CONTROL ARRANGEMENT FOR A RESONANT MODE POWER CONVERTER
First Claim
1. A method of controlling a switching frequency of a power converter having an output voltage that is dependent upon the switching frequency, comprising the steps of:
- producing a first current that is dependent upon the output voltage;
producing a second current corresponding to a desired maximum value of the first current;
limiting the first current to the desired maximum value in dependence upon the second current; and
producing a control signal for the power converter with a frequency determined by the first current.
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Accused Products
Abstract
The switching frequency of an LLC converter is controlled by a control unit to which a feedback circuit provides a first current dependent upon the output voltage of the converter. An oscillator circuit produces a sawtooth waveform at a frequency dependent upon the first current, up to a limit equal to a second current set by a resistor. Two complementary switch control signals are produced for controlling two switches of the converter for conduction in alternate cycles of the sawtooth waveform. A timer produces dead times between the two complementary switch control signals in dependence upon the second current. Another resistor provides a current constituting a minimum value of the first current, and a charging current of a capacitor in series with a resistor modifies the first current for soft starting of the converter.
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Citations
20 Claims
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1. A method of controlling a switching frequency of a power converter having an output voltage that is dependent upon the switching frequency, comprising the steps of:
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producing a first current that is dependent upon the output voltage; producing a second current corresponding to a desired maximum value of the first current; limiting the first current to the desired maximum value in dependence upon the second current; and producing a control signal for the power converter with a frequency determined by the first current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A control unit for a resonant mode converter having an output voltage that is dependent upon a switching frequency of the converter, comprising:
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a feedback circuit for providing a first current dependent upon the output voltage of the converter; a resistor for producing a second current from a reference voltage; a circuit for limiting the first current to the second current; and an oscillator circuit for producing a control signal for the converter at a frequency dependent upon the first current thereby to control said output voltage. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification