Switching power supply circuit

• US 20030198062A1
• Filed: 12/06/2002
• Published: 10/23/2003
• Est. Priority Date: 12/11/2001
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yasumura, Masayuki
• Granted Patent: US 6,731,521 B2
• Time in Patent Office: Days
• US Class Current: 363/16
• CPC Class Codes: H02M 3/3382 in a push-pull circuit arrangement

Abstract

The present invention relates to a circuit which includes a combination of a current resonance type converter of a switching frequency controlling system with a partial voltage resonance circuit is configured such that, in order to improve the power factor where the load power is 150 W or more and the circuit employs an input double voltage rectification system, a series resonance capacitor or inductor is connected in series to a tertiary winding wound on the primary side of an isolation converter transformer so that the voltage is fed back to a rectification circuit composed of a high speed recovery type diode.

Claims

1. A switching power supply circuit comprising:

rectification smoothing means including a rectifier and a smoothing capacitor connected in series for rectifying and smoothing an ac voltage supplied through two lines for an ac power supply;

an isolation converter transformer including a core and a primary winding, a secondary winding and tertiary winding wound on said core for transmitting an output on a primary side obtained by said primary winding to a secondary side wherein said secondary winding is wound, said tertiary winding being provided on said primary side;

switching means including two switching elements coupled in a half-bridge coupling for intermittently outputting an output voltage of said smoothing means to said primary winding of said isolation converter transformer;

switching driving means for driving said switching elements to perform a switching operation;

a current resonance circuit formed from a leakage inductance component of said primary winding of said isolation converter transformer and a capacitance of a series resonance capacitor connected in series to said primary winding for making the operation of said switching means operation of the current resonance type;

a partial voltage resonance circuit formed from a capacitance of a parallel resonance capacitor connected in parallel to one of said switching elements and a leakage inductance component of said primary winding of said isolation converter transformer for performing a voltage resonance operation within a turnoff period of each of said switching elements; and

dc output voltage production means for receiving and rectifying an alternating voltage obtained by said secondary winding of said isolation converter transformer to produce a secondary side dc output voltage,

wherein said tertiary winding is connected between one of said two lines for the ac power supply and said smoothing capacitor.

2. A switching power supply circuit according to claim 1, further comprising a normal mode noise filter connected between said lines for the ac power supply.

3. A switching power supply circuit according to claim 1, further comprising constant voltage controlling means for controlling said switching driving means in response to the level of the secondary side dc output voltage to vary the switching frequency of said switching means to perform constant voltage control for the secondary side dc output voltage.

4. A switching power supply circuit according to claim 1, wherein a gap of a predetermined distance is formed in said core of said isolation converter transformer.

5. A switching power supply circuit according to claim 1, wherein said tertiary winding is connected to said smoothing capacitor through a high speed recovery type diode.

6. A switching power supply circuit comprising:

a rectification smoothing circuit including a voltage rectifier for rectifying ac current and a smoothing capacitor for smoothing the rectified current from said voltage rectifier;

an isolation converter transformer including a core and a primary winding, a secondary winding and tertiary winding wound on said core for transmitting an output on a primary side obtained by said primary winding to a secondary side wherein said secondary winding is wound;

switching means including two switching elements coupled in a half-bridge coupling for intermittently outputting an output voltage of said rectification smoothing circuit to said primary winding of said isolation converter transformer;

switching driving means for driving said switching elements to perform a switching operation;

a primary side series resonance circuit formed from a leakage inductance component of said primary winding of said isolation converter transformer and a capacitance of a primary side series resonance capacitor connected in series to said primary winding for making the operation of said switching means operation of the resonance type;

a partial voltage resonance circuit formed from a capacitance of a primary side partial resonance capacitor connected in parallel to one of said switching elements and a leakage inductance component of said primary winding of said isolation converter transformer for performing a voltage resonance operation within a turnoff period of each of said switching elements;

a power factor improving circuit including a first high speed recovery type diode element connected between said voltage rectifier and said smoothing capacitor, a series connection circuit of said tertiary winding and a second high speed recovery type diode element connected in parallel with said first high speed recovery type diode element; and

dc output voltage production means for receiving and rectifying an alternating voltage obtained by said secondary winding of said isolation converter transformer to produce a secondary side dc output voltage.

7. A switching power supply circuit according to claim 6, further comprising a secondary side partial voltage resonance capacitor connected in parallel to said secondary winding of said isolation converter transformer.

8. A switching power supply circuit according to claim 6, further comprising constant voltage controlling means for controlling said switching driving means in response to the level of the secondary side dc output voltage to vary the switching frequency of said switching means to perform constant voltage control for the secondary side dc output voltage.

9. A switching power supply circuit according to claim 6, wherein a gap of a predetermined distance is formed in said core of said isolation converter transformer.