Switching power circuit with secondary side parallel and series resonance
First Claim
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1. A switching power supply circuit comprising:
- switching means including a switching element operable at a switching frequency for intermittently outputting an inputted DC input voltage;
an insulating converter transformer for transmitting the output of the switching means to a secondary side;
a primary side voltage resonant circuit coupled to the switching means to operate the switching means as a voltage resonant type;
a secondary side resonant circuit constituted by a combination of a secondary side parallel resonant circuit formed of a secondary side parallel resonant capacitor connected in parallel with a secondary winding of the insulating converter transformer, and a secondary side series resonant circuit formed of a secondary side series resonant capacitor connected in series with the secondary winding of the insulating converter transformer;
DC output voltage generation means for rectifying an AC voltage obtained from the secondary winding of the insulating converter transformer to produce a secondary side DC output voltage; and
constant voltage control means for changing the switching frequency of the switching element in accordance with the secondary side DC output voltage.
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Abstract
As a secondary side resonant circuit, a secondary side parallel resonant circuit and a secondary side series resonant circuit are combined to a secondary winding of an insulating converter transformer to form a secondary side resonant circuit. By this, the constant voltage control of a secondary side DC output voltage is made the combined control of controlling a switching frequency and a conduction angle of a switching current flowing through a switching element, so that enlargement of a period in which the switching element is turned off is suppressed.
46 Citations
6 Claims
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1. A switching power supply circuit comprising:
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switching means including a switching element operable at a switching frequency for intermittently outputting an inputted DC input voltage;
an insulating converter transformer for transmitting the output of the switching means to a secondary side;
a primary side voltage resonant circuit coupled to the switching means to operate the switching means as a voltage resonant type;
a secondary side resonant circuit constituted by a combination of a secondary side parallel resonant circuit formed of a secondary side parallel resonant capacitor connected in parallel with a secondary winding of the insulating converter transformer, and a secondary side series resonant circuit formed of a secondary side series resonant capacitor connected in series with the secondary winding of the insulating converter transformer;
DC output voltage generation means for rectifying an AC voltage obtained from the secondary winding of the insulating converter transformer to produce a secondary side DC output voltage; and
constant voltage control means for changing the switching frequency of the switching element in accordance with the secondary side DC output voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification