Converter control circuit, converter and charging pile

Abstract

The embodiment of the invention relates to the technical field of electric power, in particular to a converter control circuit, a converter and a charging pile. The converter control circuit and the converter comprise the coupling unit, the power conversion unit, the bus unit and the control unit, one path of input of alternating current is converted into two paths or multiple paths of output by additionally arranging the coupling unit, in the multiple paths of output, current is isolated and equally divided, and the output current of the power conversion unit is improved. Meanwhile, the internal structure of the coupling unit suppresses the circulating current in the converter, and the circulating current loss in the power conversion unit is reduced. Furthermore, the power conversion unit is provided with a plurality of T-shaped three-level inversion units, so that a multi-level technology is realized, multi-voltage level is provided, and multi-level output can remarkably reduce harmonic content of output voltage and current, reduce current ripples and improve electric energy quality.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electrical equipment control technology, and specifically to a converter control circuit, a converter and a charging pile. Background Art

[0002] With the increasingly prominent contradiction between fuel supply and demand and the increasing attention paid to environmental protection, in order to achieve the implementation of the "dual carbon" goal, the promotion and application of electric vehicles has developed rapidly, and more and more companies are participating in the construction and operation of DC charging piles and energy storage power stations. In charging piles and energy storage power stations, the requirements for converters are getting higher and higher. Converters are now developing in the direction of high power, high power factor and high efficiency. High efficiency can be achieved by increasing the number of parallel semiconductor devices, increasing the frequency to reduce the size of inductive devices and reducing the switching frequency.

[0003] The inventors of the present application have found in their research that connecting power switches in parallel in a converter can reduce the required current rate, but may cause current imbalance and large current ripple, thereby affecting the performance of the converter. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide a converter control circuit, a converter and a charging pile to solve the above technical problems existing in the prior art.

[0005] In one embodiment of the present application, a converter control circuit is provided, comprising a coupling unit, a power conversion unit, a bus unit and a control unit;

[0006] The coupling unit includes a first winding, the first winding includes a first same-name end, a first different-name end, a second same-name end and a second different-name end; the first same-name end and the second different-name end are electrically connected to the alternating current unit;

[0007] The power conversion unit includes a first T-type three-level inverter unit and a second T-type three-level inverter unit; the first opposite-name terminal is electrically connected to the input terminal of the first T-type three-level inverter unit; the second same-name terminal is electrically connected to the input terminal of the second T-type three-level inverter unit;

[0008] The output end of the first T-type three-level inverter unit and the output end of the second T-type three-level inverter unit are electrically connected to the bus unit respectively, and the bus unit is electrically connected to the DC unit;

[0009] The output end of the control unit is electrically connected to the control end of the first T-type three-level inverter unit and the control end of the second T-type three-level inverter unit respectively; the control unit is used to generate a control signal to control the first T-type three-level inverter unit and the second T-type three-level inverter unit respectively.

[0010] Preferably, in some embodiments, the coupling unit further includes a second winding and a third winding; the power conversion unit further includes a third T-type three-level inverter unit;

[0011] The second winding includes a third like-name terminal, a third different-name terminal, a fourth like-name terminal and a fourth different-name terminal;

[0012] The third winding includes a fifth like-name terminal, a fifth different-name terminal, a sixth like-name terminal and a sixth different-name terminal;

[0013] The fourth opposite-name terminal is electrically connected to the alternating current unit; the third same-name terminal is electrically connected to the first opposite-name terminal;

[0014] The fifth same-name terminal is electrically connected to the fourth same-name terminal; the sixth different-name terminal is electrically connected to the second same-name terminal;

[0015] The third opposite-name terminal is electrically connected to the input terminal of the first T-type three-level inverter unit; the fifth opposite-name terminal is electrically connected to the input terminal of the second T-type three-level inverter unit; and the sixth same-name terminal is electrically connected to the input terminal of the third T-type three-level inverter unit.

[0016] Preferably, in some embodiments, the number of internal winding turns of the first winding, the second winding and the third winding is equal.

[0017] Preferably, in some embodiments, the input end of the control unit is electrically connected to the first opposite-name end and the second same-name end, respectively, for sampling the current signals of the first opposite-name end and the second same-name end, respectively;

[0018] The control unit is further configured to adjust the duty cycle of the control signal according to current sampling signals of the first opposite-name terminal and the second same-name terminal.

[0019] Preferably, in some embodiments, the input end of the control unit is electrically connected to the third opposite-name end, the fifth opposite-name end and the sixth same-name end, respectively, for sampling the current signals of the third opposite-name end, the fifth opposite-name end and the sixth same-name end, respectively;

[0020] The control unit is further used to adjust the duty cycle of the control signal according to the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal.

[0021] Preferably, in some embodiments, the control unit is further configured to adjust the duty cycle of the control signal according to the difference between the current sampling signals of the first opposite-name terminal and the second opposite-name terminal; or,

[0022] The control unit is further configured to adjust the duty cycle of the control signal according to the difference between the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal.

[0023] Preferably, in some embodiments, the control unit further comprises a comparator;

[0024] The comparator is used to compare the current sampling signals of the first opposite-name terminal and the second same-name terminal, or the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal. If the current sampling signals are higher than a first preset threshold of the comparator, the control unit stops sending the control signal to the power conversion unit.

[0025] Preferably, some embodiments further include a protection circuit; the comparator is used to compare the current sampling signals of the first opposite-name terminal and the second same-name terminal, or the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal. If the current sampling signals are higher than a second preset threshold of the comparator, the protection circuit is activated to shut down the power conversion unit, and the first preset threshold is less than the second preset threshold.

