Adjustable Resonant Apparatus for Power Converters

• US 20150124487A1
• Filed: 11/04/2013
• Published: 05/07/2015
• Est. Priority Date: 11/04/2013
• Status: Active Grant

• Current Assignee: Huawei Digital Power Technologies Company Limited (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Fu, Dianbo, Dai, Heping, Ye, Liming, Chen, Daoshen
• Granted Patent: US 9,484,821 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• 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 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/015 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit
• 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 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 7/4818 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
• 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

An apparatus comprises a first series resonant inductor coupled to a switching network and a transformer, a first series resonant capacitor coupled to the switching network and the transformer, a first parallel inductor coupled to the switching network through the first series resonant inductor and the first series resonant capacitor, a resonant frequency adjusting device coupled to the switching network and the transformer and a switch connected in series with the resonant frequency adjusting device.

Claims

1. An apparatus comprising:

a first series resonant inductor coupled to a switching network and a transformer;

a first series resonant capacitor coupled to the switching network and the transformer;

a first parallel inductor coupled to the switching network through the first series resonant inductor and the first series resonant capacitor;

a resonant frequency adjusting device coupled to the switching network and the transformer; and

a switch connected in series with the resonant frequency adjusting device.

2. The apparatus of claim 1, wherein:

the resonant frequency adjusting device is a capacitor.

3. The apparatus of claim 2, wherein:

the switch and the capacitor form a second series resonant capacitor; and

the second series resonant capacitor and the first series resonant capacitor are connected in parallel.

4. The apparatus of claim 1, wherein:

the resonant frequency adjusting device is an inductor.

5. The apparatus of claim 4, wherein:

the switch and the inductor form a second series resonant inductor; and

the second series resonant inductor and the first series resonant inductor are connected in parallel.

6. The apparatus of claim 1, wherein:

the switch is formed by two back-to-back connected switching elements.

7. The apparatus of claim 1, wherein:

the first parallel inductor is implemented as a magnetizing inductance of the transformer.

8. The apparatus of claim 1, wherein:

the first parallel inductor is implemented as a separate inductor coupled between a primary side winding of the transformer.

9. The apparatus of claim 8, wherein the switch is controlled such that:

the switch is turned on when a load current flowing through the switching network is less than a predetermined threshold; and

the switch is turned off when the load current flowing through the switching network is greater than the predetermined threshold.

10. A system comprising:

an input power source;

a switching network comprising;

a first pair of switches coupled between the input power source; and

a second pair of switches coupled between the input power source;

a resonant tank connected between the switching network and a primary side of a transformer, wherein the resonant tank comprises;

a first series resonant inductor coupled to the switching network and the transformer;

a first series resonant capacitor coupled to the switching network and the transformer;

a first parallel inductor coupled to the switching network through the first series resonant inductor and the first series resonant capacitor;

a resonant frequency adjusting device coupled to the switching network and the transformer; and

a switch connected in series with the resonant frequency adjusting device;

a rectifier coupled to a secondary side of the transformer; and

an output filter coupled to the rectifier.

11. The system of claim 10, wherein:

the switching network, the resonant tank, the transformer, the rectifier and the output filter form an LLC resonant converter.

12. The system of claim 11, wherein the switch is configured such that:

the LLC resonant converter is of a first resonant frequency when the switch is turned on; and

the LLC resonant converter is of a second resonant frequency when the switch is turned off.

13. The system of claim 10, wherein:

the switch is formed by two back-to-back connected metal oxide semiconductor transistors.

14. The system of claim 10, wherein:

the transformer is a center-tapped transformer; and

the rectifier is a synchronous rectifier.

15. The system of claim 10, wherein:

the transformer is a non center-tapped transformer; and

the rectifier is a full-wave rectifier.

16. A method comprising:

providing a resonant tank coupled between a switching network and a transformer, wherein the resonant tank comprises;

a first series resonant inductor coupled to a switching network and the transformer;

a first series resonant capacitor coupled to the switching network and the transformer;

a first parallel inductor coupled to the switching network through the first series resonant inductor and the first series resonant capacitor;

a resonant frequency adjusting device coupled to the switching network and the transformer; and

a switch connected in series with the resonant frequency adjusting device;

in response to a load increase, turning off the switch and configuring the switching network to operate at a first switching frequency approximately equal to a first resonant frequency; and

in response to a load drop, turning on the switch and configuring the switching network to operate at a second switching frequency approximately equal to a second resonant frequency.

17. The method of claim 16, further comprising:

detecting a load current flowing through the switching network;

comparing the load current with a predetermined load threshold;

turning on the switch when the load current is less than the predetermined load threshold; and

turning off the switch when the load current is greater than the predetermined load threshold.

18. The method of claim 17, wherein:

the predetermined load threshold is about 50% of a full load of the switching network.

19. The method of claim 16, wherein:

the resonant frequency adjusting device is a capacitor, wherein the capacitor and the first series resonant capacitor are connected in parallel through the switch.

20. The method of claim 16, further comprising:

coupling the switching network to a dc input power source;

coupling a primary side of a converter and a secondary side of the converter through the transformer providing isolation between the primary side and the secondary side of the converter;

coupling a rectifier to the secondary side; and

coupling an output filter to the rectifier.