Harmonic suppression method for VIENNA rectifier

Abstract

The invention discloses a harmonic suppression method for a VIENNA rectifier. The waveform sine degree and ripple size of an input current of the VIENNA rectifier affect the harmonic distortion rate,and the VIENNA rectifier obtains an input current with low distortion rate through the current tracking control and voltage modulation. The harmonic suppression method comprises the steps that currenttracking control uses a nonlinear controller to reduce a current tracking error; a five-section and seven-section hybrid space voltage vector modulation method is used for eliminating distortion at the zero crossing point of the input current, the change rate of modulation voltage serves as a pulse modulation frequency parameter, periodic modulation with variable switching frequency is formed, and then input current ripples are reduced. Non-linear current tracking control, five-section and seven-section hybrid modulation and a variable modulation frequency method are combined, so that currentdistortion is eliminated, current ripples are reduced, and current harmonics are suppressed.

Description

technical field [0001] The invention relates to the technical field of harmonic suppression, in particular to a harmonic suppression method for a VIENNA rectifier. Background technique [0002] The typical feature of the VIENNA rectifier is the use of bidirectional switches to form a circuit topology in which the current flows in one direction. The sine degree and ripple size of the input current waveform of the VIENNA rectifier will affect the harmonic distortion rate of the current. The harmonic distortion rate reflects the operation of the rectifier in the power grid. indicators of performance. The input current quality and power utilization rate of VIENNA rectifier are related to the current tracking control method and voltage modulation technology. [0003] Among them, the reasons for the ripple generation of the VIENNA rectifier and the reasons for affecting the current quality are as follows: the rate of change of the inductor current is proportional to the voltage a...

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to provide a harmonic suppression method for VIENN rectifiers to solve the problem that the five-segment and fixed-frequency PWM modulation methods in the prior art will increase the input current ripple, and the fixed virtual damping will easily lead to an increase in the PWM modulation ratio. The phenomenon of over-modulation occurs, which causes the current tracking error to further increase and affects the technical problem of system stability.

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