Clamping and auxiliary power supply integrated constant-current and constant-voltage converter and starting method thereof

Abstract

The invention discloses a clamping and auxiliary power supply integrated constant-current and constant-voltage converter and a starting method thereof, and belongs to the field of power conversion. The constant-current and constant-voltage converter comprises a main converter and a regenerative clamping circuit; the main converter comprises a reverse blocking H bridge, a main inductor, a main transformer, a reverse conducting H bridge and a main capacitor; the regeneration clamping circuit comprises a diode clamping circuit, a clamping capacitor and a feedback circuit. At least two bridge arms of the reverse blocking H bridge of the main converter are respectively formed by connecting a reverse conducting switch device and a diode in series, the series connection points are respectively connected with the anodes and the cathodes of the two diodes of the clamping diode circuit, and the connection point of the other two bridge arms of the reverse blocking H bridge of the main converter is connected with the midpoint of the half bridge of the diode of the clamping circuit; therefore, a path of the clamping current and the charging current of the current source is provided. The circuit structure provided by the invention not only can effectively suppress the voltage spike of the reverse blocking bridge arm, but also can provide an auxiliary power supply for the drive circuit of the reverse blocking bridge arm.

Description

Technical Field

[0001] The invention relates to the field of power conversion, in particular to an isolated DC-DC converter for self-collecting energy from an auxiliary power source. Background Art

[0002] Compared with connecting to low-voltage AC systems, low-voltage, high-power power sources, loads, energy storage, etc. can be directly connected to medium- and high-voltage DC grids through converters to achieve higher efficiency, reliability, controllability, and lower costs. Traditional DC systems are mostly voltage bus (DC Voltage Bus, DVB) systems, such as Figure 1a As shown. When the low-voltage DC (LVDC) bus is connected to the medium-voltage or high-voltage DVB (MV / HV-DVB), the DC-DC converter needs to withstand higher voltage stress. Due to the voltage level limitation of power devices, a modular structure is usually required, which increases the volume and cost. If multiple low-voltage converters are connected in series, it is difficult to achieve power decoupling control of the LVDC ports of each converter because the total voltage on the series side is fixed to the bus voltage. Therefore, this multi-port system based on DVB usually requires a complex decoupling algorithm and is generally only used in situations where the port power difference is not large. Current source converters (CSC) are widely used due to their reliable short-circuit protection, low output EMI, and wide range of DC voltage. The DC side of several current source converters connected in series with a DC inductor can form a DC current bus (DCB) system, which provides a new solution for low-voltage equipment to access high-voltage systems. In medium and high-voltage DCB (MV / HV-DCB) systems such as Figure 1b As shown in the figure, each low-voltage converter does not have to bear high voltage stress after being connected in series to the DCB. Moreover, since the converter port voltage on one side of the DCB is not limited by the bus voltage, the power of each converter can be adjusted independently. Therefore, the HV-DCB system has obvious advantages in situations where multiple low-voltage devices need to be connected to the high-voltage system. In recent years, the DCB coupling method has received more and more attention. For example, the DC-link (voltage bus) of the offshore wind power converter is connected in series to the public current loop (i.e., DCB) through an isolated DC-DC, eliminating the need for a large power frequency transformer and converter station. In the power supply system of the Haiti observation network, the onshore power system is connected in series with the isolated DC-DC converters of each observation point through the DCB to power the equipment at each observation point. Some scholars have also proposed a multi-port power electronic transformer based on DCB to realize energy interaction between multiple LVDC ports and the medium-voltage power grid.

[0003] Most LVDC buses are DVB, so the DC-DC converter between the LVDC bus and the MV / HV-DCB must be able to connect to a voltage source and a current source. In addition, the port voltage on one side of the DCB is required to be able to change significantly from 0 upwards, so that the power can be adjusted from 0 upwards. If energy is required to flow in both directions, the voltage polarity on the DCB side of the converter is also required to be able to flip. Isolated DC-DC converters with DC voltage sources on both sides, such as traditional dual active bridges (DAB) and LLC / CLLC resonant converters, usually find it difficult to meet such requirements. Such a DC-DC converter with a voltage source (VS) connected to one end and a current source (CS) connected to the other end is sometimes called a hybrid DC-DC converter (H-DCC).

[0004] The isolated bidirectional H-DCC connected to the DCB system should have a reverse-resistance bridge arm on the CS side to meet the requirements of DCB unipolar current characteristics and bidirectional power transmission. The reverse-resistance bridge arm is either directly composed of a reverse-resistance switch, or a reverse-conducting switch connected in series with a diode, or two reverse-conducting switches connected in reverse series. This type of bidirectional H-DCC can achieve power reversal by changing the polarity of the average DC voltage on the CS side while keeping the polarity of the DC current on the CS side unchanged. The isolated full-bridge H-DCC is a typical bidirectional isolated H-DCC topology, such as Figure 2 As shown. Sometimes it is also called Hybrid Dual Active Bridge (H-DAB). Under appropriate modulation methods, the CS side switch of H-DAB can achieve zero current shutdown, and the VS side switch can achieve zero voltage turn-on, see the literature "A DC-current-bus-coupled multi-port power electronic transformer and its control strategy," in Proc. IEEE Int. Power Electron. Appl. Symp. (PEAS), 2021, Le Sun, Xiaoqiang. Guo, Yong Han, etc.

[0005] However, if Figure 2 The hybrid isolated DC-DC circuit shown faces two important issues in the DCB system:

[0006] First, the bridge arm of the H-bridge on the CS side may be subjected to a high voltage spike during the switching process, which is mainly caused by the oscillation between the equivalent capacitance of the bridge arm and the leakage inductance of the transformer. In order to solve this problem, three methods can usually be adopted. The first is to use energy-consuming absorption circuits such as RC or RCD, but this will cause great losses. The second is to use special modulation and control methods to avoid oscillation. Although such methods are used in circuits such as matrix converters, they are usually not applicable to the hybrid isolated DC-DC circuit shown in Figure 3. The third is to use a regenerative clamping circuit, that is, a clamping circuit is formed by a diode and a clamping capacitor, and the absorbed voltage spike energy is fed back to the VS side port through an isolated converter. This method is more practical, such as the literature "Research on the voltage spike suppression strategy for three-phase high-frequency link matrix-type inverter," IEEE Journal of Emerging and SelectedTopics in Power Electronics, 2022, Youzheng Wang, Hongchen Liu, Wheeler, Patrick. That is, a regenerative clamping circuit is formed by an uncontrolled rectifier bridge + clamping capacitor + flyback circuit to suppress the voltage spike of the high-frequency link matrix inverter. However, this type of method requires additional hardware circuits, which undoubtedly increases cost and volume.

