This paper presents a transition algorithm for wide-speed-range operation of sensorless interior permanent magnet synchronous
motor (IPMSM) drives. For the low speed range, a continuous high frequency signal is injected to the motor to extract the rotor
position by signal processing method using the measure axis. For the middle and high speed range, the rotor position information
is estimated using a disturbance observer based on the extended back electro-motive-force (EEMF) model. The previous transition
algorithm between two speed ranges is executed at a specific operation point for wide-speed-range operation. However, this
transition algorithm can cause speed overshoot during load changes and change the speed transition point due to parameter
variations of IPMSM. Therefore, this paper proposes a new and simple weighting function for stable transition operation between
two speed ranges. Experiments are carried out to show the effectiveness of the proposed transition algorithm.