Accurate estimation of initial rotor position for brushless DC motor position sensorless drive

It is necessary to estimate the initial rotor position accurately when the sensorless control is applied to brushless DC motor. First, we explain the estimation method of initial rotor position. Next, we investigate the influence of the amplitude and frequency of high-frequency input voltage on the estimation accuracy and obtain the optimal values. The brushless DC motor can start smoothly by using four optimal values of high-frequency input voltage.