Research Of SVM-DTC System For Ipmsm Based On Sliding Mode Theory

Interior permanent magnet synchronous motor(IPMSM)has gradually gained attention from the public due to advantages of small volume,high efficiency and high power density.As a typical multivariable and strong coupled nonlinear system,however,conventional control is far from meeting the demands of control performance and reliability in practical engineering application.The motor control strategy based on modified sliding mode theory and the estimation method of motor's rotor position and speed without sensors are developed in this thesis upon the foundationof the IPMSM direct torque control(DTC)system application.The main researches are as follows:Firstly,the mathematical model of the interior permanent magnet synchronous motor is establishedand the basic principle of the IPMSM-DTC is introduced.Space vector pulse width modulation(SVPWM)technology is adopted against the large ripple of torque and flux and variant switching frequency of the inverter.An over-modulation SVPWM algorithm is studied and implemented by the simulation.This thesis also analyzes the principle and implementation of the IPMSM SVM-DTC system and the deficiencies of conventional SVM-DTC system.Secondly,to solve the deficienciesin conventional IPMSM SVM-DTC control system which consists of two PI regulators related to speed and torque,a torque and flux fractional order sliding mode controller(FOSMC)is developed based on the sliding mode control theory and the principle that fractional calculus system decaying with time could reduce chattering.Consequently,not only the quick responsiveness of DTC system is saved,but also the ripple of torque and flux is dramatically diminished.Then,combining fast terminal sliding mode(FTSM)speed controller with load torque observer,a novel composite sliding mode speed controller is designed,which could optimize the high precision control of system speed,alleviate the effect of torque disturbance on IPMSM system,enhance the anti-disturbance capability and suppress the chattering of sliding mode.Thirdly,a modified second order nonsingular terminal sliding mode(NTSM)observer with equivalent back EMF is adopted on basis of conventional sliding mode observer with extended back EMF,which could dislodge the low-pass filter dispensable in conventional sliding mode observer,diminish the influence of salient pole in IPMSM,simplify the observer model,eliminate the speed variable in the observer,increase the estimation precision of rotor position and speed in sensorless IPMSM,extend the system's application range in complicated conditions and improve the reliability of the system.Lastly,on basis of aforementioned theories,the hardware and software design of the system are developed using the DSP chip TMS320F2812 of TI company as the core.Eventually,experimental results validate the validity of the designed system.