Self-oscillating high frequency power converter
First Claim
1. A self-oscillating power converter comprising:
- input means for accepting a DC voltage source.a semiconductor power switch including first and second main conduction path electrodes and a control electrode and further including at least an interelectrode capacitance between the first main conduction path electrode and the control electrode and having its first main conduction path electrode coupled to the input means,a feedback network for sustaining oscillations in the power converter including;
the interelectrode capacitance coupling the first main conduction path electrode and the control electrode, anda variable inductive circuit coupling the control electrode to the second main conduction path electrode,the interelectrode capacitance and the variable inductive circuit having reactive values such that a sinusoidal voltage is generated at the control electrode causing oscillations to occur whereby the interelectrode capacitance is sufficient to be operative as an exclusive feedback path;
a tuned network connected to the first main conduction path electrode and having an inductive reactive impedance and operative at a frequency of oscillation as established by the feedback network for controlling a voltage waveform at the first main conduction path electrode to be continuing for a portion of a cycle of operation while the semiconductor power switch is nonconducting and to be discontinued while the semiconductor power switch is conducting.
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Abstract
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.
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Citations
23 Claims
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1. A self-oscillating power converter comprising:
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input means for accepting a DC voltage source. a semiconductor power switch including first and second main conduction path electrodes and a control electrode and further including at least an interelectrode capacitance between the first main conduction path electrode and the control electrode and having its first main conduction path electrode coupled to the input means, a feedback network for sustaining oscillations in the power converter including; the interelectrode capacitance coupling the first main conduction path electrode and the control electrode, and a variable inductive circuit coupling the control electrode to the second main conduction path electrode, the interelectrode capacitance and the variable inductive circuit having reactive values such that a sinusoidal voltage is generated at the control electrode causing oscillations to occur whereby the interelectrode capacitance is sufficient to be operative as an exclusive feedback path; a tuned network connected to the first main conduction path electrode and having an inductive reactive impedance and operative at a frequency of oscillation as established by the feedback network for controlling a voltage waveform at the first main conduction path electrode to be continuing for a portion of a cycle of operation while the semiconductor power switch is nonconducting and to be discontinued while the semiconductor power switch is conducting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A power converter comprising:
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input means for accepting a DC power source, output means for accepting a load to be energized, a transistor switch coupled for receiving power from the input means and having a control electrode, first and second power carrying electrodes and having interelectrode capacitance between the first and second power carrying electrodes and between each power carrying electrode and the control electrode, a tuned network coupling the first power carrying electrode to the output means and operative for controlling a voltage waveform at the first electrode lasting for portion of a half-cycle of operation of the transistor switch during its nonconducting state, a feedback network including an interelectrode capacitance coupling the first power carrying electrode and the control electrode and a frequency control network including an inductance and a variable capacitance coupling the control electrode to the second power carrying electrode, the interelectrode capacitance and the inductance and variable capacitance being tuned to generate a quasi-sinewave voltage at the gate electrode with a leading phase of 120°
to 180°
with respect to a fundamental component of the pulsed voltage waveform at the first power carrying electrode, andthe feedback network being operative to generate the quasi sinewave voltage at the gate electrode at a frequency when the interelectrode capacitance is operative as an exclusive feedback path. - View Dependent Claims (11, 12, 13, 14)
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15. A power converter comprising:
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input means for accepting a DC power source, output means, a MOSFET power switch coupled for receiving power from the input means and including interelectrode capacitances, a frequency tuned network coupling an output electrode of the MOSFET power switch to the output means, and operative for maintaining current through the power switch exclusive of voltage across the power switch, an oscillatory feedback network including; an interelectrode capacitance coupling the output electrode to a control electrode of the MOSFET power switch and a frequency control circuit including an inductor and variable capacitance coupling the control electrode to a third electrode of the MOSFET power switch, and operative for supplying a continuous sinusoidal drive signal at the control electrode at a sufficiently high frequency so that the interelectrode capacitance coupling the output electrode to the control electrode is an exclusive feedback path. - View Dependent Claims (16, 17, 18)
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19. A self-oscillating power converter comprising:
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input means for accepting a DC voltage source output means, a semiconductor power switch coupled for controlling energy flow from the input means to the output means and including first and second main conduction path electrodes and a control electrode for controlling current flow in a main conduction path of the power switch, a tuned network coupling the first main conduction path electrode to the output means and operative for controlling a voltage waveform at the first main conduction path electrode to be continuous for a portion of a half-cycle of operation of the semiconductor power switch during its nonconducting state, a tunable narrow bandwidth drive network for driving the power switch including; capacitive means coupling the first main conduction path electrode to the control electrode, and inductive means having variable inductance in response to a control signal and coupling the second main conduction path electrode to the control electrode, control means for supplying a control signal varying the inductance of the inductive means, whereby the capacitive means and inductive means operate cooperatively to supply a quasi sinewave voltage at the control electrode and the control means is operative for varying a frequency of operation of the converter to control a signal amplitude at the output means. - View Dependent Claims (20, 21, 22, 23)
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Specification