Hamilton Sundstrand Corporation

Howard Simmons

John E Games

A system for controlling an electric motor includes a controller and a position indicator that provides position information regarding at least one motor component to the controller. The controller utilizes phase relationships indicative of the position information to determine the actual position of the component of interest. The phase information in one example is derived from the output of a resolver that provides two output signals corresponding to sin (&#x3b8;) and cos (&#x3b8;), where &#x3b8; is the angular position. Utilizing the phase relationship simplifies the task of determining accurate position information that is useful to modify motor control signals to compensate for latency when making position determinations, velocity calculations or both. The inventive system makes it possible to use less expensive electronics to arrive at more reliable results.

Electric motor control system including position determination and error correction

A commutation and velocity control system of a brushless DC motor receives a velocity command signal and provides command signals to drive the brushless DC motor. The system includes a summer that receives the velocity command signal and a velocity feedback signal and provides a velocity error signal indicative of the difference. A velocity loop compensator receives said velocity error signal and provides a compensated velocity error signal. A magnitude sensing circuit senses the magnitude of said compensated velocity error signal and provides a velocity magnitude signal indicative thereof. A polarity sensing circuit senses the polarity of the said compensated velocity error signal and provides a velocity polarity signal indicative thereof. The system also includes an integrated circuit having: (i) a velocity calculation circuit that receives a first sampled digitized signal indicative of resolver position at a first time and a second sampled digitized signal indicative of resolver position at a second time, and determines velocity based upon the difference between said first and second sampled digitized signals and provides a sensed digitized velocity signal indicative thereof; (ii) a commutation logic circuit that receives said first sampled digitized signal, said velocity magnitude signal and said velocity polarity signal, and provides said command signal; and (iii) a counter that receives a signal indicative of said sensed digitized velocity signal and provides a pulse width modulated output signal indicative thereof. A filter receives said pulse width modulated output signal and generates said velocity feedback signal.

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Barkhamstead, CT, United States of America

Howard Simmons