Constant-current constant-voltage converter integrated with clamping and auxiliary power supply and starting method thereof

Abstract

The application discloses a constant-current constant-voltage converter integrated with a clamping and auxiliary power supply and a starting method thereof, and belongs to the field of power conversion, comprising a main converter and a regenerative clamping circuit; the main converter comprises an inverse resistance H-bridge, a main inductor, a main transformer, an inverse direction H-bridge and a main capacitor; the regenerative clamping circuit comprises a diode clamping circuit, a clamping capacitor and a feedback circuit. The inverse resistance H-bridge of the main converter has at least two bridge arms which are respectively formed by series connection of inverse direction switching devices and diodes, and the series connection points are respectively connected with the anode and cathode of two diodes of the diode clamping circuit; the other two bridge arm connection points of the inverse resistance H-bridge of the main converter are connected with the midpoint of the diode half-bridge of the clamping circuit, so that the passage of the clamping current and the charging current of the current source is provided. The circuit structure provided by the application can not only effectively inhibit the voltage peak of the inverse resistance bridge arm, but also provide an auxiliary power supply for the driving circuit of the inverse resistance bridge arm.

Description

Technical Field

[0001] This invention relates to the field of power conversion, and in particular to an isolated DC-DC converter with self-powered auxiliary power supply. Background Technology

[0002] Compared to connecting to low-voltage AC systems, directly connecting low-voltage, high-power power sources, loads, and energy storage to medium- and high-voltage DC grids via converters can achieve higher efficiency, reliability, controllability, and lower costs. Traditional DC systems are mostly DC Voltage Bus (DVB) systems, such as... Figure 1a As shown. When a low-voltage DC (LVDC) bus is connected to a medium-voltage or high-voltage DVB (MV / HV-DVB), the DC-DC converter needs to withstand high voltage stress. Due to the voltage level limitations of power devices, a modular structure is usually required, which increases size 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, such multi-port systems based on DVB usually require complex decoupling algorithms and are generally only used in situations where the port power difference is not significant. Current source converters (CSCs) are widely used due to their reliable short-circuit protection, low output EMI, and wide range of DC voltage. Several current source converters connected in series with a DC inductor on the DC side can form a DC current bus (DCB) system, which provides a new solution for connecting low-voltage equipment to high-voltage systems. In medium- and high-voltage DCB (MV / HV-DCB) systems, such as... Figure 1b As shown, after each low-voltage converter is connected in series to the DCB, it does not need to withstand high voltage stress. Furthermore, since the converter port voltage on the DCB side is not limited by the bus voltage, the power of each converter can be independently adjusted. Therefore, the HV-DCB system has significant advantages in situations requiring multiple low-voltage devices to be connected to a high-voltage system. In recent years, DCB coupling methods have received increasing attention. For example, in offshore wind power converters, the DC-link (voltage bus) is connected in series to a common current loop (i.e., DCB) via an isolated DC-DC converter, eliminating the need for a large power frequency transformer and converter station. In the power supply system of the seaborne observation network, the onshore power system is connected in series to the isolated DC-DC converters at each observation point via the DCB to power the equipment at each observation point. Some scholars have also proposed multi-port power electronic transformers based on DCB to realize energy interaction between multiple LVDC ports and the medium-voltage grid.

[0003] Most LVDC buses are DVBs, so the DC-DC converter between LVDC bus and MV / HV-DCB should have the ability to connect voltage source and current source. Moreover, the port voltage on the DCB side is required to change greatly from 0 upwards, so that the power can be adjusted from 0 upwards. If bidirectional energy flow is required, the voltage polarity on the DCB side of the converter is also required to be reversed. Isolated DC-DC converters with DC voltage sources on both sides, such as traditional dual active bridge (DAB) and LLC / CLLC resonant converters, usually cannot meet such requirements. Thus, the DC-DC converter with one end connected to voltage source (VS) and the other end connected to current source (CS) is sometimes called hybrid DC-DC converter (H-DCC).

[0004] The isolated bidirectional H-DCC accessing the DCB system should have a reverse blocking bridge arm on the CS side to meet the requirements of DCB unipolar current characteristics and bidirectional power transmission. The reverse blocking bridge arm is either directly composed of reverse blocking switches, or composed of reverse conducting switches in series with diodes, or composed of two reverse conducting switches in anti-series. This kind of bidirectional H-DCC can realize power reversal by changing the polarity of the average DC voltage on the CS side without changing the polarity of the DC current on the CS side. The isolated full-bridge H-DCC is a typical bidirectional isolated H-DCC topology, as shown in Figure 2 It is sometimes called hybrid dual active bridge (H-DAB). Under appropriate modulation methods, the switches on the CS side of the H-DAB can achieve zero-current turn-off, and the switches on the VS side can achieve zero-voltage turn-on, see "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, et al.

