Resonant switching power supply circuit with voltage doubler output

• US 6,687,137 B1
• Filed: 06/03/2002
• Issued: 02/03/2004
• Est. Priority Date: 05/10/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yasumura, Masayuki
• Primary Examiner(s): Han, Jessica
• Application Number:
  US10/030,839
• Time in Patent Office: 610 Days
• Field of Search: 363/18, 363/19, 363/20, 363/21.01, 363/21.02, 363/21.03, 363/21-4-, 363/95, 363/97
• US Class Current: 363/21.01
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/338 in a self-oscillating arrangement H02M3/337 takes precedence
• CPC Class Codes: H02M 3/3381 using a single commutation path
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence
• 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 switching power supply circuit includes an insulating converter transformer where the insulating converter transformer has a gap formed therein so that a coupling which is efficient for a loose coupling is obtained; switching circuit, a primary side parallel resonance circuit formed from a leakage inductance component from the primary winding of the insulating converter transformer and a capacitance of a parallel resonance capacitor and a secondary side series resonance circuit including a secondary side series resonance capacitor and a secondary winding of the insulating converter transformer; a dc output voltage production means for performing a voltage multiplying full-wave rectification operation to produce a secondary side dc output voltage substantially equal to twice the input voltage level; and a constant voltage control means for varying a switching frequency of the switching element in order to perform constant voltage control of the secondary side output voltage.

Claims

1. A switching power supply circuit, comprising:

rectifier smoothing means for receiving a commercial ac power supply, producing a rectified smoothed voltage and outputting said rectified smoothed voltage as a dc voltage;

an insulating converter transformer for transmitting a primary side output to a secondary side, said insulating converter transformer having a gap formed therein so that a coupling which is efficient for a loose coupling is obtained;

switching means including a switching element for switching the dc input voltage between on and off states so as to be outputted to a primary winding of said insulating converter transformer;

a primary side parallel resonance circuit formed from a leakage inductance component from said primary winding of said insulating converter transformer and a capacitance of a parallel resonance capacitor for enabling said switching means to operate as a voltage resonance type;

a secondary side series resonance circuit including a secondary side series resonance capacitor and a secondary winding of said insulating converter transformer, said capacitor connected in series to said secondary winding of said insulating converter transformer, such that a series resonance circuit is formed from a leakage inductance component of said secondary winding of said insulating converter transformer and a capacitance of said secondary side series resonance capacitor;

dc output voltage production means for receiving an alternating voltage obtained at said secondary winding of said insulating converter transformer and performing a voltage multiplying full-wave rectification operation for the alternating voltage to produce a secondary side dc output voltage substantially equal to twice the input voltage level; and

constant voltage control means for varying a switching frequency of said switching element in response to a level of the secondary side dc output voltage to perform constant voltage control of the secondary side output voltage.

2. A switching power supply circuit according to claim 1, wherein said switching means further includes a series resonance circuit formed from at least a series connection of a driving winding and a resonance capacitor.

3. A switching power supply circuit according to claim 2, and further comprising a self-excited oscillation driving circuit for driving said switching element in a self-excited manner based on a resonance output of said series resonance circuit.

4. A switching power supply circuit according to claim 3, wherein said constant voltage control means includes:

an orthogonal control transformer serving as a saturable reactor on which a detection winding and said driving winding connected in series to said primary winding of said insulating converter transformer, and

a control winding whose winding direction is orthogonal to the winding directions of said detection winding and said driving winding are wound, whereby control current which is variable in response to a level of the secondary side dc output voltage is supplied to said control winding to vary the inductance of said driving winding to variably control the switching frequency.

5. A switching power supply circuit according to claim 1, wherein said switching means further includes a separately excited driving circuit for driving said switching element in a separately excited manner, and said constant voltage control means variably controls an on period of said switching element in response to a level of the secondary side dc output voltage while keeping an off period of said switching element fixed thereby to variably control the switching frequency.

6. A switching power supply circuit according to claim 1, wherein said switching means includes a Darlington circuit which includes a bipolar transistor as said switching element.

7. A switching power supply circuit according to claim 1, wherein said switching means includes a MOS field effect transistor as said switching element.

8. A switching power supply circuit according to claim 1, wherein said switching means includes an insulated gate bipolar transistor as said switching element.

9. A switching power supply circuit according to claim 1, wherein said switching means includes an electrostatic induction thyristor as said switching element.