Converter control method, converter, and chip

Abstract

The present application relates to a converter control method, a converter, and a chip. The converter comprises an alternating-current side half-bridge circuit and a controller, and the method is used in the controller. The converter control method comprises: when the alternating-current side half-bridge circuit satisfies a zero-crossing switching condition, switching the control mode of the alternating-current side half-bridge circuit from a first mode to a second mode, wherein the second mode comprises: switch devices located on a same bridge arm are turned on in a preset sequence or turned off in a preset sequence, and corresponding switch devices located on different bridge arms are complementarily turned on. The converter control method has high reliability.

Description

Converter control method, converter and chip

[0001] Related applications

[0002] This disclosure claims priority to Chinese patent application number 2024101843376, filed on February 19, 2024, entitled “Converter Control Method, Converter and Chip,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to the field of power control technology, and in particular to a converter control method, a converter, and a chip. Background Art

[0004] In a DC-to-AC converter or AC-to-DC converter, the AC-side half-bridge circuit connected to the grid needs to be switched according to the grid voltage's zero-crossing point. However, in practical applications, the controller often has difficulty accurately detecting the grid voltage's zero-crossing point, which results in inaccurate switching control of the converter. This can cause the AC-side half-bridge circuit connecting the converter to the grid to short-circuit or experience overvoltage stress, potentially damaging the AC-side switching components.

[0005] The converter control method in the related art controls the switching devices in the same bridge arm of the AC side half-bridge circuit to be turned on or off at the same time near the estimated zero-crossing point, and the switching devices in different bridge arms are turned on complementary.

[0006] However, the above converter control method has low reliability.

[0007] Summary of the Invention

[0008] Based on this, it is necessary to provide a converter control method, a converter and a chip that can improve reliability in order to address the above technical problems.

[0009] In a first aspect, the present disclosure provides a converter control method, wherein the converter includes an AC side half-bridge circuit and a controller, and the method is used in the controller, and the method includes:

[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. The second mode includes: the switching devices located in the same bridge arm are turned on or turned off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementarily.

[0011] In one embodiment, the zero-crossing switching condition includes: the absolute value of the AC voltage of the AC side power grid decreases from greater than a voltage threshold to a voltage threshold, or a preset zero-crossing starting phase, or a preset zero-crossing starting time.

[0012] In one embodiment, the upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, the lower arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device, and the second switching device and the third switching device are respectively connected to the midpoint of the bridge arm of the AC side half-bridge circuit;

[0013] The second mode includes a second positive mode, and the second positive mode includes: the first switching device and the third switching device are complementary turned on, the second switching device is turned on before the first switching device is turned on, the second switching device is turned off after the first switching device is turned off, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned on before the third switching device is turned on;

[0014] Switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes:

[0015] The control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode.

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

[0017] The fourth switching device is turned off when the second switching device is turned on, and the fourth switching device is turned on when the second switching device is turned off.

[0018] In one embodiment, an upper arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and a 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 bridge arm of the AC side half-bridge circuit; the second mode includes a second negative mode, and the second negative mode includes: the second switching device and the fourth switching device are complementary turned on, the first switching device is turned off after the second switching device is turned off, the first switching device is turned on before the second switching device is turned on, the third switching device is turned on before the fourth switching device is turned on, and the third switching device is turned off after the fourth switching device is turned off;

[0019] Switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes:

[0020] The control mode of the AC side half-bridge circuit is switched from the first mode to the second negative mode.

[0021] In one embodiment, the second negative mode further comprises:

[0022] The third switching device is turned on when the first switching device is turned off, and the third switching device is turned off when the first switching device is turned on.

[0023] In one embodiment, the second mode includes a second positive mode and a second negative mode, and 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:

[0024] When the positive half cycle of the AC side voltage 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 positive mode;

[0025] Switching the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode;

[0026] The method further includes: when the negative half cycle of the AC side voltage satisfies a switching exit condition, switching the control mode of the AC side half-bridge circuit from the second negative mode to the first mode;

[0027] The switching exit condition includes: the absolute value of the AC voltage of the AC side power grid increases from less than the voltage threshold to the voltage threshold, or a preset zero-crossing end phase, or a preset zero-crossing end time.

