q5 and Q7 is t. n3 -t n2 The dead time between switching devices Q6 and Q8 is t. n4 -t n1 .

[0129] Please refer to Figure 11 To illustrate the leakage inductance current freewheeling path diagram corresponding to the control timing in this embodiment, when the leakage inductance current flows from the leakage inductance Lr to point C, the lower bridge arm circuit is turned on in the sequence of Q7 first and Q8 last. The leakage inductance current is provided freewheeling path through the body diode of Q8 and Q7, reducing the risk of Q7 and Q6 being damaged by overvoltage. The upper bridge arm circuit is turned off in the sequence of Q6 first and Q5 last, ensuring the dead time of Q6 and Q8.

[0130] Please refer to Figure 12 This embodiment provides a schematic diagram of the freewheeling path in the second positive mode when the leakage inductance current flows from point C to the leakage inductance Lr. In the upper bridge arm circuit, switch Q6 is turned off first, followed by switch Q5. The body diode of switch Q6 and switch Q5 provide a freewheeling path for the leakage inductance current, reducing the risk of overvoltage damage to switches Q7 and Q6. In the lower bridge arm circuit, switch Q7 is turned on first, followed by switch Q8, ensuring the dead time of switches Q6 and Q8.

[0131] Meanwhile, switch Q5 turns off after switch Q7 turns on, so there is an overlap in the conduction time between switch Q5 and switch Q7. This makes the conduction time of the switch providing the freewheeling path as long as possible, avoiding the risk of overvoltage breakdown of switch Q6 and switch Q7 during the dead time of switch Q6 and switch Q8.

[0132] In related technologies, after switching device Q5 is turned off, switching device Q7 is turned on again. This only guarantees one [function / function]. Figure 11 or Figure 12In the illustrated freewheeling path, one freewheeling path has a relatively long freewheeling time. If a large power disturbance occurs during the operation of the power converter, the direction of the leakage inductance current during the switching of the bridge arm circuit's conduction state cannot be accurately determined, which may result in a short freewheeling time. Switching devices Q6 and Q7 still face a significant risk of breakdown. Using the method provided in this application embodiment, switching device Q5 is turned off after a preset conduction time for switching device Q7, ensuring that both freewheeling paths have a long freewheeling time. Regardless of whether the leakage inductance current flows towards point C or towards the leakage inductance Lr during the switching of the bridge arm circuit's conduction state, a longer freewheeling time can be provided for the leakage inductance current, improving the reliability of the circuit operation.

[0133] In an exemplary embodiment, the provided power converter control method further includes a second negative mode in which: a first switching device is turned off before a fourth switching device is turned on; and / or, a third switching device is turned on after the second switching device is turned off.

[0134] In one possible implementation, please refer to Figure 8 Switching device Q5 is turned off before switching device Q8 is turned on; for example Figure 8 As shown, t n4 -t n3 >0.

[0135] In one possible implementation, please refer to Figure 8 Switching device Q7 is turned on after switching device Q6 is turned off; for example Figure 8 As shown, t n2 -t n1 >0.

[0136] In one possible implementation, please refer to Figure 8 Switch Q5 is turned off before switch Q8 is turned on, and switch Q7 is turned on after switch Q6 is turned off; for example Figure 7 As shown, t n2 -t n1 >0, t n3 -t n2 >0, t n4 -t n3 >0.

[0137] In some other embodiments, the provided power converter control method includes a second negative mode comprising: a first switching device being turned off at the same time as or after a fourth switching device is turned on; and / or, a third switching device being turned on at the same time as or before a second switching device is turned off.

[0138] In one exemplary embodiment, the second negative mode includes: the first switching device being turned off simultaneously with or after the fourth switching device is turned on. In one possible implementation, please refer to... Figure 9 Switching device Q5 is turned off at the same time as switching device Q8 is turned on; for example Figure 9 As shown, t n4 =t n3 In one possible implementation, please refer to... Figure 10 Switching device Q5 is turned off after switching device Q8 is turned on; for example Figure 10 As shown, t n4 <t n3 .

[0139] In one exemplary embodiment, the second negative mode includes: the third switching device being turned on simultaneously with or before the second switching device is turned off. In one possible implementation, please refer to... Figure 9 Switching device Q7 is turned on at the same time as switching device Q6 is turned off; for example Figure 9 As shown, t n1 =t n2 In one possible implementation, please refer to... Figure 10 Switching device Q7 is turned on before switching device Q6 is turned off; for example Figure 10 As shown, t n2 <t n1 .

