FULLY DIGITAL, VECTOR-CONTROLLED PWM VSI-FED AC DRIVES WITH AN INVERTER DEAD-TIME COMPENSATION STRATEGY

A dead-time compensation method in vector-controlled PWM VSI's is proposed. The method is based on a feedforward approach that produces compensating signals obtained from the I(d)-I(q) current and inverter output angular frequency references in the rotating reference (d-q) frame. It provides excellent inverter output voltage distortion correction for both fundamental and harmonic components. The correction is not affected by the magnitude of the inverter output voltage or current distortions. Since this dead-time compensation method allows current loop calculations in the d-q frame at a slower sampling rate, with a conventional microprocessor, than calculations in the stationary reference frame, a fully digital, vector-controlled speed regulator with just a component current control loop is realized for PWM VSI's. Simulations and test results obtained for the compensation method are also described.