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Vahid Rashtchi

Rashtchi Vahid; Safaei Amir; Abdullad Amir
High Precision and Auto Tune Class D Amplifier for Piezoelectric Transducers

In the applications of piezoelectric transducers, the existence of power supply is unavoidable. In the operation point of the piezoelectric transducers due to generated heat, loading effect and other environment conditions, the resonance frequency of the whole system may vary and caused to reduction of efficiency. In this paper a novel Class D amplifier with ability of self tuning is presented. The proposed amplifier has the ability of resonance frequency finding of the system in many operating conditions in a real time process. The efficiency of this class D amplifier is greater than 95%. Output frequency of the amplifier is in the range of 17 kHz to 40 kHz with resolution of 1 Hz. Also the power delivered to load can be controlled by varying of pulse width modulation (PWM) duty cycle with precision of 1%. Implementation of such amplifier with current analog power supplies may be caused to instability or reduction of efficiency. So the proposed amplifier has a fully digital control unit and its output frequency and amplitude are independent of environment conditions. Experimental results show that this low cost amplifier is able to tune and maintain the piezoelectric transducers in their resonance frequency and deliver the maximum power to load.



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