Method and System for Determining the Position of a Synchronous Motor's Rotor

摘要

To establish an initial/resting position of a permanent magnet rotor, all motor stator windings are stimulated (voltage applied thereto) in sequence, the time it takes for current in the stimulated stator winding to rise to a specific current value is measured for each stator winding and these time measurement results processed. From the measured time results rotor position to within 60 degrees is determined and the position sector is known prior to starting/rotating the motor. Once the rotor position is known, the next commutation point in a six step sequence is known before actually starting/rotating the motor. Position measurement winding stimulation may be interleaved with commutation pulses, or the unexcited stator winding may be stimulated between commutation pulses to the other two excited stator, wherein one of the two stator windings remains connected to the power and provides a current return path to the unexcited but stimulated stator winding.

主权项

1. A method for determining a rotor position in a synchronous three phase motor, said method comprising the steps of:
coupling combinations of two of three stator windings to a first voltage; coupling third ones of the three stator windings to a second voltage; measuring first times for currents through all combinations of the three stator windings to equal a reference current; and determining a rotor position from the measured first times.