Resonant converters with secondary-side resonance
First Claim
1. A quasi-resonant converter comprising:
- (a) a voltage source;
(b) a transformer having a primary winding and a secondary winding, said transformer exhibiting a characteristic leakage inductance;
(c) switch means operating periodically at a switching frequency Fs for coupling said voltage source to said primary winding, whereby a charging current is delivered to said secondary winding;
(d) a capacitor exhibiting a characteristic capacitance and directly coupled to said secondary winding to form with said characteristic leakage inductance a resonant circuit therewith having a resonant frequency determined by the values of said capacitor and said characteristic leakage inductance so that its resonant frequency is greater than Fs, said capacitor being selectively charged by said charging current from said secondary winding to establish a resonating voltage on said capacitor, said resonating voltage being applied back through said transformer so that said switch means couples said voltage source to said primary winding at zero current conditions across said switch means;
(e) a load; and
(f) means coupled between said capacitor and said load for rectifying and applying said voltage stored on said capacitor to said load.
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Accused Products
Abstract
A family of quasi-resonant converters is disclosed as comprising a voltage source, a transformer having primary and secondary windings, and a switch for periodically coupling the voltage source to the primary winding, whereby a charging current appears on the secondary winding. The transformer exhibits a characteristic leakage inductance. A capacitor exhibiting a characteristic capacitance is coupled to the secondary winding to form a resonant circuit including the leakage inductance and the capacitor. The secondary winding is coupled to apply the charging current to the capacitor. A rectifying circuit couples the capacitor to a load, whereby the voltage stored in the capacitor is delivered to the load. The capacitor is directly connected to the secondary winding and to the rectifying circuit to permit positive and negative going voltages to be stored therein, whereby magnetic flux within the core of the transformer is dissipated and the transformer magnetically reset.
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Citations
14 Claims
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1. A quasi-resonant converter comprising:
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(a) a voltage source; (b) a transformer having a primary winding and a secondary winding, said transformer exhibiting a characteristic leakage inductance; (c) switch means operating periodically at a switching frequency Fs for coupling said voltage source to said primary winding, whereby a charging current is delivered to said secondary winding; (d) a capacitor exhibiting a characteristic capacitance and directly coupled to said secondary winding to form with said characteristic leakage inductance a resonant circuit therewith having a resonant frequency determined by the values of said capacitor and said characteristic leakage inductance so that its resonant frequency is greater than Fs, said capacitor being selectively charged by said charging current from said secondary winding to establish a resonating voltage on said capacitor, said resonating voltage being applied back through said transformer so that said switch means couples said voltage source to said primary winding at zero current conditions across said switch means; (e) a load; and (f) means coupled between said capacitor and said load for rectifying and applying said voltage stored on said capacitor to said load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification