| 摘要 |
PURPOSE: An apparatus is provided to control operation of ultrasonic motor in a stable and efficient manner by using, as a control parameter, the internal impedance phase angle of the ultrasonic motor. CONSTITUTION: An apparatus comprises a frequency/phase controller(100) for inputting a frequency information(f(k)) and a phase difference information(Φ(k)), and generating and outputting square wave signals(GA,GB); a high speed inverter(200) for converting the square wave signals into AC voltages(VA,VB) and outputting the converted voltages to an ultrasonic motor(300); a pulse encoder(400) for encoding the information regarding the size of frequency at the ultrasonic motor, and phase difference, and outputting the result; a current-voltage phase difference detection unit(500) for detecting phase difference of the voltage(VA) and current(iA) being supplied to the ultrasonic motor, and outputting the detected phase difference in the form of an impedance phase angle; and a micro controller(600) for taking, as an input, the impedance phase angle output from the current-voltage phase difference detection unit, and outputting the frequency information and phase difference information for following the resonance frequency of the ultrasonic motor.
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