Patent ID: 8907596

Claim:
A method for controlling a first motor and a second motor of a common assembly, the method comprising: generating a plurality of commanded speeds of a first rotor of a first electric motor for a first time interval and a second time interval within a series of time intervals; detecting a plurality of observed speeds of the first rotor for the first time interval and the second time interval, each one of the observed speeds corresponding to a respective commanded speed; determining a first ratio based on a relationship between respective commanded speeds and corresponding observed speeds for the first time interval and the second time interval; incrementing a persistence counter for the first motor if the first ratio decreases or changes during the series of time intervals; estimating a first motor deceleration or first motor rate of change in first rotor speed of the first motor if the persistence counter exceeds a stall limit count; and adjusting a target rotor speed of a second motor based on the estimated first motor rate of change to track the first motor rate of change or the first rotor speed if the persistence counter exceeds the stall limit count, wherein the adjusting further comprises decreasing the target rotor speed and current of the second motor to be proportional to the first motor deceleration multiplied by an elapsed time, between the first time interval and the second time interval, plus a previous second rotor speed of the second motor.