[0026] Preferably, in some embodiments, the bus unit includes a first capacitor and a second capacitor; the negative electrode of the first capacitor is electrically connected to the positive electrode of the second capacitor, serving as a neutral point BUSN; the positive electrode of the first capacitor serves as a positive pole BUS+; the negative electrode of the second capacitor serves as a negative pole BUS-;

[0027] The first T-type three-level inverter unit, the second T-type three-level inverter unit and the third T-type three-level inverter unit respectively include a first power switch tube, a second power switch tube, a third power switch tube and a fourth power switch tube;

[0028] The drain of the first power switch tube is electrically connected to the positive pole BUS+ as an output terminal; the source of the first power switch tube is electrically connected to the coupling unit as an input terminal;

[0029] The source of the second power switch tube is electrically connected to the source of the first power switch tube, the drain of the second power switch tube is electrically connected to the drain of the third power switch tube, and the source of the third power switch tube is electrically connected to the neutral point BUSN;

[0030] The drain of the fourth power switch tube is electrically connected to the source of the first power switch tube, and the source of the fourth power switch tube is electrically connected to the negative pole BUS- as an output end;

[0031] The gates of the first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube are respectively electrically connected to the output end of the control unit as control ends.

[0032] On the other hand, an embodiment of the present application further proposes a converter, comprising an alternating current unit and the converter control circuit described in any of the above embodiments; the alternating current unit is electrically connected to the converter control circuit.

[0033] Preferably, the AC power unit includes a three-phase AC power output terminal; the converter control circuit includes multiple coupling units, multiple power conversion units and multiple bus units; the coupling units, the power conversion units and the bus units are connected one by one; the AC power output terminal of each phase is electrically connected to each coupling unit, and the control unit is electrically connected to each power conversion unit.

[0034] According to a third aspect of the embodiments of the present application, a charging pile is further proposed, which includes the converter described in the above embodiments.

[0035] In summary, the converter control circuit, converter and charging pile proposed in the embodiment of the present application convert one input of AC power into two or more outputs by adding a coupling unit. In the multiple outputs, the current is isolated and evenly distributed, thereby increasing the output current of the power conversion unit. At the same time, the internal structure of the coupling unit suppresses the circulating current inside the converter and reduces the circulating current loss inside the power conversion unit. Furthermore, the power conversion unit realizes multi-level technology and provides multiple voltage levels by setting multiple T-type three-level inverter units. The multi-level output can significantly reduce the harmonic content of the output voltage and current, reduce the current ripple, and improve the power quality.

[0036] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present application. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings:

[0038] Figure 1 A schematic diagram of a converter control circuit provided in an embodiment of the present application is shown;

[0039] Figure 2 The structure diagram of the two-phase interleaved control circuit of the converter provided in the embodiment of the present application is shown;

[0040] Figure 3 The positive half-wave control timing diagram provided by the embodiment of the present application is shown;

[0041] Figure 4 The negative half-wave control timing diagram provided in an embodiment of the present application is shown.

[0042] Figure 5 A schematic diagram of sampling signal control provided in an embodiment of the present application is shown;

[0043] Figure 6 A structure diagram of a three-phase interleaved control circuit of a converter provided by another embodiment of the present application is shown;

[0044] Figure 7 A coupling circuit structure diagram provided in an embodiment of the present application is shown;

[0045] Figure 8 The structure diagram of the converter proposed in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0046] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0048] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0049] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0050] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0051] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0052] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0053] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0054] With the popularity of electric vehicles and the increase in charging demand, the technology of charging piles and converters is also constantly improving, and further requirements are placed on the charging speed and efficiency of charging piles to meet the market demand for fast charging. In high-power electric vehicle charging applications, the design of converters needs to consider high efficiency to cope with the challenges brought by high current and high power density.

[0055] The inverter is mainly used as a power conversion device in charging piles, which is responsible for converting the AC power of the power grid into the DC power required by the electric vehicle battery. The DC charging pile has a built-in high-power DC charging module, which can directly convert the AC power of the power grid into DC power, and the output current can be as high as 100A or more. The AC charging pile converts the AC power into DC power for charging through the on-board charger built into the electric vehicle.

[0056] The inventor of the present application has found in his research that in order to improve the working efficiency and power factor of the converter, multiple power switch tubes can be connected in parallel in the converter, and the overall power of the converter can be increased by reducing the required current rate through the parallel power switch tubes. However, in this way, the energy will cause current imbalance during the flow process, and then generate current ripple. The current ripple is mainly caused by the switching action in the converter, which will cause the current to fluctuate when it is turned on and off. This fluctuation not only affects the output quality of the power supply, but may also cause interference to the connected electronic equipment.

[0057] The converter control circuit proposed in the embodiment of the present application can be applied to both rectifiers and inverters, and can realize the bidirectional flow of energy between AC and DC, and can be applied to various application scenarios such as energy storage devices, charging devices, discharging devices, and V2X devices. In the application embodiment, the AC-DC conversion scenario is used as an example for explanation.

[0058] In view of this, the embodiment of the present application proposes a converter control circuit, a converter and a charging pile. The converter control circuit and converter proposed in the embodiment of the present application include a coupling unit, a power conversion unit, a bus unit and a control unit. The embodiment of the present application converts one input of AC power into two or more outputs by adding a coupling unit. In the two or more outputs, the current is isolated and evenly divided, thereby increasing the output current of the power conversion unit. At the same time, the internal structure of the coupling unit suppresses the circulating current inside the converter and reduces the circulating current loss inside the power conversion unit. Furthermore, the power conversion unit realizes multi-level technology by setting multiple T-type three-level inverter units, provides multiple voltage levels, and the multi-level output can significantly reduce the harmonic content of the output voltage and current, reduce the current ripple, and improve the power quality.

[0059] like Figure 1 and Figure 2 As shown, an embodiment of the present application proposes a converter control circuit, which includes a coupling unit 200, a power conversion unit 300, a bus unit 400 and a control unit 500.

