Device straight-string type multi-resonant-cavity multi-direct-current-bus transformer

Abstract

The transformer is composed of a clamping circuit, a device series inverter circuit and a multi-isolation conversion rectification circuit, the clamping circuit is electrically connected with a direct current at an input end, two ends of the clamping circuit are electrically connected with the device series inverter circuit, and the device series inverter circuit is electrically connected with the multi-isolation conversion rectification circuit. And the output end connected with the device series inverter circuit is electrically connected with the multi-isolation conversion rectifier circuit. The direct current bus transformer is formed by the clamping circuit, the device series inverter circuit, the multi-isolation conversion rectification circuit and the non-isolation adjusting circuit, and the direct current bus transformer can meet the requirements of compact high-capacity direct current bus power conversion of a future data center and large-scale renewable energy direct current aluminum production or hydrogen production.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a device direct series type multi-resonant cavity multi-DC bus transformer. Background Art

[0002] The large-capacity of new energy power generation has led to an increase in the capacity of the converter, which requires the use of power devices with larger power levels, or the use of a topological structure of multiple low-voltage converters in parallel to meet the requirements of high-power conversion. Among them, the use of a multi-low-voltage converter parallel structure has flexible redundant control characteristics, which can effectively improve the reliability of the system. However, when the load is low, its efficiency is much lower than the efficiency under rated conditions. It is necessary to adopt a control strategy to optimize and improve the overall efficiency of the parallel system. At the same time, the number of devices required for multiple low-voltage converters in parallel is large, the cost is high, and the area occupied is large. At present, the power of a single low-voltage converter is generally less than 500kW. In addition, as the power consumption of data centers continues to increase, the capacity of existing DC bus voltage converters will not be able to meet the future high-power conversion needs. The existing conventional DC power supply has a small capacity, a large number, and a large area, which cannot meet the future data center compact large-capacity DC bus power conversion, large-scale renewable energy DC aluminum production, and hydrogen production needs. Summary of the invention

[0003] The present invention provides a device direct series type multi-resonant cavity multi-DC bus transformer, which can realize single machine direct hanging of medium voltage bus, multi-channel DC bus output, single machine large capacity can reach tens of megawatts, and has the characteristics of high compactness, high efficiency and simple control.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: A device direct series type multi-resonant cavity multi-DC bus transformer, the transformer consists of a clamping circuit, a device series inverter circuit and a multi-isolation conversion rectifier circuit, the clamping circuit is electrically connected to the DC voltage at the input end, the two ends of the clamping circuit are electrically connected to the device series inverter circuit, and the output end connected to the device series inverter circuit is electrically connected to the multi-isolation conversion rectifier circuit.

[0005] The above clamping circuit includes a reactance , reactance With clamping diode , , And clamping capacitor Series connection, the two ends of the series connection are connected with a DC voltage Electrical connection, reactance With clamping diode , , There is a clamping resistor in parallel at both ends of , reactance With clamping diode The connection point between the The line segments are respectively used as positive and negative output terminals and are electrically connected to the device series inverter circuit.

[0006] The above-mentioned device series inverter circuit is composed of four bridge arm switch groups, which include a first bridge arm switch group, a second bridge arm switch group, a third bridge arm switch group and a fourth bridge arm switch group. The first bridge arm switch group and the second bridge arm switch group constitute a first series branch, the third bridge arm switch group and the fourth bridge arm switch group constitute a second series branch, and the two ends of the first series branch and the second series branch in parallel are electrically connected to the output end of the clamping circuit. The middle connection point between the first bridge arm switch group and the second bridge arm switch group, and the middle connection point between the third bridge arm switch group and the fourth bridge arm switch are electrically connected to the multi-isolation conversion rectifier circuit as the output end.

[0007] The first bridge arm switch group includes a series of fully controlled power switches , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The second bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The third bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The fourth bridge arm switch group includes a series-connected fully controlled power switch , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor . The above-mentioned multi-isolation conversion and rectification circuit is composed of a plurality of isolation conversion and rectification circuits, the input sides of the isolation conversion and rectification circuits are connected in parallel, and the output sides are independent of each other.

[0008] The input end of the above-mentioned isolation conversion rectifier circuit is composed of a resonant inductor , magnetizing inductance and resonant capacitor Series structure, magnetizing inductance The two ends are electrically connected to the input end of the step-down AC transformer, the output end of the step-down AC transformer is electrically connected to the bridge rectifier circuit, and the two ends of the bridge rectifier circuit are connected in parallel with an output capacitor , output capacitor The two ends of the output DC voltage.

