Optimal vector modulation of a PWM current source converter according to minimal switching losses

A PWM current source frequency converter is an alternative to control variable speed AC-drives instead of commonly used voltage source frequency converters. Space vector control techniques are widely adopted for high performance drives while the control system is most conveniently implemented by microprocessors, microcontrollers and DSPs. Space vector pulse width modulation is also an appropriate technique for the phase current modulation of a current source converter (CSC). Either “5-switch” or “4-switch” space vector modulation can be used, the latter being perhaps more popular. Different modulation strategies can be developed by selecting an appropriate vector sequence for the switching cycle. Therefore this paper discusses the significance of the vector sequence on the IGBT switching voltages in order to reduce switching losses of the CSC bridge. An optimal vector modulation strategy, which minimizes the switching losses of the CSC bridge, is developed and analyzed in detail. Finally, the results are verified by PSpice(R) simulations