[0028] In one embodiment, 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 further includes:

[0029] When the negative half cycle of the AC side voltage 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 negative mode;

[0030] Switching the control mode of the AC side half-bridge circuit from the second negative mode to the second positive mode;

[0031] The method also includes:

[0032] When the positive half cycle of the AC side voltage meets the switching exit condition, the control mode of the AC side half-bridge circuit is switched from the second positive mode to the first mode.

[0033] In a second aspect, the present disclosure further provides a converter, comprising an AC side half-bridge circuit and a controller;

[0034] The controller is used to switch the control mode of the AC side half-bridge circuit from a first mode to a second mode when the AC side half-bridge circuit meets the zero-crossing switching condition. In the second mode, the switching devices located in the same bridge arm are turned on or off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementary.

[0035] In a third aspect, the present disclosure further provides a chip comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method of the first aspect when executing the computer program.

[0036] The above-mentioned converter control method, converter and chip, wherein the converter includes an AC side half-bridge circuit and a controller, and the method is used in the controller. 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 a first mode to a second mode. The second mode includes: each switching device located in the same bridge arm is turned on or off in a preset order, and the corresponding switching devices located in different bridge arms are complementary. In this way, a group of switching devices in the same bridge arm are not turned on or off at the same time, but are turned on or off in a preset order. This can avoid the problem of low reliability caused by the leakage inductance current of the two switching devices near the midpoint of the bridge arm being broken down during the conduction dead zone. The converter control method provided by the present disclosure has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the traditional technology, the drawings required for use in the embodiments or the traditional technology description will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without paying any creative work.

[0038] FIG1 is a circuit topology of a single-stage isolated grid-connected inverter according to an embodiment;

[0039] FIG2 is a circuit topology of a single-stage isolated grid-connected inverter in another embodiment;

[0040] FIG3 is a schematic diagram of a zero-crossing interval in one embodiment;

[0041] FIG4 is an exemplary schematic diagram of a control timing corresponding to a second positive mode in one embodiment;

[0042] FIG5 is an exemplary schematic diagram of a control timing corresponding to a second negative mode in one embodiment;

[0043] FIG6 is an exemplary schematic diagram of a control timing corresponding to the second mode in one embodiment;

[0044] FIG7 is a schematic flow chart of a converter control method provided in one embodiment;

[0045] FIG8 is a structural block diagram of a converter control device provided in one embodiment. DETAILED DESCRIPTION

[0046] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure.

[0048] It will be understood that the terms "first," "second," etc., used in this disclosure may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this disclosure. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0049] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0050] It should be understood that the term "based on" as used in this disclosure is used to describe one or more factors that influence a determination, and 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 may be based entirely or at least partially on factor B. In other words, B is a factor that influences the determination of A, but does not exclude the determination of A being based on C as well.

[0051] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0052] The converter control method provided in the embodiments of the present disclosure can be used in a controller in a converter employing a half-bridge circuit structure on the AC side, wherein both the upper and lower arms of the half-bridge circuit are implemented by bidirectional switches, and the controller is connected to at least each switching device in the converter to control the on / off frequency, duty cycle, and phase shift of each switching device. The converter can be a direct current alternating current (DC-AC) converter, such as a single-stage isolated grid-connected inverter, or an alternating current direct current (AC-DC) converter, such as a single-stage isolated rectifier.

[0053] Please refer to Figure 1 and Figure 2, which are the circuit topology of a single-stage isolated grid-connected inverter. dc Indicates the DC side power supply voltage, V ac is the AC side grid voltage; the AC side adopts a half-bridge circuit, wherein the upper arm circuit of the AC side half-bridge circuit is realized based on a bidirectional switch composed of switching devices Q5 and Q6, and the lower arm circuit is realized based on a bidirectional switch composed of switching devices Q7 and Q8, and the midpoint C of the bridge arm is connected to the leakage inductance L of the converter. r , upper bridge arm circuit and capacitor C p Correspondingly, the lower bridge arm circuit and capacitor C n Correspondingly, the capacitor C p and capacitor C n In series, capacitor C o and resistor Z g A filter circuit is formed.

[0054] Among them, the controller is not shown in Figures 1 and 2. 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 customized controller chip; the embodiments of the present disclosure do not limit the specific implementation hardware of the controller.

[0055] Please refer to FIG2 , for example, the converter control method provided by the embodiment of the present disclosure can be implemented using an H-bridge circuit on the DC side of the converter, wherein the first arm circuit of the DC side H-bridge circuit includes switching devices Q1 and Q2, and the second arm circuit includes switching devices Q3 and Q4. Points A and B are load interfaces of the DC side H-bridge circuit, and T r For transformer.

