Research On High Performance USM Driving And Testing System

USM is a new kind of motor developed in the 1980 s.It works under the friction between the rotor and stator which vibrates within the ultrasonic frequency band due to the inverse piezoelectric effort.Compared with the traditional electromagnetic motor,USM have advantages in power self-locking,greater torque in low speed and responses more quickly.At present,USM has been applied in high technology fields such as aerospace and robots.The traditional PWM inverter driving system for USM has many disadvantages like too much harmonic distortion and low efficiency.In this paper,a new USM driving scheme based on sinusoidal signal power amplification is designed.The a sinusoidal signal generator with adjustable frequency,amplitude and phase is designed with MCU and DDS chip.The power amplifier circuit based on Class AB and Class D power amplifier is designed respectively,and the transformer is designed.The match circuits for TRUM-40 and TRUM-60 were designed to realize reactive power compensation.The driving system based on Class AB has the advantages of very low signal distortion,convenient voltage regulation and so on.The driving system based on Class D has the advantages of low harmonic component,low cost,high efficiency and so on.Due to the rapid response of USM,acceleration may produce large impact on the base when the motor starts.This effect can not be ignored when a smooth start is needed.In this paper,the driving system based on Class AB is used to test the startup characteristics of TRUM-60.The speed is measured by photoelectric encoder.The data is uploaded to computer through MCU and data is processed by MATLAB.The speed curve of the TRUM-60 motor during sweep frequency start-up and sweep amplitude start-up is tested and analyzed,which can be reference to realize a smooth start-up of USM.