Multi-level converter employing multi-winding intermediate-high frequency transformer

Abstract

The invention relates to a multi-level converter employing a multi-winding intermediate-high frequency transformer. The multi-level converter comprises a voltage current measuring unit, wherein the voltage current measuring unit is connected between two ends of a power grid in parallel; the voltage current measuring unit sends a measured voltage current signal of the power grid to a control unit; a current signal output by the power grid is filtered and current-limited by an inducer and then is input in a H-bridge rectifier; the H-bridge rectifier converts the input alternating current into the direct current with stable amplitude according to the control signal sent by the control unit; the output end of the H-bridge rectifier is connected with a plurality of inverters; the output ends of the inverters are connected the input end of the multi-winding intermediate-high frequency transformer; the output end of the multi-winding intermediate-high frequency transformer is connected with a load converter through a plurality of rectifiers; a voltage current measuring module, all inverters and all rectifiers perform information interaction with the control unit; and the load converter supplies power to the load under the control of the control unit. The cost of the multi-level converter in the invention is saved; the size and the weight of the multi-level converter are reduced; and the multi-level converter can be widely applied in an electrical system and electric traction.

Description

technical field [0001] The invention relates to a topology structure of a multi-level converter, in particular to a multi-level converter using a multi-winding mid-high frequency transformer. Background technique [0002] With the application of large-capacity motor speed control systems and power electronic converters in power systems, the requirements for the output voltage level of power electronic converters are also getting higher and higher. Limited by the withstand voltage and current levels of power devices, traditional two-level converters can no longer meet the needs of high-voltage and large-capacity applications. Compared with the direct series connection of devices and the voltage multiplexing technology, the voltage-type multi-level technology is the main development direction of the large-capacity converter at present. [0003] At present, the commonly used multi-level topologies mainly include diode-clamped, capacitor-clamped, H-bridge cascaded, and so on. ...

AI Technical Summary

Problems solved by technology

Among them, the diode-clamped and capacitor-clamped topologies have the following disadvantages: 1. The voltage of the bus capacitors above five levels needs to be additionally controlled by hardware or software, otherwise the capacitor voltage may appear incorrect. stable, resulting in circuit instability or a decrease in the number of output levels

2. As the number of output levels increases, the number of clamping diodes or capacitors will increase rapidly according to the quadratic power of the number of levels, the circuit cost will increase too much, and the control will be more complicated

3. The modularization of the circuit is poor, and the fault operation ability of the circuit is low

But the isolation transformer in this topology is bulky, heavy and expensive

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