[0140] In one exemplary embodiment, the second negative mode includes: the first switching device being turned off simultaneously with or after the fourth switching device being turned on, and the third switching device being turned on simultaneously with or before the second switching device being turned off. In one possible implementation, please refer to... Figure 9 and Figure 10 Switching device Q5 is turned off at the same time as or after switching device Q8 is turned on, and switching device Q7 is turned on at the same time as or before switching device Q6 is turned off; where t n2 ≤t n1 , t n3 -t n2 >0, t n4 ≤t n3 Thus, a freewheeling path is formed for the entire time period during the dead time of switching devices Q6 and Q8.

[0141] In an exemplary embodiment, the provided power converter control method further includes a second negative mode in which: a first switching device is turned on before the second switching device is turned on, a third switching device is turned off after the second switching device is turned off, and the third switching device is turned off after the first switching device is turned on.

[0142] Please continue to refer to this. Figure 8 , Figure 8 and Figure 10 At time t n1 up to time t n8 In the corresponding switching cycle, at time t n5 Switching device Q8 is turned off at time t. n6 Switching device Q5 is turned on at time t n7 Switching device Q7 is turned off at time t n8 Switching device Q6 is turned on. Where, t n7 -t n6 >0, t n7 -t n5 >0, t n8 -t n6 >0; where the preset duration of the overlapping conduction between switching device Q5 and switching device Q7 is t. n7 -t n6 The dead time between switching devices Q6 and Q8 is t. p8 -t p5 .

[0143] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on after the fourth switching device is turned off; and / or, the third switching device being turned off before the second switching device is turned on.

[0144] In one possible implementation, please refer to Figure 8 Switching device Q5 is turned on after switching device Q8 is turned off; for example Figure 8 As shown, t n6 -t n5 >0.

[0145] In one possible implementation, please refer to Figure 8 Switching device Q7 is turned off before switching device Q6 is turned on; for example Figure 8 As shown, t n8 -t n7 >0.

[0146] In one possible implementation, please refer to Figure 8 Switch Q5 turns on after switch Q8 turns off, and switch Q7 turns off before switch Q6 turns on; for example Figure 8 As shown, t n6 -t n5 >0, t n8 -t n7 >0, t n7 -t n6 >0.

[0147] In some other embodiments, the provided power converter control method further includes a second negative mode in which: the first switching device is turned on at the same time as or before the fourth switching device is turned off; and / or, the third switching device is turned off at the same time as or after the second switching device is turned on.

[0148] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on simultaneously with or before the fourth switching device is turned off. In one possible implementation, please refer to... Figure 9 Switching device Q5 is turned on at the same time as switching device Q8 is turned off; for example Figure 9 As shown, t n6 =t n5 In one possible implementation, please refer to... Figure 10 Switching device Q5 is turned on before switching device Q8 is turned off; for example Figure 10 As shown, t n6 <t n5 .

[0149] In one exemplary embodiment, the second negative mode further includes: the third switching device being turned off simultaneously with or after the second switching device is turned on. In one possible implementation, please refer to... Figure 9 Switching device Q7 is turned off at the same time as switching device Q6 is turned on; for example Figure 9 As shown, t n8 =t n7 In one possible implementation, please refer to... Figure 10 Switching device Q7 is turned off after switching device Q6 is turned on; for example Figure 10 As shown, t n8 <t n7 .

[0150] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on simultaneously with or before the fourth switching device being turned off, and the third switching device being turned off simultaneously with or after the second switching device being turned on. In one possible implementation, please refer to... Figure 9 and Figure 10 Switching device Q5 is turned on at the same time as or before switching device Q8 is turned off, and switching device Q7 is turned off at the same time as or after switching device Q6 is turned on; for example Figure 8 As shown, t n6 ≤t n5 , t n8 ≤t n7 , t n7 -t n6 >0. Thus, a freewheeling path is formed for the entire time period during the dead time of switching devices Q6 and Q8.

[0151] In one exemplary embodiment, please refer to Figure 13 and Figure 14 The upper arm circuit of the AC-side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC-side half-bridge circuit includes a third switching device and a fourth switching device. The second and third switching devices are respectively connected to the midpoint of the arm of the AC-side half-bridge circuit. The second mode includes a second positive mode and a second negative mode. The process of switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode when the AC-side half-bridge circuit meets the zero-crossing switching condition in the power converter control method provided in this embodiment includes steps 1302 to 1304, wherein:

[0152] Step 1302: When the zero-crossing switching condition is met during the positive half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode.

