Flux based and predictive voltage based current regulators for motor drive applications

Abstract

This paper presents a comparative evaluation of a flux based current regulator and a predictive voltage based current regulator implemented by an analog space vector modulator. For motor drive applications. In the flux based current regulator, the inverter flux or volt-sec is the controlled quantity and is implemented, in the synchronous reference frame, by a hysteresis rule based carrier-less PWM strategy. In the predictive voltage based current regulator, an average voltage vector reference is generated and synthesized, in the stationary reference frame, by a carrier based space vector modulator. The performance of both methods is compared, particularly for low inductance motor drives such as for electric vehicle applications. The comparisons are made at the same switching frequency, albeit, the flux based method employs the characteristics of a two phase modulator or discontinuous switching, whereas the predictive voltage based method incorporates a conventional three phase continuous switching space vector modulator. Simulation results are given under steady state and transient conditions for both methods, with high modulation indices and for a low inductance (<10%) motor drive application. Experimental results are given for a flux based current regulated IGBT inverter driving a 2.2 kW induction motor, at no-load and light load conditions.