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Control circuit for a brushless DC motor

  • US 4,814,674 A
  • Filed: 03/25/1987
  • Issued: 03/21/1989
  • Est. Priority Date: 03/26/1986
  • Status: Expired due to Term
First Claim
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1. A monolithically integrable control circuit for a brushless DC motor comprising:

  • a commutation signal source for producing motor commutation signals, the commutation signal source being controlled by rotational rotor position signals,a driver circuit controlled in accordance with the commutation signals and serving for applying driving pulses, which result in a rotating magnetic field, to the motor windings, with one driver stage being provided for each motor winding phase, anda pulse shaping circuit which effects sloping of the driving pulse edges, the pulse shaping circuit being connected to the driver circuit to provide drive control pulses thereto and additionally being connected to an external edge sloping impedance means for sloping the edges of the driver control pulses,wherein a sloped driver control pulse (VCA, VCB) for a particular motor phase is initiated substantially by the termination of a sloped driver control pulse (VCA, VCB) for the preceding motor phase, andwherein the driver stages (15) are designed as feedback-free amplifier stages, each including a source stage (Q4, Q5) supplying current into a connected motor winding, and a drain stage (Q6, Q7) receiving current from the connected motor winding, with the source stage (Q4 Q5) and the drain stage (Q6, Q7) being controllable independently of each other, with the drain stage (Q6, Q7) being designed as a switch and the source stage (Q4, Q5) having a conductive stage wherein it is controllable analogously with said sloped driver control pulse (VCA, VCB), so that the output voltage of the driver stages (15) is controllable with the sloped driver control pulses (VCA, VCB) and a voltage corresponding to said sloped river control pulse (VCA, VCB) is thus applied to the particular activated motor winding.

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