[0009] The present invention provides a device direct series type multi-resonant cavity multi-DC bus transformer, which combines a clamping circuit, a device series inverter circuit, multiple isolation conversion rectifier circuits and a non-isolated regulation circuit to form a DC bus transformer, which can be suitable for compact large-capacity DC bus power conversion in future data centers, large-scale renewable energy DC aluminum or hydrogen production needs. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is an electrical schematic diagram of a direct series type multi-resonant cavity multi-DC bus transformer of the device of the present invention; Figure 2 This is the working waveform of the direct-series multi-resonant cavity type multi-DC bus transformer of the device of the present invention. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following content will systematically and completely describe the specific technical solutions of the present invention in combination with the drawings provided according to the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0011] Embodiment 1: like Figure 1As shown in the figure, a device direct series type multi-resonant cavity multi-DC bus transformer is composed of a clamping circuit, a device series inverter circuit and a multi-isolation conversion rectifier circuit. The clamping circuit is electrically connected to the DC voltage at the input end, the two ends of the clamping circuit are electrically connected to the device series inverter circuit, and the output end connected to the device series inverter circuit is electrically connected to the multi-isolation conversion rectifier circuit.

[0012] The above clamping circuit includes a reactance , reactance With clamping diode , , And clamping capacitor Series connection, the two ends of the series connection are connected with a DC voltage Electrical connection, reactance With clamping diode , , There is a clamping resistor in parallel at both ends of , reactance With clamping diode The connection point between the The line segments are respectively used as positive and negative output terminals and are electrically connected to the device series inverter circuit.

[0013] The above-mentioned device series inverter circuit is composed of four bridge arm switch groups, which include a first bridge arm switch group, a second bridge arm switch group, a third bridge arm switch group and a fourth bridge arm switch group. The first bridge arm switch group and the second bridge arm switch group constitute a first series branch, the third bridge arm switch group and the fourth bridge arm switch group constitute a second series branch, and the two ends of the first series branch and the second series branch in parallel are electrically connected to the output end of the clamping circuit. The middle connection point between the first bridge arm switch group and the second bridge arm switch group, and the middle connection point between the third bridge arm switch group and the fourth bridge arm switch are electrically connected to the multi-isolation conversion rectifier circuit as the output end.

[0014] The first bridge arm switch group includes a series of fully controlled power switches , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The second bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The third bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The fourth bridge arm switch group includes a series-connected fully controlled power switch , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor . The above-mentioned multi-isolation conversion and rectification circuit is composed of a plurality of isolation conversion and rectification circuits, the input sides of the isolation conversion and rectification circuits are connected in parallel, and the output sides are independent of each other.

[0015] The input end of the above-mentioned isolation conversion rectifier circuit is composed of a resonant inductor , magnetizing inductance and resonant capacitor Series structure, magnetizing inductance The two ends are electrically connected to the input end of the step-down AC transformer, the output end of the step-down AC transformer is electrically connected to the bridge rectifier circuit, and the two ends of the bridge rectifier circuit are connected in parallel with an output capacitor , output capacitor The two ends of the output DC voltage.

[0016] Working principle: The fixed duty cycle is preferably about 0.48. When three isolated conversion rectifier circuits are used, the primary and secondary turns ratios of the AC transformers Tr1~Tr3 are both 5:0.75, and the input voltage Vin is 5kV, two 4500V 5000A IGCT devices are connected in series, a total of 8 fully controlled devices, and the output of the three voltages Vout1~Vout3 can be achieved with a total output power of 12MW.

[0017] In addition, the number of isolated conversion and rectification circuits and the turns ratio of the AC transformer therein can be flexibly adjusted according to the specific output voltage level and the number of output ports to form different voltage port outputs.

[0018] The fully controlled devices in the proposed DC bus transformer can achieve quasi-zero voltage turn-on and quasi-zero current turn-off, and the secondary rectifier diode can achieve zero current turn-off, which greatly reduces the switching loss of the IGCT device and the rectifier diode. And because the proposed DC transformer can flexibly adjust the output end.

[0019] The number can fully utilize the high voltage and high current capabilities of IGCT devices to achieve large capacity, compactness and high efficiency of a single machine.

[0020] Embodiment 2: The device direct series type multi-resonant cavity multi-DC bus transformer is composed of a clamping circuit, a device series inverter circuit, a multi-isolation conversion rectifier circuit, and a non-isolation regulation circuit.

[0021] The clamping circuit is composed of an anode reactance, a clamping diode, a clamping resistor and a clamping capacitor. The clamping circuit can limit the current change rate when the switch tube is turned on, and can limit the oscillation amplitude of the AC input voltage of the inverter circuit.

[0022] The device series inverter circuit includes four bridge arm switches: the bridge arm switches include a fully controlled power switch, an anti-parallel diode, a series current limiting resistor, a dynamic voltage balancing capacitor, and a parallel voltage balancing resistor; the fully controlled power switch is composed of a gate turn-off thyristor, a high-power transistor, a power field effect transistor or an insulated gate bipolar transistor.

[0023] When power field effect transistors or insulated gate bipolar transistor devices are used in series, a clamping circuit can be used or removed.

[0024] The multi-isolation conversion rectifier circuit includes multiple isolation conversion rectifier circuits; the input sides of the isolation conversion rectifier circuits are connected in parallel, and the output sides are independent of each other. The isolation conversion rectifier circuit is composed of a resonant inductor, a resonant capacitor, a magnetizing inductor, a step-down AC transformer, a bridge rectifier circuit, and an output capacitor. The resonant inductor can be externally matched, or replaced by the transformer's own leakage inductance to reduce system cost and volume; the resonant capacitor can be placed on the primary or secondary side of the transformer; the magnetizing inductor can be externally matched, or the transformer's own magnetizing inductance can be used to reduce system cost and volume; the step-down AC transformer in each isolation conversion rectifier circuit can adopt different transformation ratios and capacities to achieve outputs of different voltage levels and powers.

[0025] The four-arm switch tubes of the multi-resonant cavity multi-DC bus transformer adopt fixed duty cycle control to achieve fixed ratio conversion from medium voltage DC bus to low voltage bus.

Claims

1. A device direct series type multi-resonant cavity multi-DC bus transformer, characterized in that: The transformer is composed of a clamping circuit, a device series inverter circuit and a multi-isolation conversion rectifier circuit. The clamping circuit is electrically connected to the DC voltage at the input end, both ends of the clamping circuit are electrically connected to the device series inverter circuit, and the output end connected to the device series inverter circuit is electrically connected to the multi-isolation conversion rectifier circuit.

2. According to the device direct series type multi-resonant cavity multi-DC bus transformer described in claim 1, it is characterized in that: The clamping circuit includes a reactance , reactance With clamping diode , , And clamping capacitor Series connection, the two ends of the series connection are connected with a DC voltage Electrical connection, reactance With clamping diode , , There is a clamping resistor in parallel at both ends of , reactance With clamping diode The connection point between the The line segments are respectively used as positive and negative output terminals and are electrically connected to the device series inverter circuit.

3. The device direct series type multi-resonant cavity multi-DC bus transformer according to claim 2, characterized in that: The device series inverter circuit is composed of four bridge arm switch groups, which include a first bridge arm switch group, a second bridge arm switch group, a third bridge arm switch group and a fourth bridge arm switch group. The first bridge arm switch group and the second bridge arm switch group constitute a first series branch, the third bridge arm switch group and the fourth bridge arm switch group constitute a second series branch, the two ends of the first series branch and the second series branch in parallel are electrically connected to the output end of the clamping circuit, and the middle connection point of the first bridge arm switch group and the second bridge arm switch group, as well as the middle connection point of the third bridge arm switch group and the fourth bridge arm switch are electrically connected to the multi-isolation conversion rectifier circuit as the output end.

4. The device direct series type multi-resonant cavity multi-DC bus transformer according to claim 3, characterized in that: The first bridge arm switch group includes a fully controlled power switch connected in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The second bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The third bridge arm switch group includes a fully controlled power switch in series , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor ; The fourth bridge arm switch group includes a series-connected fully controlled power switch , , , , each fully controlled power switch There is an anti-parallel diode in parallel , Current limiting resistor and dynamic voltage balancing capacitors Series circuit and voltage equalizing resistor .

5. The device direct series type multi-resonant cavity multi-DC bus transformer according to claim 4, characterized in that: The multi-isolation conversion rectifier circuit is composed of a plurality of isolation conversion rectifier circuits, the input sides of the isolation conversion rectifier circuits are connected in parallel, and the output sides are independent of each other.

6. The device direct series type multi-resonant cavity multi-DC bus transformer according to claim 5, characterized in that: The input end of the isolation conversion rectifier circuit is composed of a resonant inductor , magnetizing inductance and resonant capacitor Series structure, magnetizing inductance The two ends are electrically connected to the input end of the step-down AC transformer, the output end of the step-down AC transformer is electrically connected to the bridge rectifier circuit, and the two ends of the bridge rectifier circuit are connected in parallel with an output capacitor , output capacitor The two ends of the output DC voltage.

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