Research On Servo Motor Resolver And Sin/Cos Encoder Zero Point Calibration System

In modern manufacturing system, the Permanent Magnet Synchronous Motor (PMSM)is widely used. PMSM is not only the driving component but also provides position andvelocity information by its encoder, which is very important for close-loop control of servosystem. In the production process of PMSM, it is a very important procedure to position andcalibrate the zero point of encoders. The purpose is to match and record the certain positionrelationship between rotor’s magnetic pole and encoder’s zero point. This positioninformation will be provided to the servo driver manufacturer, which enables the servo driverto know the initial position of the rotor so as to smoothly control motor motion. Therefore,zero point positioning and calibration have significant meaning for the manufacturing,assembly, and control processes of PMSM.The zero point calibration of different PMSM equipped with different encoders needdifferent servo drivers, and it is also very time and energy consuming. To solve this problem,this thesis developed a specific servo driver based on servo control and drive principles,which is applicable to PMSM equipped with resolvers and sin/cos encoders.The system’s hardware mainly includes digital controller and power driver board. Thecontrol board based on DSP is designed to deal with encoder signals and motor controlalgorithm, and other control programs. The power driver board is developed based onrectifier and inverter circuits, which drive motors to rotate according to the basic principle of“various voltage various frequency”. The system’s software is based on state machines,which means the shift between several different states can be easily controlled. Additionally,the user friendly human-machine interface can not only monitor the real-time condition ofwhole system but also allows user to change and save all kinds of parameters. Finally,through the system debug, our design satisfied the user’s technical requirements.In summary, the zero point positioning and calibration system in this thesis is a specificservo motor driver which can automatically position the zero point of resolver and sin/cosencoder. It has the advantages of high calibration accuracy and easy operation. Therefore, thisinstrument has important practical meaning for improving the overall productivity of PMSMmanufactures.