Evaluation of SVM modulation methods for indirect two-level three-phase frequency converter and direct frequency converter

Abstract

In current practice, indirectly structured frequency converters are popular because of the simple switch and control circuit diagram, and pulse width modulation (PWM) can be used to control the semiconductor switches. The PWM method has the advantage of a simple control circuit but has large switching losses and generates a common-mode voltage that causes motor damage. The development of the space vector modulation (SVM) method takes advantage of the PWM method, reducing the switching loss of the switches and reducing the harmonic at the output of the inverter. With direct converters, there are many types depending on the circuit structure and semiconductor key structure, including matrix frequency converters which are widely studied. The classical modulation method according to the duty-cycle matrix approach for matrix converter has disadvantages such as complex computational algorithms, which require many trigonometric calculations. Based on the PWM and SVM modulation algorithms for indirect converters, a space vector modulation method for matrix converters will be developed. Compared with the indirect converter, the SVM modulation method for the matrix converter will be based on two separate modulation principles: control the input current vector and control the output voltage vector. The relationship between current and voltage at the converter input is closely related to the voltage and current at the output. The relationship between current and voltage at the converter input is closely related to the voltage and current at the output. Make sure at the input of the converter, the power factor cosφ = 1 and can be adjusted, it has the quality of sine input and outputs current and the exchange power in two directions.