[0153] The second positive mode includes: the first and third switching devices being complementaryly turned on; and the second switching device being turned on before the first switching device is turned on, the fourth switching device being turned off after the third switching device is turned off, the fourth switching device being turned off after the second switching device is turned on, the second switching device being turned on after the third switching device is turned off, and the fourth switching device being turned off before the first switching device is turned on; and the second switching device being turned off after the first switching device is turned off, the fourth switching device being turned on before the third switching device is turned on, the fourth switching device being turned on before the second switching device is turned off, and the fourth switching device being turned on after the first switching device is turned off; and / or, the second switching device being turned off before the third switching device is turned on.

[0154] Optionally, the zero-crossing switching conditions include: the absolute value of the AC voltage on the AC side of the power grid decreasing from greater than the voltage threshold to the voltage threshold, or a preset zero-crossing start phase, or a preset zero-crossing start time.

[0155] Step 1304: Switch the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode.

[0156] The second negative mode includes: the second and fourth switching devices being complementary in conduction; and the first switching device being turned off after the second switching device is turned off, the third switching device being turned on before the fourth switching device is turned on, the first switching device being turned off after the third switching device is turned on, the first switching device being turned off before the fourth switching device is turned on, and the third switching device being turned on after the second switching device is turned off; and the first switching device being turned on before the second switching device is turned on, the third switching device being turned off after the second switching device is turned off, the third switching device being turned off after the first switching device is turned on, the first switching device being turned on after the fourth switching device is turned off, and the third switching device being turned off before the second switching device is turned on.

[0157] For example, the time of switching from the second positive mode to the second negative mode can be the sampled zero-crossing point. As another example, the time of switching from the second positive mode to the second negative mode can also be a preset switching time, which can be preset based on the actual zero-crossing point of the power grid.

[0158] In this embodiment, the provided power converter control method further includes step 1306, wherein:

[0159] Step 1306: When the switching exit condition is met during the negative half-cycle of the AC side half-bridge, switch the control mode of the AC side half-bridge circuit from the second negative mode to the first mode.

[0160] For example, the switching exit conditions include: the absolute value of the AC voltage on the AC side of the power grid increases from less than a voltage threshold to a voltage threshold, or a preset zero-crossing end phase, or a preset zero-crossing end time.

[0161] In one possible implementation, please continue to refer to Figure 13 When the AC-side half-bridge circuit meets the zero-crossing switching condition, the process of switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode further includes steps 1308 and 1310, wherein:

[0162] Step 1308: When the zero-crossing switching condition is met during the negative half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second negative mode.

[0163] Step 1310: Switch the control mode of the AC side half-bridge circuit from the second negative mode to the second positive mode.

[0164] For example, the time of switching from the second negative mode to the second positive mode can be the sampling zero-crossing point; and for another example, the time of switching from the second negative mode to the second positive mode can also be a preset switching time, which can be preset based on the actual zero-crossing point of the power grid.

[0165] In this possible implementation, the provided power converter control method further includes step 1312, wherein:

[0166] Step 1312: When the switching exit condition is met during the positive half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the second positive mode to the first mode.

[0167] In this embodiment, the AC-side half-bridge circuit is driven by the second positive mode in the zero-crossing interval corresponding to the positive half-cycle, and the AC-side half-bridge circuit is driven by the second negative mode in the zero-crossing interval corresponding to the negative half-cycle. The driving mode that is more suitable for the corresponding polarity is adopted according to the different polarities of the grid voltage, thereby further improving the reliability of the control.

[0168] In this embodiment, the AC-side half-bridge circuit is driven by the second positive mode in the zero-crossing interval corresponding to the positive half-cycle, and the AC-side half-bridge circuit is driven by the second negative mode in the zero-crossing interval corresponding to the negative half-cycle. The driving mode that is more suitable for the corresponding polarity is adopted according to the different polarities of the grid voltage, thereby further improving the reliability of the control.

[0169] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise expressly stated herein, there is no strict order restriction on the execution of these steps; they can be executed in other orders, or multiple steps can be executed simultaneously. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the steps or stages of other steps.

