Patent ID: 9374028
Filing Date: 2016-06-21
CPC Classification: H02P

Claim Text:
1. A method for sensorless motor speed control in a motor drive having an inverter, the method comprising: generating a first position signal or value from a desired frequency or motor speed signal or value; generating a second position signal or value using an EMF-based position estimator according to inverter output current signals or values and inverter output voltage signals or values; generating voltage command signals or values for pulse width modulation operation of the inverter using a speed controller according to a desired speed signal or value, a feedback speed signal or value, and a selected commutation position signal or value; setting the selected commutation position signal or value to the first position signal or value in a first mode for a first range of speeds or to the second position signal or value in a second mode for a second higher range of speeds according to the desired speed signal or value; setting the feedback speed signal or value to a fixed value for open loop control in the first mode for the first range of speeds; and computing the feedback speed signal or value according to the second position signal or value for closed loop control in the second mode for the second range of speeds.