Research On Control Strategy Of Magnetically Coupled Resonant Brushless Excitation System

With the deterioration of the global environment and the depletion of fossil energy,new energy vehicles have become a future industry that countries around the world are vying to develop.Permanent magnet synchronous motors are widely used in new energy vehicles due to their excellent characteristics.However,when operating in a high temperature environment,the permanent magnets may demagnetize,resulting in a decrease in motor performance.Electric excitation motor has the advantages of no permanent magnet,low cost and high efficiency,and is considered to be one of the most potential automotive motors.Traditional electric excitation motors have brushes and collector rings,which will wear out during commutation,and long-term operation will cause damage to the motor.In order to realize the brushless excitation of the electric excitation motor,the magnetic coupling resonance technology is applied to the motor excitation to achieve the brushless excitation of the motor,replacing the brush in the electric excitation motor,and the operation of the motor is safer.With the support of the National Natural Science Foundation of China,this paper mainly carried out related research on the constant voltage output,mutual inductance parameter identification and experiments of the magnetically coupled resonant brushless excitation system.The main research contents are as follows:1.Introduced the principle of the magnetically coupled resonant brushless excitation system,compared the structure of the loosely coupled transformer and the tightly coupled transformer in the system,and established the mathematical model of the mutual inductance transformer.The mathematical models of the traditional firstorder compensation topology and the LCC-S compensation topology are derived,and the LCC-S compensation topology is selected as the compensation topology of the system,which lays the foundation for the follow-up control strategy research.2.The traditional sliding mode algorithm and the improved sliding mode algorithm are introduced for the research on the constant voltage output of the magnetically coupled resonant brushless excitation system.Aiming at the slow convergence speed and low control precision of the traditional algorithm,the sliding mode surface and approach rate of the algorithm are improved to increase the convergence speed and control precision.Through modeling and simulation analysis,the superiority of the improved sliding mode algorithm in controlling the voltage stability of the system is proved.3.Research on the mutual inductance parameter identification of the magnetically coupled resonant brushless excitation system,and introduce the traditional particle swarm algorithm and the improved particle swarm algorithm.Aiming at the problems that the traditional algorithm is not accurate enough and easy to fall into local optimum,the particle velocity equation and displacement equation are improved.Through modeling and simulation analysis,it is proved that the improved particle swarm optimization algorithm has more advantages in identifying the mutual inductance parameters of the system.4.Based on the DSP28335 development board and other hardware circuits,an experimental platform for a magnetically coupled resonant brushless excitation system was built.Based on the above platform,experiments on stabilizing output voltage and identifying mutual inductance parameters were carried out,and the results obtained from multiple experiments were compared and analyzed to verify the feasibility of the scheme.