Design of high step-up driving circuit for linear ultrasonic motor

Linear ultrasonic motor, which usually operates at ultrasonic wave, has the merits of smaller dimension, silence, high thrust at low speed, and no electromagnetic interference (EMI) problems such that it has been widely used in industrial applications, especially in high-precision motion control. In this study, one provides the output specifications to be AC frequency of 39.6k Hz controllable sine wave voltage for driving the motor by using a 12V rechargeable battery as a supply of power. Thus, the motor can operates stably, including sudden acceleration, sudden deceleration and stopping. The commercial drive directly access to electricity, but not be used in low-voltage state. For convenience, this study replaces the original supply from 48V to 12V. Besides, the original resonant tank is a simple LC resonant circuit to be sensitive to load change. In this study, it utilizes a LLCC resonant circuit instead of LC resonant circuit. Despite the low voltage gain, it can compensate by a step-up converter. In order to deal with commercially available drivers with higher input voltages, a high-efficiency high step-up converter is utilized in this study.