[0060] like Figure 1 and Figure 2As shown, the coupling unit 200 includes a first winding Tu1, the first winding Tu1 includes a first same-name terminal A11, a first different-name terminal A12, a second same-name terminal A14 and a second different-name terminal A13; the first same-name terminal A11 and the second different-name terminal A13 are electrically connected to the AC unit 100; the power conversion unit 300 includes a first T-type three-level inverter unit and a second T-type three-level inverter unit; the first different-name terminal A12 is electrically connected to the input end of the first T-type three-level inverter unit; the second same-name terminal A14 is electrically connected to the second T-type three-level inverter unit The input end of the inverter unit is electrically connected; the output end of the first T-type three-level inverter unit and the output end of the second T-type three-level inverter unit are electrically connected to the bus unit 200 respectively, and the bus unit 200 is electrically connected to the DC unit 600; the output end of the control unit 500 is electrically connected to the control end of the first T-type three-level inverter unit and the control end of the second T-type three-level inverter unit respectively; the control unit 500 is used to generate a control signal to control the first T-type three-level inverter unit and the second T-type three-level inverter unit respectively.

[0061] The coupling unit 200 is used to electrically connect with the AC unit 100. The AC unit 100 can be single-phase AC or multi-phase AC, such as three-phase AC. The coupling unit 200 is used to couple the AC output by the AC unit 100 and output multiple current signals. For the convenience of description, in the embodiment of the present application, the AC is single-phase AC as an example. The voltage input of the AC unit 100 is the voltage at point U, and the output is the voltage at point A. Figure 2 As shown, it is a circuit diagram for interleaving the current output by the AC unit in two phases. The coupling unit 200 includes a first winding Tu1, and the first winding Tu1 includes a first same-name terminal A11, a first different-name terminal A12, a second same-name terminal A14, and a second different-name terminal A13. The current at point A output by the AC unit 100 flows in through the first same-name terminal A11, and is electrically connected to the power conversion unit 300 through the first different-name terminal A12; at the same time, the current at point A flows in through the second different-name terminal A13, and is electrically connected to the power change unit through the second same-name terminal A14. Through the first winding Tu1, the current at point A is converted into two outputs, and the current output terminal A1 and the current output terminal A2 are electrically connected to the first T-type three-level inverter unit and the second T-type three-level inverter unit of the power conversion unit 300, respectively. In the internal structure of the first winding Tu1, the number of internal winding turns is the same. In this way, the two currents IA1 and IA2 are isolated and evenly divided. The current values ​​of the currents IA1 and IA2 are the same, and their phases differ by 180 degrees. In this way, the current ripple becomes smaller.

[0062] At the same time, the embodiment of the present application sets the number of winding turns inside the first winding Tu1 to be the same. This internal structure suppresses the circulating current between the A1 current output terminal and the A2 current output terminal, thereby reducing the circulating current loss of the power conversion unit 300. At the same time, in order to further reduce the volume of the coupling unit 200, the winding of the first winding Tu1 can be wound on the same magnetic core device, thereby reducing the volume of the combined application of two magnetic core devices and improving the power density of the first winding Tu1. Furthermore, since the coupling unit 200 isolates and divides the current at point A, the output current passing through the power conversion unit 300 can be increased, achieving a doubling of the power level under the same conditions. At the same time, assuming that the switching frequency of the power switch tube of the power conversion unit 300 is 20kHz, the current frequency of the first winding Tu1 can be 40kHz, which further reduces the design size of the first winding Tu1, facilitates the design of the EMI filter circuit, and improves the power density of the inductive device.

[0063] Corresponding to the two current outputs of the first winding Tu1, the power conversion unit 300 is internally provided with a first T-type three-level inverter unit and a second T-type three-level inverter unit, the first T-type three-level inverter unit and the second T-type three-level inverter unit have the same structure, and are electrically connected to the two output ends of the first winding Tu1 respectively. The T-type three-level inverter unit is a multi-level inverter topology structure, which realizes multi-level output voltage by controlling the upper and lower arm switch states of the voltage. Compared with the traditional two-level inverter, the T-type three-level inverter can output three different levels: positive level, zero level and negative level, thereby providing a higher quality output waveform and higher efficiency during the power conversion process. The T-type three-level inverter circuit is usually composed of two half-bridge inverter units and a neutral point, forming a "T"-shaped circuit topology. Each half-bridge contains two switching elements (such as IGBTs) and corresponding freewheeling diodes. By finely controlling the switching states of the two half-bridges, the T-type three-level inverter unit can generate a five-level voltage waveform at the load end.

[0064] It should be pointed out that the coupling unit 200 can adopt a winding method of different coils of multiple windings to form a one-to-two structure, or it can directly adopt coupled inductors to form a one-to-two structure. In terms of composition and actual use effect, the two are the same. In the embodiments of the present application, the two can be considered to be equivalent implementation methods.

[0065] like Figure 2As shown, the first T-type three-level inverter unit includes a first power switch tube Sa1, a second power switch tube Sa2, a third power switch tube Sa3 and a fourth power switch tube Sa4; the second T-type three-level inverter unit includes a first power switch tube Sb1, a second power switch tube Sb2, a third power switch tube Sb3 and a fourth power switch tube Sb4. The first power switch tube Sa1 and the fourth power switch tube Sa4 of the first T-type three-level inverter unit form a half-bridge inverter unit, and the second power switch tube Sa2 and the third power switch tube Sa3 form another half-bridge inverter unit, wherein point O is a neutral point. The first power switch tube Sb1 and the fourth power switch tube Sb4 of the second T-type three-level inverter unit form a half-bridge inverter unit, and the second power switch tube Sb2 and the third power switch tube Sb3 form another half-bridge inverter unit.

[0066] In the first T-type three-level inverter unit, the source of the first power switch tube Sa1 is electrically connected to the A1 current output terminal of the first winding Tu1 to form a point a; the drain of the first power switch tube Sa1 is electrically connected to the bus unit 200. The drain of the fourth power switch tube Sa4 is electrically connected to the A1 current output terminal of the first winding Tu1, that is, connected to point a, and the source of the fourth power switch tube Sa4 is electrically connected to the bus unit 200. The source of the second power switch tube Sa2 is connected to point a, the drain of the second power switch tube Sa2 is electrically connected to the drain of the third power switch tube Sa3, and the source of the third power switch tube Sa3 is connected to the neutral point O. The gates of the first power switch tube Sa1, the second power switch tube Sa2, the third power switch tube Sa3 and the fourth power switch tube Sa4 are electrically connected to the control unit 500 respectively. Through the above connection mode, the first power switch tube Sa1 and the second power switch tube Sa2 can share a driving power supply, which reduces the volume of the power conversion unit. In order to reduce the loss of each power switch tube, in the embodiment of the present application, the first power switch tube Sa1 and the fourth power switch tube Sa4 can select SiC MOS tube devices, and the second power switch tube Sa2 and the third power switch tube Sa3 can select SiC MOS tube devices or IGBT devices.

[0067] In the second T-type three-level inverter unit, the source of the first power switch tube Sb1 is electrically connected to the A2 current output terminal of the first winding Tu1 to form a point b; the drain of the first power switch tube Sb1 is electrically connected to the bus unit 200. The drain of the fourth power switch tube Sb4 is electrically connected to the A2 current output terminal of the first winding Tu1, that is, connected to point b, and the source of the fourth power switch tube Sb4 is electrically connected to the bus unit 200. The source of the second power switch tube Sb2 is connected to point b, the drain of the second power switch tube Sb2 is electrically connected to the drain of the third power switch tube Sb3, and the source of the third power switch tube Sb3 is connected to the neutral point O. The gates of the first power switch tube Sb1, the second power switch tube Sb2, the third power switch tube Sb3 and the fourth power switch tube Sb4 are electrically connected to the control unit 500 respectively. In order to reduce the loss of each power switch tube, in the embodiment of the present application, the first power switch tube Sb1 and the fourth power switch tube Sb4 can select SiC MOS tube devices, and the second power switch tube Sb2 and the third power switch tube Sb3 can select SiC MOS tube devices or IGBT devices.

[0068] In order to reduce the volume of the power conversion unit, the first power switch tube and the fourth power switch tube, the second power switch tube and the third power switch tube can be packaged into a module, and the lead position of the module can be adjusted according to the layout and wiring optimization requirements of the PCB. The module can be a SiC MOS tube module, or a module combining a SiC MOS tube and an IGBT.

[0069] Continue to refer Figure 2 ,exist Figure 2 In the figure, the bus unit 200 includes a first capacitor C1 and a second capacitor C1; the negative electrode of the first capacitor C1 is electrically connected to the positive electrode of the second capacitor C1, serving as a neutral point BUSN, and the neutral point BUSN is electrically connected to the center point O; the positive electrode of the first capacitor C1 serves as a positive pole BUS+; the negative electrode of the second capacitor C1 serves as a negative pole BUS-.

[0070] Among them, the first capacitor C1 and the second capacitor C1 can be electrolytic capacitors, film capacitors or high-voltage ceramic capacitors, etc. The neutral point BUSN is coupled to the power conversion unit 300 through the first capacitor C1 and the second capacitor C1. The charging and discharging process of the first capacitor C1 and the second capacitor C1 and the switching of the power switch tube in the power conversion unit 300 enable the output voltage to smoothly transition between three different levels, reducing the harmonic content caused by the step waveform in the traditional two-level inverter. At the same time, the first capacitor C1 and the second capacitor C1 can store energy, which can be maintained for half a cycle time when the AC unit is powered off, and can be maintained for half a cycle time when the DC unit 600 is powered off. At the same time, the number of levels from point A to point O is changed from the traditional three levels to five levels, reducing the ripple demand of the bus unit 200 and the number of capacitors required for the bus unit 200, thereby improving the power density of the capacitor.

[0071] The control unit 500 may be a DSP or other MCU unit, which is mainly used to generate a control signal to control the first T-type three-level inverter unit and the second T-type three-level inverter unit respectively, wherein the control signal may be a PWM control signal or other types of control signals. The control end of the control unit 500 is connected to the gates of the first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube in the first T-type three-level inverter unit and the second T-type three-level inverter unit respectively, and by sending a control signal to each power switch tube, the power conversion unit 300 can be accurately controlled to work accurately.

[0072] The control unit 500 adopts a three-level wave generation method, such as Figure 3 As shown, a positive half-cycle wave timing diagram and a voltage waveform diagram at both ends of the coupling unit are shown, wherein the positive half-cycle refers to the situation where the output voltage of the AC unit at point A is in the positive half-cycle.

[0073] For the first T-type three-level inverter unit, Figure 3 In the embodiment of the present application, the control signals of the first power switch tube Sa1 and the third power switch tube Sa3 are in a complementary relationship. At the same time, in order to prevent the power switch tube from being directly connected, in the embodiment of the present application, a dead zone is set between the control signals of the first power switch tube Sa1 and the third power switch tube Sa3. The duration of the dead zone can be set according to the circuit requirements. In the embodiment of the present application, preferably, the dead zone is set to 300ns. The control signal of the second power switch tube Sa2 is a continuous high level, and the control signal of the fourth power switch tube Sa4 is a continuous low level. Therefore, in the positive half cycle, the second power switch tube Sa2 is in a long-on state, and the fourth power switch tube Sa4 is in a long-off state.

[0074] For the second T-type three-level inverter unit, Figure 3 In the embodiment of the present application, the control signals of the first power switch tube Sb1 and the third power switch tube Sb3 are complementary. In order to prevent the power switch tube from being directly connected, in the embodiment of the present application, a dead zone is also set between the control signals of the first power switch tube Sb1 and the third power switch tube Sb3. The duration of the dead zone can be set according to the circuit requirements. In the embodiment of the present application, preferably, the dead zone is set to 300ns. The control signal of the second power switch tube Sb2 is a continuous high level, and the control signal of the fourth power switch tube Sb4 is a continuous low level. Therefore, in the positive half cycle, the second power switch tube Sb2 is in a long-on state, and the fourth power switch tube Sb4 is in a long-off state.

