Importance

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Abstract

A motor control apparatus is disclosed for controlling the rotational velocity of a drive shaft of an electric motor in accordance with a reference time period indicative of the desired rotational speed of the drive shaft. A sensor in the form of a tachometer provides a train of pulses. The period between tachometer pulses is measured and the difference between the reference and measured time periods is obtained. This difference is digitally processed by integrating, dividing and summing with a signal proportional to the difference to provide a motor command signal. The gains of the motor control apparatus are set to reduce phase delays and the deleterious effects thereof. Further, sensors in the form of Hall effect devices are disposed about the motor to each provide a train of timing signals. The timing signals are used to control the application of an energizing signal by corresponding switches to the motor coils; the level of the energization signal or current is set by the motor command signal. Further, the waveshapes of at least one Hall effect device output and the tachometer output are compared to identify a relationship occurring once in a rotor revolution, to generate a corresponding index or position pulse.

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First Claim