Closed-loop zero-sequence voltage optimized injection method for cascaded H-bridge converter

Abstract

The invention discloses a closed-loop zero-sequence voltage optimized injection method for a cascaded H-bridge converter. The method is applied to the phase-to-phase power control of the cascaded H-bridge converter, can expand the adjustment range of the phase-to-phase power of the cascaded H-bridge, increases a converter DC bus voltage utilization rate, and prevents over-modulation after the zero-sequence voltage is injected into the three-phase modulation wave in the form of closed-loop control. The method is characterized by obtaining the three-phase original modulating wave and the zero-sequence signal fundamental frequency component Vzero, f of the cascaded H-bridge; then inputting a modulating signal into an over-modulated component extraction function fext to obtain a over-modulatedcomponent extraction signal Dover; passing the signal Dover through a low-pass filter transfer function, a gain coefficient and a fundamental frequency wave trap to obtain a zero-sequence signal component Vzero, h for suppressing over-modulation; finally, adding the Vzero, h to the zero-sequence signal fundamental frequency component Vzero, f to obtain the optimized zero-sequence voltage Vzero, op, injecting the optimized zero-sequence voltage Vzero into the original modulating wave, and outputting a corresponding switching signal.

Description

Technical field [0001] The present invention relates to the technical field of converters, in particular to a closed-loop zero-sequence voltage optimization injection method. Specifically, the method is applied to phase-to-phase power control of cascaded H-bridge converters, which can expand the zero-sequence voltage injection range and improve the conversion The DC bus voltage utilization rate of the converter is used to prevent overmodulation after the three-phase modulation wave is injected into the zero sequence voltage in the form of closed-loop control. Background technique [0002] Current conversion technology is a technology that converts electrical energy from DC to AC or AC to DC, and plays an important role in today's industrial applications. The cascaded H-bridge converter is widely used in high-voltage and high-power energy supply occasions. Its principle is to use the H-bridge circuit composed of four switch tubes as the basic unit. The main circuit is built in ser...

AI Technical Summary

Problems solved by technology

After the zero-sequence voltage is injected, the modulation signal amplitude may exceed the carrier amplitude, and overmodulation occurs. At this time, the cascaded H-bridge power balance and output current power quality cannot meet the requirements.

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