[0075] Depend on Figure 3 From the given control timing, it can be seen that for the first T-type three-level inverter unit, when the gate of the first power switch tube Sa1 is at a low level and the gate of the third power switch tube Sa3 is at a high level, the first power switch tube Sa1 is disconnected. Since the gate of the second power switch tube Sa2 is always at a high level, the third power switch tube Sa3 is turned on, and BUSN is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the first power switch tube Sb1 is at a high level and the gate of the third power switch tube Sb3 is at a low level, the first power switch tube Sb1 is turned on, that is, BUS+ is directly connected to point b, and at this time, the voltage across the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is VBUS-.

[0076] For the first T-type three-level inverter unit, when the gate of the first power switch tube Sa1 is at a high level and the gate of the third power switch tube Sa3 is at a low level, the first power switch tube Sa1 is turned on, and BUS+ is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the first power switch tube Sb1 is at a high level and the gate of the third power switch tube Sb3 is at a low level, the first power switch tube Sb1 is turned on, that is, BUS+ is directly connected to point b, and at this time the voltage at both ends of the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is 0.

[0077] For the first T-type three-level inverter unit, when the gate of the first power switch tube Sa1 is at a high level and the gate of the third power switch tube Sa3 is at a low level, the first power switch tube Sa1 is turned on, and BUS+ is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the first power switch tube Sb1 is at a low level and the gate of the third power switch tube Sb3 is at a high level, since the gate voltage of the second power switch tube Sb2 is always at a high level, the third power switch tube Sb3 is turned on, that is, BUSN is directly connected to point b, and at this time the voltage across the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is VBUS+.

[0078] By analogy, in a complete signal cycle, the voltage across the coupling unit 200 switches between VBUS+, 0, and VBUS-.

[0079] Similarly, in the negative half-cycle, if Figure 4 As shown, a negative half-cycle wave timing diagram and a voltage waveform diagram at both ends of the coupling unit are shown, wherein the negative half-cycle refers to the voltage at point A being in a negative half-cycle state.

[0080] For the first T-type three-level inverter unit, Figure 4 In the embodiment of the present application, the control signals of the second power switch tube Sa2 and the fourth power switch tube Sa4 are in a complementary relationship. At the same time, in order to prevent the power switch tube from being directly connected, in the embodiment of the present application, a dead zone is set between the control signals of the second power switch tube Sa2 and the fourth power switch tube Sa4. The duration of the dead zone can be set according to the circuit requirements. In the embodiment of the present application, preferably, the dead zone is set to 300ns. The control signal of the third power switch tube Sa3 is a continuous high level, and the control signal of the first power switch tube Sa1 is a continuous low level. Therefore, in the negative half cycle, the third power switch tube Sa3 is in a long-on state, and the first power switch tube Sa1 is in a long-off state.

[0081] For the second T-type three-level inverter unit, Figure 4 In the embodiment of the present application, the control signals of the second power switch tube Sb2 and the fourth power switch tube Sb4 are in a complementary relationship. At the same time, in order to prevent the power switch tube from being directly connected, in the embodiment of the present application, a dead zone is set between the control signals of the second power switch tube Sb2 and the fourth power switch tube Sb4. The duration of the dead zone can be set according to the circuit requirements. In the embodiment of the present application, preferably, the dead zone is set to 300ns. The control signal of the fourth power switch tube Sb4 is a continuous high level, and the control signal of the first power switch tube Sb1 is a continuous low level. Therefore, in the negative half cycle, the fourth power switch tube Sb4 is in a long-on state, and the first power switch tube Sb1 is in a long-off state.

[0082] Depend on Figure 4 It can be seen that for the first T-type three-level inverter unit, when the gate of the second power switch tube Sa2 is at a high level and the gate of the fourth power switch tube Sa4 is at a low level, since the gate of the third power switch tube Sa3 is always at a high level, the second power switch tube Sa2 is turned on, and BUSN is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the fourth power switch tube Sb4 is at a high level and the gate of the second power switch tube Sb2 is at a low level, the fourth power switch tube Sb4 is turned on, that is, BUS- is directly connected to point b, and at this time, the voltage at both ends of the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is VBUS+.

[0083] For the first T-type three-level inverter unit, when the gate of the fourth power switch tube Sa4 is at a high level and the gate of the second power switch tube Sa2 is at a low level, the fourth power switch tube Sa4 is turned on, and BUS- is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the second power switch tube Sb2 is at a low level and the gate of the fourth power switch tube S4 is at a high level, the fourth power switch tube Sb4 is turned on, that is, BUS- is directly connected to point b, and at this time the voltage at both ends of the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is 0.

[0084] For the first T-type three-level inverter unit, when the gate of the fourth power switch tube Sa4 is at a high level and the gate of the second power switch tube Sa2 is at a low level, the fourth power switch tube Sa4 is turned on, and BUS- is directly connected to point a; for the second T-type three-level inverter unit, at this time, when the gate of the second power switch tube Sb1 is at a high level and the gate of the fourth power switch tube Sb3 is at a low level, since the gate voltage of the third power switch tube Sb3 is always at a high level, the second power switch tube Sb2 is turned on, that is, BUSN is directly connected to point b, and at this time the voltage at both ends of the coupling unit, that is, the voltage difference between the voltage at point a and the voltage at point b is VBUS-.

[0085] By analogy, in the negative half-cycle of the signal cycle, the voltage across the coupling unit switches between VBUS+, 0, and VBUS-.

[0086] In the above embodiment, the pulse width of the interleaved waves of the control unit 500 must remain consistent, and the control signals of the control unit 500 for the first T-type three-level inverter unit and the second T-type three-level inverter unit can share the same comparison value, and the driving of the fourth power switch tubes Sa4 and Sb4 also shares the comparison value to ensure the consistency of the control signal.

[0087] Furthermore, on the basis of the above-mentioned embodiment, in order to ensure the relative balance between the two paths of staggered parallel connection to the greatest extent, the pulse width of the staggered wave of the control signal output by the control unit needs to be strictly maintained consistent. In the embodiment of the present application, the input end of the control unit is electrically connected to the first opposite-name terminal A12 and the second same-name terminal A14, respectively, for sampling the current signals of the first opposite-name terminal A12 and the second same-name terminal A14, respectively; the control unit adjusts the duty cycle of the control signal according to the current sampling signals of the first opposite-name terminal A12 and the second same-name terminal A14.

