| 摘要 |
The invention relates to a method for electrically exciting a piezoelectric actuator of an ultrasonic motor having a mechanical resonance frequency Fm, wherein the ultrasonic motor has at least one acoustic standing wave generator, which comprises an exciter electrode and a general electrode, wherein a capacitance Co is developed between the exciter electrode and the general electrode. According to the invention, the method comprises the following steps: applying a rectangular exciter voltage Ug to the exciter electrode and the general electrode of the at least one acoustic standing wave generator, wherein the frequency of the rectangular exciter voltage Ug differs from the mechanical resonance frequency Fm of the actuator; providing a voltage ug with the aid of a feedback element, wherein the voltage ug is proportional to a current Ig flowing through the standing wave generator, wherein said current is the sum of a piezoelectric current Ip and a charging and discharging current Ic of the capacitance Co; separating a voltage up from a voltage uc with the aid of a pulse filter, wherein the voltage up is proportional to the piezoelectric current Ip and the voltage uc is proportional to the charging and discharging current Ic of the capacitance Co; and changing the frequency of the rectangular exciter voltage in such a way that the phase shift between the piezoelectric current Ip and the rectangular exciter voltage Ug is substantially zero. The invention further relates to a device for electrically exciting a piezoelectric actuator of an ultrasonic motor. |
