Isolated charging power supply for unbalanced power grid and modulation method thereof

Abstract

The invention provides an isolated charging power supply for an unbalanced power grid and a modulation method thereof. The charging power supply comprises three sampling resistors, a three-phase four-bridge-arm matrix converter, a high-frequency transformer, a rectifier circuit and a control circuit. The charging power supply adopts a three-phase four-bridge-arm current-type high-frequency chain matrix rectifier comprising the three-phase four-bridge-arm matrix converter formed by adding one bridge arm on the basis of a three-phase three-bridge-arm converter to provide a zero-sequence current path for the input unbalanced current when the power grid is unbalanced. The modulation method combines an SPWM modulation method and the de-coupling and re-coupling idea; through use of the de-coupling and re-coupling idea+the SPWM modulation method, DC bus voltage utilization rate is improved, component withstand voltage level is reduced, network-side unit power factor is improved and the content of low-order harmonics of input current is reduced; and integral drive solves the problem of primary side voltage peak caused by inductance leakage of the transformer, thereby reducing switching loss and improving quality of output voltage waveform.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to an isolated charging power supply and a modulation method for an unbalanced power grid. Background technique [0002] The matrix rectifier is a topological device that converts AC power into DC power. Compared with traditional rectifiers, it has a more standard output sinusoidal current. The input side can obtain unity power factor, and the input and output sides are used to filter out high Subharmonic small-capacity filter to replace the bulky large-capacity energy storage element. The difference between the high-frequency chain rectification technology and the conventional rectification technology is that it uses a high-frequency transformer to realize energy transfer and electrical isolation between the AC side and the DC side, thereby reducing the volume and weight of the transformer, improving the utilization rate of electric energy, and improving the working characteristics...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide an isolated charging power supply and its modulation method for unbalanced power grids, so as to overcome the technical defect of low working efficiency of three-phase three-leg high-frequency matrix rectifiers when the power grid is unbalanced, and improve charging efficiency. The working efficiency of the power supply when the power grid is unbalanced and overcome the technical defect of large voltage spikes at both ends of the switching tube during the working process of the charging power supply

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