[0007] The second is that the control and drive circuits of the H-bridge on the CS side require an auxiliary power supply. Due to the different potentials of the HV-DCB and LVDC systems, the auxiliary power supply on the current source side of the hybrid isolated DC-DC converter and the auxiliary power supply on the voltage source side require electrical isolation at a higher insulation level. For ordinary isolated DC-DC converters with DC capacitors on both sides, the power of the auxiliary power supplies on both sides can be taken from their respective DC capacitors. For hybrid isolated DC-DC converters, only the input power of the auxiliary power supply on the voltage source side can be directly taken from the DC capacitor, while the current source side lacks energy storage capacitors, so it can only add a conversion link with high voltage isolation capability to provide input power for the APS on the current source side, which will increase the cost of the converter.

[0008] In addition, when there is no power supply on the voltage source side, all auxiliary power supplies cannot work, and the switch of the reverse resistance bridge arm on the current source side is in the off state, which causes the entire DCB to be in a blocked state. This means that not only the hybrid isolated DC-DC converter with no power supply on the voltage source side port cannot be started, but also all converters along the DCB cannot work properly.

[0009] Therefore, it is necessary to comprehensively solve the voltage spike suppression of the H-bridge on the CS side, the auxiliary power supply power supply, and the startup problem under passive conditions on the voltage source side. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a constant current and constant voltage converter integrating clamping and auxiliary power supply and a starting method thereof, aiming to overcome the above three types of deficiencies faced when the hybrid isolated DC-DC circuit is applied to the medium voltage DCB system, combining the regenerative clamping circuit and the auxiliary power supply system, and improving the circuit topology structure, while achieving effective suppression of voltage spikes, power supply from the auxiliary power supply on the current source side, and starting under passive conditions of the voltage source port.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0012] A constant current and constant voltage converter with integrated clamping and auxiliary power supply, comprising a main converter and a regenerative clamping circuit; the main converter comprises a reverse resistance H-bridge, a main transformer circuit, a reverse conduction H-bridge and a main capacitor; the regenerative clamping circuit comprises a diode clamping circuit, a clamping capacitor and a feedback circuit;

[0013] The reverse resistance H bridge comprises four bridge arms; the first bridge arm and the second bridge arm of the reverse resistance H bridge are both formed by a reverse conduction switch and a diode in series; the cathode of the diode in the first bridge arm of the reverse resistance H bridge is connected to the reverse conduction switch; the anode of the diode in the second bridge arm of the reverse resistance H bridge is connected to the reverse conduction switch; the first bridge arm of the reverse resistance H bridge is connected in series with the second bridge arm of the reverse resistance H bridge, and the connection point is one end of each reverse conduction switch, and the connection point constitutes the first AC terminal of the reverse resistance H bridge; the third bridge arm and the fourth bridge arm of the reverse resistance H bridge are connected by the reverse conduction switch and a diode in series, or is composed of a reverse resistance switch; the third bridge arm of the reverse resistance H bridge and the fourth bridge arm of the reverse resistance H bridge are connected in series, and the connection point constitutes the second AC terminal of the reverse resistance H bridge; one end of the series branch is connected to the anode of the diode of the first bridge arm of the reverse resistance H bridge, and the connection point constitutes the DC positive terminal of the reverse resistance H bridge; the other end of the series branch is connected to the cathode of the diode of the second bridge arm of the reverse resistance H bridge, and the connection point constitutes the DC negative terminal of the reverse resistance H bridge; after the DC positive terminal and the DC negative terminal are led out, they constitute the current source port of the main converter;

[0014] The AC port of the reverse resistance H-bridge formed by the AC terminals is connected to one port of the main transformer circuit, and the other port of the main transformer circuit is connected to the AC port of the reverse conduction H-bridge; the DC port of the reverse conduction H-bridge is connected to both ends of the main capacitor and to the auxiliary power supply on the voltage source side, and both ends are led out to form the voltage source port of the converter;

[0015] The diode clamping circuit of the regenerative clamping circuit includes four diodes, wherein the anode of the first diode is connected to the cathode of the diode of the first bridge arm of the reverse resistance H bridge, and the cathode of the first diode is connected to the positive end of the clamping capacitor; the cathode of the second diode is connected to the anode of the diode of the second bridge arm of the reverse resistance H bridge, and the anode of the second diode is connected to the negative end of the clamping capacitor; the anode of the third diode is connected to the cathode of the fourth diode, and the connection point is connected to the second AC terminal of the reverse resistance H bridge, the cathode of the third diode is connected to the positive end of the clamping capacitor, and the anode of the fourth diode is connected to the negative end of the clamping capacitor; the two ends of the clamping capacitor are connected to the auxiliary power supply on the current source side, and are also connected to the input port of the feedback circuit.

[0016] A further improvement of the technical solution of the present invention is that: the reverse-conducting H-bridge of the main converter includes four bridge arms, all of which are composed of reverse-conducting fully-controlled switching devices; the first and second bridge arms are connected in sequence to form the first fully-controlled half-bridge of the reverse-conducting H-bridge, and the connection point constitutes the first AC terminal of the reverse-conducting H-bridge; the third and fourth bridge arms are connected in sequence to form the second fully-controlled half-bridge of the reverse-conducting H-bridge, and the connection point constitutes the second AC terminal of the reverse-conducting H-bridge; the first fully-controlled half-bridge and the second fully-controlled half-bridge are connected in parallel, one end of the parallel branch is the DC positive terminal of the reverse-conducting H-bridge, and the other end constitutes the DC negative terminal of the reverse-conducting H-bridge, the DC positive terminal and the DC negative terminal constitute the DC port of the reverse-conducting H-bridge; the first and second AC terminals of the reverse-conducting H-bridge constitute its AC port.

[0017] A further improvement of the technical solution of the present invention is that: the main transformer circuit includes a transformer, or a transformer and an inductor; when the main transformer includes a transformer and an inductor, the transformer and the inductor are respectively called the main transformer and the main inductor; one end of the main inductor is connected to a winding of the main transformer, and the other end and the other end of the winding constitute a port of the main transformer circuit; the two ends of the other winding constitute another port of the main transformer circuit; when the main transformer circuit includes only one transformer, the transformer is called the main transformer, and its two ports are the ports of the main transformer circuit.

[0018] A further improvement of the technical solution of the present invention is that the main capacitor includes one capacitor, or a branch formed by connecting a plurality of capacitors in series and in parallel.

[0019] A further improvement of the technical solution of the present invention is that: in the regenerative clamping circuit, the clamping capacitor is a single capacitor or a series-parallel branch of several capacitors, and the two ends of the clamping capacitor are respectively a positive end and a negative end;

[0020] The feedback circuit is an isolated DC / DC circuit or an isolated DC / AC circuit; when the feedback circuit is an isolated DC / DC circuit, its input and output ports are both DC ports, and the output DC port is connected to the voltage source port of the main converter; when the feedback circuit is an isolated DC / AC circuit, its input port is a DC port, its output port is an AC port, and the output AC port is connected to the AC port of the reverse conducting H-bridge.

[0021] The further improvement of the technical solution of the present invention is that: the clamping capacitor is formed by two capacitors connected in series, and the connection point of the two capacitors is the midpoint of the clamping capacitor; the feedback circuit is composed of an auxiliary full-controlled half-bridge circuit and an auxiliary transformer circuit;

[0022] The auxiliary transformer circuit includes a transformer, or a transformer and an inductor; when the auxiliary transformer includes a transformer and an inductor, the transformer and the inductor are respectively called auxiliary transformer and auxiliary inductor; one end of the auxiliary inductor is connected to a winding of the auxiliary transformer, and the other end and the other end of the winding constitute a port of the auxiliary transformer circuit; the two ends of the other winding constitute another port of the auxiliary transformer circuit; when the auxiliary transformer circuit includes only one transformer, the transformer is called auxiliary transformer, and its two ports are ports of the auxiliary transformer circuit;

[0023] The auxiliary fully-controlled half-bridge circuit is connected in sequence by two reverse-conducting fully-controlled switching devices, the two ends of the half-bridge are respectively connected to the positive end and the negative end of the clamping capacitor, the midpoint of the half-bridge is connected to one end of a port of the auxiliary transformer circuit, and the other end of the port is connected to the midpoint of the clamping capacitor;

[0024] Another port of the auxiliary transformer circuit constitutes the output port of the feedback circuit and is connected to the AC port of the reverse conducting H bridge of the main converter.

[0025] A further improvement of the technical solution of the present invention is that: the feedback circuit is composed of an auxiliary fully controlled H-bridge and an auxiliary transformer circuit;

[0026] The auxiliary transformer circuit includes a transformer, or a transformer and an inductor; when the auxiliary transformer includes a transformer and an inductor, the transformer and the inductor are respectively called auxiliary transformer and auxiliary inductor; one end of the auxiliary inductor is connected to a winding of the auxiliary transformer, and the other end and the other end of the winding constitute a port of the auxiliary transformer circuit; the two ends of the other winding constitute another port of the auxiliary transformer circuit; when the auxiliary transformer circuit includes only one transformer, the transformer is called auxiliary transformer, and its two ports are ports of the auxiliary transformer circuit;

[0027] The auxiliary fully controlled H-bridge includes four bridge arms, all of which are composed of reverse-conducting fully controlled switching devices; the first and second bridge arms are connected in sequence to form the first fully controlled half-bridge of the auxiliary fully controlled H-bridge, and the connection point forms the first AC terminal of the auxiliary fully controlled H-bridge; the third and fourth bridge arms are connected in sequence to form the second fully controlled half-bridge of the auxiliary fully controlled H-bridge, and the connection point forms the second AC terminal of the auxiliary fully controlled H-bridge; the first fully controlled half-bridge and the second fully controlled half-bridge are connected in parallel, one end of the parallel branch is the DC positive terminal of the auxiliary fully controlled H-bridge, and the other end forms the DC negative terminal of the auxiliary fully controlled H-bridge, and the DC positive terminal and the DC negative terminal form the DC port of the auxiliary fully controlled H-bridge; the first and second AC terminals of the auxiliary fully controlled H-bridge form its AC port;

[0028] The DC positive terminal and the DC negative terminal of the auxiliary full-controlled H-bridge are connected to the positive end and the negative end of the clamp capacitor respectively; the AC port of the auxiliary full-controlled H-bridge is connected to a port of the auxiliary transformer circuit;

[0029] Another port of the auxiliary transformer circuit constitutes the output port of the feedback circuit and is connected to the AC port of the reverse conducting H bridge of the main converter.

[0030] A further improvement of the technical solution of the present invention is that the feedback circuit is composed of a flyback circuit, the input port of the flyback circuit is connected in parallel with both ends of the clamping capacitor, and the output port is connected to the voltage source port of the main converter.

[0031] A further improvement of the technical solution of the present invention is that a bypass device is also connected in parallel to the input port of the main transformer, and the bypass device is a thyristor or a mechanical switch.

[0032] A method for starting a constant current and constant voltage converter with a clamp and an auxiliary power supply, comprising the following steps:

[0033] S1, control current source port voltage;

[0034] The controllable external power supply connected to the current source port works in the voltage source mode, gradually increasing the voltage of the main converter current port so that the clamping capacitor voltage uax reaches the input voltage threshold U that can start the auxiliary power supply on the current source side. thcs The above; thereby starting the auxiliary power supply on the current source side and supplying power to the control and drive circuits on the current source side, so that they start working;

[0035] S2, start hysteresis control of clamp capacitor voltage and main capacitor voltage;

[0036] Under the control of the controller, the switch tubes of the first reverse resistance bridge arm and the second reverse resistance bridge arm are turned on when the clamping capacitor voltage uax is higher than the hysteresis upper limit Uaxref+DUaxup, and are locked when the clamping capacitor voltage uax is lower than the hysteresis lower limit Uaxref-DUaxdown; the feedback circuit stops transmitting power to the voltage source port side when the main capacitor voltage Uc is higher than the hysteresis upper limit uax+DUcup, and transmits power to the voltage source port side when the main capacitor voltage Uc is lower than the hysteresis lower limit uax-DUcdown;

[0037] S3, control the current of the current source port;

[0038] The controllable external power supply connected to the current source port is switched to the current source mode, and the input current of the main converter current port is controlled to a small current value I low ;

[0039] S4, increase the clamp capacitor voltage uax and the main capacitor voltage uc;

[0040] Under the control of the controller, the reference value Uaxref of the hysteresis control of uax is increased to near the rated value UaxN, and Uc rises accordingly, exceeding the input voltage starting threshold U of the auxiliary power supply on the voltage source side. thvs , so that the auxiliary power supply on the voltage source side is started; the auxiliary power supply on the voltage source side supplies power to the control and drive circuits on the voltage source side;

[0041] S5, the main converter switches to normal control mode;

[0042] The reverse resistance H-bridge and reverse conduction H-bridge of the main converter start to work normally, and the main capacitor voltage uc and the clamping capacitor voltage uax are closed-loop controlled respectively; the closed-loop control of the main capacitor voltage uc is to adjust the main converter power command Pmain according to the difference between uc and the command Ucref, and then determine the switching signals of the reverse resistance H-bridge and the reverse conduction H-bridge according to Pmain; the closed-loop control of the clamping capacitor uax is to adjust the switching signal of the feedback circuit according to the difference between the clamping capacitor voltage uax and the command Uaxref; wherein the value of Uaxref is equal to k*Ucref, k=k1*k T , where k T is the transformation ratio of the main transformer, k1 is a value greater than 1;

[0043] S6, increase the current of the current source port to the rated value;

[0044] The controllable external power supply connected to the current source port adjusts the input current of the main converter current port to the rated current I N ; The startup process is completed.

[0045] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0046] 1. The clamping circuit in the present invention also provides the energy required by the auxiliary power supply on the current source side, so that there is no need for a special isolated DC-DC conversion link to provide energy for the auxiliary power supply on the current source side, saving hardware costs.

[0047] 2. The auxiliary power supply on the current source side of the present invention utilizes the energy input by the clamping circuit due to absorbing the voltage spike locally, thereby reducing the power borne by the feedback circuit and reducing the current stress and loss.