[0056] It should be noted that the embodiments of the present disclosure do not limit the specific circuit structure adopted on the DC side, and FIG2 is only an exemplary diagram.

[0057] Among them, the switching devices involved in the embodiments of the present disclosure can also be called power switching tubes; for example, the switching devices can use MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor). The present disclosure does not limit the specific types and models of the switching devices.

[0058] In an exemplary embodiment, a converter includes an AC side half-bridge circuit and a controller. The provided converter method is used in the controller, and 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.

[0059] The first mode corresponds to the normal working mode of the converter, as shown in FIG3 : the AC side grid voltage V ac In the positive half cycle, the switch device Q5 and the switch device Q7 are complementary turned on at high frequency (vertical frame part), the switch device Q6 and the switch device Q8 are always on, and the AC side grid voltage V ac In the negative half cycle, the switching device Q6 and the switching device Q8 are complementary turned on at high frequency (vertical line frame part), and the switching device Q5 and the switching device Q7 are constantly turned on.

[0060] The zero-crossing switching condition is defined as the moment when the AC grid voltage is about to drop from the positive half-cycle to zero voltage, or about to increase from the negative half-cycle to zero voltage. Referring to Figure 3, the zero-crossing switching condition can be understood as the condition for entering the zero-crossing interval, where the zero-crossing interval corresponds to the midpoint box of the control timing sequence shown in Figure 3.

[0061] In one possible implementation, the zero-crossing interval is determined based on the voltage amplitude of the AC power grid. Correspondingly, the zero-crossing switching condition includes: the absolute value of the AC voltage of the AC power grid decreases from greater than a voltage threshold to a voltage threshold. During the positive half-cycle, the zero-crossing switching condition corresponds to the AC voltage decreasing from greater than the voltage threshold to the voltage threshold, ultimately reaching zero voltage. During the negative half-cycle, the zero-crossing switching condition corresponds to the AC voltage increasing from less than the negative voltage threshold to greater than the negative voltage threshold, ultimately reaching zero voltage.

[0062] 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 absolute value of the AC voltage corresponding to the AC side circuit decreases from greater than the voltage threshold to the voltage threshold, the control mode of the AC side half-bridge circuit is switched from the first mode to the second mode.

[0063] In one possible embodiment, the zero-crossing interval is determined based on the voltage phase of the AC side power grid, and correspondingly, the zero-crossing switching condition includes a preset zero-crossing starting phase. The zero-crossing starting phase corresponding to the positive half-cycle is a preset phase slightly smaller than 180°. For example, the zero-crossing starting phase corresponding to the positive half-cycle ranges from 168° to 177°; optionally, the zero-crossing starting phase corresponding to the positive half-cycle is 170° or 175°; the zero-crossing starting phase corresponding to the negative half-cycle is a preset phase slightly smaller than 360°. For example, the zero-crossing starting phase corresponding to the negative half-cycle ranges from 348° to 357°; optionally, the zero-crossing starting phase corresponding to the negative half-cycle is 350° or 355°.

[0064] In this possible implementation, 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 phase of the AC side voltage is a preset starting phase, switching the control mode of the AC side half-bridge circuit from the first mode to the second mode.

[0065] In this embodiment, the phase is used as a normalized attribute value of the AC voltage, and the phase of the AC side voltage is used as a basis for determining zero-crossing switching, thereby improving the efficiency of converter control.

[0066] It can be understood that the AC side grid voltage is a periodically changing sine wave, so the zero-crossing starting phase also changes periodically, that is, the zero-crossing switching condition of the controller includes a set of zero-crossing starting phases.

[0067] In one possible implementation, the zero-crossing interval is determined based on a preset switching moment. The zero-crossing switching condition includes a preset zero-crossing start moment. Referring to FIG. 3 , for example, the zero-crossing interval is the moment t p To time t n Time t p is the zero-crossing start time corresponding to the positive half cycle, time t n is the zero-crossing end time corresponding to the negative half cycle, time t z It is the sampling zero-crossing point of the grid voltage.

