Brushless DC motor
First Claim
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1. A brushless DC motor comprising:
- n phase drive coils mounted fixedly on a stator yoke;
a magnetic rotor assembly positioned to be rotated by said drive coils;
a rotary encoder coupled to said magnetic rotor assembly to be rotated thereby, m tracks of digitally coded waveform data being recorded on said rotary encoder, said m tracks of waveform data collectively representing a plurality of different values at a respective plurality of different positions around the periphery of said rotary encoder;
a stationary m-channel detecting element for detecting waveform data produced by rotating said rotary encoder to produce an m-bit parallel signal having a plurality of relative positions of said encoder and said detecting element;
a code converter circuit for code converting said m-bit parallel signal from said detecting element to form n phase drive signals each having a different value determined in accordance with the value of said m-bit parallel signal; and
power amplifiers for amplifying said n phase drive signals from said converter circuit to apply in response thereto currents to said drive coils.
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Abstract
A brushless DC motor utilizing only a single position detector and which provides a uniform torque output characteristic with little or no vibration. N phase drive coils are fixedly mounted on a stator yoke. A magnetic rotor assembly, which is rotated by the drive coils, is coupled to rotate a rotary encoder on which m tracks of digitally coded waveform data are recorded. A single m-channel stationary detecting element detects the waveform data produced by rotating the rotary encoder to provide an m-bit parallel signal. The m-bit parallel signal is code converted and applied through power amplifiers to drive the drive coils.
33 Citations
8 Claims
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1. A brushless DC motor comprising:
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n phase drive coils mounted fixedly on a stator yoke; a magnetic rotor assembly positioned to be rotated by said drive coils; a rotary encoder coupled to said magnetic rotor assembly to be rotated thereby, m tracks of digitally coded waveform data being recorded on said rotary encoder, said m tracks of waveform data collectively representing a plurality of different values at a respective plurality of different positions around the periphery of said rotary encoder;
a stationary m-channel detecting element for detecting waveform data produced by rotating said rotary encoder to produce an m-bit parallel signal having a plurality of relative positions of said encoder and said detecting element;a code converter circuit for code converting said m-bit parallel signal from said detecting element to form n phase drive signals each having a different value determined in accordance with the value of said m-bit parallel signal; and power amplifiers for amplifying said n phase drive signals from said converter circuit to apply in response thereto currents to said drive coils. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification