Open-Loop Validation of a decoupled model of an Induction Motor Supplied by a PWM Inverter

This paper proposes analytical expressions of a decoupled model of an induction motor supplied by a PWM inverter for the design of synchronous-frame current regulators for electrical drives that operate at low switching frequency (below 1 kHz) where the effects of cross-coupling terms of the plant model cannot be compensated by the current regulators with the traditional feedforward compensation network. The proposed approach enables the original model of the plant (motor and PWM inverter) to be independent from these effects partially due to imaginary terms introduced by the rotation of the synchronous-frame. This method starts by deriving an accurate expression of the induction motor in 2 × 2 transfer matrix and it then introduces a linear decoupling matrix between the linear controller to be designed and the model of the plant. Finally, a decoupled dynamic of the plant original model is obtained and validated in open-loop (without speed and current regulators) through simulations and experimentations.