Space vector PWM (pulse width modulation) harmonic analysis method

Abstract

The invention discloses a space vector PWM (pulse width modulation) harmonic analysis method. The method comprises the following steps: first storing an acting sequence of a basic voltage vector into a basic voltage vector sequence matrix, secondly calculating an acting time of the basic voltage vector, then storing the acting time of the basic voltage vector in a time matrix, and finally analyzing harmonic characteristics. When the method is used for the harmonic analysis on a three-phase inverter, the basic voltage vector sequence matrix contains three rows which are used for respectively storing a level state corresponding to a switch state of the three phases. The ripple current and the voltage pulse sequences of all space vector PWM strategies are integrated into a same processing formula and process, the output voltage is digitally sampled, the analysis on the harmonic performance is carried out by utilizing a computer derivation and fast Fourier transform method, so that the harmonic characteristic comparison, performance evaluation and development of novel strategies can be rapidly carried out for various space vector PWM strategies.

Description

technical field [0001] The invention belongs to the technical field of AC frequency conversion, and in particular relates to a space vector PWM harmonic analysis method. Background technique [0002] In pulse width modulation (PWM) technology, space vector PWM (SVPWM) technology is a very important category, widely used in the occasion of converting direct current into alternating current. Since SVPWM technology is based on the principle of volt-second balance, in addition to the necessary fundamental wave, harmonics are inevitable during the conversion process. Due to its simple structure and load characteristics, voltage source inverters are widely used. From a voltage point of view, the output of a voltage source inverter is a sequence of voltage pulses. The theoretical mathematical expression of the frequency spectrum of the voltage pulse sequence output by the inverter is very complicated, and the coefficients of harmonics in the expressions corresponding to different...

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Problems solved by technology

The derivation process of the ripple current formula is tedious, complicated, and extremely error-prone, and it increases sharply with the increase in the complexity of the SVPWM strategy

[0004] The theoretical formulas involved in the time-domain and frequency-domain characteristics of the harmonics in the output voltage and current of the inverter are complex and difficult to derive. The characteristics of different SVPWM strategies vary widely, which is not conducive to the comparison of harmonic characteristics between different strategies, which greatly Limits the design of SVPWM strategy, performance evaluation and development of new strategies

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