Multifunctional Position Detection And Integration Method Research Of Permanent Magnet AC Servo System

AC servo system has been widely used in various industries. As a closed-loopsystem,position feedback detection and current feedback detection are importantfeedback units of servo system to achieve, the accuracy of information detectionaffects speed response and performance of the entire system. At present, the trend thatservo system turning to high-speed and high precision is spreading, seeking moreprecise and respond of location information detection and current detection methodswhich the paper focus on, became one of the key technologies.Firstly, the paper established the dynamic mathematical model of PMSM in theABC stationary coordinate and rotating dq coordinate system, researched the id=0magnetic field oriented vector control method, Analysed the space vector pulse widthmodulation (SVPWM). Then combining with common servo schematic diagramoutlined the importance high-performance permanent magnet AC servo systemposition detection and current detection.Absolute encoder can read position of the rotor when system power on, theproblem of initial rotor position does not exist, but for incremental encoder, it can notread out the absolute position of the rotor directly when power on,when using theid=0rotor field oriented vector control, if the stator current vector is in any directionwhen power on, it may cause electromagnetic torque of permanent magnetsynchronous motor to zero or very small, so the motor does not start properly,therefore, to find initial position of the permanent magnet synchronous motor rotorhas great significance. The paper gives a method for finding initial positioning of therotor by making full use of DSP quadrature encoder module.Position detection requirements in different industrial applications are different,incremental encoder which has a simple structure, simple calculation,stronganti-interference ability, low cost, is suitable for occasions which just need generalaccuracy. Resolver can patience high temperature, humidity, shock, interference, etc., always apply to some more serious occasions. For high servo performance andaccuracy requirements of occasions, some domestic manufacturers have usedhigh-resolution absolute serial encoder, as is the serial communication, the connectionis simple, and the high accuracy of position detection. In order to use the rightposition detection mode on different occasions,The paper use CPLD as interfacebetween DSP and encoders and analysis how to integrate these position detectionmodes.Current detection,which is the important detection link of servo system,improving its accuracy can improve peroformence and positioning accuracy of thewhole system, the paper made a detailed research of current detection.System plan used the structure of DSP+CPLD, DSP is mainly responsible forcompleting the id=0rotor field oriented vector control algorithm, as an auxiliarycontroller CPLD is responsible for the current sampling, location informationacquisition, alarm summary functions, DSP and CPLD exchange information in acertain time. based on integrating multi-functional position detection which isregarded as a start point,the paper not only analysed the principle of2500lineincremental encoder, resolver,17absolute serial encoder, high-precision currentsampling. but also designed program, hardware circuits, software and debugged,captured and analysed the waveform. Experimental results demonstrated thefeasibility of the system.