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

[0006] First, the bridge arm of the CS side H-bridge may suffer from high voltage spikes during switching, which is mainly caused by the oscillation between the equivalent capacitance of the bridge arm and the leakage inductance of the transformer. To solve this problem, three methods can be generally taken, the first is to use RC or RCD and other energy dissipation type absorption circuits, but this will cause a lot of loss. The second is to use a special modulation and control method to avoid oscillation, which is often used in matrix converters and other circuits, but it is usually not suitable for the hybrid isolated DC-DC circuit shown in FIG. 3. The third is to use a regenerative clamp circuit, that is, a clamp circuit is formed by a diode and a clamp capacitor, and the energy of the absorbed voltage spikes is fed back to the VS side port through an isolated converter. This method is more practical, such as the document "Research on the voltage spike suppression strategy for three-phase high-frequency link matrix-type inverter," IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022, Youzheng Wang, Hongchen Liu, Wheeler, Patrick. That is, a regenerative clamp circuit is formed by using a non-controlled rectifier bridge + clamp capacitor + flyback circuit to suppress the voltage spikes of the high-frequency link matrix inverter. But this kind of method needs to add extra hardware circuit, which undoubtedly increases the cost and volume.

[0007] Second, the control and drive circuit of the CS side H-bridge needs an auxiliary power supply. Because the HV-DCB and the LVDC system have different potentials, the current source side auxiliary power supply and the voltage source side auxiliary power supply of the hybrid isolated DC-DC converter need high insulation level electrical isolation. For ordinary isolated DC-DC converters with DC capacitors on both sides, the power of the auxiliary power supply on both sides can be taken from their respective DC capacitors. For hybrid isolated DC-DC converters, only the input power of the voltage source side auxiliary power supply can be directly taken from the DC capacitor, and the current source side lacks an energy storage capacitor, and only a conversion link with high voltage isolation capability can be added to provide input power for the current source side APS, which will increase the cost of the converter.

[0008] In addition, without a power supply on the voltage source side, all auxiliary power supplies cannot work, and the switching of the reverse blocking bridge arm on the current source side is in the off state, which results in the entire DCB being in a blocking state. This means not only that the hybrid isolated DC-DC converter without a power supply on the voltage source side cannot start, but also that all converters along the DCB line cannot work normally.

[0009] Therefore, it is necessary to comprehensively solve the voltage peak suppression of the CS side H bridge, the auxiliary power supply power taking, and the starting problem under the passive condition of the voltage source side. SUMMARY

[0010] The technical problem to be solved by the present application is to provide a constant current and constant voltage converter integrated with a clamping and auxiliary power supply and a starting method thereof, aiming to overcome the above three types of deficiencies in the application of hybrid isolation DC-DC circuit and medium voltage DCB system, combine the regenerative clamping circuit and auxiliary power supply system, improve the circuit topology structure, and simultaneously realize effective suppression of voltage peak, auxiliary power supply power taking on the current source side, and starting under the passive condition of the voltage source port.

[0011] To solve the above technical problems, the technical solution adopted by the present application is:

[0012] A constant current and constant voltage converter integrated with a clamping and auxiliary power supply, comprising a main converter and a regenerative clamping circuit; the main converter comprises an inverse resistance H bridge, a main transformer circuit, an inverse 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 inverse resistance H bridge comprises four bridge arms; the inverse resistance H bridge first bridge arm and the inverse resistance H bridge second bridge arm are both composed of an inverse conduction switch and a diode in series; the cathode of the diode in the inverse resistance H bridge first bridge arm is connected with the inverse conduction switch; the anode of the diode in the inverse resistance H bridge second bridge arm is connected with the inverse conduction switch; the inverse resistance H bridge first bridge arm and the inverse resistance H bridge second bridge arm are connected in series, and the connection point is one end of the respective inverse conduction switch, which constitutes the first alternating current terminal of the inverse resistance H bridge; the inverse resistance H bridge third bridge arm and the inverse resistance H bridge fourth bridge arm are composed of an inverse conduction switch and a diode in series, or are composed of an inverse resistance switch; the inverse resistance H bridge third bridge arm and the inverse resistance H bridge fourth bridge arm are connected in series, and the connection point constitutes the second alternating current terminal of the inverse resistance H bridge; one end of the series branch is connected with the anode of the diode of the inverse resistance H bridge first bridge arm, and the connection point constitutes the direct current positive terminal of the inverse resistance H bridge; the other end of the series branch is connected with the cathode of the diode of the inverse resistance H bridge second bridge arm, and the connection point constitutes the direct current negative terminal of the inverse resistance H bridge; after the direct current positive terminal and the direct current negative terminal are led out, the current source port of the main converter is constituted;

[0014] The alternating current terminal of the inverse resistance H bridge constitutes the alternating current port of the inverse resistance H bridge, and is connected with one port of the main transformer circuit; the other port of the main transformer circuit is connected with the alternating current port of the inverse conduction H bridge; the direct current port of the inverse conduction H bridge and the main capacitor are connected, and are also connected with the auxiliary power supply on the voltage source side, and the two ends are led out to constitute the voltage source port of the converter;

[0015] The diode clamping circuit of the regenerative clamping circuit comprises four diodes, wherein the anode of the first diode is connected to the diode cathode of the first bridge arm of the inverse 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 diode anode of the second bridge arm of the inverse 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, the connection point is connected to the second alternating current terminal of the inverse 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 side auxiliary power supply of the current source, and are also connected to the input port of the feedback circuit.

