Study On Double Integrated Vehicle Drive Motor System Based On MAP

With the increase of automobile yield and quantities existed, the pressure of oil demand and environmental protection continuously increase.Thus, the global vehicle industry speed up to seek new energy-saving power systems. As energy saving and environmental protection vehicle, electric vehicles begin to step onto the stage of history. As the power source for all kinds of electric vehicle, vehicle drive motor system has become the key which influences vehicle performance of electric vehicles. So, this paper carry out the research on vehicle drive motor system from three aspects of control method, system integration and reliability.Firstly, when traditional vector control method is applied to vehicle drive motor, efficient work area becomes narrow and feedback loop control leads to over-current. So, this paper presents a feedforward vector control method based on MAP for vehicle drive motor. According to command torque and motor speed, this method directly controls the magnitude and phase of voltage space vector to realize the control of motor torque and speed. The result of simulation and bench experiment proves this method can not only increase the efficient work area, but also avoid the over-current problem leaded by closed loop control, meanwhile break through the dependence on current measurement to evade the problem of being unable to control motor under the condition of current sensor’s malfunction.Secondly, the addings of some components such as main/vice motor and inverter, DC/DC converter and planetary gear in parallel-series hybrid system bring a problem of assembly layout. So, this paper presents a design scheme of double integrated vehicle drive motor control system. The scheme highly integrates main/vice inverter and DC/DC converter in the same motor controller, and use double-side design of top/down layers to realize the layout of IGBT module, DC/DC converter, main control board and etc. The high integration of main/vice inverter and DC/DC converter can realize the sharing of DC bus, filter capacitor and water cooling system, which simplifys system structure, reduces the volume and cost.The result of bench experiment proves the designed double integrated motor controller can achieve the function of controlling main/vice motor at the same time and converting high voltage to low voltage of power battery.Finally, electric vehicles have high reliability requirement for vehicle drive motor. So, this paper presents three measures to promote the reliability of vehicle drive motor. First, this paper presents a method of flexible electromagnetic coupling torque transmission for vehicle drive motor. This method uses the interaction force between excitation magnetic field of outer rotor generated by excitation windings and permanent magnet magnetic field of inner rotor to transmit torque. In an overload situation, this method can realize relative sliding between inner rotor and outer rotor so as to protect motor, which can promote the reliability of motor system. Second, this paper presents a method of online magnetism loss monitoring for vehicle permanent magnet synchronous drive motor. The method judges whether the rotor magnet magnetism loses by comparing the back EMF between actual value in a certain speed and theory value in a state which the rotor magnet magnetism dosen’t lose. The method can realize the function of alarm for rotor magnet magnetism loss so as to promote the reliability of motor system. Third, this paper presents a strategy of mode switch control for vehicle drive motor. This strategy uses suitable motor control method in different conditions and different situations of sensor fault. The strategy can realize complementary advantages among different motor control methods so as to promote the reliability of motor system.