IMPLEMENTATION OF DISCRETE-TIME FIELD-ORIENTED CURRENT CONTROL

This paper studies performance sensitive issues encountered in the imp lementation of all-digital discrete-time field oriented current contro l of an ac motor. In particular, the focus here is on the interface be tween the vector current control algorithm itself, and the motor/inver ter system. The effects of interface components such as antialiasing f ilters, rotational transformations, and phase-to-line-voltage transfor mations are analyzed. In addition, a straightforward all-digital pulse width modulator is presented along with a new algorithm to naturally inject triplen harmonics into the motor line voltages, and thereby inc rease power supply utilization by 15%. Real-time operation of a discre te-time vector current controller verifies the analysis.