Switching power supply device

• US 7,315,460 B2
• Filed: 05/04/2006
• Issued: 01/01/2008
• Est. Priority Date: 06/23/2005
• Status: Expired due to Fees

• Current Assignee: Sanken Electric Company Limited
• Original Assignee: Sanken Electric Company Limited
• Inventors: Kyono, Yoichi
• Primary Examiner(s): Riley; Shawn
• Application Number:
  US11/417,153
• Publication Number:
  US 20060291117A1
• Time in Patent Office: 607 Days
• Field of Search: 363/15, 363/16, 363/131, 363/140
• US Class Current: 363/16
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/38 Means for preventing simultaneous conduction of switches
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A series circuit in which a first switching element and a second switching element are connected in series at both ends of an output of an input rectifier circuit for rectifying an alternating current of an alternating current power supply, a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of the first switching element or the second switching element, a rectifying and smoothing circuit for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of the first switching element or the second switching element, a control circuit for alternately turning on/off the first switching element and the second switching based on a voltage from the rectifying and smoothing circuit, and a voltage detecting circuit for outputting a voltage detecting signal when a voltage at both ends of one switching element of the first switching element and the second switching element, which is turned on at a time of transmitting electric power to the rectifying and smoothing circuit, becomes equal to a predetermined voltage or more. The control circuit turns on the other switching element of the first switching element and the second switching element based on the voltage detecting signal from the voltage detecting circuit.

Claims

1. A switching power supply device, comprising:

a series circuit in which a first switching element and a second switching element are connected in series at both ends of an output of an input rectifier circuit for rectifying an alternating voltage of an alternating current power supply or at both ends of a direct current power supply;

a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of any one of the first switching element and the second switching element;

at least one pair of rectifying and smoothing circuits for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of any one of the first switching element and the second switching element;

a control circuit for alternately turning on/off the first switching element and the second switching element based on a voltage from the at least one pair of the rectifying and smoothing circuits; and

a voltage detecting circuit for outputting a voltage detecting signal when a voltage at both ends of one switching element of the first switching element and the second switching element, which is turned on at a time of transmitting electric power to the at least one pair of the rectifying and smoothing circuits, becomes equal to a predetermined voltage or more,

wherein the control circuit turns on the other switching element of the first switching element and the second switching element based on the voltage detecting signal from the voltage detecting circuit.

2. The switching power supply device according to claim 1, wherein the voltage detecting circuit outputs a voltage detecting signal by detecting a change of the voltage at both ends of the one switching element.

3. The switching power supply device according to claim 1, wherein the control circuit turns on the other switching element after a predetermined period has passed since the one switching element is turned off in a case where the voltage detecting signal from the voltage detecting circuit is absent when the one switching element, which is turned on at the time of transmitting electric power to the at least one pair of the rectifying and smoothing circuits, is turned off.

4. A switching power supply device, comprising:

a series circuit in which a first switching element and a second switching element are connected in series at both ends of an output of an input rectifier circuit for rectifying an alternating voltage of an alternating current power supply or at both ends of a direct current power supply;

a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of any one of the first switching element and the second switching element;

at least one pair of rectifying and smoothing circuits for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of any one of the first switching element and the second switching element;

a control circuit for alternately turning on/off the first switching element and the second switching element based on a voltage from the at least one pair of the rectifying and smoothing circuits; and

a voltage detecting circuit for outputting a voltage detecting signal when a voltage at both ends of one switching element of the first switching element and the second switching element, which is turned off at a time of transmitting electric power to the at least one pair of the rectifying and smoothing circuits, becomes equal to a predetermined voltage or less,

wherein the control circuit turns on the one switching element based on the voltage detecting signal from the voltage detecting circuit.

5. The switching power supply device according to claim 4, wherein the voltage detecting circuit outputs a voltage detecting signal by detecting a change of the voltage at both ends of the one switching element.

6. The switching power supply device according to claim 4, wherein the control circuit turns on the one switching element after a predetermined period has passed since the other switching element is turned off in a case where the voltage detecting signal from the voltage detecting circuit is absent when the other switching element of the first switching element and the second switching element, which is turned on at the time of transmitting electric power to the at least one pair of the rectifying and smoothing circuits, is turned off.

7. A switching power supply device, comprising:

a series circuit in which a first switching element and a second switching element are connected in series at any one both ends of an output of an input rectifier circuit for rectifying an alternating voltage of an alternating current power supply or at both ends of a direct current power supply;

a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of any one of the first switching element and the second switching element;

at least one pair of rectifying and smoothing circuits for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of any one of the first switching element and the second switching element;

a control circuit for alternately turning on/off the first switching element and the second switching element based on a voltage from the at least one pair of the rectifying and smoothing circuits; and

an output voltage detecting circuit for detecting an output voltage,

wherein the control circuit turns on the other switching element of the first switching element and the second switching element after a predetermined period has passed since the one switching element is turned off in a case where the output voltage from the output voltage detecting circuit is equal to a predetermined voltage or less when the one switching element of the first switching element and the second switching element, which is turned on at a time of transmitting electric power to the at least one pair of the rectifying and smoothing circuits, is turned off, and changes the predetermined period according to the output voltage.

8. The switching power supply device according to claim 7, wherein the output voltage detecting circuit includes an auxiliary winding wound around the transformer, and outputs a voltage generated across the auxiliary winding to the control circuit as the output voltage.