Combined PWM-FM control method and circuit for the high efficiency control of resonant switch mode inverters/converters
First Claim
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1. A circuit for controlling resonant power inverters/converters with a combined PWM-FM method comprising:
- (a) a power switch, comprising first and second controlled power switching elements, for transferring energy from a DC power supply to a load through a resonant coupling circuit;
(b) first and second diodes, parallel with the first and second controlled switching element, respectively, to provide a unidirectional current path around the associated switching element when the associated switching element is turned off;
(c) a driver circuit which provides a drive signal to control electrodes of the first and second power switching elements;
(d) a pulse-width modulator having a first input which is connected to receive a timing signal from a voltage or current controlled oscillator and a second control input which is connected to receive a control voltage which controls the pulse-width of the output pulse sequence of the pulse-width modulator,the output providing the input signal to the driver circuit;
(e) a voltage or current controlled oscillator the timing signal of which is connected to the first input of the pulse-width modulator, and having a frequency control input which is connected to the output of a nonlinear functionshaper, the frequency of the voltage or current controlled oscillator being controlled by the voltage or current connected to its frequency control input; and
(f) a function shaper circuit the input of which is connected to the control voltage, the output voltage or current of the function shaper circuit being connected to the frequency control input of the voltage or current controlled oscillator to control the frequency of the oscillator as a single-valued nonlinear function of the control voltage.
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Abstract
A PWM-FM control method and circuit is employed to control the output level of a resonant switch-mode inverter/converter. The frequency of the inverter/converter is controlled via a nonlinear function shaper and VCO or ICO by the same voltage which controls the pulse-width such that the turn-on of the controlled switching element(s) always occur(s) at substantially zero voltage and substantially zero current across the switching element(s), thereby minimizing switching losses and maximizing efficiency.
24 Citations
8 Claims
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1. A circuit for controlling resonant power inverters/converters with a combined PWM-FM method comprising:
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(a) a power switch, comprising first and second controlled power switching elements, for transferring energy from a DC power supply to a load through a resonant coupling circuit; (b) first and second diodes, parallel with the first and second controlled switching element, respectively, to provide a unidirectional current path around the associated switching element when the associated switching element is turned off; (c) a driver circuit which provides a drive signal to control electrodes of the first and second power switching elements; (d) a pulse-width modulator having a first input which is connected to receive a timing signal from a voltage or current controlled oscillator and a second control input which is connected to receive a control voltage which controls the pulse-width of the output pulse sequence of the pulse-width modulator,the output providing the input signal to the driver circuit; (e) a voltage or current controlled oscillator the timing signal of which is connected to the first input of the pulse-width modulator, and having a frequency control input which is connected to the output of a nonlinear functionshaper, the frequency of the voltage or current controlled oscillator being controlled by the voltage or current connected to its frequency control input; and (f) a function shaper circuit the input of which is connected to the control voltage, the output voltage or current of the function shaper circuit being connected to the frequency control input of the voltage or current controlled oscillator to control the frequency of the oscillator as a single-valued nonlinear function of the control voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification