Lighting apparatus with inductor current limiting for noise reduction

• US 9,192,016 B1
• Filed: 05/22/2014
• Issued: 11/17/2015
• Est. Priority Date: 05/22/2014
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Athalye, Praneet Jayant, McIntyre, Michael
• Primary Examiner(s): Le, Don
• Application Number:
  US14/284,643
• Publication Number:
  US 20150342004A1
• Time in Patent Office: 544 Days
• Field of Search: 315/85, 315/283, 315/297
• US Class Current: 1/1
• CPC Class Codes: H02M 1/081 wherein the phase of the control voltage is adjustable with reference to the AC source
• CPC Class Codes: H02M 1/126 using passive filters
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]

Abstract

A lighting apparatus includes a lighting circuit (e.g., an LED lighting circuit) and a driver circuit having an output coupled to the lighting circuit and an input configured to be coupled to a power source, such as a phase cut dimmer, that provides a varying voltage waveform. The driver circuit includes an electromagnetic interference (EMI) suppression inductor configured to be coupled in series with the power source and a bypass circuit configured to divert current from the EMI filter inductor to limit a current in the EMI filter inductor.

Claims

1. A lighting apparatus comprising:

a lighting circuit; and

a driver circuit having an output coupled to the lighting circuit and an input configured to be coupled to a power source that provides a varying voltage waveform, the driver circuit comprising an electromagnetic interference (EMI) filter inductor configured to be coupled in series with the power source and a bypass circuit configured to conduct a bypass current to thereby divert current from the EMI filter inductor for a first state of a voltage across the EMI filter inductor to limit a current in the EMI filter inductor and to terminate conduction of the bypass current for a second state of the voltage across the EMI filter inductor.

2. The lighting apparatus of claim 1, wherein the bypass circuit is configured to divert current responsive to an edge of the varying voltage waveform.

3. The lighting apparatus of claim 1, wherein the edge comprises a leading edge of a phase cut AC waveform.

5. The lighting apparatus of claim 1, wherein the bypass circuit is configured to limit the current in the EMI filter inductor responsive to the voltage across the EMI filter inductor.

6. The lighting apparatus of claim 1, wherein the bypass circuit comprises a diode.

7. The lighting apparatus of claim 1, wherein the bypass circuit is coupled in parallel with the EMI filter inductor.

8. The lighting apparatus of claim 7, wherein the bypass circuit comprises a TVS coupled in parallel with the EMI filter inductor.

9. The lighting apparatus of claim 1, wherein the lighting circuit comprises an LED lighting circuit.

10. The lighting apparatus of claim 1, wherein the power source comprises a phase cut dimmer.

4. The lighting apparatus 3, wherein the bypass circuit is configured to limit a magnitude of the voltage across the EMI filter inductor to a value less than a saturation threshold of the EMI inductor and greater than a maximum magnitude of the voltage across the EMI filter inductor when the power source is applying a non-phase cut AC waveform to the input of the driver circuit.

11. A lighting apparatus comprising:

a lighting circuit; and

a driver circuit having an output coupled to the lighting circuit and an input configured to be coupled to a power source that provides a varying voltage waveform, the driver circuit comprising an electromagnetic interference (EMI) filter inductor configured to be coupled in series with the power source and a bypass circuit configured to divert current from the EMI filter inductor to limit a current in the EMI filter inductor, wherein the bypass circuit comprises a transient voltage suppressor (TVS) coupled in parallel with the EMI filter inductor.

12. The lighting apparatus of claim 11, wherein the TVS is configured to clamp a magnitude of a voltage across the EMI filter inductor to a value less than a saturation threshold of the EMI filter inductor.

13. A lighting apparatus comprising:

a lighting circuit; and

a driver circuit having an output coupled to the lighting circuit and an input configured to be coupled to a power source that provides a varying voltage waveform, the driver circuit comprising an electromagnetic interference (EMI) filter inductor configured to be coupled in series with the power source and a bypass circuit configured to divert current from the EMI filter inductor to limit a current in the EMI filter inductor, wherein the bypass circuit comprises a series combination of a TVS and a resistor coupled in parallel with the EMI filter inductor.

14. A lighting apparatus comprising:

a lighting circuit; and

a driver circuit having an output coupled to the lighting circuit and an input configured to be coupled to a dimmer, the driver circuit comprising an inductor coupled to the input and an inductor current limiter circuit configured to initiate a diversion of current from the EMI filter inductor and thereby limit a current in the inductor responsive to a leading edge of a phase cut voltage applied to the input.

15. The lighting apparatus of claim 14, wherein the inductor current limiter circuit comprises a bypass circuit configured to divert current from the inductor responsive to the leading edge.

16. The lighting apparatus of claim 15, wherein the bypass circuit is configured to limit the current through the inductor responsive to a voltage across the inductor.

17. The lighting apparatus of claim 15, wherein the bypass circuit is coupled across the inductor.

18. The lighting apparatus of claim 15, wherein the bypass circuit comprises a transient voltage suppressor (TVS) coupled in parallel with the inductor.

19. The lighting apparatus of claim 15, wherein the bypass circuit comprises a series combination of a TVS and a resistor coupled in parallel with the inductor.

20. The lighting circuit of claim 14, wherein the inductor comprises an EMI filter inductor.

21. The lighting apparatus of claim 14, wherein the inductor current limiter circuit is configured to terminate the diversion of current within a cycle of the phase cut voltage following the leading edge.

22. A driver circuit for a lighting apparatus, the driver circuit comprising:

an inductor configured to be coupled to an AC power source;

a capacitor coupled to the power source via the inductor; and

a bypass circuit configured to divert current away from the inductor responsive to an edge of a phase cut voltage produced by the AC power source.

23. The driver circuit of claim 22, wherein the bypass circuit is coupled across the inductor.

24. The driver circuit of claim 23, wherein the bypass circuit comprises at least one diode coupled across the inductor.

25. The driver circuit of claim 24, wherein the at least one diode comprises a TVS.

26. The driver circuit of claim 24, wherein the bypass circuit comprises a series combination of a TVS and a resistor.

27. The driver circuit of claim 22, wherein the inductor comprises an EMI filter inductor.

28. The driver circuit of claim 27, wherein the bypass circuit is configured to limit a magnitude of a voltage across the EMI filter inductor to a value less than a saturation threshold of the EMI inductor and greater than a maximum magnitude of the voltage across the EMI filter inductor when the AC power source produces a non-phase cut AC voltage.

29. The driver circuit of claim 22, wherein the edge comprises a leading edge.