Position sensorless control scheme of high-e?ciency Permanent Magnet Synchronous Motors (PMSM) for small size, light weight and low cost is developed. The characteristics of the position sensorless control are decided by the combination system both the sensorless control algorithm and the test motor. By the experimental results using the prototype, it is confirmed that the requirement specifications for the sensorless drive system are satisfied. This paper presents the experimental characteristics of the position sensorless control system. This paper shows the functions of the simulation tools, which integrate the motor design and the control system, for shortening the development period and reducing the cost.