SWITCHING POWER SUPPLY DEVICE, AND ADJUSTABLE POWER SUPPLY SYSTEM INCLUDING THE SAME

• US 20120069616A1
• Filed: 09/14/2011
• Published: 03/22/2012
• Est. Priority Date: 09/17/2010
• Status: Active Grant

• Current Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Lighting & Technology Corporation (Toshiba Corporation)
• Inventors: Kitamura, Noriyuki, Takahashi, Yuji, Takahashi, Koji, Ishikita, Toru, Suzuki, Koji
• Granted Patent: US 8,797,015 B2
• Time in Patent Office: Days
• US Class Current: 363/126
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/385 using flyback topology
• 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

According to one embodiment of the invention, there is provided a switching power supply device including a rectifying circuit and a switching operation conversion circuit. The rectifying circuit receives a phase-controlled alternating voltage to rectify to a direct voltage. The switching operation conversion circuit starts up by being applied with the direct voltage, and includes a normally on type switching element and an off driving circuit. The normally on type switching element passes an input current, and the off driving circuit turns off the switching element when the input current reaches a prescribed value. The switching operation conversion circuit converts the direct voltage to an output voltage different from the direct voltage by repeating a switching operation of turning on and off the switching element.

Claims

1. A switching power supply device comprising:

a rectifying circuit configured to receive a phase-controlled alternating voltage to rectify to a direct voltage; and

a switching operation conversion circuit configured to start up by being applied with the direct voltage, including a normally on type switching element and an off driving circuit, the normally on type switching element passing an input current, the off driving circuit turning off the switching element when the input current reaches a prescribed value, and configured to convert the direct voltage to an output voltage different from the direct voltage by repeating a switching operation of turning on and off the switching element.

2. The switching power supply device according to claim 1, wherein the input current at start up is smaller than the prescribed value.

3. The switching power supply device according to claim 1, wherein the off driving circuit is a constant current element connected in series to the switching element.

4. The switching power supply device according to claim 3, wherein

the switching element is an field-effect transistor having a source, a drain and a gate, and

the off driving circuit turns off the switching element by lowering a voltage between the gate and the source of the switching element than a threshold voltage by a terminal voltage of the constant current element when the input current exceeds the prescribed value.

5. The switching power supply device according to claim 1, wherein

the off driving circuit includes

a normally off type constant current element, and

a capacitor connected to a control terminal of the normally off type constant current element.

6. The switching power supply device according to claim 1, further comprising:

an inductor connected to the switching element and passing the input current.

7. The switching power supply device according to claim 6, further comprising:

a driving winding configured to control turning on or off the switching element by magnetically coupling with the inductor and supplying an induced voltage to a control terminal of the switching element.

8. A switching power supply device comprising:

a pair of normally on type switching elements configured to start up by being applied with a phase-controlled alternating voltage to pass an input current;

a pair of off driving circuits configured to turn off the pair of switching elements when the input current reaches a prescribed value; and

a pair of rectifying elements connected between an output terminal and each of the pair of switching elements, and configured to output a rectified direct voltage to the output terminal.

9. The switching power supply device according to claim 8, where the input current at start up is smaller than the prescribed value.

10. The switching power supply device according to claim 8, wherein the pair of off driving circuits are a pair of constant current elements connected in series to each of the pair of switching elements.

11. The switching power supply device according to claim 8, further comprising:

an inductor connected to the switching element and passing the input current.

12. The switching power supply device according to claim 11, further comprising:

a driving winding configured to control turning on or off the switching element by magnetically coupling with the inductor and supplying an induced voltage to a control terminal of the switching element.

13. An adjustable power supply system comprising:

a phase control circuit configured to phase-control an alternating voltage;

a switching power supply device configured to receive an alternating voltage phase-controlled by the phase control circuit to output an output voltage; and

a load configured to be operated by an output voltage of the switching power supply device,

the switching power supply device including

a rectifying circuit configured to receive the alternating voltage phase-controlled to rectify a direct voltage, and

a switching operation conversion circuit configured to start up by being applied with the direct voltage, including a normally on type switching element and an off driving circuit, the normally on type switching element passing an input current, the off driving circuit turning off the switching element when the input current reaches a prescribed value, and configured to convert the direct voltage to an output voltage different from the direct voltage by repeating a switching operation of turning on and off the switching element.

14. The adjustable power supply system according to claim 13, wherein

the phase control circuit includes a phase control element and

an input current to the switching power supply device is larger than a self-holding current of the phase control element.

15. The adjustable power supply system according to claim 13, wherein the input current at start up is smaller than the prescribed value.

16. The adjustable power supply system according to claim 13, wherein the off driving circuit is a constant current element connected in series to the switching element.

17. The adjustable power supply system according to claim 16, wherein

the switching element is an field-effect transistor having a source, a drain and a gate, and

the off driving circuit turns off the switching element by lowering a voltage between the gate and the source of the switching element than a threshold voltage by a terminal voltage of the constant current element when the input current exceeds the prescribed value.

18. The adjustable power supply system according to claim 13, wherein

the off driving circuit includes

a normally off type constant current element, and

a capacitor connected to a control terminal of the normally off type constant current element.

19. The adjustable power supply system according to claim 13, further comprising:

an inductor connected to the switching element and passing the input current.

20. The adjustable power supply system according to claim 19, further comprising:

a driving winding configured to control turning on or off the switching element by magnetically coupling with the inductor and supplying an induced voltage to a control terminal of the switching element.