Techniques for ASIC implementation of vector control

Abstract

Harmonic-free vector control, in which both the phase and amplitude of a three-phase current are controlled digitally to within close limits, is a common requirement in many power conversion applications. These include the control of three-phase motors, and the conversion of electrical power from three-phase AC to DC, or the inverse, with low supply harmonic content. Vector control at a specified frequency relies upon the generation of accurate sine and cosine waves, computation of the in-phase and quadrature components of the input current, and then reconversion to the three-phase sinusoidally varying drive values. The authors discuss the options available for implementation of the reference sine generator as an ASIC cell, and show how an application specific processor can be designed to achieve the very high performance combined with small area necessary to deal with the current transformation. Both functions are integrated in a design using less than 25000 gate equivalents at 16-bit accuracy.