[0016] Further improvement of the technical scheme of the application is that the inverse direction H-bridge of the main transformer comprises four bridge arms, each of which is composed of an inverse direction fully controllable switching device; wherein the first and second bridge arms are connected in sequence to form a first fully controllable half bridge of the inverse direction H-bridge, and the connection point forms a first alternating current terminal of the inverse direction H-bridge; the third and fourth bridge arms are connected in sequence to form a second fully controllable half bridge of the inverse direction H-bridge, and the connection point forms a second alternating current terminal of the inverse direction H-bridge; the first fully controllable half bridge and the second fully controllable half bridge are connected in parallel, one end of the parallel branch is a direct current positive terminal of the inverse direction H-bridge, and the other end forms a direct current negative terminal of the inverse direction H-bridge, and the direct current positive terminal and the direct current negative terminal form a direct current port of the inverse direction H-bridge; the first and second alternating current terminals of the inverse direction H-bridge form an alternating current port thereof.

[0017] Further improvement of the technical scheme of the application is that the main transformer circuit comprises a transformer or a transformer and an inductor; when the main transformer comprises a transformer and an inductor, the transformer and the inductor are respectively referred to as a main transformer and a main inductor; one end of the main inductor is connected to one winding of the main transformer, and the other end forms a port of the main transformer circuit together with the other end of the winding; the two ends of the other winding form another port of the main transformer circuit; when the main transformer circuit only comprises a transformer, the transformer is referred to as a main transformer, and the two ports thereof are the ports of the main transformer circuit.

[0018] Further improvement of the technical scheme of the application is that the main capacitor comprises a single capacitor or a branch formed by connecting a plurality of capacitors in series or in parallel.

[0019] Further improvement of the technical scheme of the application is that in the regenerative clamping circuit, the clamping capacitor is a single capacitor or a series-parallel branch of a plurality of 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, both input and output ports of the feedback circuit are DC ports, and the output DC port is connected with the voltage source port of the main converter; when the feedback circuit is an isolated DC / AC circuit, the input port of the feedback circuit is a DC port, the output port of the feedback circuit is an AC port, and the output AC port is connected with the AC port of the inverse-derivation H-bridge.

[0021] Further improvement of the technical scheme of the application is that the clamping capacitor is composed of two capacitors 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 comprises one transformer or one transformer and one inductor; when the auxiliary transformer comprises one transformer and one 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 with one winding of the auxiliary transformer, and the other end of the auxiliary inductor is connected with the other end of the winding to form one port of the auxiliary transformer circuit; the two ends of the other winding form the other port of the auxiliary transformer circuit; when the auxiliary transformer circuit comprises only one transformer, the transformer is referred to as an auxiliary transformer, and the two ports of the auxiliary transformer are the ports of the auxiliary transformer circuit;

[0023] The auxiliary full-controlled half-bridge circuit is composed of two inverse-derivation full-controlled switching devices connected in series, the two ends of the half-bridge are connected with the positive end and the negative end of the clamping capacitor respectively, the midpoint of the half-bridge is connected with one end of one port of the auxiliary transformer circuit, and the other end of the port is connected with the midpoint of the clamping capacitor;

[0024] The other port of the auxiliary transformer circuit forms the output port of the feedback circuit and is connected with the AC port of the inverse-derivation H-bridge of the main converter.

[0025] Further improvement of the technical scheme of the application is that the feedback circuit is composed of an auxiliary full-controlled H-bridge and an auxiliary transformer circuit;

[0026] The auxiliary transformer circuit comprises one transformer or one transformer and one inductor; when the auxiliary transformer comprises one transformer and one 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 with one winding of the auxiliary transformer, and the other end of the auxiliary inductor is connected with the other end of the winding to form one port of the auxiliary transformer circuit; the two ends of the other winding form the other port of the auxiliary transformer circuit; when the auxiliary transformer circuit comprises only one transformer, the transformer is referred to as an auxiliary transformer, and the two ports of the auxiliary transformer are the ports of the auxiliary transformer circuit;

[0027] The auxiliary full-controlled H-bridge comprises four bridge arms, each of which is composed of a reverse-conducting full-controlled switching device; the first and second bridge arms are connected in sequence to form a first full-controlled half-bridge of the auxiliary full-controlled H-bridge, and the connection point forms a first alternating-current terminal of the auxiliary full-controlled H-bridge; the third and fourth bridge arms are connected in sequence to form a second full-controlled half-bridge of the auxiliary full-controlled H-bridge, and the connection point forms a second alternating-current terminal of the auxiliary full-controlled H-bridge; the first full-controlled half-bridge and the second full-controlled half-bridge are connected in parallel, one end of the parallel branch is a direct-current positive terminal of the auxiliary full-controlled H-bridge, and the other end forms a direct-current negative terminal of the auxiliary full-controlled H-bridge, and the direct-current positive terminal and the direct-current negative terminal form a direct-current port of the auxiliary full-controlled H-bridge; the first and second alternating-current terminals of the auxiliary full-controlled H-bridge form an alternating-current port of the auxiliary full-controlled H-bridge;

[0028] The direct-current positive terminal and the direct-current negative terminal of the auxiliary full-controlled H-bridge are connected with the positive terminal and the negative terminal of the clamping capacitor respectively; and the alternating-current port of the auxiliary full-controlled H-bridge is connected with one port of the auxiliary transformer circuit.

[0029] The other port of the auxiliary transformer circuit forms an output port of the feedback circuit and is connected with the alternating-current port of the main converter reverse-conducting H-bridge.

