04874993 is referenced by 33 patents and cites 11 patents.

In a brushless motor of the kind not employing a sensor for detecting rotor position, a rotational reference position of the rotor is detected based on an induction voltage in a stator excitation coil, and an energization switching point of the stator excitation coil is determined to occur a delayed time from the reference position. The time delay is increased or decreased in response to the rotational speed of the motor, so that energization switching of the excitation coils is performed at the optimum position in accordance with corresponding changes in the rotational speed of the motor. Signal masking is performed so that noise generated by the excitation coil switching does not interfere with the detection of the rotor reference position.

Title
Sensorless brushless motor
Application Number
7/251236
Publication Number
4874993
Application Date
September 30, 1988
Publication Date
October 17, 1989
Inventor
Toshiya Kan
Tokyo
JP
Masato Tanaka
Tokyo
JP
Agent
Jay H Maioli
Lewis H Eslinger
Assignee
Sony Corporation
JP
IPC
H02P 6/02
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