Gate drive apparatus for resonant converters

Patent metadata

Field	Value
Publication number	US-9876435-B2
Application number	US-201615297818-A
Country	US
Kind code	B2
Filing date	Oct 19, 2016
Priority date	Nov 12, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A method comprises providing a resonant converter comprising a switching network comprising a first high-side switch, a second high-side switch, a first low-side switch and a second low-side switch, a resonant tank coupled between the switching network and a transformer and a rectifier coupled to a secondary side of the transformer, coupling a driver to the switching network and the rectifier, wherein the driver includes a first winding coupled to the rectifier, a second winding coupled to the first high-side switch and a third winding coupled to the second high-side switch, detecting a signal indicating a soft switching process of the driver and adjusting a resonant frequency of the driver until the resonant frequency of the driver approximately matches a switch frequency of the resonant converter.

First claim

What is claimed is:

1. A method comprising:
providing a resonant converter comprising:
a switching network comprising a first high-side switch, a second high-side switch, a first low-side switch and a second low-side switch;
a resonant tank coupled between the switching network and a transformer; and
a rectifier coupled to a secondary side of the transformer;

coupling a driver to the switching network and the rectifier, wherein the driver comprises:
a bridge coupled between a bias voltage and ground;
a resonant device coupled to the bridge; and
a signal transformer having a primary winding coupled to the resonant device, a first secondary winding coupled to the rectifier, a second secondary winding coupled to the first high-side switch and a third secondary winding coupled to the second high-side switch;

detecting a signal indicating a soft switching process of the driver; and
adjusting a resonant frequency of the driver until the resonant frequency of the driver approximately matches a switch frequency of the resonant converter.

2. The method of claim 1 , wherein the bridge comprises:
a first switch and a second switch connected in series and coupled between the bias voltage and ground; and
a third switch and a fourth switch connected in series and coupled between the bias voltage and ground, and wherein:
a gate drive signal of the first low-side switch is applied to a common node of the first switch and the second switch; and
a gate drive signal of the second low-side switch is applied to a common node of the third switch and the fourth switch.

3. The method of claim 2 , further comprising:
adjusting a duty cycle of the first switch so that the duty cycle of the first switch is in a range from about 5% to about 25%;
adjusting a duty cycle of the second switch so that the duty cycle of the second switch is about 50%;
adjusting a duty cycle of the third switch so that the duty cycle of the third switch is in a range from about 5% to about 25%; and
adjusting a duty cycle of the fourth switch so that the duty cycle of the fourth switch is about 50%.

4. The method of claim 2 , further comprising:
adjusting a duty cycle of the first switch so that the duty cycle of the first switch is less than 40%;
adjusting a duty cycle of the second switch so that the duty cycle of the second switch is in a range from about 40% to about 60%;
adjusting a duty cycle of the third switch so that the duty cycle of the third switch is less than 40%; and
adjusting a duty cycle of the fourth switch so that the duty cycle of the fourth switch is in a range from about 40% to about 60%.

5. The method of claim 2 , wherein the resonant device comprises:
a fixed capacitance, a gate capacitance and a magnetizing inductance.

6. The method of claim 5 , further comprising:
an adjustable capacitance coupled to the fixed capacitance, wherein:
the fixed capacitance is formed by a first capacitor coupled between the common node of the first switch and the second switch, and the common node of the third switch and the fourth switch; and
the adjustable capacitance is formed by a second capacitor and an auxiliary switch, wherein the second capacitor and the auxiliary switch are connected in series to form a switchable capacitor, and wherein the switchable capacitor is coupled between the common node of the first switch and the second switch, and the common node of the third switch and the fourth switch.

7. The method of claim 5 , further comprising:
an adjustable capacitance coupled to the fixed capacitance, wherein:
the fixed capacitance is formed by a first capacitor coupled between the common node of the first switch and the second switch, and the common node of the third switch and the fourth switch; and
the adjustable capacitance is formed by a second capacitor, a first auxiliary switch, a third capacitor and a second auxiliary switch, and wherein:
the second capacitor and the first auxiliary switch are connected in series to form a first switchable capacitor, and wherein the first switchable capacitor is connected in parallel with the second switch; and
the third capacitor and the second auxiliary switch are connected in series to form a second switchable capacitor, and wherein the second switchable capacitor is connected in parallel with the fourth switch.

8. The method of claim 5 , wherein:
the fixed capacitance is formed by a first capacitor connected in parallel with the first switch and a second capacitor connected in parallel with the third switch.

9. The method of claim 5 , wherein:
the fixed capacitance is formed by a first capacitor connected in parallel with the second switch and a second capacitor connected in parallel with the fourth switch.

10. The method of claim 5 , further comprising:
a capacitor connected in series with at least one winding of secondary windings of the signal transformer.

11. The method of claim 5 , further comprising:
a blocking capacitor connected in series with the primary winding of the signal transformer.

12. A method comprising:
providing a resonant converter comprising:
a switching network comprising a first high-side switch, a second high-side switch, a first low-side switch and a second low-side switch;
a resonant tank coupled between the switching network and a transformer; and
a rectifier coupled to a secondary side of the transformer;
coupling a driver to the switching network and the rectifier, wherein the driver comprises:
a bridge coupled between a bias voltage and ground;
a resonant device coupled to the bridge; and

a signal transformer comprising a first winding coupled to the rectifier, a second winding coupled to the first high-side switch and a third winding coupled to the second high-side switch;
detecting a load level of the resonant converter; and
adjusting the bias voltage of the driver in response to different load conditions.

13. The method of claim 12 , further comprising:
in response to a light load operating condition of the resonant converter, reducing the bias voltage of the driver; and
in response to a heavy load operating condition of the resonant converter, increasing the bias voltage of the driver.

14. The method of claim 12 , further comprising:
varying the bias voltage of the driver when the resonant converter operates in a startup process.

15. The method of claim 12 , further comprising:
detecting a signal indicating a soft switching process of the driver; and
adjusting a resonant frequency of the driver until the resonant frequency of the driver approximately matches a switch frequency of the resonant converter.

16. A method comprising:
providing a resonant converter comprising:
a switching network comprising a first high-side switch, a second high-side switch, a first low-side switch and a second low-side switch;
a resonant tank coupled between the switching network and a transformer; and
a rectifier coupled to a secondary side of the transformer;

coupling a driver to the switching network and the rectifier, wherein the driver includes a first winding coupled to the rectifier, a second winding coupled to the first high-side switch and a third winding coupled to the second high-side switch;
detecting a signal indicating a soft switching process of the driver; and
adjusting a resonant frequency of the driver until the resonant frequency of the driver approximately matches a switch frequency of the resonant converter.

17. The method of claim 16 , wherein the driver comprises:
a bridge comprising a first driver switch and a second driver s

Assignees

• Futurewei Technologies Inc

Inventors

• Chen Daoshen
• Dai Heping
• Liu Xujun
• Ye Liming
• Fu Dianbo

Classifications

• Y02B70/1491

  Cross-Sectional Technologies · mapped topic

• Y02B70/1441

  Cross-Sectional Technologies · mapped topic

• H02M3/33553

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title

• H02M2001/0058

  Electricity · mapped topic

• H02M3/33576

  having at least one active switching element at the secondary side of an isolation transformer · CPC title