A trial small size and ultra-high speed motor drive system of 5kW and 240,000rpm is designed and built. And we had described our prototype drive system and some experimental results in previous papers. For evaluating the motor drive system, we also are working on an electric and magnetic coupled-analysis in which we use not only the motor model from FEM but also the drive and control system models in the circuit simulation. This paper describes how total motor drive systems are modeled by using the coupled analysis to represent for entire system simulation. The simulation results are verified in comparison with the experimental results.