Converter control method, converter control device, converter, and storage medium

Abstract

The application discloses a kind of converter control method, converter control device, converter and storage medium, it is related to converter control field, in determining that the grid voltage of converter input is in positive half cycle and first switch tube is open state and the inverter current on inverter inductance is by positive negative through zero point, control third switch tube open, make the freewheeling path of third switch tube open in advance, avoid inverter current continuous decline;In determining that grid voltage is in negative half cycle and fourth switch tube is open state and the inverter current on converter is by negative positive through zero point, control second switch tube open, make the freewheeling path of second switch tube open in advance, avoid inverter current continuous rise.Through second switch tube and third switch tube open in advance make inverter inductance work in intermittent mode, inhibit the ripple current on inverter inductance, guarantee the sinusoidal degree of the output current of converter, to improve the power quality of converter output at light load.

Description

Technical Field

[0001] This invention relates to the field of converter control, and in particular to a converter control method, a converter control device, a converter, and a storage medium. Background Technology

[0002] In related technologies, when controlling a converter, the switching transistors in the converter are turned on or off according to a fixed switching cycle. When the converter is in light-load mode, the control method in related technologies will cause the inverter inductor in the converter to operate in continuous mode. This results in a longer freewheeling time of the inverter inductor under the influence of the grid voltage. After the inverter inductor freewheels, the output current of the converter changes from positive to negative, that is, it drops to 0 in the reverse direction. Furthermore, since the freewheeling transistor in the converter is not turned off, the inverter inductor continues to freewheel, and the reverse current continues to increase. This leads to a further increase in the ripple current of the inverter inductor, which is detrimental to the sinusoidal nature of the converter's output current and affects the power quality of the converter output under light load. Summary of the Invention

[0003] The purpose of this invention is to provide a converter control method, converter control device, converter, and storage medium that can suppress ripple current on the inverter inductor, ensure the sinusoidal nature of the converter's output current, and thus improve the power quality of the converter output under light load conditions.

[0004] To solve the above-mentioned technical problems, the present invention provides a converter control method, wherein the converter includes a first switch, a second switch, a third switch, a fourth switch, a first diode, a second diode, and an inverter inductor; the first to fourth switches are connected in series, and the two ends of the series circuit are used to input the grid voltage; one end of the series circuit of the first and second diodes is connected to the common terminal of the first and second switches, and the other end is connected to the common terminal of the third and fourth switches; the common terminal of the second and third switches is connected to the first end of the inverter inductor.

[0005] The converter control method includes:

[0006] When it is determined that the grid voltage is in the positive half-cycle, the first switch is in the off state, and the inverter current on the inverter inductor passes through zero from positive to negative, the third switch is controlled to be turned off.

[0007] When it is determined that the grid voltage is in the negative half-cycle, the fourth switch is in the off state, and the inverter current on the inverter passes through zero from negative to positive, the second switch is controlled to turn off.

[0008] Preferred options also include:

[0009] A first drive signal is generated according to the direction of the grid voltage to control the conduction state of the first switch, and the first drive signal is output to the control terminal of the first switch.

[0010] The first driving signal switches between high and low levels at a first preset frequency during the positive half-cycle of the grid voltage and remains at a low level during the negative half-cycle of the grid voltage.

[0011] Preferably, when it is determined that the grid voltage is in the positive half-cycle, the first switch is off, and the inverter current on the inverter inductor crosses zero from positive to negative, controlling the third switch to turn off includes:

[0012] Generate a third initial drive signal whose potential is opposite to that of the first drive signal;

[0013] A first logic signal is generated, and the first logic signal is low when the third initial drive signal is high and the inverter current is less than 0;

[0014] The signal obtained by ANDing the third initial driving signal and the first logic signal is used as the third driving signal;

[0015] The third drive signal is output to the control terminal of the third switch to control the switching state of the third switch.

[0016] Preferred options also include:

[0017] A fourth driving signal is generated according to the direction of the grid voltage to control the conduction state of the fourth switch, and the fourth driving signal is output to the control terminal of the fourth switch.