[0170] It is understood that the term "based on" as used in this application is used to describe one or more factors that influence the determination, but does not exclude other factors that may influence the determination. For example, the phrase "determine A based on B" means that the determination of A can be based entirely or at least partially on factor B. That is, B is a factor that influences the determination of A, but does not exclude the fact that the determination of A is also based on C.

[0171] Based on the same inventive concept, this application also provides a power converter control device for implementing the power converter control method described above. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more power converter control device embodiments provided below can be found in the limitations of the power converter control method described above, and will not be repeated here.

[0172] In one exemplary embodiment, a power converter control device is provided for use in a controller of a power converter, the power converter further including an AC-side half-bridge circuit, the device comprising:

[0173] The first switching module is used to switch the control mode of the AC side half-bridge circuit from the first mode to the second mode when the zero-crossing switching condition is met. The second mode includes: each switching device in the same bridge arm circuit is turned on or turned off according to a preset timing sequence; corresponding switching devices in different bridge arm circuits are turned on complementaryly; and the switching device that is turned on first in one bridge arm circuit is turned on for a preset time, and the switching device that is turned off later in another bridge arm circuit is turned off.

[0174] In an exemplary embodiment, the upper arm circuit of the AC-side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC-side half-bridge circuit includes a third switching device and a fourth switching device. The second and third switching devices are respectively connected to the midpoint of the arms of the AC-side half-bridge circuit. The second mode includes a second positive mode, which includes: the first and third switching devices are complementary in conduction, the second switching device is turned on before the first switching device is turned on, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned off after the second switching device is turned on. The first switching module is used to switch the control mode of the AC-side half-bridge circuit from the first mode to the second positive mode.

[0175] In one exemplary embodiment, the second positive mode further includes: the second switching device being turned on after the third switching device is turned off; and / or, the fourth switching device being turned off before the first switching device is turned on.

[0176] In one exemplary embodiment, the second positive mode further includes: the second switching device being turned on at the same time as or before the third switching device is turned off; and / or, the fourth switching device being turned off at the same time as or after the first switching device is turned on.

[0177] In one exemplary embodiment, the second positive mode further includes: the second switching device turning off after the first switching device turns off, the fourth switching device turning on before the third switching device turns on, and the fourth switching device turning on before the second switching device turns off.

[0178] In one exemplary embodiment, the second positive mode further includes: a fourth switching device being turned on after the first switching device is turned off; and / or, the second switching device being turned off before the third switching device is turned on.

[0179] In one exemplary embodiment, the second positive mode further includes: the fourth switching device being turned on at the same time as or before the first switching device is turned off; and / or, the second switching device being turned off at the same time as or after the third switching device is turned on.

[0180] In an exemplary embodiment, the second mode includes a second negative mode, which includes: a second switching device and a fourth switching device being complementaryly turned on; a first switching device being turned off after the second switching device is turned off; a third switching device being turned on before the fourth switching device is turned on; and a first switching device being turned off after the third switching device is turned on. The first switching module is used to switch the control mode of the AC-side half-bridge circuit from the first mode to the second negative mode.

[0181] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned off before the fourth switching device is turned on; and / or, the third switching device being turned on after the second switching device is turned off.

[0182] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned off simultaneously with or after the fourth switching device is turned on; and / or,

[0183] The third switching device is turned on at the same time as or before the second switching device is turned off.

[0184] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on before the second switching device is turned on, the third switching device being turned off after the second switching device is turned off, and the third switching device being turned off after the first switching device is turned on.

[0185] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on after the fourth switching device is turned off; and / or, the third switching device being turned off before the second switching device is turned on.

[0186] In one exemplary embodiment, the second negative mode further includes: the first switching device being turned on at the same time as or before the fourth switching device is turned off; and / or, the third switching device being turned off at the same time as or after the second switching device is turned on.

[0187] Each module in the aforementioned power converter control device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware within or independently of the processor in a computer device, or stored in software within the memory of a computer device, so that the processor can call and execute the corresponding operations of each module.

[0188] This application also provides a power converter, including an AC-side half-bridge circuit and a controller. The controller is used to execute the steps described in the above method embodiments.

[0189] In an exemplary embodiment, the upper arm circuit of the AC-side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC-side half-bridge circuit includes a third switching device and a fourth switching device, with the second and third switching devices respectively connected to the midpoint of the AC-side half-bridge circuit.

[0190] Please refer to Figure 1 and Figure 15 The first end of the AC winding of the power converter is connected to the midpoint of the bridge arm of the AC half-bridge circuit.

