Self-starting transducerless, brushless D.C. motor controller
AssigneeImec
InventorsDonald E. Fulton, William P. Curtiss, William T. Fejes, Jr.
Life of this patent
Estimating the term…
Abstract
A transducerless brushless permanent magnet motor in which a signal induced by the rotor in an unexcited winding is used to sense the rotor position. The sensed voltage, induced in the winding by the rotor, is integrated to provide a representation of the magnetic flux coupling the rotor and winding. Before start-up, both the rotor position and the integrator are initialized to align the circuit representation of the flux with the actual flux. In an additional embodiment of the invention, a self-initialization circuit is provided to automatically preset the rotor and flux integrator to pre-determined and corresponding values.
Claims24
A self-starting brushless permanent magnet motor, comprising:
- first and second windings;
- a magnetic member, the windings and the magnetic member being rotatable about an axis relative to each other;
- means for defining an initialization period prior to operation of the motor;
- means for rotating the magnetic member to a predetermined position during the initialization period;
- means for integrating an input signal applied thereto to provide an output signal;
- means for initializing the integrating means during the initialization period such that the integrating means output signal represents the flux coupling the magnetic member to the first winding when the magnetic member is at said predetermined position;
- means, operative after the initialization period, for applying to the integrating means input a signal produced in the first winding by the magnetic flux coupling the magnetic member and the first winding, so that the integrator output signal is representative of the position of the rotor with respect to the windings;
- and
- means, responsive to the integrating means output signal, for sending a drive current through the second winding to produce a torque on the magnetic member, the drive current being determined as a function of the integrator output signal while the motor is operating, thereby to provide closed-loop starting and operation of the permanent magnet motor.
A method for providing a self-starting permanent magnet motor having first and second windings and a magnetic member, the windings and the magnetic member being rotatable about an axis relative to each other, the method comprising the steps of:
- providing a first signal representative of the magnetic field coupling the magnetic member and the first winding;
- rotating the magnetic member to a predetermined position during an initialization period prior to operation of the motor;
- initializing an integrator during the initialization period so that the integrator output signal represents the flux coupling the magnetic member to the first winding when the magnetic member is at said predetermined position;
- integrating the first signal with the integrator during motor operation to provide an integrator output signal representative of the position of the magnetic member relative to the windings;
- and
- applying a drive current to the second winding to provide a magnetic field therefrom for producing a torque on the magnetic member, the drive current being a function of the integrator output signal and being applied to the second winding during motor operation, thereby to provide closed-loop starting and operation of the motor.
Dependencies are inferred from the claim text.