Circuit for adjusting the output voltage for a resonant DC/DC converter
First Claim
1. A method for controlling a resonant DC/DC converter, which adjusts an output voltage by changing a turn-on frequency of at least one input switch device of a resonant circuit of the converter, comprising:
- adjusting a duty ratio of the at least one input switch device based on a feedback signal from a load circuit wherein the at least one input switch device of the resonant circuit is controlled by a driving pulse through a drive circuit, where acquisition of the driving pulse includes;
acquiring the feedback signal of the load circuit;
determining based on the feedback signal whether the load operates at a light load or non-load state; and
using a pulse signal as the driving pulse of the drive circuit wherein both the frequency and the duty ratio are adjusted in accordance with a change in the feedback signal if the load operates in a range of between the light load and the non-load state so as to have the resonant circuit operate in a combined mode of pulse width modulation (PWM) control and pulse frequency modulation (PFM) control; and
otherwise using a pulse signal as the driving pulse of the drive circuit wherein the duty ratio is stable and the frequency varies in accordance with the change of the feedback signal, so as to have the resonant circuit operate in a PFM control mode.
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Accused Products
Abstract
A method and circuit for controlling a resonant DC/DC converter which adjusts an output voltage by changing a turn-on frequency of input switch devices of a resonant circuit of the converter. The method extends the range of the output voltage of the resonant circuit by adjusting the duty ratio of the switch devices based on the feedback signal of the load circuit. The method and circuit uses two modes to control resonance of the DC/DC converter-frequency modulation and frequency modulation plus pulse width modulation. Frequency modulation is used when the operating frequency of the power supply is low. Frequency modulation plus pulse width modulation is used when the operating frequency of the power supply is too high.
26 Citations
14 Claims
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1. A method for controlling a resonant DC/DC converter, which adjusts an output voltage by changing a turn-on frequency of at least one input switch device of a resonant circuit of the converter, comprising:
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adjusting a duty ratio of the at least one input switch device based on a feedback signal from a load circuit wherein the at least one input switch device of the resonant circuit is controlled by a driving pulse through a drive circuit, where acquisition of the driving pulse includes; acquiring the feedback signal of the load circuit; determining based on the feedback signal whether the load operates at a light load or non-load state; and using a pulse signal as the driving pulse of the drive circuit wherein both the frequency and the duty ratio are adjusted in accordance with a change in the feedback signal if the load operates in a range of between the light load and the non-load state so as to have the resonant circuit operate in a combined mode of pulse width modulation (PWM) control and pulse frequency modulation (PFM) control; and otherwise using a pulse signal as the driving pulse of the drive circuit wherein the duty ratio is stable and the frequency varies in accordance with the change of the feedback signal, so as to have the resonant circuit operate in a PFM control mode. - View Dependent Claims (2, 3, 4)
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5. A resonant DC/DC converter, including a drive circuit and a resonant circuit, the drive circuit controlling at least one input switch device of the resonant circuit in accordance with an input driving pulse, the resonant circuit providing a converted power supply to a load circuit, comprising:
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a negative feedback compensation regulator for performing a negative feedback compensation operation on a feedback voltage sampled from the load circuit to obtain a feedback signal; a discriminator for determining a load state of the load circuit based on the input feedback signal and outputting a driving pulse modulation signal; and a driving pulse generator for modulating and outputting a driving pulse in accordance with the driving pulse modulation signal, wherein if the load operates in a range of between the light load and the non-load state, the frequency and duty ratio of the driving pulse is adjusted in accordance with the feedback signal, otherwise, the duty ratio remains stable and the frequency of the driving pulse varies in accordance with the feedback signal, wherein the driving pulse generator includes a pulse frequency control circuit and a pulse frequency control plus pulse width modulation (PFC+PWM) circuit; wherein if the discriminator determines that the load operates in the range of between the light load and the non-load state, the PFC+PWM circuit is provided with the driving pulse modulation signal and controlled to output the driving pulse, where both the frequency and the duty ratio vary in accordance with the feedback signal; otherwise, the pulse frequency control circuit is provided with the driving pulse modulation signal and controlled to output the driving pulse, where the duty ratio is stable and the frequency varies in accordance with the feedback signal. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification