Apparatus and efficiency point tracking method for high efficiency resonant converters

Patent metadata

Field	Value
Publication number	US-10116219-B2
Application number	US-201615263121-A
Country	US
Kind code	B2
Filing date	Sep 12, 2016
Priority date	Oct 17, 2013
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A method comprises connecting a first resonant converter and a second resonant converter in parallel, detecting a first signal indicating a first soft switching process of the first resonant converter and a second signal indicating a second soft switching process of the second resonant converter and adjusting a first switching frequency of the first resonant converter by a first control circuit and a second switching frequency of the second resonant converter by a second control circuit until a load current flowing through the first resonant converter is substantially equal to a load current flowing through the second resonant converter.

First claim

What is claimed is:

1. A system comprising:
a first converter comprising:
a first input stage coupled to a power source, wherein the first input stage comprises a plurality of power switches;
a first resonant tank coupled to the plurality of power switches;
a first transformer coupled to the first resonant tank;
a first output stage coupled to the first transformer;
a first detector configured to receive a first efficiency point tracking indicator obtained from the first converter; and
a first control circuit configured to receive a first efficiency point tracking signal from the first detector and adjust a first switching frequency of the first converter based upon the first efficiency point tracking signal; and

a second converter having an second input stage connected in parallel with the first input stage of the first converter, wherein the second converter comprises:
a second resonant tank coupled between a second input stage and a second transformer;
a second detector configured to receive a second efficiency point tracking indicator obtained from the second converter; and
a second control circuit configured to receive a second efficiency point tracking signal from the second detector and adjust a second switching frequency of the second converter based upon the second efficiency point tracking signal, wherein the second switching frequency is different from the first switching frequency.

2. The system of claim 1 , wherein:
the first efficiency point tracking indicator is a voltage across a first resonant inductor of the first resonant tank; and
the second efficiency point tracking indicator is a voltage across a second resonant inductor of the second resonant tank.

3. The system of claim 1 , wherein:
the first efficiency point tracking indicator is a voltage across a first resonant inductor of the first resonant tank; and
the second efficiency point tracking indicator is a current flowing through a common mode capacitor coupled to the second transformer.

4. The system of claim 1 , wherein:
the first efficiency point tracking indicator is a current flowing through a common mode capacitor coupled to the first transformer; and
the second efficiency point tracking indicator is a voltage across a second resonant inductor of the second resonant tank.

5. The system of claim 1 , wherein:
the first efficiency point tracking indicator is a current flowing through a first common mode capacitor coupled to the first transformer; and
the second efficiency point tracking indicator is a current flowing through a second common mode capacitor coupled to the second transformer.

6. The system of claim 5 , wherein:
the first common mode capacitor is coupled to a midpoint of a secondary side of the first transformer; and
the second common mode capacitor is coupled to a midpoint of a secondary side of the second transformer.

7. The system of claim 6 , wherein:
the first common mode capacitor is coupled to ground through a first resistor, wherein the first detector is configured to detect the current flowing through the first common mode capacitor through detecting a voltage across the first resistor; and
the second common mode capacitor is coupled to ground through a second resistor, wherein the second detector is configured to detect the current flowing through the second common mode capacitor through detecting a voltage across the second resistor.

8. The system of claim 1 , wherein the first detector comprises:
a dc blocking capacitor;
a rectifier coupled to the dc blocking capacitor, wherein the rectifier is configured to convert an ac signal into a dc signal;
a load resistor; and
a voltage divider coupled to the rectifier.

9. The system of claim 8 , wherein the rectifier comprises:
a first capacitor and a second capacitor connected in series; and
a first diode and a second diode connected in series, wherein the load resistor is coupled between a common node of the first capacitor and the second capacitor, and a common node of the first diode and the second diode.

10. The system of claim 8 , wherein the rectifier comprises a diode and a capacitor, and wherein:
the diode is coupled between an input node and an output node of the rectifier;
the capacitor is coupled between the output node of the rectifier and ground; and
the load resistor is coupled between the input node of the rectifier and ground.

11. The system of claim 1 , wherein:
the first control circuit and the second control circuit are configured to adjust the first switching frequency of the first converter and the second switching frequency of the second converter until a voltage gain of the first converter is substantially equal to a voltage gain of the second converter.

12. A method comprising:
connecting an input stage of a first resonant converter and an input stage of a second resonant converter in parallel, wherein each converter comprises:
the input stage coupled to a power source, wherein the input stage comprises a plurality of power switches;
a resonant tank coupled to the plurality of power switches;
a transformer coupled to the resonant tank; and
an output stage coupled to the transformer;

detecting a first signal indicating a first soft switching process of the first resonant converter and a second signal indicating a second soft switching process of the second resonant converter; and
adjusting a first switching frequency of the first resonant converter by a first control circuit and a second switching frequency of the second resonant converter by a second control circuit until a load current flowing through the first resonant converter is substantially equal to a load current flowing through the second resonant converter, wherein the second switching frequency is different from the first switching frequency.

13. The method of claim 12 , further comprising:
detecting the first signal indicating the first soft switching process of the first resonant converter, wherein the first signal is proportional to a voltage across a resonant inductor of the first resonant converter; and
detecting the second signal indicating the second soft switching process of the second resonant converter, wherein the second signal is proportional to a voltage across a resonant inductor of the second resonant converter.

14. The method of claim 12 , further comprising:
detecting the first signal indicating the first soft switching process of the first resonant converter, wherein the first signal is proportional to a current flowing through a first common mode capacitor coupled to a midpoint of a secondary winding of the transformer of the first resonant converter; and
detecting the second signal indicating the second soft switching process of the second resonant converter, wherein the second signal is proportional to a current flowing through a second common mode capacitor coupled to a midpoint of a secondary winding of the transformer of the second resonant converter.

15. The method of claim 14 , wherein:
the first common mode capacitor is coupled between the midpoint of the secondary winding of the transformer of the first resonant converter and a first resistor connected to ground; and
the second common mode capacitor is coupled to the midpoint of the secondary winding of the transformer of the second resonant converter and a second resistor connected to ground.

16. The method of claim 15 , further comprising:
a third common mode capacitor having a first terminal directly connected to the midpoint of the secondary winding of the transformer of the first resonant converter and a seco

Assignees

• Futurewei Technologies Inc

Inventors

• Chen Daoshen
• Dai Heping
• Liu Xujun
• Liu Zhihua
• Ye Liming
• Fu Dianbo
• Liu Ce
• Cai Bing

Classifications

• H02M3/156

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• H02M3/325

  using devices of a triode or a transistor type requiring continuous application of a control signal · CPC title

• H02M3/33507 Primary

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

• H02M3/3376

  with automatic control of output voltage or current · CPC title

• H02M1/14

  Arrangements for reducing ripples from DC input or output · CPC title