[0191] In one possible implementation, please refer to Figure 1 The second end of the AC side winding is connected to the midpoint of the AC side capacitor bridge arm of the power converter.

[0192] Please refer to Figure 6 , Figure 7 , Figure 11 and Figure 12 , for adoption Figure 1 The circuit topology of the power converter shown is an example of the freewheeling path of the leakage inductance current in the second mode.

[0193] In one possible implementation, please refer to Figure 15 The second end of the AC side winding is connected to one end of the AC side half-bridge circuit of the power converter.

[0194] For example, the first end of the AC side winding is connected between switching devices Q6 and Q7, and the second end of the AC side winding is connected to the corresponding end of switching device Q8 in the AC side half-bridge circuit, such as... Figure 15 As shown. Capacitor C1 is a resonant capacitor, which, together with the leakage inductance Lr, forms the resonant circuit of the power converter. For example, capacitor C1 is positioned between the first terminal of the AC winding and the AC half-bridge circuit, as shown... Figure 15 As shown. In other examples, capacitor C1 may also be placed between the second end of the AC side winding and the AC side half-bridge circuit.

[0195] For example, please refer to Figure 16 , for adoption Figure 15 When the circuit topology of the power converter shown is such that the leakage inductance current flows from the leakage inductance Lr to point C, the following is adopted: Figure 3 or Figure 4 or Figure 5 The diagram shows the freewheeling path of the leakage inductance current in the second mode.

[0196] For example, please refer to Figure 17 , for adoption Figure 15 When the circuit topology of the power converter shown is such that the leakage inductance current flows from the leakage inductance Lr to point C, the following is adopted: Figure 3 or Figure 4 or Figure 5 The diagram shows the freewheeling path of the leakage inductance current in the second mode.

[0197] Based on the descriptions of the continuous flow paths in the foregoing embodiments, those skilled in the art can clearly deduce that when using... Figure 15 When using the circuit topology of the power converter shown, Figure 8 or Figure 9 or Figure 10 The freewheeling path of the leakage inductance current in the second negative mode shown will not be described in detail here.

[0198] In an exemplary embodiment, the first end of the AC side winding of the power converter is connected between the first and second switching devices, and the second end of the AC side winding is connected between the third and fourth switching devices.

[0199] Please refer to Figure 18 The first end of the AC side winding is connected between switching devices Q5 and Q6, and the second end of the AC side winding is connected between switching devices Q7 and Q8. Capacitor C1 is a resonant capacitor, forming the resonant circuit of the power converter together with the leakage inductance Lr. For example, capacitor C1 is positioned between the first end of the AC side winding and the AC side half-bridge circuit, such as... Figure 18 As shown. In other examples, capacitor C1 may also be placed between the second end of the AC side winding and the AC side half-bridge circuit.

[0200] For example, please refer to Figure 19 , for adoption Figure 18 When the circuit topology of the power converter shown is such that the leakage inductance current flows from the leakage inductance Lr to point C, the following is adopted: Figure 3 or Figure 4 or Figure 5 The diagram shows the freewheeling path of the leakage inductance current in the second mode.

[0201] For example, please refer to Figure 20 , for adoption Figure 18 When the circuit topology of the power converter shown is such that the leakage inductance current flows from the leakage inductance Lr to point C, the following is adopted: Figure 3 or Figure 4 or Figure 5 The diagram shows the freewheeling path of the leakage inductance current in the second mode.

[0202] Based on the descriptions of the continuous flow paths in the foregoing embodiments, those skilled in the art can clearly deduce that when using... Figure 17 When using the circuit topology of the power converter shown, Figure 8 or Figure 9 or Figure 10 The freewheeling path of the leakage inductance current in the second negative mode shown will not be described in detail here.

[0203] In one exemplary embodiment, the AC-side conversion circuit of the power converter employs a full-bridge conversion circuit, which is equivalent to the AC-side conversion circuit comprising two AC-side half-bridge circuits. The two ends of the AC-side winding are respectively connected to the midpoints of the two AC-side half-bridge circuits.

[0204] For example, please refer to Figure 21 The first end of the AC side winding is connected between switching devices Q6 and Q7, and the second end of the AC side winding is connected between switching devices Q10 and Q11.

