Study On Asynchronous Motor Control Based On Digital And Analog Hybrid Control

Asynchronous motor has the advantages of simple structure and easy manufacture.The rapid development of the modern power electronics makes the asynchronous motor speed control system have a fast dynamic response,high speed accuracy,wide speed range,high efficiency and four quadrant operation and other excellent performance.Static and dynamic characteristics of asynchronous motor are comparable with those of the DC motor speed control system.The control of asynchronous motor is implemented by means of digital and analog hybrid control method.The triangular wave carrier signal is generated by triangular wave generating chip and the sinusoidal signal is outputted by DSP28335 D/A module.The triangular wave and the sine wave form the analog-to-digital ratio to generate the drive signal of the power device to control the asynchronous motor.And the asynchronous motor digital and analog hybrid control system based on DSP28335 is built.The method of digital and analog hybrid control can make the output SPWM wave form reach the sine wave to the greatest extent.Firstly,The dynamic mathematical model of asynchronous motor and the principle of SPWM control mode are analyzed in this paper.The realization of SPWM control algorithm:natural sampling method and Symmetric regular sampling method is also expatiated.In this paper,the system block diagram of digital and analog hybrid control method is given,and the composition and function of each part of the control system are introduced.Then,The hardware and software part of the system based on DSP28335 are designed.The hardware part comprises main circuit,signal detection circuit and control circuit.The main circuit includes power AC power,rectifier circuit,inverter circuit and AC motor module.The signal detection circuit includes current sensor,photoelectric encoder and others.The control circuit comprises DSP28335 control chip,peripheral circuit,triangular wave generating circuit and driving circuit.Inverter circuit is based on FSBB30CH60D chip and its peripheral circuit to achieve.The software part mainly includes the main program,the PI adjustment program,the AD sampling program,the QEP rotational speed computation program,the sine wave generation program and others.the software part of the design is achieved by Using C language programming based on CCS3.3 development platform.In the end,The no-load test of the asynchronous motor by the digital and analog hybrid control method is carried out in this paper,and the feasibility and validity of the digital and analog hybrid control method are verified by experiments.