Research On Control Strategy For Permanent Magnet Synchronous Motor Of Hybrid Electric Vehicle

With the gradual depletion of oil resources, rising oil prices and intensification of the greenhouse effect, more and more people pay attention to the new energy vehicles. At the same time, in the Twelfth Five Years Plan China decides to develop new energy vehicle. As a major form of new energy vehicles, hybrid electric vehicle will accelerate its development.Vehicle driving motor is one of the key components of hybrid electric vehicle; the choice of motors directly affects vehicle performance. For its high performance, high power density and wide speed range, the permanent magnet synchronous motor has become the best choice to be a HEV drive motor. The control strategy will not only directly affect the accuracy of motor control, but also has a impact on the power, fuel economy and exhaust emission. This paper mainly does a theoretical analysis about VVVF control strategy, direct torque control strategy, vector control strategy based on PI control and aptitude control strategy. VVVF control strategy applies the situation that the load slowly changes. The direct torque control strategy has lower computation, simple control and a good dynamic response, but it does not control PMSM well when in low speed and its controlled parameters are difficult to measure.The vector control based on PI control would lead to the consequence of over current in the motor controller, and this will create a bad impression about the controller life. The aptitude control strategy is not mature at present. For these control strategies exist some problems, this paper mainly researches and puts forward the feed-forward vector control based on motor n-T table, this control strategy can guarantee a smooth torque, protect the controller from over current, improves the control accuracy without current sensors, and can suit for the using of vehicles. Then do the theoretical analysis about the theoretical basis of the control strategy, interpolation theory, feed-forward vector process and its advantages.This paper studies about permanent magnet synchronous motor which its rated power is 20kw, peak power is 30kw,rated speed is3600rpm.Design and manufacture the permanent magnet synchronous motor controller for hybrid electric vehicle; Then do the lower voltage experiments, strong power experiments, torque control experiments, loading experiments, and it is confirmed that the controller is safe and reliable vehicle and can control the vehicle permanent magnet synchronous motor well. Set up test bench, adjust the motor target torque and speed, when the three-phase alternating current is smallest, choose the optimal motor voltage vector and phase angle which are used in the linear interpolation table as the optimal values of the peg point, then manipulate data to construct the motor n-T map, finally store the map in the motor program in the form of table for real-time lookup, or through on-line interpolation calculate voltage and phase which are required to make the motor to arrive at the appointed torque and speed, to achieve feed-forward vector control based on motor n-T map.Experimental results proves that the control strategy has its feasibility and advantages. And study the non-linear relationship between mechanical angle and measured angle, improve the sine driving waveform of permanent magnet synchronous motor, in order to enhance the control precision of vector control.