Supply device, and LED lighting equipment using the same

• US 8,654,551 B2
• Filed: 08/22/2011
• Issued: 02/18/2014
• Est. Priority Date: 12/10/2010
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sase, Takashi, Kanouda, Akihiko, Tsuyuki, Yosuke
• Primary Examiner(s): Zhang, Jue
• Assistant Examiner(s): LEE III, HENRY E
• Application Number:
  US13/214,540
• Publication Number:
  US 20120147494A1
• Time in Patent Office: 911 Days
• Field of Search: 363 59- 62, 363/65, 363/67, 363 69- 70, 363 74- 85, 363 87- 93
• US Class Current: 363/70
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A power supply device includes two buck converters, having a coupling inductor Lo composed of two mutually-coupled inductors L1, L2, and a output capacitor Co, wherein of the two buck converters, a first buck converter is operated during a positive half-cycle period of an AC input voltage, and a second buck converter is operated during a negative half-cycle period of the AC input voltage, to obtain a DC output voltage at both ends of the output capacitor Co from the AC input voltage, is provided. Herewith, is provided the power-supply device using the buck converter, which can be reduced in the number of components and produced in a low cost without a diode bridge.

Claims

1. A power-supply device comprising:

an AC-DC converter including a first buck converter and a second buck converter, the first and second buck converters sharing a coupling inductor, the coupling inductor including a first inductor and a second inductor that are electromagnetically-coupled with each other;

wherein the first buck converter includes;

the first inductor of the coupling inductor,

a first power semiconductor switching element configured to intermittently switch on and off a current flowing into the first inductor,

a first diode configured to circulate a current which flows out of the first inductor, when the first power semiconductor switching element is kept off,

an output capacitor,

a second diode configured to limit a reflex path of a current, when the first power semiconductor switching element is kept on, and

a second body diode connected in parallel with a second power semiconductor switching element,

wherein the second buck converter includes;

the second inductor of the coupling inductor,

a second power semiconductor switching element configured to intermittently switch on and off a current flowing into the second inductor,

the second diode configured to circulate a current which flows out of the second inductor, when the second power semiconductor switching element is kept off,

the output capacitor,

the first diode configured to limit a reflex path of a current, when the second power semiconductor switching element is kept on, and

a first body diode connected in parallel with the first power semiconductor switching element; and

wherein one end of the first inductor and one end of the second inductor are electrically connected with each other through a common junction point with which one end of the output capacitor electrically connected, and each of a current flowing through the first inductor and a current flowing through the second inductor flows through the common junction point to the output capacitor.

2. The power-supply device according to claim 1, wherein a coupling coefficient of the coupling inductor of the first inductor and the second inductor is more than or equal to 0.9.

3. The power-supply device according to claim 1, wherein the first buck converter is operated during the positive half-cycle period of an AC input voltage, and the second buck converter is operated during the negative half-cycle period of the AC input voltage.

4. The power-supply device according to claim 3, wherein a PWM pulse controls a switching operation of the first power semiconductor switching element of the first buck converter during the positive half-cycle period of the AC input voltage, and controls the switching operation of the second power semiconductor switching element of the second buck converter during the negative half-cycle period of the AC input voltage are controlled.

5. The power-supply device according to claim 3, wherein the PWM pulse controls, at any time, the switching operation of the first power semiconductor switching element and the second power semiconductor switching element, regardless of the positive or the negative half-cycle period of the AC input voltage.

6. The power-supply device according to claim 3, wherein while a value of the AC input voltage is more than or equal to a value of the DC output voltage, the PWM pulse controls an operation of the second power semiconductor switching element of the first buck converter, and controls an operation of the first power semiconductor switching element of the second buck converter.

7. The power-supply device according to claim 1, wherein the second power semiconductor switching element and the first power semiconductor switching element are connected in series.

8. The power-supply device according to claim 1, wherein a power semiconductor switching element having a reverse blocking function is used for the first and the second power semiconductor switching element, and the first and the second power semiconductor switching element are connected in parallel.

9. The power-supply device according to claim 1, further comprising:

a current transformer disposed between the coupling inductor and the output capacitor, or a sense resistance in a current path of a low electric voltage side of the output capacitor.

10. The power-supply device according to claim 4, further comprising:

a third power semiconductor switching element; and

a fourth power semiconductor switching element;

wherein the third power semiconductor switching element is connected in parallel to the first diode, the fourth power semiconductor switching element is connected in parallel to the second diode; and

wherein the fourth power semiconductor switching element is controlled by a reversed pulse of the PWM pulse during the positive half-cycle period of the AC input voltage; and

wherein the third power semiconductor switching element, is controlled by a reversed pulse of the PWM pulse during the negative half-cycle period of the AC input voltage.

11. The power-supply device according to claim 10,

wherein switching operations of the first power semiconductor switching element and the second power semiconductor switching element are controlled by the PWM pulse at any time, regardless of the positive or the negative half-cycle period of the AC input voltage;

wherein the fourth power semiconductor switching element is controlled by a reversed pulse of the PWM pulse during the positive half-cycle period of the AC input voltage; and

wherein the third power semiconductor switching element, is controlled by the reversed pulse of the PWM pulse during the negative half-cycle period of the AC input voltage.

12. The power-supply device according to claim 1,

wherein first and second buck converters are arranged in parallel;

wherein each of the first and second buck converters is controlled by PWM pulses; and

wherein phases of the PWM pulses that control one of the first and second buck converters are shifted 180 degrees to phases of the PWM pulses that control the other of the first and second buck converters, for an interleaved operation of the first and second buck converters.

13. The power-supply device according to claim 12,

wherein the first and second buck converters share the output capacitor.

14. A power-supply device comprising:

an AC-DC converter including a first buck converter and a second buck converter, the first and second buck converters sharing an output capacitor and two circuits, each circuit including one of two inductors;

wherein the first buck converter includes;

a first inductor of the two inductors,

a first power semiconductor switching element configured to intermittently switch on and off a current flowing into the first inductor,

a first diode configured to circulate a current which flows out of the first inductor, when the first power semiconductor switching element is kept off,

the output capacitor,

a third power semiconductor switching element configured to switch on and off between the first inductor and the output capacitor,

a second diode configured to limit a reflex path of a current, when the first power semiconductor switching element is kept on, and

a second body diode connected in parallel with a second power semiconductor switching element;

wherein the second buck converter includes;

a second inductor of the two inductors,

the second power semiconductor switching element configured to intermittently switch on and off a current flowing into the second inductor,

the second diode confiqured to circulate a current which flows out of the second inductor, when the second power semiconductor switching element is kept off,

the output capacitor,

a fourth power semiconductor switching element configured to switch on and off between the second inductor and the output capacitor,

the first diode configured to limit a reflex path of a current, when the second power semiconductor switching element is kept on, and

a first body diode connected in parallel with the first power semiconductor switching element; and

wherein the fourth power semiconductor switching element is kept off during the positive half-cycle period of the AC input voltage, and the third power semiconductor switching element is kept off during the negative half-cycle period of the AC input voltage.

15. The power-supply device according to claim 14,

wherein the first buck converter is operated during the positive half-cycle period of an AC input voltage;

wherein the second buck converter is operated during the negative half-cycle period of the AC input voltage;

wherein by a PWM pulse controls switching operations of the first power semiconductor switching element and the second power semiconductor switching element;

wherein an operation of the third power semiconductor switching element is controlled by a PWM pulse during the positive half-cycle period of the AC input voltage, and is off-state during the negative half-cycle period of the AC input voltage; and

wherein an operation of the fourth power semiconductor switching element is off-state during the positive half-cycle period of the AC input voltage, and is controlled by the PWM pulse during the negative half-cycle period of the AC input voltage.

17. The power-supply device of claim 14,

wherein the first inductor is connected in series with the third power semiconductor switching element, and the second inductor is connected in series with the fourth power semiconductor switching element.

16. An LED lighting equipment comprising:

a plurality of LED connected in series; and

a power-supply device supplying constant current to the plurality of LED connected in series;

wherein the power-supply device includes an AC-DC converter including a first buck converter and a second buck converter, the first and second buck converters sharing an output capacitor and a coupling inductor, the coupling inductor including a first inductor and a second inductor that are electromagnetically-coupled with each other;

wherein the first buck converter includes;

the first inductor of the coupling inductor,

a first power semiconductor switching element configured to intermittently switch on and off a current flowing into the first inductor,

a first diode configured to circulate a current which flows out of the first inductor, when the first power semiconductor switching element is kept off,

the output capacitor,

a second diode configured to limit a reflex path of a current, when the first power semiconductor switching element is kept on, and

a second body diode connected in parallel with a second power semiconductor switching element;

wherein the second buck converter includes;

a second inductor of the coupling inductor,

the second power semiconductor switching element configured to intermittently switch on and off a current flowing into the second inductor,

the second diode configured to circulate a current which flows out of the second inductor, when the second power semiconductor switching element is kept off,

the output capacitor,

the first diode configured to limit a reflex path of a current, when the second power semiconductor switching element is kept on, and

a first body diode connected in parallel with the first power semiconductor switching element;

wherein one end of the first inductor and one end of the second inductor are electrically connected with each other through a common junction point with which one end of the output capacitor electrically connected, and each of a current flowing through the first inductor and a current flowing through the second inductor flows through the common junction point to the output capacitor.