[0048] 3. The present invention provides a charging path from the current source port to the clamping capacitor, thereby allowing the auxiliary power supply to be powered by the power supply connected to the current source port when there is no power at the voltage source port, thereby achieving startup under passive conditions of the voltage source port and avoiding current bus circuit breaking caused by the lack of driving power on the current source side. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1a A solution for connecting traditional low-voltage equipment based on high-voltage DC voltage bus to high-voltage system at multiple terminals;

[0050] Figure 1b A solution for multi-terminal access of low-voltage equipment to high-voltage systems based on high-voltage DC current bus;

[0051] Figure 2 It is the main circuit of the existing hybrid isolated DC-DC converter;

[0052] Figure 3a is a schematic diagram of Embodiment 1 of the present invention;

[0053] Figure 3b It is a schematic diagram of the second embodiment of the present invention;

[0054] Figure 3c This is a schematic diagram of Embodiment 3 of the present invention;

[0055] Figure 4 Start the control flow chart for the present invention;

[0056] Figure 5 This is a schematic diagram of an implementation of the present invention in a specific application scenario 1 (a series-connected offshore wind power system with an offshore service function);

[0057] Figure 6 This is a schematic diagram of an implementation of the present invention in specific application scenario 2 (series-type seabed observation network power supply system);

[0058] Among them, 1. current source port; 2. bypass mechanism; 3. reverse resistance H-bridge; 4. first bridge arm of reverse resistance H-bridge; 5. second bridge arm of reverse resistance H-bridge; 6. third bridge arm of reverse resistance H-bridge; 7. fourth bridge arm of reverse resistance H-bridge; 8. main transformer circuit; 9. reverse conduction H-bridge; 10. main capacitor; 11. voltage source port; 12. auxiliary power supply on voltage source side; 13. control and drive circuit on voltage source side; 14. auxiliary transformer circuit; 15. feedback circuit; 16. auxiliary fully controlled half-bridge circuit; 17. clamping capacitor; 18. control and drive circuit on current source side; 19. auxiliary power supply on current source side; 20. diode clamping circuit; 21. controllable external power supply; 22. auxiliary fully controlled H-bridge; 23. flyback circuit. DETAILED DESCRIPTION

[0059] The present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0060] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" ... etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention.

[0061] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "several" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0062] The present invention provides a constant current and constant voltage converter with a clamp and an auxiliary power supply integrated therein. In a specific embodiment, Figure 3a As shown, it includes a main converter and a regenerative clamping circuit; the main converter includes a reverse resistance H bridge 3, a main transformer circuit 8, a reverse conduction H bridge 9 and a main capacitor 10; the regenerative clamping circuit includes a diode clamping circuit 20, a clamping capacitor 17 and a feedback circuit 15.

[0063] The reverse resistance H-bridge 3 of the main converter includes four bridge arms; the first bridge arm 4 and the second bridge arm 5 of the reverse resistance H-bridge are both formed by a reverse conducting fully controlled switch device and a diode connected in series, and have a current unidirectional conduction characteristic; the cathode of the diode in the first bridge arm 4 of the reverse resistance H-bridge is connected to the reverse conducting fully controlled switch device, and the current flows in from the anode of the diode and flows out from the other end of the reverse conducting switch device; the anode of the diode in the second bridge arm 5 of the reverse resistance H-bridge is connected to the reverse conducting fully controlled switch device, and the current flows out from the cathode of the diode and flows in from the other end of the reverse conducting fully controlled switch device; the current outflow end of the first bridge arm 4 of the reverse resistance H-bridge is connected to the current inflow end of the second bridge arm 5 of the reverse resistance H-bridge, and the connection point constitutes the first AC terminal of the reverse resistance H-bridge 3;

[0064] like Figure 3a As shown, the third bridge arm 6 of the reverse resistance H bridge and the fourth bridge arm 7 of the reverse resistance H bridge have the same structure as the first bridge arm 4 of the reverse resistance H bridge and the second bridge arm 5 of the reverse resistance H bridge, or as shown in FIG. Figure 3b As shown, it is directly composed of a fully controlled reverse-resistance switch device and has a unidirectional conduction characteristic; the current outflow end of the third bridge arm 6 of the reverse-resistance H-bridge is connected to the current inflow end of the fourth bridge arm of the reverse-resistance H-bridge, and the connection point constitutes the second AC terminal of the reverse-resistance H-bridge 3.

[0065] The first bridge arm 4 of the reverse resistance H-bridge is connected to the current inflow end of the third bridge arm 6 of the reverse resistance H-bridge, and the connection point constitutes the DC current inflow terminal of the reverse resistance H-bridge 3; the second bridge arm 5 of the reverse resistance H-bridge is connected to the current outflow end of the third bridge arm 6 of the reverse resistance H-bridge, and the connection point constitutes the DC current outflow terminal of the reverse resistance H-bridge 3; after the current inflow terminal and the current outflow terminal are led out, they constitute the current source port 1 of the main converter.

[0066] The reverse conducting H-bridge 9 of the main converter includes four bridge arms, all of which are composed of reverse conducting fully controlled switching devices; the first and second bridge arms are connected in sequence to form the first fully controlled half-bridge of the reverse conducting H-bridge, and the connection point constitutes the first AC terminal of the reverse conducting H-bridge 9; the third and fourth bridge arms are connected in sequence to form the second fully controlled half-bridge of the reverse conducting H-bridge 9, and the connection point constitutes the second AC terminal of the reverse conducting H-bridge 9. The first fully controlled half-bridge and the second fully controlled half-bridge are connected in parallel, and one end of the parallel branch is the DC positive terminal of the reverse conducting H-bridge 9, and the other end constitutes the DC negative terminal of the reverse conducting H-bridge 9. The DC positive terminal and the DC negative terminal constitute the DC port of the reverse conducting H-bridge 9. The first and second AC terminals of the reverse conducting H-bridge 9 constitute its AC port.

[0067] like Figure 3b As shown, the main transformer circuit 8 includes a transformer, or Figure 3aAs shown, a transformer and an inductor. When the main transformer circuit 8 includes a transformer and an inductor, the transformer and the inductor are respectively called the main transformer and the main inductor. One end of the main inductor is connected to a winding of the main transformer, and the other end and the other end of the winding constitute a port of the main transformer circuit 8. The two ends of the other winding constitute another port of the main transformer circuit 8. When the main transformer circuit 8 includes only one transformer, the transformer is called the main transformer, and its two ports are the ports of the main transformer circuit 8.

[0068] The main capacitor 10 includes a capacitor or a branch formed by connecting a plurality of capacitors in series and in parallel.

[0069] The AC port formed by the AC terminals of the reverse resistance H bridge 3 is connected in sequence to one port of the main transformer circuit 8, and the other port of the main transformer circuit 8 is connected to the AC port of the reverse conduction H bridge 9. The DC port of the reverse conduction H bridge 9 is connected to both ends of the main capacitor 10. Both ends of the main capacitor 10 are led out to form the voltage source port 11 of the converter. The voltage source port 11 of the converter is also connected to the auxiliary power supply 12 on the voltage source side. The auxiliary power supply 12 on the voltage source side supplies power to the control and drive circuit 13 on the voltage source side.

[0070] The present invention also includes a bypass mechanism 2 connected in parallel to the current source port, which can be as follows: Figure 3a The thyristor shown can also be Figure 3b , Figure 3c The bypass switch shown in FIG. Its function is to bypass the converter at the current source port when a converter fails to prevent it from affecting the operation of other converters in the system.

[0071] like Figure 3b As shown, the clamping capacitor 17 is a single capacitor, or as Figure 3a As shown, a series-parallel branch of several capacitors, the two ends of the clamping capacitor 17 are respectively a positive end and a negative end.

[0072] The diode clamping circuit 20 of the regenerative clamping circuit includes four diodes, wherein the anode of the first diode is connected to the cathode of the series diode contained in the first bridge arm 4 of the reverse resistance H bridge 3, and the cathode of the first diode is connected to the positive end of the clamping capacitor 17; the cathode of the second diode is connected to the anode of the series diode contained in the second bridge arm 5 of the reverse resistance H bridge 3, and the anode of the second diode is connected to the negative end of the clamping capacitor 17, the anode of the third diode is connected to the cathode of the fourth diode, and the connection point is connected to the second AC terminal of the reverse resistance H bridge 3, the cathode of the third diode is connected to the positive end of the clamping capacitor 17, and the anode of the fourth diode is connected to the negative end of the clamping capacitor 17.

[0073] The positive and negative ends of the clamp capacitor 17 constitute a feeding port, which is connected to the input port of the current source side auxiliary power supply 19 and is also connected to the input port of the feedback circuit 15 .

[0074] The feedback circuit 15 is an isolated DC / DC circuit or an isolated DC / AC circuit. Figure 3c As shown, when the feedback circuit 15 is an isolated DC / DC circuit, its input and output ports are both DC ports, and the output DC port is connected to the voltage source port 11 of the main converter; Figure 3a or Figure 3b As shown, when the feedback circuit 15 is an isolated DC / AC circuit, its input port is a DC port, its output port is an AC port, and the output AC port is connected to the AC port of the reverse conducting H-bridge 9.

[0075] Embodiment 1

[0076] like Figure 3a As shown, the clamping capacitor 17 is composed of two capacitors connected in series, and the connection point of the two capacitors is the midpoint of the clamping capacitor. The feedback circuit is composed of an auxiliary full-controlled half-bridge circuit 16 and an auxiliary transformer circuit 14.

[0077] like Figure 3a As shown, as a preferred solution, the auxiliary transformer circuit 14 includes a transformer and an inductor. The transformer and the inductor are respectively referred to as an auxiliary transformer and an auxiliary inductor. One end of the auxiliary inductor is connected to a winding of the auxiliary transformer, and the other end of the auxiliary inductor and the other end of the winding constitute a port of the auxiliary transformer circuit 14. The two ends of the other winding constitute another port of the auxiliary transformer circuit 14.

[0078] like Figure 3a As shown, as a preferred solution, the auxiliary fully-controlled half-bridge circuit 16 is composed of two reverse-conducting fully-controlled switching devices connected in sequence, the two ends of the half bridge are respectively connected to the positive and negative ends of the clamping capacitor, the midpoint of the half bridge is connected to one end of a port of the auxiliary transformer circuit, and the other end of the port is connected to the midpoint of the clamping capacitor 17.

[0079] As a preferred solution, another port of the auxiliary transformer circuit 14 constitutes the output port of the feedback circuit 15 and is connected to the AC port of the reverse conducting H-bridge 9 of the main converter.

[0080] Embodiment 2

[0081] like Figure 3b As shown, the feedback circuit is composed of an auxiliary fully-controlled H-bridge 22 and an auxiliary transformer circuit 14.

[0082] like Figure 3b As shown, as a preferred solution, the auxiliary transformer circuit 14 includes a transformer, which is called a main transformer, and its two ports are ports of the main transformer circuit 14.

[0083] like Figure 3bAs shown, as a preferred solution, the auxiliary fully controlled H-bridge 22 includes four bridge arms, all of which are composed of reverse-conducting fully controlled switching devices. The first and second bridge arms are connected in sequence to form the first fully controlled half-bridge of the auxiliary fully controlled H-bridge 22, and the connection point constitutes the first AC terminal of the auxiliary fully controlled H-bridge 22; the third and fourth bridge arms are connected in sequence to form the second fully controlled half-bridge of the auxiliary fully controlled H-bridge 22, and the connection point constitutes the second AC terminal of the auxiliary fully controlled H-bridge 22. The first fully controlled half-bridge and the second fully controlled half-bridge are connected in parallel, and one end of the parallel branch is the DC positive terminal of the auxiliary fully controlled H-bridge 22, and the other end constitutes the DC negative terminal of the auxiliary fully controlled H-bridge 22. The DC positive terminal and the DC negative terminal constitute the DC port of the auxiliary fully controlled H-bridge. The first and second AC terminals of the auxiliary fully controlled H-bridge 22 constitute its AC port.

[0084] like Figure 3b As shown, as a preferred solution, the DC positive terminal and DC negative terminal of the auxiliary fully controlled H bridge 22 are respectively connected to the positive terminal and negative terminal of the clamp capacitor 17. The AC port of the auxiliary fully controlled H bridge 22 is connected to a port of the auxiliary transformer circuit 14.

[0085] like Figure 3b As shown, as a preferred solution, another port of the auxiliary transformer circuit 14 constitutes the output port of the feedback circuit 15 and is connected to the AC port of the reverse conducting H bridge 9 of the main converter.

[0086] Embodiment 3

[0087] like Figure 3c As shown, the feedback circuit 15 is composed of a flyback circuit 23, the input port of the flyback circuit 23 is connected in parallel with both ends of the clamping capacitor 17, and the output port is connected to the voltage source port 11 of the main converter. The other parts are the same as the second embodiment.

[0088] like Figure 4 As shown, a startup method for taking power from a current source port includes the following steps:

[0089] S1, control the voltage at the current source port to a certain smaller value;

[0090] The specific method is: a controllable external power source 21 (such as Figure 3a , 3b 3c) works in the voltage source mode, gradually increases the voltage of the main converter current port 1, so that the voltage uax of the clamping capacitor 17 reaches the input voltage threshold U that can start the current source side auxiliary power supply 19 thcs As a result, the auxiliary power supply 19 on the current source side is started, and supplies power to the control and drive circuit 18 on the current source side, so that they start to work.

[0091] S2, start hysteresis control of the voltage of the clamping capacitor 17 and the voltage of the main capacitor 10;

[0092] The specific method is as follows: under the control of the controller, the switch tubes of the first reverse resistance bridge arm 4 and the second reverse resistance bridge arm 5 are turned on when the clamping capacitor voltage uax is higher than the hysteresis upper limit Uaxref+DUaxup, and are locked when the clamping capacitor voltage uax is lower than the hysteresis lower limit Uaxref-DUaxdown. The feedback circuit 15 stops transmitting power to the voltage source port 11 side when the main capacitor voltage Uc is higher than the hysteresis upper limit uax+DUcup, and transmits power to the voltage source port 11 side when the main capacitor voltage Uc is lower than the hysteresis lower limit uax-DUcdown.

[0093] S3, control the current source port current to a certain smaller value;

[0094] The controllable external power source 21 connected to the current source port is switched to the current source mode, and the input current of the main converter current port 1 is controlled to a certain smaller value I low .

[0095] S4, increase the voltage uax of the clamping capacitor 17 and the voltage uc of the main capacitor 10;

[0096] The specific method is: under the control of the controller, the reference value Uaxref of the hysteresis control of uax is increased to near the rated value UaxN, and Uc rises accordingly, exceeding the input voltage starting threshold U of the auxiliary power supply 12 on the voltage source side. thvs , so that the voltage source side auxiliary power supply 12 is started. The voltage source side auxiliary power supply 12 supplies power to the voltage source side control and drive circuit 13.

[0097] S5, the main converter switches to normal control mode;

[0098] The specific method is as follows: the reverse resistance H-bridge 3 and reverse conduction H-bridge 9 of the main converter start to work normally, and close-loop control is performed on the main capacitor voltage uc and the clamping capacitor voltage uax respectively. The closed-loop control of the main capacitor voltage uc is to adjust the main converter power command Pmain according to the difference between uc and the command Ucref, and then determine the switching signal of the reverse resistance H-bridge 3 and the reverse conduction H-bridge 9 according to Pmain. The closed-loop control of the clamping capacitor uax is to adjust the switching signal of the feedback circuit 15 according to the difference between the clamping capacitor voltage uax and the command Uaxref. The value of Uaxref is equal to k*Ucref, k=k1*k T , where k T For the transformation ratio of the main transformer, k1 is a value greater than 1. The reason why it is greater than 1 is to limit the current of the clamping diode.

[0099] S6. Increase the current of the current source port to the rated value.

[0100] The specific method is: the controllable external power supply 21 connected to the current source port 1 adjusts the input current of the main converter current port 11 to the rated current I N . The startup process is complete.

[0101] In order to further illustrate the beneficial effects of the present invention, two specific application scenarios are described below.

[0102] Application scenario 1

[0103] Application scenario 1 is a series-connected offshore wind power system with offshore service functions, such as Figure 5 As shown. In the traditional offshore wind power DC transmission mode, the electric energy generated by each wind turbine is generally collected by AC and boosted by industrial frequency, and then sent to the high-voltage DC bus through a unified rectification, and then sent to the onshore converter station through the high-voltage DC transmission line. In the series offshore wind power system, the electric energy generated by each wind turbine is converted to low-voltage DC through a high-frequency isolated DC-DC circuit converter, and then connected in series to the high-voltage current bus. This can save the huge offshore converter station. In the series offshore wind power system, the high-frequency isolated DC-DC circuit usually has a unidirectional energy flow, but with the development of offshore wind power systems, the use of offshore wind farms to provide more diversified offshore services has attracted increasing attention. These diversified services include the configuration of 5G base stations, marine environment monitoring systems, ship charging piles, inspection drone charging piles, seawater hydrogen production, etc. near offshore wind power towers and their vicinity. This means that there may be more local loads in wind farms in the future. These local loads require reliable power supply, but due to the intermittent nature of wind power, it is difficult to ensure the reliable operation of local loads by relying solely on wind turbines to generate electricity. Therefore, in the series-connected offshore wind power system with offshore service function, the high-frequency isolated DC-DC circuit must have bidirectional energy flow and the ability to feed in a mixed current source and voltage source. Figure 2 The hybrid isolated DC-DC converter shown. However, on the one hand, the hybrid isolated DC-DC converter has the problem of voltage spikes on the reverse resistance H-bridge on the current source side. On the other hand, if the auxiliary power supply of the reverse resistance H-bridge relies on a special isolation conversion link to obtain energy from the voltage source side, it not only increases the hardware cost, but also cannot realize the power-on of the auxiliary power supply when the wind turbine is not generating electricity, thus causing the problem of difficulty in starting. The novel hybrid isolated DC-DC converter proposed in the present invention combines the regenerative clamping circuit with the auxiliary power supply system, and innovatively adjusts the connection relationship between the clamping diode and the H-bridge on the current source side, and introduces a diode conduction path from the current bus to the clamping capacitor, thereby solving the problems of voltage spike suppression, auxiliary power supply power supply on the current source side, and auxiliary power supply starting under passive conditions on the voltage source side. According to the circuit and starting strategy proposed in the present invention, even if the wind turbine is not working, the auxiliary power supplies are all powered on, and the current output by the onshore converter station can also pass through the following Figure 5The path shown by the middle dotted line is through the series diode of the first bridge arm of the reverse resistance H-bridge, the first diode of the clamping diode circuit, the clamping capacitor, the second diode of the clamping diode circuit, and the series diode of the second bridge arm of the reverse resistance H-bridge, so as to charge the clamping capacitor and start the auxiliary power supply on the CS side.

[0104] Application scenario 2

[0105] Application scenario 2 is the series-type submarine observation network power supply system, such as Figure 6 As shown. Compared with the traditional offline, short-term, non-real-time ocean observation methods based on ships, drilling, submersibles, etc., the cable-based seabed observation network can conduct real-time and continuous seabed observations, which is of great significance for geological exploration, earthquake monitoring, marine scientific research, ecological and environmental protection, and national defense security. In the cable-based seabed observation network, submarine power transmission technology is very important for the normal and reliable operation of observation equipment. According to the type of shore-based converter, submarine power transmission technology can be divided into two categories: constant voltage transmission and constant current electric shock. Among them, the constant current power supply system has a strong ability to resist short-circuit faults, and the converter voltage ratio of each submarine branch unit is not high, so it only needs to withstand lower voltage stress and is easy to achieve control decoupling. Therefore, it has more advantages in scenarios with high reliability requirements.

[0106] The branch units of traditional constant current power supply systems often use push-pull circuits as constant current / constant voltage power conversion, but the push-pull circuit has high switch stress and bias magnetic problems. The hybrid isolated DC-DC circuit shown in Figure 3 can overcome its shortcomings. In the future submarine observation network, energy storage and even wave power generation devices may be added to the observation nodes as backup power supplies. The use of a hybrid isolated DC-DC circuit with bidirectional energy flow can better realize the interconnection and mutual assistance of electric energy at each observation point and realize off-grid operation without shore-based power supply. However, as mentioned above, the hybrid isolated DC-DC circuit shown in Figure 3 has problems such as voltage spikes on the H-bridge on the current source side, auxiliary power supply, and system startup. To solve these problems, the constant current and constant voltage converter with integrated clamping and auxiliary power supply described in the present invention can be used. Its working principle and startup method are similar to those of application scenario 1, which will not be repeated here.

[0107] In summary, the present invention aims to overcome the above three types of deficiencies faced when the hybrid isolated DC-DC circuit is applied to the medium voltage DCB system, combines the regenerative clamping circuit and the auxiliary power supply system, and improves the circuit topology structure, while achieving effective suppression of voltage spikes, auxiliary power supply power supply on the current source side, and startup under passive conditions of the voltage source port.

Claims

1. A constant current and constant voltage converter integrating clamping and auxiliary power supply, characterized in that: The invention comprises a main converter and a regenerative clamping circuit; the main converter comprises a reverse resistance H-bridge (3), a main transformer circuit (8), a reverse conduction H-bridge (9) and a main capacitor (10); the regenerative clamping circuit comprises a diode clamping circuit (20), a clamping capacitor and a feedback circuit (15); The reverse resistance H-bridge (3) comprises four bridge arms; the first bridge arm (4) of the reverse resistance H-bridge and the second bridge arm (5) of the reverse resistance H-bridge are both formed by a reverse conduction switch and a diode connected in series; the cathode of the diode in the first bridge arm (4) of the reverse resistance H-bridge is connected to the reverse conduction switch; the anode of the diode in the second bridge arm (5) of the reverse resistance H-bridge is connected to the reverse conduction switch; the first bridge arm (4) of the reverse resistance H-bridge and the second bridge arm (5) of the reverse resistance H-bridge are connected in series, and the connection point is one end of each reverse conduction switch, and the connection point constitutes a first AC terminal of the reverse resistance H-bridge (3); the third bridge arm (6) of the reverse resistance H-bridge and the fourth bridge arm (7) of the reverse resistance H-bridge are formed by a reverse conduction switch The reverse resistance H bridge is composed of a conductive switch and a diode connected in series, or is composed of a reverse resistance switch; the third bridge arm (6) of the reverse resistance H bridge and the fourth bridge arm (7) of the reverse resistance H bridge are connected in series, and the connection point constitutes the second AC terminal of the reverse resistance H bridge (3); one end of the series branch is connected to the anode of the diode of the first bridge arm (4) of the reverse resistance H bridge, and the connection point constitutes the DC positive terminal of the reverse resistance H bridge (3); the other end of the series branch is connected to the cathode of the diode of the second bridge arm (5) of the reverse resistance H bridge, and the connection point constitutes the DC negative terminal of the reverse resistance H bridge (3); after the DC positive terminal and the DC negative terminal are led out, they constitute the current source port (1) of the main converter; The AC port of the reverse resistance H-bridge formed by the AC terminals is connected to one port of the main transformer circuit (8), and the other port of the main transformer circuit (8) is connected to the AC port of the reverse conduction H-bridge (9); the DC port of the reverse conduction H-bridge (9) is connected to both ends of the main capacitor (10), and is also connected to the auxiliary power supply (12) on the voltage source side, and both ends are led out to form the voltage source port (11) of the converter; The diode clamping circuit (20) of the regenerative clamping circuit comprises four diodes, wherein the anode of the first diode is connected to the cathode of the diode of the first bridge arm of the reverse resistance H bridge, and the cathode of the first diode is connected to the positive end of the clamping capacitor; the cathode of the second diode is connected to the anode of the diode of the second bridge arm of the reverse resistance H bridge, and the anode of the second diode is connected to the negative end of the clamping capacitor; the anode of the third diode is connected to the cathode of the fourth diode, and the connection point is connected to the second AC terminal of the reverse resistance H bridge, the cathode of the third diode is connected to the positive end of the clamping capacitor, and the anode of the fourth diode is connected to the negative end of the clamping capacitor; the two ends of the clamping capacitor are connected to the auxiliary power supply (19) on the current source side, and are also connected to the input port of the feedback circuit (15).

2. The constant current and constant voltage converter with integrated clamping and auxiliary power supply according to claim 1, characterized in that: The reverse conducting H-bridge (9) of the main converter comprises four bridge arms, all of which are composed of reverse conducting fully controlled switch devices; wherein the first and second bridge arms are connected in sequence to form a first fully controlled half-bridge of the reverse conducting H-bridge (9), and the connection point forms a first AC terminal of the reverse conducting H-bridge (9); the third and fourth bridge arms are connected in sequence to form a second fully controlled half-bridge of the reverse conducting H-bridge (9), and the connection point forms a second AC terminal of the reverse conducting H-bridge (9); the first fully controlled half-bridge and the second fully controlled half-bridge are connected in parallel, one end of the parallel branch is a DC positive terminal of the reverse conducting H-bridge (9), and the other end forms a DC negative terminal of the reverse conducting H-bridge (9), and the DC positive terminal and the DC negative terminal form a DC port of the reverse conducting H-bridge (9); the first and second AC terminals of the reverse conducting H-bridge (9) form its AC port.

3. The constant current and constant voltage converter with integrated clamping and auxiliary power supply according to claim 1, characterized in that: The main transformer circuit (8) includes a transformer, or a transformer and an inductor; when the main transformer includes a transformer and an inductor, the transformer and the inductor are respectively referred to as the main transformer and the main inductor; one end of the main inductor is connected to a winding of the main transformer, and the other end of the main inductor and the other end of the winding constitute a port of the main transformer circuit (8); the two ends of the other winding constitute another port of the main transformer circuit (8); when the main transformer circuit (8) includes only one transformer, the transformer is referred to as the main transformer, and its two ports are ports of the main transformer circuit (8).

4. The constant current and constant voltage converter with integrated clamping and auxiliary power supply according to claim 1, characterized in that: The main capacitor (10) includes a capacitor or a branch formed by connecting a plurality of capacitors in series and in parallel.

5. The constant current and constant voltage converter with integrated clamp and auxiliary power supply according to claim 1, characterized in that: In the regenerative clamping circuit, the clamping capacitor is a single capacitor or a series-parallel branch of several capacitors, and the two ends of the clamping capacitor are respectively a positive end and a negative end; The feedback circuit (15) is an isolated DC / DC circuit or an isolated DC / AC circuit; when the feedback circuit (15) is an isolated DC / DC circuit, its input and output ports are both DC ports, and the output DC port is connected to the voltage source port (11) of the main converter; when the feedback circuit (15) is an isolated DC / AC circuit, its input port is a DC port, its output port is an AC port, and the output AC port is connected to the AC port of the reverse conducting H-bridge (9).

