US 4,344,122 AGranted

Current sourced inverter with saturating output transformer

AssigneeGeneral Electric Company

InventorDwight V. Jones

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Abstract

A Royer circuit, which includes an inverter and a saturating output transformer, is powered from a current source rather than from a voltage source, thereby reducing transistor current overshoot when the output transformer saturates. A current source inductor and a PWM (pulse width modulated) power transistor are series connected in the current return line of the inverter. The PWM power transistor emitter is connected so that potential between it and the common DC input power terminal will be low. This permits the PWM power transistor to be direct-coupled from a low voltage PWM switched mode power supply control circuit. A start-up circuit for supplying start-up power to inverter control circuitry from the DC input source is provided. Feedback loop control for the PWM power transistor is also provided.

Claims13

Dependent claims

A converter for converting an unregulated input voltage from a voltage source having a common terminal, to a regulated output voltage comprising:

a square wave inverter including an output transformer having primary and secondary windings;
a constant current source coupled to said inverter and supplying current to said inverter so that a substantially square wave alternating current flows in said primary winding;
control circuit means for sensing said output voltage and providing a control signal when said output voltage varies by more than a predetermined amount;
a transistor switch coupled in series with said constant current source, said transistor switch being responsive to said control signal for controlling the voltage on said primary winding so that said output voltage is maintained within predetermined limits, said transistor switch and said constant current source being coupled in the current return line of said inverter;
and
circuit means coupled between the voltage source common terminal and the emitter of said transistor switch for maintaining the emitter voltage of said transistor switch near the voltage on the common terminal of said input voltage source, allowing said control signal to be applied directly to said transistor switch.

3 more elements

An inverter for converting a DC input voltage from a DC input voltage source to an output voltage comprising:

a saturating output transformer having primary and secondary windings;
a constant current source connected in the current return line of said inverter and powered by said DC input voltage, said constant current source being connected to supply current to said primary winding;
first and second transistor switch means, each connected in series with said constant current source;
means for biasing one of said first and second transistor switch means into conduction and biasing the other of said first and second transistor switch means into nonconduction upon saturation of said output transformer, said constant current source being adapted to limit current flow to said inverter circuit upon saturation of said output transformer;
a feedback control circuit for sensing said output voltage and providing control signals when said output voltage varies by more than a predetermined amount;
third transistor switch means coupled in series with said constant current source for controlling the average voltage applied to said primary winding in response to said control signals from said feedback control circuit.

3 more elements

Dependencies are inferred from the claim text.