[0018] The fourth driving signal remains at a low level during the positive half-cycle of the grid voltage and switches between high and low levels at a second preset frequency during the negative half-cycle of the grid voltage.

[0019] Preferably, when it is determined that the grid voltage is in the negative half-cycle, the fourth switch is in the off state, and the inverter current on the inverter crosses zero from negative to positive, controlling the second switch to turn off includes:

[0020] Generate a second initial drive signal whose potential is opposite to that of the fourth drive signal;

[0021] A second logic signal is generated, and the second logic signal is low when the second initial drive signal is high and the inverter current is greater than 0;

[0022] The signal obtained by ANDing the second initial drive signal and the second logic signal is used as the second drive signal;

[0023] The second drive signal is output to the control terminal of the second switch to control the switching state of the second switch.

[0024] Preferred options also include:

[0025] When the grid voltage is in the positive half-cycle, if the first switch is in the on state and / or the inverter current on the inverter inductor does not pass through zero from positive to negative, the third switch is controlled to be complementary to the first switch.

[0026] When the grid voltage is in the negative half-cycle, if the fourth switch is in the on state and / or the inverter current on the inverter inductor does not cross zero from negative to positive, the fourth switch is controlled to conduct in a complementary manner with the second switch.

[0027] To address the aforementioned technical problems, this application also provides a converter control device, comprising:

[0028] Memory, used to store computer programs;

[0029] A processor is used to implement the steps of any of the above-described converter control methods when executing the computer program.

[0030] To solve the above-mentioned technical problems, this application also provides a converter, including the above-mentioned converter control device, and further including a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first diode, a second diode, and an inverter inductor;

[0031] The first to the fourth switching transistors are connected in series, and the two ends of the circuit formed by the series connection are used to input the mains voltage; one end of the circuit formed by the first and second diodes connected in series is connected to the common terminal of the first and second switching transistors, and the other end is connected to the common terminal of the third and fourth switching transistors; the common terminal of the second and third switching transistors is connected to the first end of the inverter inductor.

[0032] Preferably, it also includes a filter capacitor and a filter inductor;

[0033] The first end of the filter capacitor and the first end of the filter inductor are connected, and the common terminal of the connection is connected to the second end of the inverter inductor. The second end of the filter inductor is connected to the common terminal of the first diode and the second diode. The second end of the filter inductor and the second end of the filter capacitor serve as the output terminal of the converter.

[0034] To address the aforementioned technical problems, this application also provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described converter control methods.

[0035] The beneficial effects of this application lie in providing a converter control method, converter control device, converter, and storage medium. When the grid voltage input to the converter is determined to be in the positive half-cycle, the first switch is off, and the inverter current on the inverter inductor crosses zero from positive to negative, the third switch is controlled to open, thus disconnecting the freewheeling path of the third switch in advance and preventing the inverter current from continuously decreasing. When the grid voltage is determined to be in the negative half-cycle, the fourth switch is off, and the inverter current on the converter crosses zero from negative to positive, the second switch is controlled to open, thus disconnecting the freewheeling path of the second switch in advance and preventing the inverter current from continuously increasing. By opening the second and third switches in advance, the inverter inductor operates in discontinuous mode, suppressing the ripple current on the inverter inductor and ensuring the sinusoidal nature of the converter's output current, thereby improving the power quality of the converter output under light load conditions. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A first flowchart of a converter control method provided by the present invention;

[0038] Figure 2 This is a second flowchart of a converter control method provided by the present invention;

[0039] Figure 3 This is a switching transistor drive logic diagram for a converter control method in the prior art.

[0040] Figure 4 A switching transistor driving logic diagram for a converter control method provided by the present invention;

[0041] Figure 5 A circuit diagram of a converter provided by the present invention;

[0042] Figure 6 This is a schematic diagram of the structure of a converter control device provided by the present invention. Detailed Implementation

[0043] The core of this invention is to provide a converter control method, a converter control device, a converter, and a storage medium, which can suppress ripple current on the inverter inductor, ensure the sinusoidal nature of the converter's output current, and thus improve the power quality of the converter output under light load conditions.

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Please refer to Figure 1 , Figure 1 This is a first flowchart of a converter control method provided by the present invention, the converter control method comprising:

[0046] S1: When it is determined that the grid voltage is in the positive half-cycle, the first switch Q1 is in the off state, and the inverter current on the inverter inductor L1 passes through zero from positive to negative, the third switch Q3 is controlled to be turned off.

[0047] S2: When it is determined that the grid voltage is in the negative half-cycle, the fourth switch Q4 is in the off state, and the inverter current on the inverter passes through zero from negative to positive, the second switch Q2 is controlled to open.

[0048] The converter control method provided in this application controls a converter; please refer to [reference needed]. Figure 5 , Figure 5 The present invention provides a circuit diagram of a converter, which includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a first diode D1, a second diode D2, and an inverter inductor L1; the first to fourth switches are connected in series, and the two ends of the series circuit are used to input the grid voltage; one end of the series circuit of the first diode D1 and the second diode D2 is connected to the common terminal of the first switch Q1 and the second switch Q2, and the other end is connected to the common terminal of the third switch Q3 and the fourth switch Q4; the common terminal of the second switch Q2 and the third switch Q3 is connected to the first end of the inverter inductor L1.

[0049] In related technologies, when controlling the inverter, the inductance of the inverter inductor L1 decreases relatively when the inverter is under light load, resulting in a relatively large ripple current on the inverter inductor L1. Furthermore, in these technologies, since the inverter inductor L1 operates continuously, the inverter current changes from negative to positive and continues to rise when the first switch Q1 is turned on; when the first switch Q1 is turned off, the inverter current gradually decreases to 0 due to the freewheeling current of the second switch Q2. And because the third switch Q3 remains on, the inverter current, under the influence of the grid voltage, gradually changes from 0 to negative through the freewheeling current of the third switch Q3 and the second diode D2. This prevents the inverter's output current from forming a sinusoidal envelope, resulting in relatively low power quality. The waveform diagram of the inverter's output current, i.e., the inverter current on the inverter inductor L1, in these technologies can be found in [reference needed]. Figure 3 , Figure 3 This is a diagram of the switching transistor drive logic in a current converter control method. Figure 3 Vge-Q1 to Vge-Q4 are the drive signals corresponding to the first switch Q1 to the fourth switch Q4, respectively. iL corresponds to the inverter current. It can be seen that the direction of the inverter current changes continuously in both the positive and negative half-cycles of the grid voltage, without forming a sinusoidal envelope, resulting in low power quality of the converter output.

[0050] Therefore, in this application, when the inverter is under light load, the freewheeling path of the third switch Q3 is disconnected in advance when the first switch Q1 is off, and the freewheeling path of the second switch Q2 is disconnected in advance when the fourth switch Q4 is off, so that the inverter inductor L1 operates in discontinuous mode.

[0051] Specifically, in this application, the conduction state of the third switch Q3 is controlled by considering three conditions: the direction of the grid voltage, the conduction state of the first switch Q1, and the direction of the inverter current. When the grid voltage is in the positive half-cycle, if the first switch Q1 is off, to prevent the inverter current from continuously decreasing and changing from positive to negative due to the effect of the third switch Q3, the third switch Q3 is immediately turned off when the inverter current crosses zero from positive to negative, thereby disconnecting the freewheeling circuit. Similarly, in this application, the conduction state of the second switch Q2 is controlled by considering three conditions: the direction of the grid voltage, the conduction state of the fourth switch Q4, and the direction of the inverter current. When the grid voltage is in the negative half-cycle, if the fourth switch Q4 is off, to prevent the inverter current from continuously increasing and changing from negative to positive due to the effect of the fourth switch Q4, the second switch Q2 is immediately turned off when the inverter current crosses zero from negative to positive, thereby disconnecting the freewheeling circuit and preventing the inverter current from continuously increasing. By prematurely disconnecting the second switch Q2 and the third switch Q3, the inverter inductor L1 operates in discontinuous mode, suppressing the ripple current on the inverter inductor L1, ensuring the sinusoidal nature of the converter's output current, and thus improving the power quality of the converter output under light load conditions.

[0052] Controlling each switch in the converter can be achieved by outputting drive signals to the control terminals of each switch. In the following embodiments, the switch is turned on when its control terminal is high and turned off when its control terminal is low. The generation process of the drive signals for each switch in this application is described in detail below:

[0053] As a preferred embodiment, it also includes:

[0054] A first drive signal is generated according to the direction of the grid voltage to control the conduction state of the first switch Q1, and the first drive signal is output to the control terminal of the first switch Q1.

[0055] The first driving signal switches between high and low levels at a first preset frequency during the positive half-cycle of the grid voltage and remains at a low level during the negative half-cycle of the grid voltage.

[0056] To enable the converter to perform basic power conversion functions, in this embodiment, the first switching transistor Q1 is controlled to switch its conduction state at a first preset frequency during the positive half-cycle of the grid voltage, and is kept off during the negative half-cycle of the grid voltage. Correspondingly, the first driving signal used to control the conduction state of the first switching transistor Q1 switches between high and low levels at the first preset frequency during the positive half-cycle of the grid voltage, and remains at a low level during the negative half-cycle of the grid voltage. The specific value of the first preset frequency can be set according to actual needs, and this application does not impose any particular limitation.

[0057] As a preferred embodiment, when it is determined that the grid voltage is in the positive half-cycle, the first switch Q1 is off, and the inverter current on the inverter inductor L1 crosses zero from positive to negative, controlling the third switch Q3 to turn off includes:

[0058] Generate a third initial drive signal whose potential is opposite to that of the first drive signal;

[0059] A first logic signal is generated, and the first logic signal is low when the third initial drive signal is high and the inverter current is less than 0.

[0060] The signal obtained by ANDing the third initial drive signal and the first logic signal is used as the third drive signal;

[0061] The third drive signal is output to the control terminal of the third switch Q3 to control the switching state of the third switch Q3.

[0062] In this embodiment, a third initial drive signal is first generated based on a first drive signal used to control the conduction state of the first switch Q1. In the normal control mode, the first switch Q1 and the third switch Q3 are complementary in conduction, therefore the potential of the third initial drive signal is opposite to that of the first drive signal. Then, to ensure that the third switch Q3 can be turned off early, a first logic signal is also generated in this embodiment. The first logic signal is low when the third initial drive signal is high and the inverter current is less than 0, thus ensuring that the AND operation between the first logic signal and the third initial drive signal results in a low level. Finally, the signal obtained by ANDing the third initial drive signal and the first logic signal is used as the third drive signal to control the on / off state of the third switch Q3.

[0063] As a preferred embodiment, it also includes:

[0064] A fourth drive signal is generated based on the direction of the grid voltage to control the conduction state of the fourth switch Q4, and the fourth drive signal is output to the control terminal of the fourth switch Q4.

[0065] The fourth driving signal remains at a low level during the positive half-cycle of the grid voltage and switches between high and low levels at a second preset frequency during the negative half-cycle of the grid voltage.

[0066] To enable the converter to perform basic converter functions, in this embodiment, the fourth switch Q4 is kept off during the positive half-cycle of the grid voltage, and its conduction state is switched at a second preset frequency during the negative half-cycle. Correspondingly, the fourth drive signal used to control the conduction state of the fourth switch Q4 remains at a low level during the positive half-cycle of the grid voltage, and switches between high and low levels at the second preset frequency during the negative half-cycle. The specific value of the second preset frequency can be set according to actual needs, and this application does not impose any particular limitation.

