Abstract:
A commutation control circuit for a motor including a power thyristor and an auxiliary thyristor for switching the power thyristor under control of a variable frequency pulse generator making use of a capacitor for commutation charged by a transformer, the charge on the capacitor being established to be ready for commutation whenever the power thyristor is gated, and the charging current being derived from a direct current source such as a lead/acid storage battery. The circuit specifically uses a positive pulse for causing conduction of the power thyristor and a negative pulse for switching the power thyristor ''''off.
Abstract:
A control circuit for controlling the effective power to a load from a power source of substantially constant direct current voltage includes a first or main solid state switching device for placing the load and the power source in series. Suitable circuitry including a commutating capacitor chargable in a direction such that its discharge will terminate conduction of the main switching device further includes resistive means serving to maintain the capacitor in constant communication with the power source. Also provided is a means for providing dynamic braking of a direct current motor load through a resistive element such that the armature terminal voltage is adjusted linearly with the speed thereof.