Phase-shifted delta-sigma pulse density modulator for multilevel converters and method of operation

Abstract

This invention discloses a phase-shifted Delta-Sigma pulse density modulator and its operating method for multilevel converters, belonging to the field of power electronic control technology. In the modulator provided by this invention, the pulse density command signal is input to a first multiplexer to obtain multiple signals to be quantized. These multiple signals are then input to a quantizer to obtain a first set of pulse signals. After a delay, the first set of pulse signals is used to obtain a second set of pulse signals. For a multilevel converter using full-bridge submodules, the first set of pulse signals is used to generate the switching signals for the leading arms of each submodule, and the second set of pulse signals is used to generate the switching signals for the lagging arms of each submodule. This invention uses pulse density modulation, making it suitable for resonant circuits and achieving wide-range soft switching under a fixed switching frequency. It provides different pulse density modulation waves for each submodule of the multilevel converter, reducing the harmonic content between converters.

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