[0068] Among them, the sampling zero-crossing point can be obtained by sampling the controller. Because the switching of the sampling circuit, the sampling rate and other factors may introduce certain errors, the sampling zero-crossing point is not completely the true zero-crossing point of the AC side grid voltage. In this embodiment, the sampling zero-crossing point is used as the reference point and the timing is preset for a period of time to determine the starting time of the zero-crossing, and the timing is preset for a period of time to determine the ending time of the zero-crossing, to ensure that the true zero-crossing point of the grid voltage falls within the zero-crossing interval.

[0069] For example, the preset time duration can be determined based on factors such as the AC side grid voltage amplitude and phase. For another example, the difference between the sampled zero-crossing point and the actual zero-crossing point is generally not very large, so the preset time duration can be determined based on empirical values. Generally, the preset time duration is in the millisecond range.

[0070] For ease of description, this embodiment illustrates the process of determining the zero-crossing interval according to the process of the positive half-cycle changing to the negative half-cycle as shown in FIG3 ; it can be understood that a corresponding zero-crossing interval is also set when the AC side grid voltage changes from the negative half-cycle to the positive half-cycle, and those skilled in the art can clearly know how to set the zero-crossing interval corresponding to the change from the negative half-cycle to the positive half-cycle based on the zero-crossing interval shown in FIG3 .

[0071] In this embodiment, 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: at a preset zero-crossing starting moment, the control mode of the AC side half-bridge circuit is switched from the first mode to the second mode.

[0072] 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.

[0073] It can be understood that the AC side grid voltage is a periodically changing sine wave, so the zero-crossing start time also changes periodically, that is, the control timing of the controller includes a (zero-crossing start time, zero-crossing end time) group.

[0074] The converter control method provided in this embodiment further includes: switching the control mode of the AC-side half-bridge circuit from the second mode to the first mode when the AC-side half-bridge circuit meets a switching exit condition. Correspondingly, the switching exit condition includes: the absolute value of the AC voltage of the AC-side 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.

[0075] In one possible embodiment, the zero-crossing end phase corresponding to the negative half-cycle is a preset phase slightly larger than 180°. For example, the zero-crossing end phase corresponding to the negative half-cycle ranges from 183° to 192°; optionally, the zero-crossing end phase corresponding to the negative half-cycle is 185° or 190°; the zero-crossing end phase corresponding to the positive half-cycle is a preset phase slightly larger than 0°. For example, the zero-crossing end phase corresponding to the positive half-cycle ranges from 3° to 12°; optionally, the zero-crossing end phase corresponding to the positive half-cycle is 5° or 10°.

[0076] In this embodiment, the second mode includes the switching devices located in the same bridge arm being turned on or off in a preset order, and the corresponding switching devices located in different bridge arms being turned on in a complementary manner. The second mode corresponds to the mode when the converter operates in a preset zero-crossing interval. For example, the zero-crossing interval corresponding to the second mode is shown in the dotted box in FIG3 , i.e., at time t p To time t n The control timing of the switching devices between.

[0077] In this embodiment, a group of switching devices in the same bridge arm are not turned on or off at the same time, but are turned on or off in a preset order. This can avoid the problem of low reliability caused by the leakage current breaking down the two switching devices near the midpoint of the bridge arm during the conduction dead zone.

[0078] For example, if a control method in which a group of switch devices on the same bridge arm in the zero-crossing interval are simultaneously turned on and off is adopted in the related art, referring to FIG2 , assuming that at a certain moment, the leakage inductance current is from the leakage inductance L r Flows to the right, that is, flows to the bridge arm midpoint C. Due to the existence of the conduction dead zone of the switch devices Q5 and the switch device Q7, when the bridge arm conduction state is switched, the leakage inductance current has no discharge path and can only be stored through the parasitic capacitance of the switch device Q7 in the lower bridge arm circuit close to the bridge arm midpoint C, resulting in a greatly increased risk of the switch device Q7 being broken down. However, the second mode provided in this embodiment is adopted, that is, a group of switch devices in the unified bridge arm circuit are turned on in a preset order. Referring to FIG4 , the switch device Q6 is turned on before the switch device Q5, and the switch device Q8 is turned off after the switch device Q7, which ensures the dead zone time (time t p1 To time t p4 ), and at the same time, the parallel diode of Q5 and Q6 provide a freewheeling loop for the leakage inductance current, greatly reducing the risk of the switch device Q7 being over-voltage and broken down. Therefore, the converter control method provided by this embodiment has high reliability. r When the current flows to the left, the principle of reducing the risk of breakdown of the switching device close to the bridge arm midpoint C in this embodiment is similar to the above example and will not be repeated here.

