PWM-less current controlled VSI-IM drive

In this paper the PWM-less current controller for a voltage source inverter is discussed. The controller is of boundary layer type and a switching table realized. It allows employment of positive definite and also positive semi-definite vector function determining reaching dynamics. In its design the fact that the calculation of the stator voltage vectors from the d-q control components does not have a unique solution is exploited. This is considered as design freedom, which is further extended with logic control introducing preassigned-order switching according to the time scale separation of magnetization and the generation of torque currents. Zero voltage vectors are selected by finite automaton to the closest previous active voltage in order to minimize the inverter switching losses, reduce chattering and gives O(T/sub s//sup 2/) error type of current.