Method and apparatus for implementing a power converter input terminal voltage discharge circuit

Patent metadata

Field	Value
Publication number	US-9735665-B2
Application number	US-201514717620-A
Country	US
Kind code	B2
Filing date	May 20, 2015
Priority date	Jul 31, 2009
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A circuit for use in a power converter includes a control circuit coupled to detect whether an electrical energy source is coupled to an input of the power converter. A switch is coupled to the control circuit, and is coupled to transfer energy from the input of the power converter to an output of the power converter during a first operating mode. The control circuit is coupled to drive the switch in the first operating mode when the electrical energy source is coupled to the input of the power converter. The control circuit is coupled to drive the switch in a second operating mode when the electrical energy source is uncoupled from the input of the power converter to drive the switch to discharge a capacitance coupled between input terminals of the power converter to a threshold voltage in less than a maximum period of time.

First claim

What is claimed is:

1. A circuit for use in a power converter, comprising:
a control circuit coupled to detect whether an electrical energy source is coupled to an input of the power converter; and
a switch coupled to the control circuit and coupled to transfer energy from the input of the power converter to an output of the power converter during a first operating mode, wherein the control circuit is coupled to drive the switch in the first operating mode when the electrical energy source is coupled to the input of the power converter, wherein the control circuit is coupled to drive the switch in a second operating mode when the electrical energy source is uncoupled from the input of the power converter, wherein the control circuit is further coupled to drive the switch in the second operating mode to discharge a capacitance coupled between input terminals of the power converter to a threshold voltage in less than a maximum period of time.

2. The circuit of claim 1 wherein the power converter is one of a boost converter, a flyback converter, a forward converter, an LLC converter.

3. The circuit of claim 1 wherein the switch is driven to perform a function of a power factor correction control circuit in the first operating mode.

4. The circuit of claim 1 wherein the switch is coupled to provide a starting current for operation of the circuit during a start up phase of the circuit.

5. The circuit of claim 1 wherein the control circuit is coupled to drive the switch to an off state during a standby mode of the control circuit.

6. The circuit of claim 1 wherein the control circuit is coupled to drive the switch to an off state during a shutdown mode of the control circuit.

7. The circuit of claim 1 wherein the threshold voltage is a Safety Extra Low Voltage (SELV) level.

8. The circuit of claim 1 wherein the output of the power converter is coupled to provide electrical energy.

9. The circuit of claim 1 wherein the output of the power converter is coupled to provide mechanical energy.

10. The circuit of claim 1 wherein the output of the power converter is coupled to an LED driver power system.

11. The circuit of claim 1 wherein the maximum period of time is unaffected by an amount of energy flow between the input of the power converter and the output of the power converter prior to the electrical energy source being uncoupled from the input of the power converter.

12. The circuit of claim 1 wherein the capacitance coupled between the input terminals of the input of the power converter comprises one or more X capacitors.

13. The circuit of claim 1 wherein the control circuit and the switch are included in an integrated circuit.

14. A circuit, comprising:
a control circuit coupled to detect whether an electrical energy source is coupled to an input of a power converter; and
a switch coupled to the control circuit, wherein the control circuit is coupled to drive the switch to transfer energy from the input of the power converter to an output of the power converter when the electrical energy source is coupled to the input of the power converter, wherein the control circuit is coupled to drive the switch to discharge a capacitance coupled between input terminals of the power converter through the switch to a threshold voltage in less than a maximum period of time when the electrical energy source is uncoupled from the input of the power converter.

15. The circuit of claim 14 wherein the switch is coupled to the input of the power converter through a rectification circuit of the power converter.

16. The circuit of claim 14 wherein the threshold voltage is a Safety Extra Low Voltage (SELV) level.

17. The circuit of claim 14 wherein the maximum period of time is unaffected by an amount of energy flow between the input of the power converter and the output of the power converter prior to the electrical energy source being uncoupled from the input of the power converter.

18. A circuit for use in a power converter, comprising:
a control circuit capable of detecting whether an AC voltage source is coupled to an input of the power converter; and
a switch coupled to the control circuit,
wherein the control circuit is capable of detecting whether the AC voltage source is uncoupled from the input of the power converter within a first predetermined maximum period of time,
wherein the control circuit is coupled to drive the switch in a first operating mode when the AC voltage source is coupled to the input of the power converter,
wherein the control circuit is coupled to drive the switch in a second operating mode when the control circuit detects the AC voltage source is uncoupled from the input of the power converter and is capable of discharging a capacitance coupled between input terminals of the power converter to a threshold voltage level through a discharge path and through the switch within a second predetermined maximum period of time, and
wherein an RC time constant of the discharge path is less than or equal to one second and the threshold voltage level is less than or equal to ten volts.

19. The circuit of claim 18 wherein the switch is coupled to provide a starting current for operation of the circuit during a start up phase of the circuit.

20. The circuit of claim 18 wherein the capacitance coupled between the input terminals of the input of the power converter comprises one or more X capacitors.

21. The circuit of claim 18 wherein the control circuit and the switch are included in an integrated circuit.

22. A circuit for use in a power converter, comprising:
a control circuit capable of detecting whether an AC voltage source is coupled to an input of a power converter; and
a switch coupled to the control circuit and coupled to the input of the power converter,
wherein the switch is coupled to provide a starting current for operation of the circuit during a start up phase of the circuit,
wherein the control circuit is capable of detecting whether the AC voltage source is uncoupled from the input of the power converter within a first predetermined maximum period of time,
wherein the control circuit is coupled to drive the switch in a first operating mode when the AC voltage source is coupled to the input of the power converter,
wherein the control circuit is coupled to drive the switch in a second operating mode when the control circuit detects the AC voltage source is uncoupled from the input of the power converter and is capable of discharging a capacitance coupled between input terminals of the power converter to a threshold voltage level through a discharge path and through the switch within a second predetermined maximum period of time, and
wherein an RC time constant of the discharge path is less than or equal to one second and the threshold level is less than or equal to ten volts.

23. The circuit of claim 22 wherein the capacitance coupled between the input terminals of the input of the power converter comprises one or more X capacitors.

24. The circuit of claim 22 wherein the control circuit and the switch are included in an integrated circuit.

25. The circuit of claim 22 wherein the switch comprises a first transistor coupled to a second transistor and one of the first and second transistors is turned on to provide the starting current.

26. The circuit of claim 25 wherein one of the first and second transistors is turned on to discharge the capacitance.

Assignees

• Power Integrations Inc

Inventors

• Balakrishnan Balu
• Kung David
• Orr Raymond Kenneth
• Matthews David Michael Hugh

Classifications

• H02M1/12

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02M1/126

  using passive filters · CPC title

• H02M1/32 Primary

  Means for protecting converters other than automatic disconnection · CPC title

• H02M2001/322

  Electricity · mapped topic