[0030] The further improvement of the technical scheme of the application is that the feedback circuit is composed of a flyback circuit, the input port of the flyback circuit is connected in parallel with the clamping capacitor, and the output port is connected with the voltage source port of the main converter.

[0031] The further improvement of the technical scheme of the application is that the input port of the main transformer is also connected in parallel with a bypass device, and the bypass device is a thyristor or a mechanical switch.

[0032] A starting method of a constant-current constant-voltage converter integrated with a clamping and auxiliary power supply, comprising the following steps:

[0033] S1, controlling the voltage of the current source port;

[0034] The controllable external power supply connected with the current source port works in a voltage source mode, gradually increases the voltage of the current source port of the main converter, and makes the voltage uax of the clamping capacitor reach the input voltage threshold U thcs of the auxiliary power supply on the current source side, so that the auxiliary power supply on the current source side is started, and the current source side control and driving circuit are powered, so that they start to work.

[0035] S2, starting the hysteresis control on the voltage of the clamping capacitor and the voltage of the main capacitor;

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

[0037] S3, controlling the current source port current;

[0038] The controllable external power source connected with the current source port is turned into a current source mode, and the input current of the main converter current port is controlled at a small current value I low ;

[0039] S4, raising the clamping capacitor voltage uax and the main capacitor voltage Uc;

[0040] Under the control of the controller, the reference value Uaxref of the uax hysteresis control is raised to the vicinity of the rated value UaxN, and Uc rises accordingly, and exceeds the input voltage starting threshold U thvs of the voltage source side auxiliary power source, so that the voltage source side auxiliary power source is started; the voltage source side auxiliary power source supplies power to the voltage source side control and driving circuit;

[0041] S5, the main converter is turned into a normal control mode;

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

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

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

[0045] Thanks to the above technical solutions, the technical progress achieved by the application is:

[0046] 1. The clamping circuit in this invention also provides the energy required by the auxiliary power supply on the current source side, thus eliminating the need for a dedicated isolated DC-DC converter to provide energy to the auxiliary power supply on the current source side, saving hardware costs.

[0047] 2. In this invention, the auxiliary power supply on the current source side utilizes the energy input by the clamping circuit due to the absorption of voltage spikes, thereby reducing the power borne by the feedback circuit and reducing current stress and losses.

[0048] 3. This invention provides a path for charging the clamping capacitor from the current source port, thereby allowing the auxiliary power supply to be supplied by the power supply connected to the current source port when there is no power supply at the voltage source port, realizing the start-up under passive conditions of the voltage source port, and avoiding the current bus circuit break caused by the lack of driving power supply on the current source side. Attached Figure Description

[0049] Figure 1a This is a traditional solution for connecting low-voltage equipment to a high-voltage system via multiple terminals based on a high-voltage DC bus.

[0050] Figure 1b A solution for connecting multiple terminals of low-voltage equipment to a high-voltage system based on a high-voltage DC current bus;

[0051] Figure 2 This is the main circuit of an existing hybrid isolation DC-DC converter;

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

[0053] Figure 3b This is a schematic diagram of Embodiment 2 of the present invention;

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

[0055] Figure 4 This is a flowchart illustrating the startup control process of the present invention.

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

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

[0058] The components are as follows: 1. Current source port; 2. Bypass mechanism; 3. Reverse resistance H-bridge; 4. First arm of reverse resistance H-bridge; 5. Second arm of reverse resistance H-bridge; 6. Third arm of reverse resistance H-bridge; 7. Fourth 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 the voltage source side; 13. Voltage source side control and drive circuit; 14. Auxiliary transformer circuit; 15. Feedback circuit; 16. Auxiliary fully controlled half-bridge circuit; 17. Clamping capacitor; 18. Current source side control and drive circuit; 19. Current source side auxiliary power supply; 20. Diode clamping circuit; 21. Controllable external power supply; 22. Auxiliary fully controlled H-bridge; 23. Flyback circuit. Detailed Implementation

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

[0060] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0061] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of that feature. In the description of this invention, "a number" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] This invention provides a constant current and constant voltage converter that integrates clamping and auxiliary power supply. In one specific embodiment, such as... 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-conducting 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 inverse resistance H-bridge 3 of the main converter comprises four bridge arms; the first bridge arm 4 and the second bridge arm 5 of the inverse resistance H-bridge are both formed by series connection of an inverse-direction fully-controlled switching device and a diode, and have a current unidirectional conduction characteristic; the cathode of the diode in the first bridge arm 4 of the inverse resistance H-bridge is connected with the inverse-direction fully-controlled switching device, and the current flows from the anode of the diode and flows out from the other end of the inverse-direction switching device; the anode of the diode in the second bridge arm 5 of the inverse resistance H-bridge is connected with the inverse-direction fully-controlled switching device, and the current flows out from the cathode of the diode and flows into the other end of the inverse-direction fully-controlled switching device; the current outflow end of the first bridge arm 4 of the inverse resistance H-bridge is connected with the current inflow end of the second bridge arm 5 of the inverse resistance H-bridge, and the connection point constitutes a first alternating current terminal of the inverse resistance H-bridge 3.

[0064] As shown in Figure 3a , the third bridge arm 6 and the fourth bridge arm 7 of the inverse resistance H-bridge are the same as the first bridge arm 4 and the second bridge arm 5 of the inverse resistance H-bridge in structure, or are directly formed by fully-controlled inverse resistance switching devices as shown in Figure 3b , and have a unidirectional conduction characteristic; the current outflow end of the third bridge arm 6 of the inverse resistance H-bridge is connected with the current inflow end of the fourth bridge arm of the inverse resistance H-bridge, and the connection point constitutes a second alternating current terminal of the inverse resistance H-bridge 3.

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

[0066] The inverse-direction H-bridge 9 of the main converter comprises four bridge arms, and each bridge arm is formed by an inverse-direction fully-controlled switching device; the first and second bridge arms are sequentially connected, and form a first fully-controlled half-bridge of the inverse-direction H-bridge, and the connection point constitutes a first alternating current terminal of the inverse-direction H-bridge 9; the third and fourth bridge arms are sequentially connected, and form a second fully-controlled half-bridge of the inverse-direction H-bridge 9, and the connection point constitutes a second alternating current terminal of the inverse-direction H-bridge 9. The first fully-controlled half-bridge and the second fully-controlled half-bridge are in parallel connection, one end of the parallel connection branch is a direct current positive terminal of the inverse-direction H-bridge 9, and the other end constitutes a direct current negative terminal of the inverse-direction H-bridge 9, and the direct current positive terminal and the direct current negative terminal constitute a direct current port of the inverse-direction H-bridge 9. The first and second alternating current terminals of the inverse-direction H-bridge 9 constitute an alternating current port of the inverse-direction H-bridge 9.

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

[0068] The main capacitor 10 includes one capacitor, or a branch formed by connecting several capacitors in series or in parallel.

[0069] The AC port formed by the AC terminals of the inverse resistance H-bridge 3 is connected in sequence with one port of the main transformer circuit 8, and the other port of the main transformer circuit 8 is connected with the AC port of the inverse conduction H-bridge 9. The DC port of the inverse conduction H-bridge 9 is connected with the two ends of the main capacitor 10. The two 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 connected with the voltage source side auxiliary power supply 12 at the same time. The voltage source side auxiliary power supply 12 supplies power to the voltage source side control and driving circuit 13.

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

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

[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 inverse 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 inverse 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 inverse 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 end and the negative end of the clamping capacitor 17 form the feeding port. The feeding port is connected with the input port of the current source side auxiliary power supply 19, and also connected with 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. As shown in Figure 3c When the feedback circuit 15 is an isolated DC / DC circuit, both of its input and output ports are DC ports, and the output DC port is connected to the voltage source port 11 of the main converter; as shown in Figure 3a or Figure 3b 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 inverse H-bridge 9.

[0075] Embodiment One

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

[0077] As shown in Figure 3a 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 the auxiliary transformer and the auxiliary inductor. One end of the auxiliary inductor is connected to one winding of the auxiliary transformer, and the other end of the auxiliary inductor and the other end of the winding constitute one port of the auxiliary transformer circuit 14. The two ends of the other winding constitute the other port of the auxiliary transformer circuit 14.

[0078] As shown in Figure 3a As a preferred solution, the auxiliary full-controlled half-bridge circuit 16 is composed of two inverse full-controlled switching devices connected in series. 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 one 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, the other 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 inverse H-bridge 9 of the main converter.

[0080] Embodiment Two

[0081] As shown in Figure 3b The feedback circuit is composed of the auxiliary full-controlled H-bridge 22 and the auxiliary transformer circuit 14.

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

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

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

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

[0086] Embodiment Three

[0087] As shown in Figure 3c , the feedback circuit 15 is composed of a flyback circuit 23, the input port of the flyback circuit 23 is connected in parallel across 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 in the second embodiment.

[0088] As shown in Figure 4 , a starting method for taking power from a current source port, comprising the following steps:

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

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

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

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

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

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

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

[0096] Specifically, under the control of the controller, the reference value Uaxref of the uax hysteresis control is raised to the vicinity of the rated value UaxN, and Uc rises accordingly, exceeding the input voltage starting threshold U thvs of the voltage source side auxiliary power supply 12, so that the voltage source side auxiliary power supply 12 starts. 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 enters the normal control mode;

[0098] Specifically, the inverse resistance H-bridge 3 and the inverse conduction H-bridge 9 of the main converter start normal work, and the main capacitor voltage uc and the clamping capacitor voltage uax are respectively controlled in a closed loop. 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 switch signals of the inverse resistance H-bridge 3 and the inverse conduction H-bridge 9 according to Pmain. The closed loop control of the clamping capacitor uax is to adjust the switch signals 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, and k=k1*k T , where k T is the transformation ratio of the main transformer, and k1 is a value greater than 1. The reason for being greater than 1 is to limit the current of the clamping diode.

[0099] S6, the current source port current is raised to the rated value.

[0100] The specific procedure is as follows: 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] To further illustrate the beneficial effects of the present invention, two specific application scenarios are described below.

[0102] Application Scenario 1

[0103] Application scenario one is a series-connected offshore wind power system that also provides offshore services, such as Figure 5 As shown. In traditional offshore wind power DC transmission, the electricity generated by each wind turbine is generally collected via AC and boosted at power frequency before being rectified and sent to a high-voltage DC bus, and then transmitted to an onshore converter station via a high-voltage DC transmission line. In a series-connected offshore wind power system, the electricity generated by each wind turbine is converted to low-voltage DC by a high-frequency isolated DC-DC converter, and then connected in series to a high-voltage current bus. This eliminates the need for a large offshore converter station. In a series-connected offshore wind power system, the high-frequency isolated DC-DC circuit typically allows for unidirectional energy flow. However, with the development of offshore wind power systems, the provision of more diversified offshore services by offshore wind farms is attracting increasing attention. These diversified services include the deployment of 5G base stations near offshore wind turbine towers, marine environmental monitoring systems, ship charging piles, charging piles for inspection drones, and seawater hydrogen production. This means that future wind farms may experience a significant number of local loads. These local loads require reliable power supply, but due to the intermittent nature of wind power, relying solely on wind turbine generation is insufficient to guarantee the reliable operation of these local loads. Therefore, in series-connected offshore wind power systems with offshore service capabilities, the high-frequency isolated DC-DC circuit must be capable of bidirectional energy flow and have the ability to feed in both current and voltage sources. For example, using... Figure 2 The hybrid isolation DC-DC converter shown is problematic. Firstly, it suffers from voltage spikes in the H-bridge on the current source side. Secondly, if the auxiliary power supply of the H-bridge relies on a dedicated isolation conversion stage to draw power from the voltage source side, it not only increases hardware costs but also fails to power on the auxiliary power supply when the wind turbine is not generating electricity, leading to startup difficulties. This invention proposes a novel hybrid isolation DC-DC converter that combines a regenerative clamping circuit and an auxiliary power supply system. Furthermore, it innovatively adjusts the connection relationship between the clamping diode and the H-bridge on the current source side, introducing a diode conduction path from the current bus to the clamping capacitor. This effectively solves the problems of voltage spike suppression, power drawing from the auxiliary power supply on the current source side, and auxiliary power supply startup under passive voltage source conditions. According to the circuit and startup strategy proposed in this invention, even when the wind turbine is not operating, the auxiliary power supply is always powered on, and the current output from the onshore converter station can be transmitted through the circuit. Figure 5The path shown by the dashed line passes through the series diode of the first 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 arm of the reverse resistance H-bridge, thereby charging the clamping capacitor and starting the auxiliary power supply on the CS side.

[0104] Application Scenario 2

[0105] Application scenario two is a series-connected power supply system for seabed observation networks, such as... Figure 6 As shown. Compared to traditional offline, short-term, and non-real-time ocean observation methods based on ships, drilling, and deep-sea submersibles, cable-tethered seabed observation networks can conduct real-time and continuous seabed observations, which is of great significance for geological exploration, earthquake monitoring, marine scientific research, ecological environmental protection, and national defense security. In cable-tethered seabed observation networks, seabed power transmission technology is crucial for the normal and reliable operation of observation equipment. Based on the type of shore-based converter, seabed power transmission technology can be divided into two categories: constant voltage transmission and constant current transmission. The constant current power supply system has strong resistance to short-circuit faults, and the voltage transformation ratio of the converters in each seabed branch unit is not high, requiring only low voltage stress and easy decoupling in control. Therefore, it has a greater advantage in scenarios with high reliability requirements.

[0106] Traditional constant current power supply systems often use push-pull circuits for constant current / constant voltage power conversion in their branch units. However, push-pull circuits suffer from high switching stress and magnetic bias. The hybrid isolated DC-DC circuit shown in Figure 3 overcomes these drawbacks. Future seabed observation networks may also add energy storage or even wave power generation devices as backup power sources at observation nodes. Using a hybrid isolated DC-DC circuit with bidirectional energy flow can better achieve interconnection and mutual support of power at various observation points, enabling off-grid operation without shore-based power supply. However, as mentioned earlier, the hybrid isolated DC-DC circuit shown in Figure 3 faces challenges such as voltage spikes in the H-bridge on the current source side, auxiliary power supply, and system startup. To solve these problems, a constant current / constant voltage converter integrating clamping and auxiliary power supply as described in this invention can be used. Its working principle and startup method are similar to those in application scenario 1 and will not be repeated here.

[0107] In summary, this invention aims to overcome the three shortcomings mentioned above when hybrid isolated DC-DC circuits are applied to medium-voltage DCB systems. By combining regenerative clamping circuits and auxiliary power supply systems, and improving the circuit topology, it achieves effective suppression of voltage spikes, auxiliary power supply on the current source side, and startup under passive conditions at the voltage source port.

