Research On Brushless Electrical Variable Transmission And Its Control System In Hybrid Electric Vehicle

Nowadays, the highly developed vehicle industry and the huge amount of cars aroused serious problems of envirment and resources. For releasing these issues, renewable power vehicle draws more and more attentions. The most promising technology is Hybrid Electric Vehicle (HEV) and Electric Vehicle (EV). EV uses pure electrical power to drive cars which ensure zero emission and free from gasoline, but the battery capacity is the key problem which hinders its commecializtion. HEV is the transition product before EV's maturation which can effectively reduce oil consumption and exaust emission. These two kind of clear vehicles became the hot point in lots of car companies all over the world, and it is forseed that the commercialization will be realized in ten years.In this thesis, the research target is the dynamic system of HEV. All of the contents can be separated into two parts, the former one is about Electrical Variable Transmission (EVT) system; the latter one is Brushless Electrical Variable Transmission (BLEVT) system. It can be treated that the former one as the foundation, the latter one as expention and innovation. For both systems, the structures and operation principles are analized, the mathematic models and equivalent circuits are established, the control strategies are brought out, simulation and experiment works are done to prove the valitaty of these strategies.For EVT, the operation principles and structure are analized. The mathematic model of the key part of EVT—Dual-Mechanical-Port Electrical Machine (DMPEM)—has been established. The model is based on Dual-Synchronous-Coordinate (DSC), the conditions that with and without the coupling of inner rotor and stator windings are considered separately. The universal method of establishing AC machine equivalent circuit is proposed, by using it all of the equivalent circuits of complex AC machines can be get easely, and the operation modes and power flow conditions can be analized. Based on this method, the equivalent circuit of DMPEM is given.Two kinds of DMPEM control strategies are brought out:Speed-Speed Control (SSC) and Torque-Speed Control (TSC) strategies. Based on the two strategies, the EVT control strategy is given. Considering the Internal Conbustion Engine (ICE) on/off conditions and optimal efficiency curve, different DMPEM control strategies will be used in different operation modes. The field weakening algorithm of Permanent Magnet Electrical Machine (PMEM) can also be used in DMPEM, but the speed range is restricted by machine structure. A protype machine is built, and an EVT simulation platform is established, on which a series of experiments are done.Based on the foundation of EVT, a brand new system for HEV—BLEVT—and its key component Brushless Dual-Mechanical-Port Electrical Machine (BLDMPEM) are proposed. BLDMPEM may have several possible structures; the research work is carried out on one of them. The working principle of the system is discussed. For special attention, the machine windings conection method is highlighted. In different operation modes, the power flows in all of the componets of BLEVT are ploted. Finally, the mathematic model and equivalent circuit of BLDMPEM are established.The control strategies of BLDMPEM are proposed, they are Power-Speed Control (PSC) and Speed-Speed Control (SSC) separately. For PSC, a new kind of three-phase-bridge control method is put forward, by using which the feedback power to DC bus can be controlled without speed of both rotors' and it is immune to machine parameters variation. Based on the two methods, the BLEVT control strategy is given. Later, a kind of asynchronous machine maximum output torque in full speed range control strategy is proposed. This algorithm ensures the furthest using of voltage and current abilities of the controller for the largest output torque. This method can also be applied to BLDMPEM. A protype machine of BLDMPEM and a BLEVT experimental platform are built, based on which, the experiments are done. The experimental and simulation results show the validaty of proposed algorithm.