Switching harmonic suppression method for inverter parallel system and inverter parallel system

Abstract

The invention discloses a switch sub-harmonic suppression method of an inverter parallel connection system and an inverter parallel connection system. The method comprises the following steps: all inverters in an inverter parallel connection system share the voltage of an AC bus, one inverter accesses the parallel connection system, and other inverters do not access the parallel connection system;after the inverter accessing the parallel connection system is operated stably, each parallel connection circuit detects the voltage of the AC bus, and a carrier synchronous signal of each inverter can be obtained according to the voltage of the AC bus; each inverter accesses the parallel connection system, and a carrier phase value of each inverter and a counting direction of the carrier wave are obtained by adopting a rectangular pulse rising edge and falling edge triggering way by virtue of capture interruption; and the obtained carrier phase value of each inverter and the counting direction of the carrier wave are compared with zero or a carrier period value to obtain an adjusting amount for the carrier period of each inverter, so that the period value of the carrier wave is adjusted,and the synchronization of carrier signals of multiple inverters can be realized.

Description

technical field [0001] The invention relates to the technical field of AC power supply. More specifically, it relates to a method for suppressing switching subharmonics of an inverter parallel system and the inverter parallel system. Background technique [0002] As China's economy enters a stage of rapid development, the process of urbanization can be described as changing with each passing day. In order to alleviate the population pressure in the central urban area and build a three-dimensional intercity and metropolitan transportation network, the intercity railway came into being. The construction of intercity railways also plays a pivotal role in my country's railway planning. The construction of intercity railways such as Beijing-Tianjin intercity and Changzhou-Zhuzhou-Tanzhou intercity can effectively relieve the pressure of passenger transport between short-distance cities and drive regional economic development. [0003] The high-power low-switching frequency inve...

AI Technical Summary

Problems solved by technology

The switching harmonics of low switching frequency inverters are particularly serious, which not only affects the equalization of fundamental power, but also causes equipment damage and accidents, seriously affecting system stability

[0004] The existing method is mainly to increase the inductance value to reduce the influence of harmonics, but in the case of high power, the inductance value should not be too large, and the problem of switching subharmonics cannot be solved well; pulse width modulation technology uses PWM high frequency It can effectively suppress the harmonics of small and medium power converters; but for high-power inverters, the increase in switching frequency and switching loss limits its application

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