US 6,639,813 B2Granted

Zero-voltage-switching power supply

AssigneeSanken Electric Co., Ltd.

InventorsToshiyuki Yamagishi, Koichi Morita

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Abstract

A power supply including a transformer having a primary winding connected to a pair of a.c. input terminals via a rectifier circuit, and a secondary winding connected to a pair of d.c. output terminals via a rectifying and smoothing circuit. Connected between the pair of outputs of the rectifier circuit via the transformer primary, a primary switch is turned on and off to keep the d.c. output voltage constant. Electromagnetically coupled together, two inductance coils are connected to the rectifier circuit for improvements in power factor and input waveform. An ancillary switch is connected in parallel with the serial connection of the transformer primary and the primary switch in order to provide a discharge circuit for a soft-switching capacitor connected in parallel with the primary switch. Switching loss is reduced by causing the soft-switching capacitor to discharge before the primary switch is turned on.

Claims10

Dependent claims

A switching power supply capable of translating a.c. voltage into d.c. voltage, comprising:

(a) a pair of a.c. input terminals for inputting a.c. voltage having a known frequency;
(b) a pair of d.c. output terminals for outputting d.c. voltage;
(c) a rectifier circuit connected to the pair of input terminals for rectifying the a.c. input voltage, the rectifier circuit having a first output conductor for outputting a first rectifier output voltage, a second output conductor for outputting a second rectifier output voltage which is substantially the same as the first rectifier output voltage, and a third output conductor;
(d) a transformer having a primary winding;
(e) a smoothing capacitor connected between a first extremity of the primary winding of the transformer and the third output conductor of the rectifier circuit;
(f) a primary switch connected between a second extremity of the primary winding and the third output conductor of the rectifier circuit;
(g) a rectifying and smoothing circuit connected between the transformer and the pair of d.c. output terminals for providing the d.c. output voltage;
(h) soft-switching capacitance means connected in parallel with the primary switch;
(i) a first ancillary winding electromagnetically coupled to the primary winding and having a first extremity connected to the first extremity of the primary winding and a first extremity of the smoothing capacitor;
(j) a second ancillary winding electromagnetically coupled to the primary winding and to the first ancillary winding and having a first extremity connected to a second extremity of the first ancillary winding;
(k) an ancillary switch connected in parallel with a serial connection of the primary winding and the primary switch via the first and the second ancillary winding;
(l) a first inductance coil connected between the second output conductor of the rectifier circuit and a second extremity of the first ancillary winding;
(m) a second inductance coil connected between the first output conductor of the rectifier circuit and the smoothing capacitor and electromagnetically coupled to the first inductance coil;
and
(n) a switch control circuit connected to the primary switch and the ancillary switch for on-off control thereof at a repetition frequency higher than the frequency of the a.c. input voltage, the switch control circuit including means for turning the ancillary switch on earlier than the primary switch is turned on and for turning the ancillary switch off not later than the primary switch is turned off;
(o) whereby the soft-switching of the primary switch is accomplished when the primary switch is turned on.

13 more elements

A switching power supply capable of translating a.c. voltage into d.c. voltage, comprising:

(a) a pair of a.c. input terminals for inputting a.c. voltage having a known frequency;
(b) a pair of d.c. output terminals for outputting d.c. voltage;
(c) a rectifier circuit connected to the pair of input terminals for rectifying the a.c. input voltage, the rectifier circuit having a first and a second output conductor;
(d) a transformer having a primary winding;
(e) a smoothing capacitor connected between a first extremity of a primary winding of the transformer and the second output conductor of the rectifier circuit;
(f) a primary switch connected between a second extremity of the primary winding and the second output conductor of the rectifier circuit;
(g) a rectifying and smoothing circuit connected between the transformer and the pair of d.c. output terminals for providing the d.c. output voltage;
(h) soft-switching capacitance means connected in parallel with the primary switch;
(i) a first ancillary winding electromagnetically coupled to the primary winding and having a first extremity connected to the first extremity of the primary winding and the smoothing capacitor;
(j) a second ancillary winding electromagnetically coupled to the primary winding and to the first ancillary winding and having a first extremity connected to a second extremity of the first ancillary winding;
(k) an ancillary switch connected in parallel with a serial connection of the primary winding and the primary switch via the first and the second ancillary winding;
(l) a first inductance coil having a first extremity connected to the first output conductor of the rectifier circuit;
(m) a second inductance coil connected between a second extremity of the first inductance coil and the smoothing capacitor and electromagnetically coupled to the first inductance coil;
(n) a first reverse-blocking diode connected between the second extremity of the first inductance coil and a junction between the first and the second ancillary winding;
(o) a second reverse-blocking diode connected in series with the second inductance coil in a position between the second extremity of the first inductance coil and the smoothing capacitor;
and
(p) a switch control circuit connected to the primary switch and the ancillary switch for on-off control thereof at a repetition frequency higher than the frequency of the a.c. input voltage, the switch control circuit including means for turning the ancillary switch on earlier than the primary switch is turned on and for turning the ancillary switch off not later than the primary switch is turned off;
(q) whereby the soft-switching of the primary switch is accomplished when the primary switch is turned on.

15 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/183,258Filed 26 Jun 2002
Priority: JP 2001-19971929 Jun 2001
Published: US 2003/0002301 A12 Jan 2003
Granted: 28 Oct 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02M 1/4258
Arrangements for improving power factor of AC input: using a single converter stage both for correction of AC input power factor and generation of…
H02M 3/33576
Having several active switching elements: having at least one active switching element at the secondary side of an isolation transformer
Y02B 70/10
Technologies for an efficient end-user side electric power management and consumption: technologies improving the efficiency by using…
H02M
Apparatus for conversion between ac and ac, between ac and dc, or