Discontinuous pulse width modulation methods with neutral point voltage balancing for three phase Vienna rectifiers

This paper presents two discontinuous pulse width modulation (DPWM) methods for three phase Vienna rectifiers with different performance optimization targets. One for switching loss minimization and one for switching loss reduction with the neutral point voltage controllability. Due to the current commutation characteristics if Vienna rectifiers, the available space voltage vectors are limited. With this consideration, different small vectors are selected for different performance optimization. The detailed implementation of the two modulation methods are presented. System performance with the proposed two modulation methods are compared with one commonly used discontinuous PWM modulation method in the aspects of semi-conductor loss and neutral point voltage ripple. The analysis is verified through both simulations and experiments based on a 3 kW Vienna rectifier with efficiency higher than 99% at nominal load.