Research Of Piezoelectric Motor Based On Forced Vibration Of Eccentric Rotor

Piezoelectric motor is a hot research focus of actuator, which has a wide range of potential applications in the fields of industrial control system, automobile appliances, office automation equipments and intelligent robots etc. However, due to the working principles, most of the currently existing piezoelectric motors need friction force, there is a series of problems of wear, low output power and low efficiency. In order to achieve excellent performances in terms of high speed, high output power and high efficiency, and be free of friction force, a new working principle and prototype development for piezoelectric motors has been explored and researched. This paper firstly proposed a new kind of piezoelectric motor based on forced vibration of eccentric rotor. The main achievements and innovation points of the paper are as following:Firstly proposed a new kind piezoelectric motor based on forced vibration of eccentric rotor. In view of the existing problems of piezoelectric motors, in order to improve the speed, output power and efficiency, devote to inventing new friction needless driving principle of piezoelectric motor, a new kind of piezoelectric motor based on forced vibration of eccentric rotor is put forward. A pair of bearings are used to realize the connection of stator and rotor. Two hall elements placed orthogonally were used to obtain the position signals of rotor, which were amplified in the next stage for driving the piezoelectric stacks. By means of forced vibration, the energy is feed directly into eccentric rotor to maintain the rotary motion. The new type of piezoelectric motor provide new research ideas for the development of piezoelectric motor.The mechanical model of the proposed motor is established, the trajectories of rotor center of mass, centroid, and the energy feed into eccentric rotor are calculated. According the derivation operation on energy, the optimal initial phase of the driving voltage is obtained as (?)0=π/2. Under the condition of the best driving signals, the sufficient description for the mechanism of motor is given to let the readers to understand easily. Thus, a theoretical basis for the new piezoelectric motor is provided.A prototype motor is fabricated and assembled. The production process of piezoelectric stacks is explored. Piezoelectric stacks with twenty-six 0.7mm-layers lead zirconate titanate (PZT-4) were made and tested. These actuators were fabricated in the laboratory with simple techniques and cost low. The new fabrication method not only greatly reduced the cost of piezoelectric stack, but also made it possible to obtain any required size of piezoelectric stacks in the laboratory. A micro-displacement amplifier to match the fabricated multilayer actuators is also designed using ANSYS software. It’s displacement amplifier ratio is 4.62, and can output a peak to peak displacement of 160 μm under the quasi-static condition. Two silicon nitride ceramic type were used in the experimental stage. After assembling the piezoelectric stacks, diplacement amplifers and bearings, the staor is obtained. An eccentric rotating part was firstly used as the rotor, and its unbanlace value mr was matched with displacement anplifier carefully. The theory speeds range of six different eccentric rotors are analyzed and obtained. After assembing the low consumption DC motor, L shape base, two hall sensors, the stator and the rotor, the mechanical and electrial system of the proposed pizeoelectric motor are finally obtained.A prototype motor is fabricated, assembled and tested. First, the starting strategy of motor was given, and the best initial phase of the driving voltage is obtained as (?)0=n/2, which is consistent with the theoretical calculation. Then, the eccentric rotor 6# was tested, it could output power of 8.45 W at 9120 r/min with an average efficiency of 25.3%. Experiment results show that the comprehensive performances of the new type of piezoelectric motor are improved. The working frequencies of the other fice eccentriacl rotors were test and the experiment results are consistent well with the theory. The maximum rotation speed of the six eccentric rotors was 15,000 rpm, which was obtained by eccentric rotor 1#. To our knowledge, this speed is a world record for a piezoelectric motor. The principle of the prototype is novel, the structure is simple, thus it has a great potential for development.The application prospect of the new type of piezoelectric motor are finally discussed The concept of piezoelectric flywheel energy storage system is firstly proposed. By using the converse piezoelectric effect of piezoelectric ceramics, the energy feed into the rotor to store energy, by using the positive piezoelectric effect of piezoelectric ceramics to realize the flywheel kinetic energy to the electric energy conversion. The new concept of piezoelectric flywheel energy storage system can achieve higher speed than traditional electromagnetic flywheel energy storage, thus can greatly improve the flywheel energy storage capacity. In addition, the new type of piezoelectric motor can also be applied to the centrifugal separation, broadband vibration excitation, plunger pump and so on.