Research On The DB-DTFC Control Of A Flux-modulated Compound-structure Electric Machine System

With the rapid development of automobile industry,environmental pollution and energy shortage have gradually attracted widespread attention.Plug-in Hybrid Electric Vehicle can run on gasoline when the battery is low,it has longer range than pure electric vehicles and more energy efficient than conventional fuel vehicles.Toyota Prius,the most successful example of the plug-in hybrid,use planetary gears to distribute power to an internal combustion engine and an electric motor.However,the planetary gear is a relatively sophisticated structure,with problems of wear,regular maintenance and poor reliability.The flux-modulated compound-structure electric machine can replace the planetary gear and generator of Toyota Prius.Firstly,this paper analyzes the working principle of the flux-modulated compound-structure electric machine system.It is found that the stator magnetoelectric frequency variation range of the flux-modulated brushless double-rotor motor is wide and the system has high requirements on the dynamic performance of the controller.In order to study the control strategy,a unified mathematical model is established.The principle of Deadbeat Direct Torque-Flux Control(DB-DTFC)is introduced and analyzed with the graphic method.At the same time,the principle of Space Vector Pulse Width Modulation(SVPWM)is briefly expounds.Then,this paper makes an in-depth analysis and improvement on several key problems of DB-DTFC algorithm.It mainly includes the influence of stator resistance on the algorithm,the importance of the state observer to the algorithm,the design of the observer,and the timing problem.These key issues are explained from both theoretical and simulation perspectives.For the case that the voltage vector obtained by the algorithm may not be synthesized when voltage is limited,the paper proposes two and three schemes according to whether the torque line and the flux circle have intersections.At the same time,the simulations of these schemes are carried out,and the rationality of the proposed scheme is further illustrated by the graphical method.The best solution is obtained through simulation comparison.Next,because there are many working modes in the actual operation of the automobile,this paper analyzes several working modes of the flux-modulated compound-structure electric machine system.The simulation model of internal combustion engine,the flux-modulated compound-structure electric machine and control system is established.The system control strategy is proposed for the specificity of the above-mentioned flux-modulated compound-structure electric machine system.The simulation verifies the four-quadrant operation of the system and the adjustment of the working point of the internal combustion engine,and compares it with the traditional PI control strategy.The simulation results show that the strategy can effectively solve the adverse effects of large torque fluctuations and severe changes in the stator electric frequency of the double-rotor motor on system performance.Finally,the driver of the flux-modulated compound-structure electric machine is designed.It mainly includes power supply,power module drive,signal fault detection and protection,and interface circuit suitable for rapid control prototype AD5436.The RCP semi-physical simulation platform is established,and the DB-DTFC control strategy of the dual rotor motor is experimentally verified.At the same time,the adverse effects of the error of the stator magnetic field angle of the double-rotor motor on the control system is further analyzed,and the problems and solutions to be followed in the next work are pointed out.