An overmodulation method for space vector PWM inverters with dc-link shunt resistor

In order to lower the cost and expand the working range of pulse width modulation voltage source inverter (PWM-VSI), the control method under the overmodulation mode with a dc-link shunt resistor is developed. The voltage utilization according to un implementable region is analyzed in overmodulation region. By using the conventional phase reconstruction method, the minimized un-implementable region can be achieved for maximizing voltage utilization and the minimizing total harmonic distortion (THD) under the overmodulation region. The new overmodulation voltage reference which has the same voltage utilization with original voltage reference is produced to minimize THD by using Fourier analysis. The effectiveness of proposed algorithm is verified through the THD comparison between conventional and proposed method. The experimental results verify the validity of new overmodulation control and behavior of phase current reconstruction method.