[0067] As a preferred embodiment, when it is determined that the grid voltage is in the negative half-cycle, the fourth switch Q4 is off, and the inverter current on the inverter crosses zero from negative to positive, controlling the second switch Q2 to turn off includes:

[0068] Generate a second initial drive signal whose potential is opposite to that of the fourth drive signal;

[0069] A second logic signal is generated, and the second logic signal is low when the second initial drive signal is high and the inverter current is greater than 0.

[0070] The signal obtained by ANDing the second initial drive signal and the second logic signal is used as the second drive signal;

[0071] The second drive signal is output to the control terminal of the second switch Q2 to control the switching state of the second switch Q2.

[0072] In this embodiment, a second initial drive signal is first generated based on the second drive signal used to control the conduction state of the second switch Q2. In the normal control mode, the second switch Q2 and the fourth switch Q4 are complementary in conduction, therefore the potential of the second initial drive signal is opposite to that of the fourth drive signal. Then, to ensure that the second switch Q2 can be turned off early, a second logic signal is also generated in this embodiment. The second logic signal is low when the second initial drive signal is high and the inverter current is greater than 0, thus ensuring that the AND operation between the second logic signal and the second initial drive signal results in a low level. Finally, the signal obtained by performing the AND operation between the second initial drive signal and the second logic signal is used as the second drive signal to control the on / off state of the second switch Q2.

[0073] As a preferred embodiment, it also includes:

[0074] When the grid voltage is in the positive half cycle, if the first switch Q1 is in the on state and / or the inverter current on the inverter inductor L1 does not pass through zero from positive to negative, the third switch Q3 is controlled to be complementary to the first switch Q1.

[0075] When the grid voltage is in the negative half-cycle, if the fourth switch Q4 is in the on state and / or the inverter current on the inverter inductor L1 does not cross the zero point from negative to positive, the fourth switch Q4 and the second switch Q2 are controlled to conduct complementaryly.

[0076] When the converter is under heavy load, the ripple current of the inverter inductor L1 will not continuously increase due to freewheeling, thus avoiding the problem of affecting the sinusoidal nature of the converter's output current and the power quality of the converter output. Therefore, the third switch Q3 and the fourth switch Q4 do not need to be turned off prematurely. In this embodiment, when the grid voltage is in the positive half-cycle, if the first switch Q1 is in the on state and / or the inverter current on the inverter inductor L1 has not crossed zero from positive to negative, the third switch Q3 is controlled to conduct complementaryly with the first switch Q1. When the first switch Q1 is in the on state, the inverter inductor L1 will not freewheel, and since the sinusoidal nature of the inverter current is not temporarily affected when the inverter current has not crossed zero from positive to negative, no intervention is required temporarily. When the grid voltage is in the negative half-cycle, if the fourth switch Q4 is in the on state and / or the inverter current on the inverter inductor L1 has not crossed zero from negative to positive, the fourth switch Q4 is controlled to conduct complementaryly with the second switch Q2. When the fourth switch Q4 is in the on state, the inverter inductor L1 will not freewheel. When the inverter does not cross zero from negative to positive, the sinusoidal nature of the inverter current is not affected, so no intervention is required for the time being.

[0077] Please refer to Figure 4 , Figure 4 This invention provides a switching transistor drive logic diagram for a converter control method. Figure 4 In the diagram, Vge-Q1 and Vge-Q4 are the first and second driving signals, respectively; Vge-Q2-Calc is the second initial driving signal; Vge-Q2-final is the second driving signal; Vge-Q3-Calc is the third initial driving signal; and Vge-Q3-final is the third driving signal. The triangular wave corresponding to iL is the inverter current, and the sine wave corresponding to iL is the output current after the inverter current has been filtered by the filter inductor L2 and the filter capacitor C1.

[0078] Please refer to the above control process. Figure 2 , Figure 2 This is a second flowchart of a converter control method provided by the present invention. Figure 2 The SVPWM waveform refers to the first drive signal, second initial drive signal, third initial drive signal, and fourth drive signal in the above embodiment. With the control method in this embodiment, the converter can ensure output power quality even under light load and operate normally under heavy load.

