Influence of digital current control strategy on the sensitivity to electrical parameter uncertainties of induction motor indirect field-oriented control

In indirect field-oriented control schemes, the current control strategy influences strongly the flux control sensitivity to electrical parameter uncertainties. This influence is shown in this paper with the help of a theoretical sensitivity analysis taking into account the saturation effect and considering different digital current control strategies. The performance obtained with a classical proportional-integral (PI) current controller is compared with the performance obtained with a novel current controller associating a feedforward action and a proportional feedback (called PFF controller). A control strategy without current measurement is also considered as a particular case of the PFF controller. It is shown that the flux control sensitivity is generally smaller when the currents are controlled by PFF controllers than by PI controllers. The theoretical study is completed by experiments on a 750 W induction motor (using a digital signal processor (DSP) TMS320C31) which confirm the theoretical results