Claims

1. A constant current constant voltage converter integrated with a clamping and auxiliary power supply, characterized by: The main converter comprises an inverse resistance H-bridge (3), a main transformer circuit (8), an inverse direction H-bridge (9) and a main capacitor (10); the regenerative clamp circuit comprises a diode clamp circuit (20), a clamp capacitor and a feedback circuit (15); The inverse resistance H-bridge (3) comprises four bridge arms; the inverse resistance H-bridge first bridge arm (4) and the inverse resistance H-bridge second bridge arm (5) are both formed by connecting an inverse resistance switch and a diode in series; the cathode of the diode in the inverse resistance H-bridge first bridge arm (4) is connected with the inverse resistance switch; the anode of the diode in the inverse resistance H-bridge second bridge arm (5) is connected with the inverse resistance switch; the inverse resistance H-bridge first bridge arm (4) and the inverse resistance H-bridge second bridge arm (5) are connected in series, and one end of the respective inverse resistance switches is the connection point, which constitutes the first alternating current terminal of the inverse resistance H-bridge (3); the inverse resistance H-bridge third bridge arm (6) and the inverse resistance H-bridge fourth bridge arm (7) are connected in series by connecting an inverse resistance switch and a diode in series; the inverse resistance H-bridge third bridge arm (6) and the inverse resistance H-bridge fourth bridge arm (7) are connected in series, and the connection point constitutes the second alternating current terminal of the inverse resistance H-bridge (3); one end of the series branch is connected with the anode of the diode of the inverse resistance H-bridge first bridge arm (4), and the connection point constitutes the direct current positive terminal of the inverse resistance H-bridge (3); the other end of the series branch is connected with the cathode of the diode of the inverse resistance H-bridge second bridge arm (5), and the connection point constitutes the direct current negative terminal of the inverse resistance H-bridge (3); after the direct current positive terminal and the direct current negative terminal are led out, the current source port (1) of the main converter is formed; The first alternating current terminal and the second alternating current terminal constitute the alternating current port of the inverse resistance H-bridge, which is connected with one port of the main transformer circuit (8); the other port of the main transformer circuit (8) is connected with the alternating current port of the inverse direction H-bridge (9); the direct current port of the inverse direction H-bridge (9) is connected with the two ends of the main capacitor (10), and simultaneously connected with the auxiliary power supply (12) on the voltage source side; the two ends of the main capacitor (10) are led out, and the voltage source port (11) of the converter is formed; The diode clamp circuit (20) of the regenerative clamp circuit comprises four diodes, wherein the anode of the first diode is connected with the cathode of the diode of the inverse resistance H-bridge first bridge arm, and the cathode of the first diode is connected with the positive terminal of the clamp capacitor; the cathode of the second diode is connected with the anode of the diode of the inverse resistance H-bridge second bridge arm, and the anode of the second diode is connected with the negative terminal of the clamp capacitor; the anode of the third diode is connected with the cathode of the fourth diode, and the connection point is connected with the second alternating current terminal of the inverse resistance H-bridge; the cathode of the third diode is connected with the positive terminal of the clamp capacitor, and the anode of the fourth diode is connected with the negative terminal of the clamp capacitor; the two ends of the clamp capacitor are connected with the auxiliary power supply (19) on the current source side, and simultaneously connected with the input port of the feedback circuit (15).

2. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 1, wherein: The inverse-connection H-bridge (9) of the main converter comprises four bridge arms, each of which is composed of inverse-connection fully-controlled switching devices; the first and second bridge arms are connected in sequence to form a first fully-controlled half-bridge of the inverse-connection H-bridge (9), and the connection point forms a first AC terminal of the inverse-connection H-bridge (9); the third and fourth bridge arms are connected in sequence to form a second fully-controlled half-bridge of the inverse-connection H-bridge (9), and the connection point forms a second AC terminal of the inverse-connection H-bridge (9); the first and second fully-controlled half-bridges are connected in parallel, one end of the parallel branch is a DC positive terminal of the inverse-connection H-bridge (9), and the other end forms a DC negative terminal of the inverse-connection H-bridge (9), and the DC positive terminal and the DC negative terminal form a DC port of the inverse-connection H-bridge (9); the first and second AC terminals of the inverse-connection H-bridge (9) form an AC port thereof.

3. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 1, wherein: The main transformer circuit (8) comprises a transformer or a transformer and an inductor; when the main transformer comprises a transformer and an inductor, the transformer and the inductor are respectively referred to as a main transformer and a main inductor; one end of the main inductor is connected to one winding of the main transformer, and the other end and the other end of the winding form a port of the main transformer circuit (8); the two ends of the other winding form another port of the main transformer circuit (8); when the main transformer circuit (8) only comprises a transformer, the transformer is referred to as a main transformer, and the two ports thereof are the ports of the main transformer circuit (8).

4. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 1, wherein: The main capacitor (10) comprises a capacitor or a branch formed by connecting a plurality of capacitors in series or in parallel.

5. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 1, wherein: In the regenerative clamping circuit, the clamping capacitor is a single capacitor or a series-parallel branch of a plurality of capacitors, and the two ends of the clamping capacitor are a positive end and a negative end, respectively; 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, the input and output ports thereof are 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, the input port thereof is a DC port, the output port thereof is an AC port, and the output AC port is connected to the AC port of the inverse-connection H-bridge (9).

6. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 5, wherein: The clamping capacitor 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 (15) is composed of an auxiliary fully-controlled half-bridge circuit (16) and an auxiliary transformer circuit (14); The auxiliary transformer circuit (14) comprises a transformer or a transformer and an inductor; when the auxiliary transformer comprises 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 one winding of the auxiliary transformer, and the other end and the other end of the winding form a port of the auxiliary transformer circuit (14); the two ends of the other winding form another port of the auxiliary transformer circuit (14); when the auxiliary transformer circuit (14) only comprises a transformer, the transformer is referred to as an auxiliary transformer, and the two ports thereof are the ports of the auxiliary transformer circuit (14); The auxiliary full-controlled half-bridge circuit (16) is connected in sequence by two reverse-conducting full-controlled switching devices, the two ends of the half-bridge are connected to the positive end and the negative end of the clamping capacitor respectively, 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; The other port of the auxiliary transformer circuit constitutes an output port of the feedback circuit (15) and is connected to the AC port of the reverse-conducting H-bridge (9) of the main transformer.