[0079] In an exemplary embodiment, referring to FIG4 , the second mode includes a second positive mode, and the second positive mode includes: the first switching device and the third switching device are complementarily turned on, the second switching device is turned on before the first switching device is turned on, the second switching device is turned off after the first switching device is turned off, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned on before the third switching device is turned on.

[0080] 2 and 4 , the first switch device corresponds to the switch device Q5 , the second switch device corresponds to the switch device Q6 , the third switch device corresponds to the switch device Q7 , and the fourth switch device corresponds to the switch device Q8 . p1 To time t p8 is a control cycle in the second mode.

[0081] In the second positive mode, the switching device Q5 and the switching device Q7 operate in a high-frequency complementary state; the switching device Q6 in the same bridge arm as the switching device Q5 is turned on earlier than the switching device Q5 and is turned off later than the switching device Q5; the switching device Q8 in the same bridge arm as the switching device Q7 is turned off later than the switching device Q7 and is turned on earlier than the switching device Q7.

[0082] As shown in Figure 4, at time t p1 To time t p8 In the corresponding control cycle, at time t p1 The switch device Q7 is turned off at time t p2 The switch device Q8 is turned off at time t p3 Switch device Q6 is turned on, at time t p4 Switch device Q5 is turned on, at time t p5 The switch device Q5 is turned off at time t p6 The switch device Q6 is turned off at time t p7 Switching device Q8 is turned on, at time t p8 Switching device Q7 is turned on. p2 -t p1 >0,t p4 -t p3 >0,t p6 -t p5 >0,t p8 -t p7 >0.

[0083] In a possible implementation, the second positive mode includes: the fourth switching device is turned off when the second switching device is turned on, and the fourth switching device is turned on when the second switching device is turned off; that is, t p3 -t p2 =0,t p7 -t p6 = 0. In this embodiment, a freewheeling path of the entire time period is formed within the dead time period, thereby improving the reliability of converter control.

[0084] In a possible implementation, referring to FIG. 4 , the second positive mode includes: the fourth switching device is turned off before the second switching device is turned on, and the fourth switching device is turned on after the second switching device is turned off, that is, t p3 -t p2 >0,tp7 -t p6 >0. For example, t p3 -t p2 and t p7 -t p6 The value is generally less than 1us (microsecond).

[0085] In this embodiment, the process of switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes: switching the control mode of the AC side half-bridge circuit from the first mode to the second positive mode.

[0086] In an exemplary embodiment, referring to FIG5 , the second mode includes a second negative mode, and the second negative mode includes: the second switching device and the fourth switching device are complementarily turned on, the first switching device is turned off after the second switching device is turned off, the first switching device is turned on before the second switching device is turned on, the third switching device is turned on before the fourth switching device is turned on, and the third switching device is turned off after the fourth switching device is turned off.

[0087] 2 and 5 , the first switch device corresponds to the switch device Q5 , the second switch device corresponds to the switch device Q6 , the third switch device corresponds to the switch device Q7 , and the fourth switch device corresponds to the switch device Q8 . n1 To time t n8 is a control cycle in the second mode.

[0088] Among them, in the second negative mode, the switching device Q8 and the switching device Q6 operate in a high-frequency complementary state; the switching device Q7 in the same bridge arm as the switching device Q8 is turned on earlier than the switching device Q8 and is turned off later than the switching device Q8; the switching device Q5 in the same bridge arm as the switching device Q6 is turned off later than the switching device Q6 and is turned on earlier than the switching device Q6.

[0089] As shown in Figure 5, at time t n1 To time t n8 In the corresponding control cycle, at time t n1 The switch device Q6 is turned off at time t n2 The switch device Q5 is turned off at time t n3 Switching device Q7 is turned on, at time t n4 Switching device Q8 is turned on, at time t n5 The switch device Q8 is turned off at time t n6 The switch device Q7 is turned off at time t n7 Switch device Q5 is turned on, at time t n8 The switch device Q8 is turned on. n2 -t n1 >0,t n4 -t n3>0,t n6 -t n5 >0,t n8 -t n7 >0.

[0090] In a possible implementation, the second negative mode includes: the third switching device is turned on when the first switching device is turned off, and the third switching device is turned off when the first switching device is turned on, that is, t n3 -t n2 =0,t n7 -t n6 = 0. In this embodiment, a freewheeling path of the entire time period is formed within the dead time period, thereby improving the reliability of converter control.

