EP0211796A2
Expired / Lapsed
EP
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High efficiency mosfet sine wave generator
Assignee: RTX Corp
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Filing: 1986-07-28
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Granted: —
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Expires: 2006-07-28
Abstract
Abstract A high efficiency MOSFET sine wave generator is provided using the class D pulse width modulation principle. A triangle wave at f₀ is compared to a variable amplitude sinusoid at about 1/10 f₀ to provide a pulse width modulated signal for driving a pair of power MOSFETS connected for switching a B+ and a B- power supply. The power switch output is LC filtered and fedback for regulating the amplitude of the modulating sinusoid.
Inventors
- 👤 John Richard Torres
- 👤 Richard Vincent Vesce
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 21:16
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/538; H02M7/53803
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
325 words
Apparatus, responsive to a variable amplitude sinusoidal source which provides a sinusoidal modulating signal at a first frequency, the source being responsive to an error signal from said apparatus for varying the amplitude of the modulating signal in response to the error signal, and said apparatus responsive to a fixed amplitude triangle wave voltage source, which provides a triangle signal at a second frequency greater than the first frequency and at an amplitude greater than or equal to the amplitude of the modulating signal, said apparatus comprising: comparator means, responsive at separate inputs thereof to the modulating signal and to the triangle signal for providing a low power modulated pulse train signal; drive amplifier means, responsive to said modulated pulse train signal for providing an amplified modulated pulse train signal; isolation transformer means, having a primary and two secondary windings, responsive at the primary thereof to said amplified modulated pulse train signal, for providing alternating isolated gate drive signals at the secondary windings; a pair of MOSFET power switches, each responsive at a gate input thereof to one but not the other of the alternating gate drive signals, one switch responsive to a positive DC source having a voltage magnitude equal but opposite in sign to a negative DC source connected to the other switch, for providing a modulated pulse train power output signal; LC filter means, responsive to said modulated pulse train power output signal for providing a sinusoidal power output signal; and error circuit means, responsive to said sinusoidal power output signal for comparing the magnitude thereof to a reference signal magnitude and for providing an error signal to the variable amplitude sinusoidal source for varying the amplitude of the modulating signal in inverse proportion to said sinusoidal power output signal so as to cause the voltage magnitude of said sinusoidal power output signal to vary in such a way as to tend to reduce the magnitude of the error signal to zero.
Claim 2
Dependent Claim
325 words
Apparatus, responsive to a variable amplitude sinusoidal source which provides a sinusoidal modulating signal at a first frequency, the source being responsive to an error signal from said apparatus for varying the amplitude of the modulating signal in response to the error signal, and said apparatus responsive to a fixed amplitude triangle wave voltage source, which provides a triangle signal at a second frequency greater than the first frequency and at an amplitude greater than or equal to the amplitude of the modulating signal, said apparatus comprising: comparator means, responsive at separate inputs thereof to the modulating signal and to the triangle signal for providing a low power modulated pulse train signal; drive amplifier means, responsive to said modulated pulse train signal for providing an amplified modulated pulse train signal; isolation transformer means, having a primary and two secondary windings, responsive at the primary thereof to said amplified modulated pulse train signal, for providing alternating isolated gate drive signals at the secondary windings; a pair of MOSFET power switches, each responsive at a gate input thereof to one but not the other of the alternating gate drive signals, one switch responsive to a positive DC source having a voltage magnitude equal but opposite in sign to a negative DC source connected to the other switch, for providing a modulated pulse train power output signal; LC filter means, responsive to said modulated pulse train power output signal for providing a sinusoidal power output signal; and error circuit means, responsive to said sinusoidal power output signal for comparing the magnitude thereof to a reference signal magnitude and for providing an error signal to the variable amplitude sinusoidal source for varying the amplitude of the modulating signal in inverse proportion to said sinusoidal power output signal so as to cause the voltage magnitude of said sinusoidal power output signal to vary in such a way as to tend to reduce the magnitude of the error signal to zero.
Claim 3
Dependent Claim
95 words
The apparatus of claim 1, wherein said error circuit means further comprises: rectifier means, responsive to said sinusoidal power output signal for providing a rectified signal; peak detector means, responsive to said rectified signal for providing a DC voltage signal having a magnitude directly proportional to the peak amplitude of said rectified signal; and error amplifier means, responsive to said DC voltage signal from said peak detector and to the reference signal for providing said error signal having a magnitude directly proportional to the difference between the magnitudes of said signal and said reference signal.
Claim 4
Dependent Claim
85 words
The apparatus of claim 1, wherein said error circuit further comprises: a square wave oscillator for providing a first square wave signal output of constant amplitude; open collector buffer means, responsive to said error signal and to said square wave signal output for providing a second square wave output having an amplitude which varies inversely with respect to variations in the magnitude of said sinusoidal power output signal; and filter means, responsive to said second square wave output signal for providing said sinusoidal modulating signal.
References Cited (Backward Citations)
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