Compensation of the effects of the forward voltage drop of power switches on direct torque controlled synchronous machine drive

The direct torque control scheme is an outstanding scheme based on space vector theory. However, at low speed, the performance is not so desirable. The effect of forward voltage drop and dead-time are analyzed and compensated in this paper. Modeling results show that the blindness to the forward voltage drop of the power switches may cause oscillation in the flux and torque of the machine. A simple compensation scheme is proposed and used in experiment to solve the problem. Better low speed performance has been observed with the compensated DTC IPMSM drive system.

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