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Predicting the vibration of a motor gearbox assembly driven by a PWM inverter in the early stages of development is demanding because the assembly is one of the dominant noise sources of electric vehicles (EVs). In this paper, we propose a simulation model that can predict the transient vibration excited by gear meshing, reaction force from the mount, and electromagnetic forces including the carrier frequency component of the inverter up to 10 kHz. By utilizing the techniques of structural model reduction and state space modeling, the proposed model can predict the vibration of assembly in the operating condition with a system level EV simulator. A verification test was conducted to compare the simulation results with the running test results of the EV.

We developed a thermal calculation 1D simulator for an electric valve timing control system (VTC). A VTC can optimize the open and close timing of the intake and exhaust valves depending on the driving situation. Since a conventional VTC is driven hydraulically, the challenges are response speed and operation limit at low temperature. Our company has been developing an electric VTC for quick response and expansion of operating conditions. Currently, it is necessary to optimize the motor and reduction gear design to balance quicker response with downsizing. Therefore, a coupled simulator that can calculate electricity, mechanics, control, and thermo characteristics is required. In 1D simulation, a thermal network method is commonly used for thermal calculation. However, an electric VTC is attached to the end of a camshaft; therefore, determining thermal resistances is difficult. We propose a method of determining thermal resistances, using both theoretical and experimental approaches.

Electric power steering system has been widely used in passenger cars to replace hydraulic power steering system. In this paper, a coupled system simulator for dual-pinion electric power steering system is developed and its dynamics is verified using experimental data. The mechanical subsystem model is developed using mass, spring-damper and experimental data with hysteresis characteristic. For the control subsystem, the controller model is developed by transplanting control program from the controller in real vehicle to the simulator. For the electric subsystem, the motor model is developed using the map of current to torque which is created by magnetic field analysis in advance. The three subsystems are combined to form the complete system simulator and numerical simulation is performed. The simulation results are compared to the experimental data and the error is less than 10%.