A dynamic decoupling control scheme for high-speed operation of induction motors

In a high-speed operation of a vector-controlled induction motor, coupling between d-q current dynamics impairs the characteristics of torque response. The feedforward decoupling scheme does not perform well if an error exists in the motor parameter estimation. We derive a dynamic decoupling condition when the two additional proportional integral current controllers are used. A great advantage of this dynamic decoupling controller is the robustness to the motor parameter estimation errors. Further, we observe that overmodulation methods lead to the violation of the decoupling condition, thereby yielding a poor performance in the high-speed high-power operation. As a method of resolving this problem, we propose a decoupling preserving overmodulation algorithm which also enhances the torque transient response. Through simulation and experimental results, we demonstrate the improved performance of the proposed controller