Efficient Driving Method for Piezoelectric Inertia Motors

Abstract:
In this study, class-d amplifier topology, which is conventionally used in audio amplifiers, was adapted for efficient driving of piezoelectric inertia motors. Gallium Nitride (GaN) transistors, which can operate at high frequencies with small ON-resistance, were implemented as the switching elements in a class-d amplifier topology. In our approach, saw-tooth signals for driving inertia motors are converted into two complementary PWM signals with a frequency of 1.0 MHz. The PWM signals are applied to a half bridge configuration implemented with GaN-transistors. The amplified PWM signal is then filtered by a LC network, in which the capacitance C in the network is the capacitance (C_a) of the piezoelectric multilayer actuator in the motor. The resulting voltage waveform on the actuator is a modified saw-tooth waveform. This driving technique allows efficiency improvement regarding electronic signal generation and reduces heat generation on the piezoelectric multilayer actuators.