[0091] In a possible implementation, referring to FIG5 , the second negative mode includes: the third switching device is turned on after the first switching device is turned off, and the third switching device is turned off before the first switching device is turned on, that is, t n3 -t n2 >0,t n7 -t n6 >0.

[0092] In this embodiment, the process of switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes: switching the control mode of the AC side half-bridge circuit from the first mode to the second negative mode.

[0093] In an exemplary embodiment, referring to FIG6 and FIG7 , the second mode includes a second positive mode and a second negative mode. When the AC side half-bridge circuit satisfies a 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 in the provided converter control method includes:

[0094] Step 702: When the AC side voltage positive half cycle meets a zero-crossing switching condition, the control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode. The zero-crossing switching condition includes: the absolute value of the AC voltage of the AC side grid decreases from greater than a voltage threshold to a voltage threshold, or a preset zero-crossing starting phase, or a preset zero-crossing starting time.

[0095] Step 704 : Switch the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode.

[0096] Exemplarily, the moment of switching from the second positive mode to the second negative mode may be a sampling zero crossing point. In another exemplary embodiment, the moment of switching from the second positive mode to the second negative mode may also be a preset switching moment, which may be preset based on a real zero crossing point of the power grid.

[0097] In this embodiment, the converter control method further includes:

[0098] Step 706: When the negative half cycle of the AC side half-bridge circuit satisfies a switching exit condition, the control mode of the AC side half-bridge circuit is switched from the second negative mode to the first mode. The switching exit condition includes: the absolute value of the AC voltage of the AC side 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.

[0099] In a possible implementation, 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:

[0100] Step 708 : When the negative half cycle of the AC side voltage 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 negative mode.

[0101] Step 710 : Switch the control mode of the AC-side half-bridge circuit from the second negative mode to the second positive mode.

[0102] Exemplarily, the moment of switching from the second negative mode to the second positive mode may be a sampling zero crossing point; and further exemplary, the moment of switching from the second negative mode to the second positive mode may also be a preset switching moment, which may be preset based on the actual zero crossing point of the power grid.

[0103] In this possible implementation, the provided converter control method further includes:

[0104] Step 712: When the positive half cycle of the AC side voltage meets the switching exit condition, the control mode of the AC side half-bridge circuit is switched from the second positive mode to the first mode.

[0105] In this embodiment, the second positive mode is used to drive the AC side half-bridge circuit in the zero-crossing interval corresponding to the positive half-cycle, and the second negative mode is used to drive the AC side half-bridge circuit in the zero-crossing interval corresponding to the negative half-cycle. In view of the different polarities of the grid voltage, a driving mode that is more suitable for the corresponding polarity is adopted to further improve the reliability of control.

[0106] It should be understood that, although the various steps in the flowcharts involved in the above embodiments are shown in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps. These steps can be executed in other orders, or multiple steps can be executed simultaneously. Moreover, at least a portion of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0107] Based on the same inventive concept, embodiments of the present disclosure also provide a converter control device for implementing the aforementioned converter control method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more converter control device embodiments provided below can be found in the definitions of the converter control method above and are not further elaborated here.

[0108] In an exemplary embodiment, referring to FIG8 , a converter control device is provided for use in a controller in a converter. The converter further includes an AC-side half-bridge circuit. The device includes:

[0109] The first switching module 802 is used to switch 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. The second mode includes: each switching device located in the same bridge arm is turned on or turned off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementary.

[0110] In an exemplary embodiment, the zero-crossing switching condition includes: the absolute value of the AC voltage of the AC side grid decreases from greater than a voltage threshold to a voltage threshold, or a preset zero-crossing starting phase, or a preset zero-crossing starting time.

[0111] 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, and the second switching device and the third switching device are respectively connected to the midpoint of the bridge arm of the AC side half-bridge circuit; the second mode includes a second positive mode, and the second positive mode includes: the first switching device and the third switching device are complementary turned on, the second switching device is turned on before the first switching device is turned on, the second switching device is turned off after the first switching device is turned off, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned on before the third switching device is turned on.

[0112] The first switching module 802 is configured to switch the control mode of the AC side half-bridge circuit from the first mode to the second positive mode.

[0113] In an exemplary embodiment, the second positive mode further includes: the fourth switching device is turned off when the second switching device is turned on, and the fourth switching device is turned on when the second switching device is turned off.

