HALF-BRIDGE LLC RESONANT CONVERTER WITH SELF-DRIVEN SYNCHRONOUS RECTIFIERS

• US 20090244933A1
• Filed: 12/30/2008
• Published: 10/01/2009
• Est. Priority Date: 04/01/2008
• Status: Active Grant

• Current Assignee: Chih-Liang Wang, GlacialTech, Inc.
• Original Assignee: Chih-Liang Wang, GlacialTech, Inc.
• Inventors: Yu, Ching-Sheng, WANG, Chih-Liang
• Granted Patent: US 7,796,408 B2
• Time in Patent Office: Days
• US Class Current: 363/21.60
• CPC Class Codes: H02M 1/0058 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 Class Codes: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• 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
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

The present invention discloses a half-bridge LLC resonant converter with self-driven synchronous rectifiers, which utilizes a primary IC controller and a gate driver to drive the secondary synchronous rectifiers. In correspondence with the gate drive output voltages of the primary IC controller to the primary switch transistors, the gate driver for the secondary synchronous rectifiers comprises a differential transformer if the primary IC controller outputs two ground-referenced gate drive voltages, which cannot directly drive the primary switch transistors but can be imposed on the differential transformer; or comprises a DC shifter, a DC restorer and a differential transformer if the primary IC controller outputs two gate-source voltages, which can directly drive the primary switch transistors but cannot be imposed on the differential transformer. The drive voltages of the primary switch transistors are unipolar; however the drive voltage of the secondary synchronous rectifiers can be bipolar or unipolar. Under the valid operation mode, this converter can decrease the rectifier conduction losses to increase the power converter efficiency.

Claims

1. A half-bridge LLC resonant converter with self-driven synchronous rectifiers, comprising:

a first switch transistor and a second switch transistor connected between an external voltage source and a primary ground terminal in a half-bridge configuration, wherein the connection point of said first switch transistor and said second switch transistor is called a first node;

an LLC resonant tank connected between said first node and said primary ground terminal, wherein said LLC resonant tank comprises a resonant capacitor, a resonant inductor, and a magnetizing inductor, and said magnetizing inductor provided by a primary winding of a power transformer;

a power loop connecting between a first secondary winding and a second secondary winding of said power transformer, wherein said power loop comprises a first synchronous rectifier transistor, a second synchronous rectifier transistor and a filter capacitor, said first synchronous rectifier transistor and said second synchronous rectifier transistor are connected in a center-tapped common-source rectifier configuration between said first and said second secondary windings of said power transformer and a secondary ground terminal, the other two terminals of said first secondary winding and said second secondary winding are connected to a voltage output terminal, and said capacitor is connected between said voltage output terminal and said secondary ground terminal;

a primary IC controller; and

a gate driver connected between said primary IC controller and gates of said first synchronous rectifier transistor and said second synchronous rectifier transistor.

2. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 1, wherein said gate driver comprises a differential transformer, a DC shifter and a DC restorer, said differential transformer comprises a primary winding and two secondary windings, said DC shifter is connected to said primary IC controller, said DC restorer is connected to primary winding of said differential transformer, said two secondary windings are constructed in a center-tapped configuration at said secondary ground terminal and connected to gates of said first synchronous rectifier and said second synchronous rectifier, respectively.

3. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 2, further comprising two combination circuits respectively connected between secondary windings of said differential transformer and gates of said first synchronous rectifier transistor and said second synchronous rectifier transistor, and each of said two combination circuits comprises a half-wave rectifier and a fast turn-off circuit.

4. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 3, wherein said half-wave rectifier comprises a diode and a resistor and said fast turn-off circuit comprises a diode and a PNP bipolar transistor.

5. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 2, wherein said DC shifter comprises a capacitor and a pulse transformer and said DC restorer comprises a capacitor and a diode.

6. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 1, wherein said gate driver comprises a differential transformer, a DC shifter, a DC restorer and a signal distributor, said differential transformer comprises a primary winding and a secondary winding, said DC shifter is connected to said primary IC controller, said DC restorer is connected to primary winding of said differential transformer, two terminals of said secondary winding of said differential transformer are respectively connected to gates of said first synchronous rectifier and said second synchronous rectifier, said signal distributor is constructed in a common-anode configuration at the secondary ground terminal and connected between two terminals of said secondary winding of said differential transformer.

7. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 6, wherein said DC shifter comprises a capacitor and a pulse transformer and said DC restorer comprises a capacitor and a diode.

8. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 1, further comprising a driving module for converting the output voltages of said primary IC controller into the drive voltages of said first switch transistor and said second switch transistor.

9. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 8, wherein said gate driver comprises a differential transformer, said differential transformer comprises a primary winding and two secondary windings, said primary winding is connected to the primary IC controller, said two secondary windings are constructed in center-tapped configuration at said secondary ground terminal and connected to gates of said first synchronous rectifier and said second synchronous rectifier, respectively.

10. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 9, further comprising two combination circuits respectively connected between secondary windings of said differential transformer and gates of said first synchronous rectifier transistor and said second synchronous rectifier transistor, and each of said two combination circuits comprises a half-wave rectifier and a fast turn-off circuit.

11. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 10, wherein said half-wave rectifier comprises a diode and a resistor and said fast turn-off circuit comprises a diode and a PNP bipolar transistor.

12. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 8, wherein said gate driver comprises a differential transformer and a signal distributor, said differential transformer comprises a primary winding and a secondary winding, said primary winding of said differential transformer is connected to said primary IC controller, two terminals of said secondary winding of said differential transformer are respectively connected to gates of said first synchronous rectifier and said second synchronous rectifier, and said signal distributor is constructed in a common-anode configuration at the secondary ground terminal and connected between two terminals of said secondary winding of said differential transformer.

13. The half-bridge LLC resonant converter with self-driven synchronous rectifiers according to claim 8, wherein said driving module is IC-based or transformer-based.