PMSM initial position detection system and method

A system for determining an initial position of a rotor of a PMSM (permanent magnet synchronous motor) motor, comprising:

• (a) a motor controller coupled to a plurality of phase windings of the PMSM motor by means of an actuation circuit;
• (b) a processor, and an interface circuit in the motor controller coupled to the processor and the phase windings;
• (c) the processor being operative to determine if the speed of the rotor is zero, and if the speed is zero, also being operative to cause the actuation circuit to sequentially apply voltage signals to the phase windings to produce corresponding phase winding current signals in the various phase windings;
• (d) circuitry for sensing and digitizing the phase winding current signals;
• and
• (e) the processor being operative to determine a position of a predetermined magnetic flux path associated with the rotor by computing the initial position of the rotor from one of the digitized phase winding current signals associated with the predetermined magnetic flux path;
• wherein the processor is operative prior to the rotor speed determining in order to provide normalized phase winding current signals by causing the voltage signals to be repeatedly, sequentially applied to the phase windings to repeatedly produce corresponding phase winding current signals in the various phase windings over a 360° angular range corresponding to one rotation of the rotor a predetermined number of times, the processor also being operative to cause the sensing and digitizing circuitry to sense and digitize the phase winding current signals, the processor also being operative to average the repeatedly produced and digitized phase winding current signals to thereby provide the normalized phase winding current signals.