[0114] In an exemplary embodiment, the second mode includes a second negative mode, and the second negative mode includes: the second switching device and the fourth switching device are complementarily turned on, the first switching device is turned off after the second switching device is turned off, the first switching device is turned on before the second switching device is turned on, the third switching device is turned on before the fourth switching device is turned on, and the third switching device is turned off after the fourth switching device is turned off.

[0115] The first switching module 802 is configured to switch the control mode of the AC side half-bridge circuit from the first mode to the second negative mode.

[0116] In an exemplary embodiment, the second negative mode further includes: the third switching device is turned on when the first switching device is turned off, and the third switching device is turned off when the first switching device is turned on.

[0117] In an exemplary embodiment, the second mode includes a second positive mode and a second negative mode, and the first switching module 802 is used to switch the control mode of the AC side half-bridge circuit from the first mode to the second positive mode when the positive half cycle of the AC side voltage meets the zero-crossing switching condition; and switch the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode.

[0118] The converter control device also includes a second switching module 804, which is used to switch the control mode of the AC side half-bridge circuit from the second negative mode to the first mode when the negative half cycle of the AC side voltage meets the switching exit condition; wherein the switching exit condition includes: the absolute value of the AC voltage of the AC side power grid increases from less than the voltage threshold to the voltage threshold, or the preset zero-crossing end phase, or the preset zero-crossing end time.

[0119] In an exemplary embodiment, the first switching module 802 is used to switch the control mode of the AC side half-bridge circuit from the first mode to the second negative mode when the negative half cycle of the AC side voltage meets the zero-crossing switching condition; and switch the control mode of the AC side half-bridge circuit from the second negative mode to the second positive mode.

[0120] The second switching module 804 is configured to switch the control mode of the AC side half-bridge circuit from the second positive mode to the first mode when the positive half cycle of the AC side voltage meets the switching exit condition.

[0121] Each module in the converter control device described above may be implemented in whole or in part through software, hardware, or a combination thereof. Each module may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0122] An embodiment of the present disclosure provides a converter, which includes an AC side half-bridge circuit and a controller.

[0123] The controller is used to switch the control mode of the AC side half-bridge circuit from a first mode to a second mode when the AC side half-bridge circuit meets the zero-crossing switching condition. In the second mode, the switching devices located in the same bridge arm are turned on or off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementary.

[0124] In an exemplary embodiment, the zero-crossing switching condition includes: the absolute value of the AC voltage of the AC side grid decreases from greater than a voltage threshold to a voltage threshold, or a preset zero-crossing starting phase, or a preset zero-crossing starting time.

[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, and the second switching device and the third switching device are respectively connected to the midpoint of the bridge arm of the AC side half-bridge circuit; the second mode includes a second positive mode, and the second positive mode includes: the first switching device and the third switching device are complementary turned on, the second switching device is turned on before the first switching device is turned on, the second switching device is turned off after the first switching device is turned off, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned on before the third switching device is turned on.

[0126] The controller is used to switch the control mode of the AC side half-bridge circuit from a first mode to a second positive mode.

[0127] In an exemplary embodiment, the second positive mode further includes: the fourth switching device is turned off when the second switching device is turned on, and the fourth switching device is turned on when the second switching device is turned off.

[0128] In an exemplary embodiment, the second mode includes a second negative mode, and the second negative mode includes: the second switching device and the fourth switching device are complementarily turned on, the first switching device is turned off after the second switching device is turned off, the first switching device is turned on before the second switching device is turned on, the third switching device is turned on before the fourth switching device is turned on, and the third switching device is turned off after the fourth switching device is turned off.

[0129] The controller is used to switch the control mode of the AC side half-bridge circuit from a first mode to a second negative mode.

[0130] In an exemplary embodiment, the second negative mode further includes: the third switching device is turned on when the first switching device is turned off, and the third switching device is turned off when the first switching device is turned on.

[0131] In an exemplary embodiment, the second mode includes a second positive mode and a second negative mode, and the controller is used to switch the control mode of the AC side half-bridge circuit from the first mode to the second positive mode when the positive half-cycle of the AC side voltage meets the zero-crossing switching condition, and switch the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode; when the negative half-cycle of the AC side voltage meets the switching exit condition, switch the control mode of the AC side half-bridge circuit from the second negative mode to the first mode.

