Arrangement for controlling the driving and braking current of a brushless D.C. motor
First Claim
1. A control circuit for a brushless DC motor having a permanent magnet rotor and first and second stator windings, comprising, first and second semiconductor switching elements in respective series with said windings, said windings being double wound on the core of said stator, the core of said stator, first and second free wheeling diodes connected respectively to the junctions of said windings and said switching elements in oppositely poled relation to said switching elements, scanning circuit commutating means for alternately switching said elements on and off in accordance with the rotary position of said rotor, first and second current measuring means in respective series relation to said switching elements and said diodes, and comparator means responsive to said current measuring means for alternately blocking and unblocking the output of said scanning circuit commutating means when said first and second current measuring means reach predetermined values.
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Abstract
The invention relates to a control circuit for controlling the driving and braking current of a brushless type DC motor of the type having a permanent magnet rotor and a pair of poles provided with two windings, the windings having a common junction which is connectable to the positive terminal of a DC voltage source. The windings are double wound on the core of the motor stator and a pair of controllable switching elements are in respective series with the windings. A scanning commutating circuit responsive to the angular position of the rotor has dual outputs for switching the switching elements on and off in a push-pull mode. Free wheeling diodes are connected respectively to the junctions of the windings and the switching elements and first and second current measuring resistors are in respective series relation to the switching elements and the diodes. A comparator circuit responsive to varying voltage drops effected by the current measuring resistors alternately blocks and unblocks the output of the scanning commutating circuit when the currents in the current measuring resistors reach predetermined values.
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5 Claims
- 1. A control circuit for a brushless DC motor having a permanent magnet rotor and first and second stator windings, comprising, first and second semiconductor switching elements in respective series with said windings, said windings being double wound on the core of said stator, the core of said stator, first and second free wheeling diodes connected respectively to the junctions of said windings and said switching elements in oppositely poled relation to said switching elements, scanning circuit commutating means for alternately switching said elements on and off in accordance with the rotary position of said rotor, first and second current measuring means in respective series relation to said switching elements and said diodes, and comparator means responsive to said current measuring means for alternately blocking and unblocking the output of said scanning circuit commutating means when said first and second current measuring means reach predetermined values.
Specification