[0079] It should also be noted that the above-mentioned converter control method, by disconnecting the switching transistors in the converter in advance to make the inverter inductor operate in discontinuous mode, suppresses the ripple current on the inverter inductor, and ensures the sinusoidal nature of the converter's output current, thereby improving the power quality of the converter output under light load, is applicable to NPC topology converters, ANPC topology converters, three-phase converters, and single-phase converters, etc. The switching transistors that need to be disconnected in advance can be determined according to the actual topology of the converter.

[0080] Please refer to Figure 6 , Figure 6 This is a schematic diagram of a converter control device provided by the present invention. The converter control device includes:

[0081] Memory 1 is used to store computer programs;

[0082] Processor 2 is used to implement the steps of any of the above-described converter control methods when executing a computer program.

[0083] For a detailed description of the converter control device provided in this application, please refer to the embodiments of the converter control method described above; this application will not repeat the details here.

[0084] Please refer to Figure 5 , Figure 5The present invention provides a circuit diagram of a converter, which includes the converter control device described above, and further includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, a first diode D1, a second diode D2, and an inverter inductor L1;

[0085] The first to fourth switching transistors are connected in series, and the two ends of the circuit after series connection are used to input the mains voltage; the first diode D1 and the second diode D2 are connected in series, and one end of the circuit after series connection is connected to the common terminal of the first switching transistor Q1 and the second switching transistor Q2, and the other end is connected to the common terminal of the third switching transistor Q3 and the fourth switching transistor Q4; the common terminal of the second switching transistor Q2 and the third switching transistor Q3 is connected to the first end of the inverter inductor L1.

[0086] The converter control method implemented by the converter control device is applicable to NPC topology converters, ANPC topology converters, three-phase converters, and single-phase converters. This embodiment uses... Figure 5 Taking the NPC topology converter shown as an example, the converter provided in this embodiment includes first switching transistors Q1 to fourth switching transistors Q4, two diodes, inverter inductor L1, and a converter control device for controlling the on / off state of each switching transistor. By controlling the second switching transistor Q2 and the third switching transistor Q3 to turn off in advance through the converter control device, the inverter inductor L1 operates in discontinuous mode, suppressing the ripple current on the inverter inductor L1, ensuring the sinusoidal nature of the converter's output current, and thus improving the power quality of the converter output under light load conditions.

[0087] Based on the above embodiments:

[0088] In a preferred embodiment, a filter capacitor C1 and a filter inductor L2 are also included;

[0089] The first end of the filter capacitor C1 is connected to the first end of the filter inductor L2, and the common terminal of the connection is connected to the second end of the inverter inductor L1. The second end of the filter inductor L2 is connected to the common terminal of the first diode D1 and the second diode D2. The second end of the filter inductor L2 and the second end of the filter capacitor C1 serve as the output terminals of the converter.

[0090] Please refer to Figure 5 , Figure 5 A circuit diagram of a converter provided by the present invention. Figure 5 C1 and L2 in the diagram represent the filter capacitor C1 and filter inductor L2, respectively. Through the control of the converter control device, the inverter current is made discontinuous. After being filtered by the subsequent filter capacitor C1 and filter inductor L2, the overall inverter current forms a sinusoidal current with a sinusoidal envelope. The converter's output current has a higher sinusoidal strength, further reducing harmonics in the grid current under light load and improving the power quality of the converter output.

[0091] To solve the above-mentioned technical problems, this application also provides a storage medium on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of any of the above-mentioned converter control methods.

[0092] For a detailed description of the storage medium provided in this application, please refer to the embodiments of the converter control method described above; this application will not repeat the details here.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0094] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0095] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

Claims

1. A converter control method, characterized in that, The converter includes a first switch, a second switch, a third switch, a fourth switch, a first diode, a second diode, and an inverter inductor; the first to fourth switches are connected in series, and the two ends of the series circuit are used to input the grid voltage; one end of the series circuit of the first and second diodes is connected to the common terminal of the first and second switches, and the other end is connected to the common terminal of the third and fourth switches; the common terminal of the second and third switches is connected to the first end of the inverter inductor. The converter control method includes: When it is determined that the grid voltage is in the positive half-cycle, the first switch is in the off state, and the inverter current on the inverter inductor passes through zero from positive to negative, the third switch is controlled to be turned off. When it is determined that the grid voltage is in the negative half-cycle, the fourth switch is in the off state, and the inverter current on the inverter passes through zero from negative to positive, the second switch is controlled to turn off.

2. The converter control method as described in claim 1, characterized in that, Also includes: A first drive signal is generated according to the direction of the grid voltage to control the conduction state of the first switch, and the first drive signal is output to the control terminal of the first switch. The first driving signal switches between high and low levels at a first preset frequency during the positive half-cycle of the grid voltage and remains at a low level during the negative half-cycle of the grid voltage.

3. The converter control method as described in claim 2, characterized in that, When it is determined that the grid voltage is in the positive half-cycle, the first switch is off, and the inverter current on the inverter inductor crosses zero from positive to negative, controlling the third switch to turn off includes: Generate a third initial drive signal whose potential is opposite to that of the first drive signal; A first logic signal is generated, and the first logic signal is low when the third initial drive signal is high and the inverter current is less than 0; The signal obtained by ANDing the third initial driving signal and the first logic signal is used as the third driving signal; The third drive signal is output to the control terminal of the third switch to control the switching state of the third switch.

4. The converter control method as described in claim 1, characterized in that, Also includes: A fourth driving signal is generated according to the direction of the grid voltage to control the conduction state of the fourth switch, and the fourth driving signal is output to the control terminal of the fourth switch. The fourth driving signal remains at a low level during the positive half-cycle of the grid voltage and switches between high and low levels at a second preset frequency during the negative half-cycle of the grid voltage.

5. The converter control method as described in claim 4, characterized in that, When it is determined that the grid voltage is in the negative half-cycle, the fourth switch is in the off state, and the inverter current on the inverter crosses zero from negative to positive, controlling the second switch to turn off includes: Generate a second initial drive signal whose potential is opposite to that of the fourth drive signal; A second logic signal is generated, and the second logic signal is low when the second initial drive signal is high and the inverter current is greater than 0; The signal obtained by ANDing the second initial drive signal and the second logic signal is used as the second drive signal; The second drive signal is output to the control terminal of the second switch to control the switching state of the second switch.

6. The converter control method according to any one of claims 1 to 5, characterized in that, Also includes: When the grid voltage is in the positive half-cycle, if the first switch is in the on state and / or the inverter current on the inverter inductor does not pass through zero from positive to negative, the third switch is controlled to be complementary to the first switch. When the grid voltage is in the negative half-cycle, if the fourth switch is in the on state and / or the inverter current on the inverter inductor does not cross zero from negative to positive, the fourth switch is controlled to conduct in a complementary manner with the second switch.

7. A converter control device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the steps of the converter control method as described in any one of claims 1 to 6.

8. A converter, characterized in that, The converter control device as described in claim 7 further includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first diode, a second diode, and an inverter inductor; The first to the fourth switching transistors are connected in series, and the two ends of the circuit formed by the series connection are used to input the mains voltage; one end of the circuit formed by the first and second diodes connected in series is connected to the common terminal of the first and second switching transistors, and the other end is connected to the common terminal of the third and fourth switching transistors; the common terminal of the second and third switching transistors is connected to the first end of the inverter inductor.

9. The converter as described in claim 8, characterized in that, It also includes filter capacitors and filter inductors; The first end of the filter capacitor and the first end of the filter inductor are connected, and the common terminal of the connection is connected to the second end of the inverter inductor. The second end of the filter inductor is connected to the common terminal of the first diode and the second diode. The second end of the filter inductor and the second end of the filter capacitor serve as the output terminal of the converter.

10. A storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the steps of the converter control method as described in any one of claims 1 to 6.

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