Three-phase AC-DC changing circuit, three-phase AC-DC changing method and control system of three-phase AC-DC changing circuit

Abstract

The invention provides a three-phase AC-DC changing circuit, a three-phase AC-DC changing method and a control system of the three-phase AC-DC changing circuit. The changing circuit comprises a three-phase alternating current source, a first AC-DC changing module, a second AC-DC changing module, a third AC-DC changing module and a direct current side output end. The three-phase alternating current source comprises a first output end, a second output end and a third output end. The first AC-DC changing module, the second AC-DC changing module and the third AC-DC changing module are electrically connected with the first output end, the second output end and the third output end of the three-phase alternating current source respectively and respectively comprises three parallelly connected AC-DC converters, namely N1, N2 and N3. The direct current side output end is electrically connected with an output end of the first AC-DC changing module, an output end of the second AC-DC changing module and an output end of the third AC-DC changing module, wherein the output ends are connected in parallel. At least one of the N1, the N2 and the N3 is larger than or equal to 2 in number. By adoption of the three-phase AC-DC changing circuit, the three-phase AC-DC changing method and the control system of the three-phase AC-DC changing circuit, two or more parallelly connected AC-DC converters in at least one AC-DC changing module are utilized for working in a parallel and staggered mode so that inductance can obtain a small incoming current ripple under small inductance and power density of a power converter can be improved.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a three-phase AC-DC conversion circuit for a power converter, a conversion method and a control system thereof. Background technique [0002] With the development of power electronic technology, the harmonic content of the input current of the power electronic converter is required to be higher and higher. For a three-phase power factor correction (PFC, Power Factor Correction) circuit, the harmonics of its input current mainly come from the current ripple caused by the switching of high-frequency switching devices. Therefore, in order to reduce the harmonics of the input current, the When the switching frequency of the high-frequency switching device remains unchanged, one solution in the prior art is to increase the inductance in the three-phase PFC circuit or improve the filtering effect of the EMI link to reduce the current ripple. However, no matter increasing the...

AI Technical Summary

Problems solved by technology

However, the increase in the number or volume of electrolytic capacitors will inevitably increase the volume of the entire system, resulting in a decrease in the power density of the converter

Another solution is to only enhance the heat dissipation capability of electrolytic capacitors, such as increasing the air volume of the system, but if the system is running in a high temperature environment, the heat dissipation effect of electrolytic capacitors is not obvious

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