6. The constant current and constant voltage converter with integrated clamping and auxiliary power supply according to claim 5, characterized in that: The clamping capacitor is formed by two capacitors connected in series, and the connection point of the two capacitors is the midpoint of the clamping capacitor; the feedback circuit (15) is composed of an auxiliary full-controlled half-bridge circuit (16) and an auxiliary transformer circuit (14); The auxiliary transformer circuit (14) includes a transformer, or a transformer and an inductor; when the auxiliary transformer includes a transformer and an inductor, the transformer and the inductor are respectively referred to as an auxiliary transformer and an auxiliary inductor; one end of the auxiliary inductor is connected to a winding of the auxiliary transformer, and the other end and the other end of the winding constitute a port of the auxiliary transformer circuit (14); the two ends of the other winding constitute another port of the auxiliary transformer circuit (14); when the auxiliary transformer circuit (14) includes only one transformer, the transformer is referred to as an auxiliary transformer, and its two ports are ports of the auxiliary transformer circuit (14); The auxiliary fully controlled half-bridge circuit (16) is connected in sequence by two reverse conducting fully controlled switch devices, the two ends of the half-bridge are respectively connected to the positive end and the negative end of the clamping capacitor, the midpoint of the half-bridge is connected to one end of a port of the auxiliary transformer circuit (14), and the other end of the port is connected to the midpoint of the clamping capacitor; Another port of the auxiliary transformer circuit forms the output port of the feedback circuit (15) and is connected to the AC port of the reverse conducting H bridge (9) of the main converter.

7. The constant current and constant voltage converter with integrated clamping and auxiliary power supply according to claim 5, characterized in that: The feedback circuit (15) is composed of an auxiliary fully controlled H-bridge (22) and an auxiliary transformer circuit (14); The auxiliary transformer circuit (14) includes a transformer, or a transformer and an inductor; when the auxiliary transformer includes a transformer and an inductor, the transformer and the inductor are respectively referred to as an auxiliary transformer and an auxiliary inductor; one end of the auxiliary inductor is connected to a winding of the auxiliary transformer, and the other end and the other end of the winding constitute a port of the auxiliary transformer circuit (14); the two ends of the other winding constitute another port of the auxiliary transformer circuit (14); when the auxiliary transformer circuit (14) includes only one transformer, the transformer is referred to as an auxiliary transformer, and its two ports are ports of the auxiliary transformer circuit (14); The auxiliary fully controlled H-bridge (22) comprises four bridge arms, all of which are composed of reverse-conducting fully controlled switch devices; wherein the first and second bridge arms are connected in sequence to form a first fully controlled half-bridge of the auxiliary fully controlled H-bridge (22), and the connection point forms a first AC terminal of the auxiliary fully controlled H-bridge (22); the third and fourth bridge arms are connected in sequence to form a second fully controlled half-bridge of the auxiliary fully controlled H-bridge (22), and the connection point forms a second AC terminal of the auxiliary fully controlled H-bridge (22); the first fully controlled half-bridge and the second fully controlled half-bridge are connected in parallel, one end of the parallel branch is a DC positive terminal of the auxiliary fully controlled H-bridge (22), and the other end forms a DC negative terminal of the auxiliary fully controlled H-bridge (22), and the DC positive terminal and the DC negative terminal form a DC port of the auxiliary fully controlled H-bridge (22); the first and second AC terminals of the auxiliary fully controlled H-bridge (22) form its AC port; The DC positive terminal and the DC negative terminal of the auxiliary fully-controlled H-bridge (22) are respectively connected to the positive end and the negative end of the clamping capacitor; the AC port of the auxiliary fully-controlled H-bridge (22) is connected to a port of the auxiliary transformer circuit; Another port of the auxiliary transformer circuit forms the output port of the feedback circuit (15) and is connected to the AC port of the reverse conducting H bridge (9) of the main converter.

8. The constant current and constant voltage converter with integrated clamp and auxiliary power supply according to claim 5, characterized in that: The feedback circuit (15) is composed of a flyback circuit (23), the input port of the flyback circuit (23) is connected in parallel with both ends of the clamping capacitor, and the output port is connected to the voltage source port (11) of the main converter.

9. The constant current and constant voltage converter with integrated clamp and auxiliary power supply according to claim 5, characterized in that: A bypass device is also connected in parallel to the input port of the main transformer, and the bypass device is a thyristor or a mechanical switch.

10. A method for starting a constant current and constant voltage converter with a clamp and an auxiliary power supply, characterized in that: Using the constant current and constant voltage converter with integrated clamp and auxiliary power supply as claimed in any one of claims 1 to 9 comprises the following steps: S1, control current source port (1) voltage; The controllable external power supply (21) connected to the current source port (1) operates in a voltage source mode, gradually increasing the voltage of the main converter current port so that the clamping capacitor voltage uax reaches the input voltage threshold U that can start the auxiliary power supply (19) on the current source side. thcs The above; thereby starting the auxiliary power supply (19) on the current source side and supplying power to the control and drive circuit (18) on the current source side, so that they start working; S2, starting hysteresis control of the clamping capacitor voltage and the main capacitor (10) voltage; Under the control of the controller, the switch tubes of the first reverse resistance bridge arm and the second reverse resistance bridge arm are turned on when the clamping capacitor voltage uax is higher than the hysteresis upper limit Uaxref+DUaxup, and are locked when the clamping capacitor voltage uax is lower than the hysteresis lower limit Uaxref-DUaxdown; the feedback circuit (15) stops transmitting power to the voltage source port (11) side when the main capacitor (10) voltage Uc is higher than the hysteresis upper limit uax+DUcup, and transmits power to the voltage source port (11) side when the main capacitor (10) voltage Uc is lower than the hysteresis lower limit uax-DUcdown; S3, control the current of the current source port (1); The controllable external power source (21) connected to the current source port (1) is switched to the current source mode to control the input current of the main converter current port to a small current value I low ; S4, increasing the clamping capacitor voltage uax and the main capacitor (10) voltage uc; Under the control of the controller, the reference value Uaxref of the hysteresis control of uax is increased to near the rated value UaxN, and Uc rises accordingly, exceeding the input voltage starting threshold U of the auxiliary power supply (12) on the voltage source side. thvs , thereby starting the auxiliary power supply (12) on the voltage source side; the auxiliary power supply (12) on the voltage source side supplies power to the control and drive circuits on the voltage source side; S5, the main converter switches to normal control mode; The reverse resistance H-bridge and reverse conduction H-bridge (9) of the main converter start to work normally, and the main capacitor (10) voltage uc and the clamping capacitor voltage uax are respectively closed-loop controlled; the closed-loop control of the main capacitor (10) voltage uc is to adjust the main converter power command Pmain according to the difference between uc and the command Ucref, and then determine the switching signal of the reverse resistance H-bridge and the reverse conduction H-bridge (9) according to Pmain; the closed-loop control of the clamping capacitor uax is to adjust the switching signal of the feedback circuit (15) according to the difference between the clamping capacitor voltage uax and the command Uaxref; wherein the value of Uaxref is equal to k*Ucref, k=k1*k T , where k T is the transformation ratio of the main transformer, k1 is a value greater than 1; S6, increasing the current of the current source port (1) to the rated value; A controllable external power source (21) connected to the current source port (1) adjusts the input current of the main converter current port to the rated current I N ; The startup process is completed.

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