American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Bell Laboratories

Wayne C Bowman

Norman Gerard Ziesse

Weyman B Suiter, Jr

Harold Seidel

William A Nitz

Randhir S Malik

Frank M Magalhaes

A power inverter efficiency is optimized at high frequency in a fully resonant inverter operating with a range of load impedance that takes into consideration switching loss and conducting loss as a combined overall effect. Within this range of load impedance the inverter is constrained to operate with switching loss which is generally considered unacceptable in a conventional high frequency high efficiency power inverter, but the overall combined high efficiency of the disclosed power inverter has a wider range of load impedances than has been previously achieved in such a resonant power inverter. Non-linear capacitance across switching the device is positively utilized in achieving this goal.

Method of optimizing the efficiency of a high frequency zero voltage

A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform. The input resistance of the rectifier is controlled so that it is invariant to frequency change within the switching frequency range of the converter but inversely proportional to the load resistance.

Resonant rectifier circuit

A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Self-oscillating high frequency power converter

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Rockaway, NJ, United States of America

Wayne C Bowman