A novel microcontroller based speed control method employing current controller for TWUSM

The relation between rotor speed of the Travelling wave ultrasonic motor (TWUSM) and current drawn by TWUSM is not linear for the TWUSM under different loads. In order to solve this nonlinearities and variation problems of TWUSM, PI controller, current controller, frequency controller and phase difference controller are proposed and implemented. The proposed system evaluates the steady-state performance of TWUSM drive system by using PI controller and current controller. Additionally, in the proposed TWUSM drive system, LC parasitic resonance impedance are added in order to obtain same peak voltage values under different loads by using frequency controller and phase difference controller. Experimental results of the proposed technique are analyzed and presented.