Overvoltage protection for a synchronous power rectifier

Patent metadata

Field	Value
Publication number	US-9755423-B2
Application number	US-201414208502-A
Country	US
Kind code	B2
Filing date	Mar 13, 2014
Priority date	Mar 13, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A circuit is described that includes a rectifier configured to rectify a DC output from an AC input, a sensing unit configured to detect a voltage level of the DC output, and a control unit configured to control the rectifier based on the voltage level of the DC output. The control unit is configured to control the rectifier output by at least controlling the rectifier to rectify the DC output from the AC input if the voltage level of the DC output does not indicate an overvoltage condition at the circuit. In addition, the control unit is configured to control the rectifier based on the voltage level of the DC output by at least controlling the rectifier to shunt current from the AC input if the voltage level of the DC output does indicate the overvoltage condition.

First claim

What is claimed is:

1. A circuit comprising:
a rectifier comprising at least one high-side element and at least one low-side switch that are configured to rectify an AC input to a DC output, wherein:
the at least one low-side switch is arranged in series between the AC input and a ground terminal of the circuit,
the at least one high-side element is coupled, at the AC input, to the at least one low-side switch, and
the at least one high-side element is arranged in series between the DC output and the AC input;

a sensing unit configured to detect a voltage level of the DC output;
a control unit configured to control the rectifier based on the voltage level of the DC output by at least controlling the at least one low-side switch of the rectifier to:
rectify the AC input to the DC output if the voltage level of the DC output does not indicate an overvoltage condition at the circuit; and
shunt current, from the AC input, through the at least one low-side switch, and to the ground terminal, if the voltage level of the DC output does indicate the overvoltage condition.

2. The circuit of claim 1 , wherein the control unit is configured to control the rectifier to shunt the current, from the AC input, through the at least one low-side switch, and to the ground terminal, if the voltage level of the DC output does indicate the overvoltage condition, by at least switching-on the at least one low-side switch.

3. The circuit of claim 2 , wherein the control unit is configured to control the rectifier to further shunt the current from the AC input if the voltage level of the DC output does indicate the overvoltage condition by at least disabling the at least one high-side element.

4. The circuit of claim 2 , wherein the control unit is configured to switch-on the at least one low-side switch by at least performing hard switching of the at least one low-side switch to maximize a rate at which the at least one low-side switch shunts the current from the AC input.

5. The circuit of claim 2 , wherein the control unit is configured to switch-on the at least one low-side switch by at least performing soft switching of the at least one low-side switch to control a rate at which the at least one low-side switch shunts the current from the AC input.

6. The circuit of claim 2 , wherein the at least one low-side switch is a MOS transistor type switch.

7. The circuit of claim 2 , wherein the at least one high-side element is a MOS transistor type switch or a diode.

8. The circuit of claim 2 , wherein the at least one low-side switch and the at least one high-side element are arranged in a half-bridge or a H-bridge configuration.

9. The circuit of claim 2 , wherein the rectifier comprises a plurality of low-side switches including the at least one low-side switch, wherein the control unit is configured to enable the at least one low-side switch by switching-on the at least one low-side switch without switching-on at least one other low-side switch of the plurality of low-side switches.

10. The circuit of claim 2 , wherein the rectifier comprises a plurality of low-side switches including the at least one low-side switch, wherein the control unit is configured to switch-on the at least one low-side switch by switching-on each of the plurality of low-side switches.

11. The circuit of claim 1 , wherein the rectifier further comprises at least one high-side element and at least one additional switching element arranged in parallel to the at least one low-side switch, wherein the control unit is configured to control the rectifier to shunt the current from the AC input if the voltage level of the DC output does indicate the overvoltage condition by enabling the at least one additional switching element.

12. The circuit of claim 1 , wherein each of the one or more switches comprises a respective body diode.

13. The circuit of claim 1 , wherein the control unit is further configured to:
compare the voltage level of the DC output to a threshold voltage; and
determine whether the voltage level of the DC output indicates the overvoltage condition at the circuit based on the comparison between the voltage level and the threshold voltage.

14. A method comprising:
detecting a voltage level of a DC output from a rectifier that receives an AC input, the rectifier comprising at least one high-side element and at least one low-side switch that are configured to rectify the AC input to the DC output, wherein:
the at least one low-side switch is arranged in series between the AC input and a ground terminal of the rectifier,
the at least one high-side element is coupled, at the AC input, to the at least one low-side switch, and
the at least one high-side element is arranged in series between the DC output and the AC input;

determining, by a control unit, whether the voltage level indicates an overvoltage condition at the rectifier;
controlling, by the control unit, the at least one low-side switch of the rectifier to rectify the AC input to the DC output if the voltage level of the DC output does not indicate the overvoltage condition; and
controlling, by the control unit, the at least one low-side switch of the rectifier to shunt, current, from the AC input, through the at least one low-side switch, and to the ground terminal, if the voltage level of the DC output does indicate the overvoltage condition.

15. The method of claim 14 , wherein controlling the at least one low-side switch of the rectifier to shunt current from the AC input, through the at least one low-side switch, and to the ground terminal, comprises switching-on the at least one low-side switch.

16. The method of claim 15 , wherein controlling the at least one low-side switch of the rectifier to shunt current from the AC input further comprises disabling the at least one high-side element.

17. The method of claim 15 , wherein switching-on the at least one low-side switch comprises hard switching, by the control unit, the at least one low-side switch of the rectifier to maximize a rate at which the at least one low-side switch shunts the current from the AC input.

18. The method of claim 15 , wherein switching-on the at least one low-side switch comprises soft switching, by the control unit, the at least one low-side switch of the rectifier to control a rate at which the at least one low-side switch shunts the current from the AC input.

19. The method of claim 14 , further comprising:
comparing, by the control unit, the voltage level of the DC output to a threshold voltage; and
determining, by the control unit, whether the voltage level of the DC output indicates the overvoltage condition based on the comparison between the voltage level and the threshold voltage.

20. A circuit comprising:
means for detecting a voltage level of a DC output from a rectifier that receives an AC input, the rectifier comprising at least one high-side element and at least one low-side switch that are configured to rectify the AC input to the DC output, wherein:
the at least one low-side switch is arranged in series between the AC input and a ground terminal of the rectifier,
the at least one high-side element is coupled, at the AC input, to the at least one low-side switch, and
the at least one high-side element is arranged in series between the DC output and the AC input;

means for determining whether the voltage level indicates an overvoltage condition at the rectifier;
means for controlling the at least one low-side switch of the rectifier to rectify the AC input to the DC output if the

Assignees

• Infineon Technologies Ag

Inventors

• Sandner Christoph
• Agostinelli Matteo

Classifications

• H02H7/1252 Primary

  responsive to overvoltage in input or output, e.g. by load dump · CPC title

• H02M7/219

  in a bridge configuration · CPC title

• H02M1/0085

  Partially controlled bridges · CPC title