Improved software-based current controller for three phase loads

A new hysteresis band current controller for voltage source inverters (VSI) is presented. The current trajectories of the of the three phase system are transformed into the static frame /spl alpha/-/spl beta/, which enables a decoupling of the current error components and facilities the application of the different shapes for the current error boundaries. This new technique, which has been experimentally verified, is based on the use of a second input current error derivative for the selection of the zero voltage vectors V(0, 7), which greatly reduces the inverter switching frequency. Computer simulations and laboratory test were made in order to investigate the performance of the regulator, and results show the effectiveness of the proposed control scheme.