Some implementation aspects of line current reconstruction in three phase PWM inverters

A method of motor current reconstruction that can be applied with all pulsewidth-modulation (PWM) schemes is discussed. The method is well suited to implementation with digital signal processors (DSPs) or application specific integrated circuits (ASICs). It is based on system variable identification by means of the least-squares method. It is shown that a sinusoidal current waveform of known frequency can be reconstructed accurately for all operating conditions from data sampled on the DDC bus. In particular, the amplitude and phase shifts of the sinusoidal waveform are obtained by combining information from the DC link current and the switching pattern. A sinusoidal PWM switching scheme is used to test the algorithm. Simulated and experimental results are presented