The Research Of Energy-Saving Control Method Of Asynchronous Motors For Electric Vehicles

As a representative of the new energy vehicles, the electric vehicles will dominatethe future automobile market, because it has some characteristics which the internalcombustion engine vehicles can’t compare to, such as no exhaust pollution and low noise.With the advantages of being reliable operation and easy maintenance repair,asynchronous motor has being widely applied to electric vehicles. But in the technicalaspects, the electric vehicles which drived by asynchronous motor are not so mature asthe internal combustion engine cars. The poor endurance of the electric vehicle, which isdue to the limited electrical energy storage of the vehicle battery, is the key problem toaffect its development. So it has profound significance to do some research on theenergy-saving control of asynchronous motors with the advanced speed adjustmenttechnology and the actual operating characteristics of the electric vehicle.This paper firstly studies the induction motor vector control based on the SVPWM.On the basis of introduced the theory of vector control, drawing the technology ofSVPWM into the vector control, then make the SVPWM vector control stimulationunder the circumstance of SIMULINK. And then, it researches the asynchronous motor’senergy-saving control based on SVPWM vector control. According to the theory ofenergy-saving control and the equivalent circuit which letting the equivalent iron lossresistance parallel to the side of the stator and rotor, the optimum flux of theasynchronous motor is calculated in the area below the base frequency. Aiming at theactual situation that the electrical vehicles always run in the high speed, weakmagnetization area, it deduces the optimal flux in weak magnetization area through theanalysis of the operating characteristics of the asynchronous motor. The conclusion of thesimulation of the energy-saving control in constant torque region and weakmagnetization area on the basis of SVPWM vector control draws that this method hasbetter energy-saving effect than the traditional one which is based on SPWM vectorcontrol. At the last, it does some research about the fast response of motor under the circumstances of energy-saving control to solve the problem that required rapid speeddynamic response when the electric vehicles frequently start and overtake. Below thefundamental frequency, the methods, reallocating the stator current and recovering therated flux level partly improve the performance index of electric vehicles when they startfrequently or climb. In the weak magnetization area, it deduces a allocation of dynamiccurrent method under the limitation of the maximum voltage and the current that theinverter can output. The simulation result proves that the control method has effectivelyimproved the speed of dynamic response in the weak magnetization area.