[0088] like Figure 5 As shown, IA1 is the sampling value of the output current of the A1 current output terminal, IA2 is the sampling value of the output current of the A2 current output terminal, and the duty cycle Duty of the control signal is adjusted by the proportional integral circuit to generate the adjusted duty cycle Duty_a to ensure the balance of the two circuits.

[0089] Furthermore, in order to improve the accuracy of control, the control unit 500 can also adjust the duty cycle of the control signal according to the difference between the current sampling signals between the first opposite-name terminal A12 and the second like-name terminal A14, taking the difference as an adjustment amount, to ensure that the two currents remain balanced and avoid magnetization and saturation of the coupling unit.

[0090] Furthermore, in some embodiments, the current output by the AC unit 100 may be split in a three-phase interleaving manner. Of course, a four-phase, five-phase or more-phase interleaving manner may also be used. This will not be described one by one in the application embodiments, and only three-phase interleaving will be used as an example for explanation. Figure 1 , Figure 6 and Figure 7 As shown, the coupling unit 200 further includes a second winding Tu2 and a third winding Tu3; the power conversion unit 300 further includes a third T-type three-level inverter unit. The second winding Tu2 includes a third same-name terminal A21, a third different-name terminal A22, a fourth same-name terminal A24 and a fourth different-name terminal A23; the third winding Tu3 includes a fifth same-name terminal A31, a fifth different-name terminal A32, a sixth same-name terminal A34 and a sixth different-name terminal A33; the fourth different-name terminal A23 is electrically connected to the AC power unit 100; the third same-name terminal A21 is electrically connected to the first different-name terminal A12; the fifth same-name terminal A31 is electrically connected to the fourth same-name terminal A24; the sixth different-name terminal A33 is electrically connected to the second same-name terminal A14; the third different-name terminal A22 is electrically connected to the input end of the first T-type three-level inverter unit; the fifth different-name terminal A32 is electrically connected to the input end of the second T-type three-level inverter unit; the sixth same-name terminal A34 is electrically connected to the input end of the third T-type three-level inverter unit.

[0091] like Figure 7As shown, the current at point A output by the AC unit 100 flows into the first same-name terminal A11, passes through the first different-name terminal A12 and the third same-name terminal A21, flows out through the third different-name terminal A22, and is electrically connected to the input terminal of the first T-type three-level inverter unit through the A1 current output terminal. At the same time, the current at point A output by the AC unit 100 flows into the fourth different-name terminal A23, passes through the fourth same-name terminal A24 and the fifth same-name terminal A31, flows out through the fifth different-name terminal A32, and is electrically connected to the input terminal of the second T-type three-level inverter unit through the A2 current output terminal. At the same time, the current at point A output by the AC unit 100 flows into the second different-name terminal A13, passes through the second same-name terminal A14 and the sixth different-name terminal A33, flows out through the sixth same-name terminal A34, and is electrically connected to the input terminal of the third T-type three-level inverter unit through the A3 current output terminal. In the internal structure of the first winding Tu1, the second winding Tu2 and the third winding Tu3, the number of turns of the windings inside is the same. In this way, the three currents IA1, IA2 and IA3 are isolated and evenly divided. The current values ​​of the currents IA1, IA2 and IA3 are the same, and the phase difference is 120 degrees, and the current ripple is reduced. The internal structure of the coupling unit suppresses the circulating currents between IA1 and IA2, between IA2 and IA3, and between IA1 and IA3, thereby reducing the circulating current loss inside the power conversion unit 300.

[0092] It should be pointed out that the coupling unit 200 can adopt a winding method of different coils of multiple windings to form a one-to-three structure, or directly adopt multiple coupled inductors to form a one-to-three structure to replace the above-mentioned first winding Tu1, second winding Tu2 and third winding Tu3. For example, the first coupled inductor, the second coupled inductor and the third coupled inductor are used to form the above-mentioned one-to-three structure, or to form a one-to-many structure. In terms of composition and actual use effect, the two are the same. In the embodiments of the present application, the two can be considered to be equivalent implementation methods.

[0093] Continue to refer to the attached Figure 6 In the power conversion unit 300, a first T-type three-level inverter unit, a second T-type three-level inverter unit and a third T-type three-level inverter unit are included, wherein the first T-type three-level inverter unit, the second T-type three-level inverter unit and the third T-type three-level inverter unit have the same structure and the same connection method as in the above embodiment. Figure 6 In the embodiment, the third T-type three-level inverter unit includes a first power switch tube Sc1, a second power switch tube Sc2, a third power switch tube Sc3 and a fourth power switch tube Sc4.

[0094] In the third T-type three-level inverter unit, the source of the first power switch tube Sc1 is electrically connected to the A3 current output terminal of the first winding Tu1 to form point c; the drain of the first power switch tube Sc1 is electrically connected to the bus unit 200. The drain of the fourth power switch tube Sc4 is electrically connected to the A3 current output terminal of the first winding Tu1, that is, connected to point c, and the source of the fourth power switch tube Sc4 is electrically connected to the bus unit 200. The source of the second power switch tube Sc2 is connected to point c, the drain of the second power switch tube Sc2 is electrically connected to the drain of the third power switch tube Sc3, and the source of the third power switch tube Sc3 is connected to the neutral point O. The gates of the first power switch tube Sc1, the second power switch tube Sc2, the third power switch tube Sc3 and the fourth power switch tube Sc4 are electrically connected to the control unit respectively.

[0095] At the same time, the control unit controls the logic of the third T-type three-level inverter unit through the control signal. It should be noted that the timing of the control unit 500 controlling the third T-type three-level inverter unit through the control signal is the same as Figure 3 and Figure 4 The timing sequence in is similar to that in the embodiment, and the voltage value at both ends of the coupling unit is also similar to the level value at both ends of the coupling unit in the above embodiment, which will not be repeated here.

[0096] In the above embodiment, the pulse width of the interleaved waves of the control unit 500 must be kept consistent, and the control signals of the control unit for the first T-type three-level inverter unit, the second T-type three-level inverter unit and the third T-type three-level inverter unit can share the same comparison value, and the driving of the fourth power switch tubes Sa4, Sb4 and Sc4 also shares the comparison value to ensure the consistency of the control signal.

[0097] Furthermore, on the basis of the above-mentioned embodiment, in order to ensure the relative balance between the three paths of staggered parallel connection to the greatest extent, the pulse width of the staggered wave of the control signal output by the control unit needs to be strictly maintained consistent. In the embodiment of the present application, the input end of the control unit is electrically connected to the third opposite-name terminal A22, the fifth opposite-name terminal A32 and the sixth same-name terminal A34, respectively, for sampling the current signals of the third opposite-name terminal A22, the fifth opposite-name terminal A32 and the sixth same-name terminal A34, respectively; the control unit is also used to adjust the duty cycle of the control signal according to the current sampling signals of the third opposite-name terminal A22, the fifth opposite-name terminal A32 and the sixth same-name terminal A34.

[0098] IA1 is the sampling value of the output current of the A1 current output terminal, IA2 is the sampling value of the output current of the A2 current output terminal, and IA3 is the sampling value of the output current of the A3 current output terminal. The duty cycle Duty of the control signal is adjusted through the proportional integral circuit to generate the adjusted duty cycle Duty_a to ensure the balance of the two circuits.

[0099] Furthermore, in order to improve the accuracy of control, the control unit 500 can also adjust the duty cycle of the control signal according to the difference between the current sampling signals of the third opposite-name terminal A22, the fifth opposite-name terminal A32 and the sixth same-name terminal A34, taking the difference as an adjustment amount to ensure that the two currents remain balanced and avoid magnetization and saturation of the coupling unit.

[0100] Furthermore, in some scenarios, the coupling unit 200 may be saturated. When the coupling unit 200 is saturated, it will cause excessive current, which will further damage the power switch tube of the power conversion unit 300. Therefore, in the embodiment of the present application, it is proposed to protect the power switch tube of the power conversion unit 300. In the embodiment of the present application, the control unit 500 also includes a comparator; the comparator is used to compare the current sampling signal of the first different-name terminal A12 and the second same-name terminal A14, or the current sampling signal of the third different-name terminal A22, the fifth different-name terminal A32 and the sixth same-name terminal A34. If it is higher than the first preset threshold of the comparator, the control unit stops sending the control signal to the power conversion unit; if it is higher than the second preset threshold of the comparator, the protection circuit is started to shut down the power conversion unit, and the first preset threshold is less than the second preset threshold.

[0101] In the embodiment of the present application, for the lower level overcurrent protection measures, the control is performed through the comparator of the control unit 500. If the value of the sampling signal is higher than the preset first preset threshold, the control unit 500 automatically blocks the drive, that is, stops sending signals to the power conversion unit, so that each power switch tube is in a cut-off state, and starts to send waves again when the sampling signal is lower than the preset first preset threshold. For the higher level overcurrent protection measures, the power conversion unit is protected by the protection circuit of the peripheral device. When the sampling current is higher than the preset second preset threshold, the protection circuit is directly started to protect the power conversion unit. In this way, the stability and safety of the power conversion unit are guaranteed.

[0102] In summary, the converter control circuit provided in the embodiment of the present application converts one input of AC power into two or more outputs by adding a coupling unit. In the multiple outputs, the current is isolated and evenly divided, thereby increasing the output current of the power conversion unit. At the same time, the internal structure of the coupling unit suppresses the circulating current inside the converter, thereby reducing the circulating current loss inside the power conversion unit. At the same time, the power conversion unit realizes multi-level technology by setting a plurality of T-type three-level inverter units, and provides multiple voltage levels. The multi-level output can significantly reduce the harmonic content of the output voltage and current, reduce the current ripple, and improve the power quality.

[0103] Furthermore, in some embodiments, a converter is also proposed, such as Figure 8 As shown, the converter includes an AC unit and a converter control circuit proposed in any of the above embodiments, and the AC unit is electrically connected to the converter control circuit. The AC unit can be single-phase or multi-phase.

[0104] When the AC power unit is three-phase electricity, for example, when the U-phase, V-phase and W-phase outputs are respectively, the converter control circuit includes multiple coupling units, multiple power conversion units and multiple bus units; the coupling units, the power conversion units and the bus units are connected one by one; the AC power output ends of each phase are electrically connected to each coupling unit, and the control unit is electrically connected to each power conversion unit.

[0105] like Figure 8 As shown, the converter notification circuit includes coupling units 200, 210 and 220, power conversion units 300, 310 and 320, and bus units 400, 410 and 420. The coupling unit 200 is electrically connected to the U phase of the AC unit, the coupling unit 210 is electrically connected to the V phase of the AC unit, the coupling unit 220 is electrically connected to the W phase of the AC unit, the control unit 500 is electrically connected to the power conversion units 300, 310 and 320, respectively, and the DC unit 600 is also electrically connected to the bus units 400, 410 and 420, respectively. In the converter, all coupling units and power conversion units are controlled and scheduled by a control unit, and all bus units share an output or input terminal.

[0106] The structures of the coupling units, power conversion units and busbar units are as described in any of the above embodiments, and can be adopted as follows: Figure 2 The two-phase interleaved control method shown in FIG. Figure 6 The three-phase staggered control method shown in FIG. will not be described in detail here.

[0107] In some embodiments, the present application also proposes a charging pile, including the converter proposed in the above embodiments.

[0108] The algorithm or display provided here are not inherently related to any specific computer, virtual system or other equipment. Various general systems can also be used together with the teaching based on this. According to the above description, it is obvious to construct the structure required for this type of system. In addition, the present application embodiment is not directed to any specific programming language yet. It should be understood that various programming languages ​​can be utilized to realize the content of the present application described here, and the above description of specific languages ​​is to disclose the best mode of implementation of the present application.