[0132] In an exemplary embodiment, the controller is used to switch the control mode of the AC side half-bridge circuit from the first mode to the second negative mode when the negative half-cycle of the AC side voltage meets the zero-crossing switching condition, and switch the control mode of the AC side half-bridge circuit from the second negative mode to the second positive mode when the positive half-cycle of the AC side voltage meets the switching exit condition.

[0133] An embodiment of the present disclosure further provides a chip, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0134] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0135] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0136] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0137] 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, stored data, displayed data, etc.) involved in this disclosure are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0138] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in the present disclosure may include at least one of non-volatile and volatile memory. Non-volatile memory may 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 may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this disclosure may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in each embodiment provided in this disclosure may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0139] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0140] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present disclosure, all of which fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the patent disclosed herein shall be determined by the appended claims.

Claims

1. A converter control method, wherein: The converter includes an AC side half-bridge circuit and a controller. The method is used in the controller, and the method includes: 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, and the second mode includes: the switching devices located in the same bridge arm are turned on or turned off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementarily.

2. The method according to claim 1, wherein The zero-crossing switching condition includes: the absolute value of the AC voltage of the AC side power grid decreases from greater than a voltage threshold to the voltage threshold, or a preset zero-crossing starting phase, or a preset zero-crossing starting time.

3. The method according to claim 1, wherein The upper bridge arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower bridge arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device, and the second switching device and the third switching device are respectively connected to the midpoint of the bridge arm of the AC side half-bridge circuit; The second mode includes a second positive mode, wherein the first switching device and the third switching device are complementary turned on, the second switching device is turned on before the first switching device is turned on, the second switching device is turned off after the first switching device is turned off, the fourth switching device is turned off after the third switching device is turned off, and the fourth switching device is turned on before the third switching device is turned on; Switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes: The control mode of the AC side half-bridge circuit is switched from the first mode to the second positive mode.

4. The method according to claim 3, wherein: The second positive mode further includes: The fourth switching device is turned off when the second switching device is turned on, and the fourth switching device is turned on when the second switching device is turned off.

5. The method according to claim 1, wherein The upper bridge arm circuit of the AC side half-bridge circuit includes a first switching device and a second switching device, and the lower bridge arm circuit of the AC side half-bridge circuit includes a third switching device and a fourth switching device, and the second switching device and the third switching device are respectively connected to the midpoint of the bridge arm of the AC side half-bridge circuit; The second mode includes a second negative mode, wherein the second switching device and the fourth switching device are complementary turned on, the first switching device is turned off after the second switching device is turned off, and the first switching device is turned off in the second The first switching device is turned on before the first switching device is turned on, the second switching device is turned on before the fourth switching device is turned on, and the third switching device is turned off after the fourth switching device is turned off; Switching the control mode of the AC side half-bridge circuit from the first mode to the second mode includes: The control mode of the AC side half-bridge circuit is switched from the first mode to the second negative mode.

6. The method according to claim 5, wherein: The second negative mode further includes: The third switching device is turned on when the first switching device is turned off, and the third switching device is turned off when the first switching device is turned on.

7. The method according to claim 2, wherein: The second mode includes a second positive mode and a second negative mode, and 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 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; Switching the control mode of the AC side half-bridge circuit from the second positive mode to the second negative mode; The method further includes: when a negative half cycle of the AC side voltage satisfies a switching exit condition, switching the control mode of the AC side half-bridge circuit from the second negative mode to the first mode; The switching exit condition includes: the absolute value of the AC voltage of the AC side power grid increases from less than the voltage threshold to the voltage threshold, or a preset zero-crossing end phase, or a preset zero-crossing end time.

8. The method according to claim 7, wherein: 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 further 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; Switching the control mode of the AC side half-bridge circuit from the second negative mode to the second positive mode; The method further comprises: When the positive half cycle of the AC side voltage meets the switching exit condition, the control mode of the AC side half-bridge circuit is switched from the second positive mode to the first mode.

9. A converter, wherein: The converter includes an AC side half-bridge circuit and a controller; The controller is used to switch the AC side half-bridge circuit when the AC side half-bridge circuit meets the zero-crossing switching condition. The control mode is switched from the first mode to the second mode, in which the switching devices located in the same bridge arm are turned on or off in a preset order, and the corresponding switching devices located in different bridge arms are turned on complementarily.

10. A chip comprising a memory and a processor, wherein the memory stores a computer program, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

Images