Brushless d.c. motor having RC time-delay stage(s) and driver transistors which prevent simultaneous conduction by the power transistors of the wound conductor pair(s) of the motor winding

DETAILED DESCRIPTION It is an object of the invention to further improve this motor.
In accordance with the invention, this object is achieved as follows: Each controllable semiconductor power-carrying element, e.
g.
power transistor, is provided with an associated driver transistor of conductivity type opposite to or complementary to that of the power-carrying element, the driver transistors thus being themselves of conductivity types that are opposite to or complementary to each other.
Additionally, there are provided resistor-capacitor time-delay means, comprising at least one RC time-delay stage associated with and influencing the operation of the driver transistors to introduce a time delay between switch-OFF of the first power-carrying element and switch-ON of the second, and to similarly introduce a time delay between switch-OFF of the second power-carrying element and switch-ON of the first.
In accordance therewith it becomes possible in an extraordinarily simple way to delay the commutation operations and to insert a currentless interval between each two successive stator-current pulses.
This improves the efficiency of such a motor; protects the power transistors, inasmuch as the commutation already begins as long as the induced voltage is still relatively high; and reduces the motor's noise, inasmuch as undesirable current spikes occuring during the commutation operation are avoided.
Further specifics and advantageous features of the invention may be had from the exemplary embodiments, described below and shown in the drawing but which in now way are to be understood as limiting the invention, and also may be had from the dependent claims.