Short-circuit protection using pulse width modulation (PWM) for resonant converters

Patent metadata

Field	Value
Publication number	US-10693379-B2
Application number	US-201715668980-A
Country	US
Kind code	B2
Filing date	Aug 4, 2017
Priority date	Aug 19, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

According to an implementation, a resonant converter for short-circuit protection includes an oscillator, a short-circuit detector configured to detect a short-circuit condition in a component of the resonant converter, and a pulse width modulation (PWM) controller configured to control the oscillator in a PWM mode before short-circuit protection is triggered. The oscillator, when in the PWM mode, is configured to generate a first clock signal for driving a first power switch and a second clock signal for driving a second power switch.

First claim

What is claimed is:

1. A resonant converter for short-circuit protection, the resonant converter, comprising:
an oscillator;
a short-circuit detector configured to detect a short-circuit condition in a component of the resonant converter; and
a pulse width modulation (PWM) controller configured to control the oscillator in a PWM mode before short-circuit protection is triggered, the oscillator, when in the PWM mode, configured to generate a first clock signal for driving a first power switch and a second clock signal for driving a second power switch.

2. The resonant converter of claim 1 , wherein the component is a pin of the resonant converter.

3. The resonant converter of claim 1 , wherein the component is an integrated current sense pin.

4. The resonant converter of claim 1 , wherein the component is a circuit element on a primary side of a transformer of the resonant converter.

5. The resonant converter of claim 1 , wherein the short-circuit detector is configured to determine that a voltage of the component is equal to or less than a voltage threshold, and the PWM controller is configured to control the oscillator in the PWM mode before the short-circuit protection is triggered.

6. The resonant converter of claim 1 , wherein the short-circuit detector includes a voltage comparator configured to compare a voltage of the component with a voltage threshold, and output a PWM control signal to the PWM controller in response to the voltage of the component being equal to or less than the voltage threshold.

7. The resonant converter of claim 1 , further comprising:
a short-circuit protection trigger configured to trigger the short-circuit protection after a period of time has elapsed from a start of the PWM mode.

8. The resonant converter of claim 7 , wherein the short-circuit protection trigger includes a counter configured to count a time from the start of the PWM mode, and trigger the short-circuit protection after the counted time reaches a threshold.

9. The resonant converter of claim 1 , wherein the PWM controller is configured to control the oscillator to reduce a duty cycle of the first clock signal and the second clock signal when in the PWM mode and before the short-circuit protection is triggered.

10. The resonant converter of claim 1 , wherein, in response to the short-circuit protection being triggered, the short-circuit protection is configured to stop operations of the oscillator.

11. A resonant converter for short-circuit protection, the resonant converter, comprising:
an oscillator;
a short-circuit detector configured to detect a short-circuit condition in an integrated current sense circuit connected to a resonant network of the resonant converter; and
a pulse width modulation (PWM) controller configured to control the oscillator in a PWM mode before short-circuit protection is triggered, the oscillator, when in the PWM mode, configured to generate a first clock signal for driving a first power switch and a second clock signal for driving a second power switch.

12. The resonant converter of claim 11 , wherein the short-circuit detector includes a voltage comparator configured to compare a voltage of an integrated current sense signal sensed by the integrated current sense circuit with a voltage threshold, and output a PWM control signal to the PWM controller in response to the voltage of the integrated current sense signal being equal to or less than the voltage threshold.

13. The resonant converter of claim 11 , wherein the integrated current sense circuit includes a first capacitor, a second capacitor, and a resistor, and the short-circuit detector is configured to detect the short-circuit condition in the integrated current sense circuit in response to at least one of the first capacitor, the second capacitor, and the resistor being shorted.

14. The resonant converter of claim 11 , further comprising:
a short-circuit protection trigger configured to trigger the short-circuit protection after a period of time has elapsed from a start of the PWM mode.

15. The resonant converter of claim 14 , wherein the short-circuit protection trigger includes a counter configured to count a time from the start of the PWM mode, and trigger the short-circuit protection after the counted time reaches a threshold.

16. The resonant converter of claim 11 , wherein the PWM controller is configured to control the oscillator to reduce a duty cycle of the first clock signal and the second clock signal when in the PWM mode and before the short-circuit protection is triggered.

17. A resonant converter for short-circuit protection, the resonant converter, comprising:
an oscillator;
a voltage comparator configured to compare a voltage of an integrated current sense signal with a voltage threshold;
a pulse width modulation (PWM) controller configured to control the oscillator in a PWM mode in response to the voltage of the integrated current sense signal being equal to or below the voltage threshold, the PWM controller configured to control the oscillator in the PWM mode before short-circuit protection is triggered, the oscillator, when in the PWM mode, configured to generate a first clock signal for driving a first power switch and a second clock signal for driving a second power switch.

18. The resonant converter of claim 17 , further comprising:
a counter configured to trigger the short-circuit protection.

19. The resonant converter of claim 17 , further comprising:
an integrated current sense circuit connected to a resonant capacitor of a resonant network of the resonant converter, the integrated current sense circuit configured to sense the integrated current sense signal using a voltage of the resonant capacitor,
wherein the voltage comparator is configured to receive the integrated current sense signal from the integrated current sense circuit.

20. The resonant converter of claim 17 , wherein the PWM controller is configured to control the oscillator to reduce a duty cycle of the first clock signal and the second clock signal when in the PWM mode and before the short-circuit protection is triggered.

Assignees

• Fairchild Korea Semiconductor Ltd
• Semiconductor Components Ind Llc

Inventors

• Moon Sangcheol
• Kim Jintae
• Choi Hangseok

Classifications

• H02M3/33571

  Half-bridge at primary side of an isolation transformer · CPC title

• H02M3/01

  Resonant DC/DC converters · CPC title

• H02M3/33515 Primary

  with digital control · CPC title

• H02M3/3376 Primary

  with automatic control of output voltage or current · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title