[0205] It should be noted that the midpoint position in the embodiments of this application does not refer to the midpoint of physical distance, but rather to the midpoint position in electrical relationship, such as... Figure 1In the context of AC-side half-bridge circuits, the midpoint refers to any point on the circuit between the upper and lower bridge arms that can be powered.

[0206] This application also provides a chip, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0207] In one embodiment, an electronic device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0208] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0209] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0210] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0211] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0212] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0213] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A power converter control method, characterized in that, The power converter includes an AC-side half-bridge circuit and a controller, and the method is used in the controller, the method comprising: When the AC-side half-bridge circuit meets the zero-crossing switching condition, the control mode of the AC-side half-bridge circuit is switched from the first mode to the second mode. The second mode includes: each switching device in the same bridge arm circuit is turned on or turned off according to a preset timing sequence; corresponding switching devices in different bridge arm circuits are turned on complementaryly; after the switching device that turns on first in one bridge arm circuit is turned on for a preset time, the switching device that turns off later in another bridge arm circuit is turned off.

2. The method according to claim 1, characterized in that, The upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device. The second switching device and the third switching device are respectively connected to the midpoint of the arm of the AC side half-bridge circuit. The second mode includes a second positive mode, which includes: the first switching device and the third switching device are complementaryly turned on, the second switching device is turned on before the first switching device is turned on, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned off after the second switching device is turned on. When the AC-side half-bridge circuit meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode includes: When the zero-crossing switching condition is met during the positive half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode.

3. The method according to claim 2, characterized in that, The second positive mode also includes: The second switching device is turned on after the third switching device is turned off; And / or, The fourth switching device is turned off before the first switching device is turned on.

4. The method according to claim 2, characterized in that, The second positive mode also includes: The second switching device is turned on at the same time as or before the third switching device is turned off; And / or, The fourth switching device is turned off at the same time as or after the first switching device is turned on.

5. The method according to any one of claims 2-4, characterized in that, The second positive mode further includes: the second switching device being turned off after the first switching device is turned off, the fourth switching device being turned on before the third switching device is turned on, and the fourth switching device being turned on before the second switching device is turned off.

6. The method according to claim 5, characterized in that, The second positive mode also includes: The fourth switching device is turned on after the first switching device is turned off; And / or, The second switching device is turned off before the third switching device is turned on.

7. The method according to claim 5, characterized in that, The second positive mode also includes: The fourth switching device is turned on at the same time as or before the first switching device is turned off; And / or, The second switching device is turned off at the same time as or after the third switching device is turned on.

8. The method according to claim 1, characterized in that, The upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device. The second switching device and the third switching device are respectively connected to the midpoint of the arm of the AC side half-bridge circuit. The second mode includes a second negative mode, which includes: the second switching device and the fourth switching device are complementaryly turned on, the first switching device is turned off after the second switching device is turned off, the third switching device is turned on before the fourth switching device is turned on, and the first switching device is turned off after the third switching device is turned on. When the AC-side half-bridge circuit meets the zero-crossing switching condition, switching the control mode of the AC-side half-bridge circuit from the first mode to the second mode includes: When the zero-crossing switching condition is met during the negative half-cycle of the AC side voltage, the control mode of the AC side half-bridge circuit is switched from the first mode to the second negative mode.

9. The method according to claim 8, characterized in that, The second negative mode also includes: The first switching device is turned off before the fourth switching device is turned on; And / or, The third switching device is turned on after the second switching device is turned off.

10. The method according to claim 9, characterized in that, The second negative mode also includes: The first switching device is turned off at the same time as or after the fourth switching device is turned on; And / or, The third switching device is turned on at the same time as or before the second switching device is turned off.

11. The method according to any one of claims 8-10, characterized in that, The second negative mode also includes: The first switching device is turned on before the second switching device is turned on, and the third switching device is turned off after the second switching device is turned off, and the third switching device is turned off after the first switching device is turned on.

12. The method according to claim 11, characterized in that, The second negative mode also includes: The first switching device is turned on after the fourth switching device is turned off; And / or, The third switching device is turned off before the second switching device is turned on.

13. The method according to claim 11, characterized in that, The second negative mode also includes: The first switching device is turned on at the same time as or before the fourth switching device is turned off; And / or, The third switching device is turned off at the same time as or after the second switching device is turned on.

14. A power converter, characterized in that, The power converter includes an AC-side half-bridge circuit and a controller, the controller being used to perform the steps of the method according to any one of claims 1 to 13.

15. A chip comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 13.

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