positioning accuracy of the ultrasonic motor

The equivalent circuit of the complex stator of traveling wave type ultrasonic motor near the resonance frequency is shown . Each parameter of piezoelectric ceramicshas the following meaning: the white is the equivalent with static capacitance, which is determined by the dielectric constant of the piezoelectric resonator and the electrode size. , that is, piezoelectric transducer sensor is clamping capacitance; which is the equivalent inductance of the composite stator, also known as dynamic inductance, it is related to the mechanical properties of the material, it is analogous to the quality of the composite stator; Cm is a dynamic capacitance; Rm is the equivalent resistance, and the mechanical loss of the material related.

The main factors that affect the positioning accuracy of the motor are the stability of the motor when is starting and shutting down the characteristics. When the motor is connected to the power supply, the stage of piezo rings transducer is from the start of the vibration sensor.the stable vibration of the stator is called on the start-up phase of the ultrasonic motor; from the time when the motor is deenergized, the vibration state of the stator is attenuated to the stage where the rotor completely stops vibrating, which is called ultrasonic. It is the shutdown phase of the motor; the phase between the piezoelectric material piezo tube is the steady-state operation phase of the motor. A good motor wants the shorter time, it takes to start and shut down, that is,piezo ceramics do not relax during vibration and vibration stoppage.

The load characteristics refers to the relationship between speed and torque of piezo tube datasheet, that is, the motor operates in the steady state, and ideally, the relationship between voltage and current in the equivalent circuit is obtained. It represents the ability of the ultrasonic motor to drive the load.

The ultrasonic motor is driven by friction,the friction causes serious heat generation, which leads to a serious temperature rise of the ultrasonic piezoelectric element, which affects the stability and reliability of the motor work and shortens the service life. Therefore, the analysis of the temperature characteristics of the ultrasonic motor on the performance of the motor and the optimization of the ultrasonic motor and the improvement of the service life have important research significan