Space voltage vector modulation method achieving common mode voltage minimization

Abstract

The invention relates to a space voltage vector modulation method achieving common mode voltage minimization. Combined with the principle of a traditional space voltage vector modulation method, in each control period, on the basis of choosing two non-zero valid vectors, two reverse non-zero vectors are adopted fixedly for forming a zero vector. The two reverse non-zero vectors are inserted into the head and tail and the middle of the control period symmetrically. Through adjusting the acting sequence of the valid vectors, a switch tube can switch on and off once in each control period. According to the invention, the modulation complexity is not increased and only the minimal change on the basis of the traditional space voltage vector modulation method, NZ-SVPWM can be realized. An advantage of constant frequency of a traditional SVPWM switch is kept and harmonic current is reduced. The algorithm is simple and digitization implementation is easy. At the same time, the common mode voltage is limited within 1/6 of DC bus voltage. Therefore, reliable and safe system operation can be ensured when the method is applied to fields of three-phase motor driving, photovoltaic power generation and the like.

Description

technical field [0001] The invention relates to a power electronic technology, in particular to a space voltage vector modulation method for minimizing common-mode voltage. Background technique [0002] The output voltage of the three-phase voltage type PWM inverter includes positive sequence components, negative sequence components (differential mode voltage) and zero sequence components (common mode voltage). Among them, the harm of the common mode voltage is particularly serious, and brings many problems to the safe and stable operation of the inverter. For example, the common-mode voltage induces a high-amplitude shaft voltage on the motor shaft, and forms a shaft current, destroys the shaft insulation, shortens the service life of the motor, and the electromagnetic interference generated will also affect the normal operation of the control system and power supply. Techniques for suppressing common-mode voltage include inserting common-mode inductors, common-mode suppre...

AI Technical Summary

Problems solved by technology

[0004] The present invention is aimed at the problem that common-mode voltage suppression and constant switching frequency are mutually contradictory in control, and proposes a space voltage vector modulation method for minimizing common-mode voltage, which does not increase modulation complexity, and only on the basis of traditional SVPWM The space voltage vector modulation with the minimum common-mode voltage can be realized with minimal changes above, which retains the advantages of constant switching frequency of the traditional SVPWM, and can limit the common-mode voltage within 1 / 6 of the DC bus voltage, and can reduce Harmonic current, the algorithm is simple and easy to realize digitally

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