| 摘要 |
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. |
