Hybrid DC-DC converter with LLC converter and full-bridge converter

Patent metadata

Field	Value
Publication number	US-9490709-B2
Application number	US-201414585925-A
Country	US
Kind code	B2
Filing date	Dec 30, 2014
Priority date	Dec 30, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

Disclosed is a hybrid dc-dc converter. The hybrid dc-dc converter includes: a pair of transformers configured to magnetically couple a primary side to a secondary side, a full-bridge converter including four switches constituting a full-bridge inverter circuit and a first transformer, and an LLC resonant converter including a resonant inductor, a resonant capacitor, and a second transformer, which constitute an LLC resonant circuit, wherein an output of the full-bridge converter and an output of the LLC resonant converter are connected to each other in series at the secondary side.

First claim

What is claimed is:

1. A hybrid dc-dc converter comprising:
a pair of transformers configured to magnetically couple a primary side to a secondary side;
a full-bridge converter including four switches, a first diode and a second diode connected to a third leg in series, a third diode and a fourth diode connected to a fourth leg in series, and a first transformer, wherein the four switches include two pairs of switches, the two pairs being connected to a first leg and a second leg in series, respectively, the first leg and the second leg are located at the primary side, and the third leg and the fourth leg are located at the secondary side; and
a half-bridge converter including two switches connected to the second leg in series among the four switches, a resonant inductor, a resonant capacitor, a fifth diode and a sixth diode connected to the fourth leg in series, two filter capacitors, and a second transformer,
wherein a secondary side of the first transformer and a secondary side of the second transformer are connected to each other in series; and
the third diode, the fourth diode, the fifth diode, and the sixth diode are connected to each other in series in a same direction.

2. The hybrid dc-dc converter of claim 1 , wherein a first filter capacitor among the two filter capacitors has one side connected to the second transformer and the other side connected to the fifth diode.

3. The hybrid dc-dc converter of claim 2 , wherein the fifth diode voltage is clamped by a sum of the first filter capacitor voltage and a second filter capacitor voltage.

4. The hybrid dc-dc converter of claim 2 , wherein the first filter capacitor has one side connected to the second transformer and the other side connected to a contact point where the fourth diode and the fifth diode meet each other,
a second filter capacitor has one side connected to a contact point where the secondary side of the first transformer and the secondary side of the second transformer meet each other and has the other side connected to a contact point where the third diode and the sixth diode meet each other.

5. The hybrid dc-dc converter of claim 1 , wherein the two filter capacitors are connected to each other in series, having one side connected to the third diode, and the other side connected to the fourth diode, and a contact point between the two filter capacitors is connected to the first transformer.

6. The hybrid dc-dc converter of claim 4 , wherein the second diode voltage is clamped by a sum of the first filter capacitor voltage and the second filter capacitor voltage.

7. The hybrid dc-dc converter of claim 1 , wherein an output of the secondary side is controlled by a substantial constant current or a substantial constant voltage.

8. The hybrid dc-dc converter of claim 1 , wherein the half-bridge converter operates as an LLC resonant converter together with a magnetizing inductor of the second transformer, the resonant inductor, and the resonant capacitor.

9. The hybrid dc-dc converter of claim 1 , wherein, the full-bridge converter is regulated by frequency modulation with a fixed duty-ratio, phase-shift modulation with a stationary frequency, or hybrid phase-shift and frequency modulation.

10. The hybrid dc-dc converter of claim 1 , wherein a switching frequency for the four switches is same as a resonant frequency between the resonant inductor and the resonant capacitor.

11. The hybrid dc-dc converter of claim 1 , wherein a ratio of a turns-ratio of the second transformer to a turns-ratio of the first transformer is higher than 0.5.

12. The hybrid dc-dc converter of claim 11 , wherein the turns-ratio of the second transformer is substantially same as 0.5.

13. The hybrid dc-dc converter of claim 11 , wherein the hybrid dc-dc converter is applied to a battery charger.

14. A hybrid dc-dc converter comprising:
a pair of transformers configured to magnetically couple a primary side to a secondary side;
a full-bridge converter including four switches constituting a full-bridge inverter circuit, and a first transformer; and
an LLC resonant converter including a resonant inductor, a resonant capacitor, and a second transformer, which constitute an LLC resonant circuit,
wherein an output of the full-bridge converter and an output of the LLC resonant converter are connected to each other in series at the secondary side;
wherein two legs are located at the secondary side,
a first diode and a second diode are connected to a first leg among the two legs in series,
third to sixth diodes are successively connected to a second leg among the two legs in series, and
a secondary side of the second transformer has one side connected to a secondary side of the first transformer and has the other side connected to a contact point between the fourth diode and the fifth diode.

15. The hybrid dc-dc converter of claim 14 , wherein a secondary side of the first transformer and a secondary side of the second transformer are connected to each other in series.

16. The hybrid dc-dc converter of claim 14 , wherein the full-bridge converter further includes four diodes, constituting a full-bridge rectifying circuit, at the secondary side.

17. The hybrid dc-dc converter of claim 16 , wherein two diodes among the four diodes located at the secondary side of the full-bridge converter and two output diodes located at a secondary side of the LLC resonant converter are connected to each other in series.

Assignees

• Korea Energy Research Inst

Inventors

• Lee Iloun
• Chae Suyong
• Song Yujin
• Oh Seashung
• Park Sukin
• Sung Yoondong

Classifications

• H02M3/33507 Primary

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• H02M3/3378 Primary

  in a push-pull configuration of the parallel type (H02M3/3374 takes precedence) · CPC title

• H02M1/0095

  Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck · CPC title

• H02M1/0077

  Plural converter units whose outputs are connected in series · CPC title

• H02M1/0058

  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 title