A New Minimum DC Voltage Ripple Generating PWM Selection Algorithm for Voltage Source Inverter

The voltage source inverters (VSIs) generate the average output voltage using the instantaneous switching voltage vector. The difference between the average output voltage and instantaneous switching voltage vector produces the error voltage, contributing to dc voltage ripple and dc source current ripple. In this work, a novel minimum dc voltage ripple generating pulsewidth modulation (PWM) selection algorithm is proposed for three phase two level VSI. To elicit the minimum dc voltage ripple, first, the dc capacitor current, dc voltage ripple, and dc source current ripple are mathematically modeled for a three-phase two-level VSI using an error voltage vector approach. Based on mathematical modeling, different continuous PWM (CPWM) and discontinuous PWMs (DPWMs) are compared to derive the minimum dc voltage ripple. After comparison, the minimum dc voltage ripple regions is identified for CPWMs and DPWMs in modulation index (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m_{a}$ </tex-math></inline-formula>) and load angle (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta $ </tex-math></inline-formula>) plane. Based on the identified regions, an adaptive switching PWM selection algorithm is proposed to ensure the minimum dc voltage ripple irrespective of the load operating conditions. The proposed method of selecting minimum voltage ripple yield PWMs is demonstrated on experimental prototype by implementing PWMs on DSP C2000 TMS320F28379D board.