Experimental Validation of a Minimum-Order Sensorless Induction Motor Control Method

This paper proposes to connect the minimum-order sensorless indirect field oriented control to an independent flux estimator. The stability of the sensorless speed estimation and control is guaranteed with a Lyapunov stability analysis, given that a pure integrator generated flux estimate is available in simulation settings. In real environment, we propose to use controller frame independent voltage model based flux estimator that does not rely on any signal from the ensuing sensorless control, as an effort to preserve the validity of the Lyapunov stability proof. A saturation time difference based offset voltage update law is proposed for robustness improvement and its parameter robustness analysis is set forth. The key step of the sensorless design is to use the flux estimates to calculate the q-axis flux, which indicates error in the d-axis angle of the indirect field orientation. It is found in slow and fast reversal experiment that our design is effective to attain dynamic performance while assuring stable operation near zero frequency.