7. The clamp and auxiliary power supply integrated constant current constant voltage converter of claim 5, wherein: The feedback circuit (15) is composed of the auxiliary full-controlled H-bridge (22) and the 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 one winding of the auxiliary transformer, and the other end thereof constitutes one port of the auxiliary transformer circuit (14) with the other end of the winding; the two ends of the other winding constitute the other port of the auxiliary transformer circuit (14); when the auxiliary transformer circuit (14) only includes a transformer, the transformer is referred to as an auxiliary transformer, and the two ports thereof are the ports of the auxiliary transformer circuit (14); The auxiliary full-controlled H-bridge (22) includes four bridge arms, each of which is composed of a reverse-conducting full-controlled switching device; the first and second bridge arms are connected in sequence to constitute a first full-controlled half-bridge of the auxiliary full-controlled H-bridge (22), and the connection point constitutes a first AC terminal of the auxiliary full-controlled H-bridge (22); the third and fourth bridge arms are connected in sequence to constitute a second full-controlled half-bridge of the auxiliary full-controlled H-bridge (22), and the connection point constitutes a second AC terminal of the auxiliary full-controlled H-bridge (22); the first full-controlled half-bridge and the second full-controlled half-bridge are connected in parallel, one end of the parallel branch is a DC positive terminal of the auxiliary full-controlled H-bridge (22), and the other end constitutes a DC negative terminal of the auxiliary full-controlled H-bridge (22), and the DC positive terminal and the DC negative terminal constitute a DC port of the auxiliary full-controlled H-bridge (22); the first and second AC terminals of the auxiliary full-controlled H-bridge (22) constitute AC ports thereof; The DC positive terminal and the DC negative terminal of the auxiliary full-controlled H-bridge (22) are connected to the positive end and the negative end of the clamping capacitor respectively; the AC ports of the auxiliary full-controlled H-bridge (22) are connected to one port of the auxiliary transformer circuit; The other port of the auxiliary transformer circuit constitutes an output port of the feedback circuit (15) and is connected to the AC port of the reverse-conducting H-bridge (9) of the main transformer.

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

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

10. A starting method of a constant current constant voltage converter integrated with a clamping and auxiliary power supply, characterized in that: The clamping and auxiliary power supply integrated constant current and constant voltage converter according to any one of claims 1-9 comprises the following steps: S1, controlling the voltage of the current source port (1); The controllable external power supply (21) connected with the current source port (1) works in voltage source mode, gradually raises the main converter current port voltage, and makes the clamping capacitor voltage uax reach the input voltage threshold U which can make the current source side auxiliary power supply (19) start thcs Thus, the current source side auxiliary power supply (19) starts, and the current source side control and driving circuit (18) is powered, so that they start to work. S2, starting hysteresis control on the voltage of the clamping capacitor and the voltage of the main capacitor (10); Under the control of the controller, the switch tubes of the first and second inverse resistance bridge arms are turned on when the clamping capacitor voltage uax is higher than the upper limit of the hysteresis (Uaxref+DUaxup), and are locked when the clamping capacitor voltage uax is lower than the lower limit of the hysteresis (Uaxref-DUaxdown); the feedback circuit (15) stops delivering power to the voltage source port (11) side when the main capacitor (10) voltage Uc is higher than the upper limit of the hysteresis (uax+DUcup), and delivers power to the voltage source port (11) side when the main capacitor (10) voltage Uc is lower than the lower limit of the hysteresis (uax-DUcdown); S3, control the current source port (1) current; The controllable external power supply (21) connected with the current source port (1) is converted to a current source mode, and the input current of the main converter current port is controlled at a small current value I low ; S4, raise the clamping capacitor voltage uax and the main capacitor (10) voltage uc; Under the control of the controller, the reference value Uaxref of the uax hysteresis control is raised to the rated value UaxN, and Uc rises accordingly, exceeding the input voltage starting threshold U thvs of the voltage source side auxiliary power supply (12), so that the voltage source side auxiliary power supply (12) starts; the voltage source side auxiliary power supply (12) supplies power to the voltage source side control and driving circuit; S5, the main converter enters the normal control mode; The inverse resistance H-bridge and the inverse conduction H-bridge (9) of the main converter start to work normally, and the voltage uc of the main capacitor (10) and the clamping capacitor voltage uax are respectively closed-loop controlled; the closed-loop control of the voltage uc of the main capacitor (10) is to adjust the main converter power instruction Pmain according to the difference between uc and the instruction Ucref, and then to determine the switching signal of the inverse resistance H-bridge and the inverse conduction H-bridge (9) according to Pmain; the closed-loop control of the clamping capacitor voltage uax is to adjust the switching signal of the feedback circuit (15) according to the difference between the clamping capacitor voltage uax and the instruction Uaxref; wherein the value of Uaxref is equal to k*Ucref, k=k1*k T , wherein k T is the transformation ratio of the main transformer, and k1 is a value greater than 1. S6, raise the current source port (1) current to the rated value; The 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 start-up process is complete.

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