Three-level DCML fed IPMSM using SPWM and CBSVPWM varying modulation index

Abstract

A voltage source inverter with variable frequency and variable voltage is applied for three-phase interior permanent magnet synchronous motor (IPMSM) drive for variable speed application. To obtain the required output voltage in the line side of the inverter a suitable pulse width modulation technique is used. The most prominent PWM techniques are Sinusoidal pulse width modulation (SPWM) and Space vector pulse width modulation (SVPWM). SPWM is simple and easy method to generate pulses for inverter, whereas SVPWM is an accurate method and generate less harmonic distortion compared to SPWM. However there is a lot of complexity involved in calculation of angle and sector as the level increases with SVPWM. To overcome this a similar and easy method known as unified pulse with modulation also know as carrier based space vector pulse width modulation technique(CBSVPWM is described using the concept of effective time. By using this method the inverter output voltage is directly synthesized by the effective times and the voltage modulation task can be greatly simplified. In this paper an IPMSM drive using CBSVPWM is simulated using MATLAB/SIMULINK software and its performance is compared with SPWM by varying modulation index (MI). The simulation study reveals that CBSVPWM simple and easy method which utilizes dc bus voltage more effectively and generates less THD compared to SPWM.