Study On Servo Control Technology Without Crurrent Sensor Based On Virtual Current Loop

Servo control technology is one of automation control subject, which is the mostwidely service and the most closely contact with industry department. Servo controlsystem has been widely used in various industries. In recent years, AC servo systemis developed towards simple, compact, economic. There was a series of in-depthresearch for no sensor or less sensor. Relative to the sensorless control technology,the research of current sensorless is not much at home and abroad, and thetechnology is not mature yet. Therefor, at present, it is a very important topic atpresent to mastering key technology and to form high level of practical goods in ashort period of time. The concept of virtual current loop is introduced in thisdissertation, where the actual current is estimated by voltage and speed, to achievevirtual current closed-loop control without current sensor.Firstly, this dissertation narrates the structure and characteristics of permanentmagnet synchronous motor(PMSM) and builds the mathematical model of PMSM;it also introduces the conventional vector control mode and studies the theory ofspace-voltage vector pulse width modulation(SVPWM) further deeply， givesequivalent voltage waveform function at same time. From the above, PMSM servocontrol is realized through setting up and analyzing virtual Current Loop controlmode without current sensor, which estimates actual stator currents by voltage andspeed using the voltage equation of PMSM, and then employs the vector controlstrategy of id=0for current loop with EMF compensation.Then，the system simulation model is built for virtual current loop servocontrol with current sensorless, using Matlab simulation software. A lot of simulationexperiments are done, which verify that the virtual current loop control methodrealize the effective control of motor current and torque, and also verify possibilityand feasibility of this system. At last, the thesis design experimental platform of thiscontrol system based on TMS320F28035, which is the Piccolo series DSP of TIcompany, and introduces each part function and structure of software and hardware. The experiment results show this control system has good control accuracy,satisfying dynamic and static characteristic, and that can meet the needs of servocontrol.