[0109] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0110] Similarly, it should be understood that in order to streamline the present application and aid in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present application, the various features of the embodiments of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the following intention: that the claimed application requires more features than those explicitly recited in each claim.

[0111] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0112] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be constructed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be understood as limitations on the order of execution.

Claims

1. A converter control circuit, characterized in that: It includes a coupling unit, a power conversion unit, a bus unit and a control unit; The coupling unit includes a first winding, the first winding includes a first same-name end, a first different-name end, a second same-name end and a second different-name end; the first same-name end and the second different-name end are electrically connected to the alternating current unit; The power conversion unit includes a first T-type three-level inverter unit and a second T-type three-level inverter unit; the first opposite-name terminal is electrically connected to the input terminal of the first T-type three-level inverter unit; the second same-name terminal is electrically connected to the input terminal of the second T-type three-level inverter unit; The output end of the first T-type three-level inverter unit and the output end of the second T-type three-level inverter unit are electrically connected to the bus unit respectively, and the bus unit is electrically connected to the DC unit; The output end of the control unit is electrically connected to the control end of the first T-type three-level inverter unit and the control end of the second T-type three-level inverter unit respectively; the control unit is used to generate a control signal to control the first T-type three-level inverter unit and the second T-type three-level inverter unit respectively.

2. The converter control circuit according to claim 1, characterized in that: The coupling unit further includes a second winding and a third winding; the power conversion unit further includes a third T-type three-level inverter unit; The second winding includes a third like-name terminal, a third different-name terminal, a fourth like-name terminal and a fourth different-name terminal; The third winding includes a fifth like-name terminal, a fifth different-name terminal, a sixth like-name terminal and a sixth different-name terminal; The fourth opposite-name terminal is electrically connected to the alternating current unit; the third same-name terminal is electrically connected to the first opposite-name terminal; The fifth same-name terminal is electrically connected to the fourth same-name terminal; the sixth different-name terminal is electrically connected to the second same-name terminal; The third opposite-name terminal is electrically connected to the input terminal of the first T-type three-level inverter unit; the fifth opposite-name terminal is electrically connected to the input terminal of the second T-type three-level inverter unit; and the sixth same-name terminal is electrically connected to the input terminal of the third T-type three-level inverter unit.

3. The converter control circuit according to claim 2, characterized in that: The number of turns of the inner windings of the first winding, the second winding and the third winding is equal.

4. The converter control circuit according to claim 1, characterized in that: The input end of the control unit is electrically connected to the first opposite-name end and the second same-name end respectively, and is used to sample the current signals of the first opposite-name end and the second same-name end respectively; The control unit is further configured to adjust the duty cycle of the control signal according to current sampling signals of the first opposite-name terminal and the second same-name terminal.

5. The converter control circuit according to claim 2, characterized in that: The input end of the control unit is electrically connected to the third different-name end, the fifth different-name end and the sixth same-name end respectively, and is used to sample the current signals of the third different-name end, the fifth different-name end and the sixth same-name end respectively; The control unit is further used to adjust the duty cycle of the control signal according to the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal.

6. The converter control circuit according to claim 4 or 5, characterized in that: The control unit is further configured to adjust the duty cycle of the control signal according to the difference between the current sampling signals of the first opposite-name terminal and the second same-name terminal; or, The control unit is further configured to adjust the duty cycle of the control signal according to the difference between the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal.

7. The converter control circuit according to claim 4 or 5, characterized in that: The control unit also includes a comparator; The comparator is used to compare the current sampling signals of the first opposite-name terminal and the second same-name terminal, or the current sampling signals of the third opposite-name terminal, the fifth opposite-name terminal and the sixth same-name terminal. If the current sampling signals are higher than a first preset threshold of the comparator, the control unit stops sending the control signal to the power conversion unit.

8. The converter control circuit according to claim 7, characterized in that: It also includes protection circuits; The comparator is used to compare the current sampling signals of the first different-name terminal and the second same-name terminal, or the current sampling signals of the third different-name terminal, the fifth different-name terminal and the sixth same-name terminal. If the current sampling signals are higher than the second preset threshold of the comparator, the protection circuit is activated to shut down the power conversion unit. The first preset threshold is less than the second preset threshold.

9. The converter control circuit according to claim 2, characterized in that: The bus unit includes a first capacitor and a second capacitor; the negative electrode of the first capacitor is electrically connected to the positive electrode of the second capacitor, serving as a neutral point BUSN; the positive electrode of the first capacitor serves as a positive pole BUS+; the negative electrode of the second capacitor serves as a negative pole BUS-; The first T-type three-level inverter unit, the second T-type three-level inverter unit and the third T-type three-level inverter unit respectively include a first power switch tube, a second power switch tube, a third power switch tube and a fourth power switch tube; The drain of the first power switch tube is electrically connected to the positive pole BUS+ as an output terminal; the source of the first power switch tube is electrically connected to the coupling unit as an input terminal; The source of the second power switch tube is electrically connected to the source of the first power switch tube, the drain of the second power switch tube is electrically connected to the drain of the third power switch tube, and the source of the third power switch tube is electrically connected to the neutral point BUSN; The drain of the fourth power switch tube is electrically connected to the source of the first power switch tube, and the source of the fourth power switch tube is electrically connected to the negative pole BUS- as an output end; The gates of the first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube are respectively electrically connected to the output end of the control unit as control ends.

10. A converter, characterized in that: comprising an alternating current unit and a converter control circuit as claimed in any one of claims 1 to 9; The AC power unit is electrically connected to the converter control circuit.

11. The converter according to claim 10, characterized in that The AC unit includes a three-phase AC output terminal; The converter control circuit comprises a plurality of coupling units, a plurality of power conversion units and a plurality of bus units; the coupling units, the power conversion units and the bus units are connected in a one-to-one correspondence; The AC output end of each phase is electrically connected to each coupling unit respectively, and the control unit is electrically connected to each power conversion unit respectively.

12. A charging pile, characterized in that: Comprising a converter as described in any one of claims 10-11.

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