Abstract: A control for a voltage fed series resonant inverter includes controllable switch means which supplies square wave voltage signals to a resonant series circuit. The output of the inverter is coupled to a rectifier to provide dc power to a load. The control comprises summer means for comparing a commanded dc voltage to an actual dc output voltage and providing an error signal. An oscillator responsive to the error signal generates a frequency signal that is coupled to the controllable switch means to vary the frequency of the square wave voltage supplied to the resonant circuit. The duty cycle of the frequency signal is adjusted so that the frequency signal is provided in bursts during low load conditions thereby minimizing circulating currents while maintaining the output voltage with closed loop frequency control.

Abstract: A circuit for limiting the peak turn-on current stress imposed upon power switch transistors in an inverter during the coasting diode cleaning interval includes a ramp step generator providing a ramp of control current to the power transistor until conduction is initiated. The power switch transistor turn-on is sensed, which triggers a step increase in turn-on current to an appropriate final value which is sufficient to quasi-saturate the power switches.

Abstract: A single transistor DC--DC battery charger provides ohmic isolation with a multiple winding high frequency transformer. The transistor's duty cycle is determined from an isolated voltage proportional to battery voltage obtained from a signal winding of the transformer when the transistor is off.

Abstract: A multipole permanent magnet rotor is positioned on a shaft and rotatably mounted in a multiphase stator having two windings per stator phase. A distributor comprising a pattern of conducting and non-conducting material is mounted to turn with the rotor shaft. Pickup "fingers" in contact with the distributor, gate appropriate FET's of the pairs of FET's associated with each stator phase in sequence, with timing dependent on the instantaneous shaft position, to generate a rotating flux field. A voltage across the windings provides the current for flux generation, and can be supplied by a full wave rectified single phase AC source. The speed of rotation of the motor can be controlled by varying the voltage supplied.

Abstract: An improved proportional base drive circuit for rapidly and efficiently switching a high current bipolar load transistor comprises a transformer having first and second serially coupled primary windings, and first and second secondary windings coupled to the collector and to the base, respectively, of a high current load transistor for supplying the transistor with collector current and base current proportional to the collector current, respectively. A diverter circuit is coupled to the second secondary transformer winding and to the base and emitter of the load transistor. During intervals when the second transformer primary winding is effectively short circuited to initiate load transistor turn-off, the diverter circuit diverts current in the second secondary winding away from the load transistor base and also removes load transistor stored charge to effect rapid load transistor turn-off, thereby assuring reliable transistor switching.

Abstract: A low cost power control circuit which achieves variable speed, quasi four-quadrant motor control well suited to the requirements of a direct drive clothes washing machine. For handling relatively low frequency motor direction control signals (one or two Hertz), four relatively inexpensive, low frequency thyristors are employed in a four-leg bridge circuit arrangement. For handling relatively high frequency chopper duty cycle control signals (10 kHz), a single high frequency power transistor is employed. To provide quasi four-quadrant control entirely suitable for clothes washing, a fifth thyristor and a series dissipation resistor are connected across the motor terminals and switched ON during agitation just prior to each motor reversal when motor velocity is decreasing and motor back emf exceeds applied emf. A feedback servomechanism is employed to control motor rotational velocity via chopper pulse width modulation.

Abstract: A filament winding forms a part of the step-up transformer in a flyback-type high-frequency, high-voltage power supply for supplying filament heating energy, in addition to the anode potential supplied by a secondary winding of the transformer, to a magnetron microwave power generator, which is a self-rectifying load. The voltage across the transformer primary winding, and the current flowing through a controllable current path in a switching device connecting the series with that primary winding, are both monitored and compared to reference voltage and current values for establishing the conduction time interval of the switching device to provide active control of the power input to the load.

Abstract: Full-wave and half-wave rectifier circuits are disclosed; the former circuit using two transistors and the latter circuit using one transistor. In both circuits transistors are connected in an inverted mode so that, for example, with an NPN transistor current flow is such that line current flows into the emitter and load current flows out of the collector. Furthermore, voltage blocking is performed by the collector-base junction instead of the emitter-base junction. High efficiency is achieved by controlling the transistor base current in response to the emitter current so that the base current is proportional to the emitter current and is also at an optimum magnitude so as to minimize circuit losses.