Texas Instruments Corporation

Kaushik Alwala

Venkata Naresh Kotikelapudi

David Patrick Magee

Siddhartha Gopal Krishna

James Lockridge

A motor control system and method for controlling a brushed direct current (BDC) motor using a feedback loop based on a corrected ripple count. Motor control circuitry, for example implemented in digital logic such as a microcontroller, receives a coil current signal and a motor voltage signal. Discontinuities in the coil current signal, such as caused by commutation of the BDC motor, are counted to generate a ripple count. An observer function derives an angular frequency model estimate for the values of the coil current and motor voltage signals using a computational model for the motor. A corrected ripple count is generated based on a comparison of a commutation angle of the motor with an angular position based on the angular frequency model estimate over a time interval between discontinuity pulses. A motor drive signal is adjusted based on the corrected ripple count.

Observer-based ripple detection for speed and position measurement for brushed direct current motors

A motor control system and method for a brushed direct current (BDC) motor using a compensated and corrected ripple count. Motor control circuitry, for example implemented in digital logic such as a microcontroller, receives a coil current signal and a motor voltage signal. Discontinuities in the coil current signal, are counted to generate a ripple count. An observer function derives an angular frequency model estimate using a computational model for the motor applying motor parameters estimated in an initial estimation interval following startup of the motor. A corrected ripple count is generated based on a comparison of a commutation angle of the motor with an angular position based on the angular frequency model estimate. Compensation for cumulative error over the initial estimation interval is derived from a behavioral motor model applying the estimated motor parameters. A motor drive signal is adjusted based on the compensated corrected ripple count.

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Kaushik Alwala