US 4,376,261 AGranted

Two-pulse brushless d.c. motor

AssigneePapst-Motoren GmbH & Co. KG

InventorsJohann von der Heide, Rolf Muller, Benno Doemen

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Abstract

In response to a Hall-IC sensor exposed to the magnetic field of the rotor of a brushless d.c. motor, two interleaved sequences of pulses are generated at separate outputs with an interpulse pause of a certain length occurring between successive interleaved pulses to prevent reduction of efficiency and increase of motor noise that would result from overlapping pulses being supplied to the stator of the motor. When these pulses are utilized to switch a semiconductor full bridge circuit, through which a single winding of the stator is energized by current pulses alternating in direction, prevention of short-circuits resulting from slow turn-off of the semiconductor switches is prevented. For overcurrent protection, only half of the bridge is intermittently blocked by a current regulator when the current reaches a predetermined limiting value, this provision also reducing generation of noise and interference by the motor.

Claims17

Dependent claims

A brushless d.c. motor having a permanent magnet rotor (11), a stator, conductor means (25) wound on said stator for energizing the stator by pulses of current, and rotor position sensing means (85) for controlling said current pulses so that in operation of said motor two current pulses are provided to said conductor means (25) for every 360.degree. el. of rotation of said rotor, said sensing means (85) having an output providing an electrical signal having two output values between which it makes substantially instantaneous transitions at instants determined by rotor position, said motor further comprising, in accordance with the invention:

means (96,97;139,142) for subjecting said output signal (u.sub.85) of said sensing means to phase reversal and delay and delivering a correspondingly modified signal at an output;
a pair of logic elements (90,98;145,146) to the respective inputs of which are applied said output signal of said sensing means and the output of said phase reversal and delay means, for producing logic stage output signals (132,133) at each of two outputs only when between said inputs of said logic elements there is a voltage difference of a predetermined polarity exceeding a predetermined minimum in magnitude, the logic stage output signals of one of said two outputs being separated in time from the logic stage output signals of the other of said two outputs by time gaps, and
means (104,105, etc.) responsive to said respective logic stage output signals for controlling the provision of current pulses to said conductor means (25) wound on said stator.

Dependencies are inferred from the claim text.