Method for eliminating flicker in emergency lighting driver devices during pulse charging

• US 10,355,518 B2
• Filed: 07/31/2017
• Issued: 07/16/2019
• Est. Priority Date: 08/31/2016
• Status: Active Grant

• Current Assignee: Tridonic GmbH & Co. KG (Zumtobel Group AG)
• Original Assignee: Tridonic GmbH & Co. KG (Zumtobel Group AG)
• Inventors: Frankland, James
• Primary Examiner(s): Deberadinis, Robert L
• Application Number:
  US15/664,569
• Publication Number:
  US 20180062425A1
• Time in Patent Office: 715 Days
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/59 for reducing or suppressing flicker or glow effects
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An emergency lighting driver device is configured to assume an operation mode in which: the battery is charged by applying the pulse signal to the transistor from the control unit, while the LED load is driven, wherein the emergency lighting driver device is configured to delay the pulse signal such that the rising edge(s) and/or falling edge(s) of the pulse signal have a transition time of at least 0.5 seconds, preferably at least 1 second, more preferred more than 1.5 seconds and preferably less than 3 seconds; and/or wherein the pulse signal is fed through a low pass filter unit of the emergency lighting driver device delaying the transition time of the rising edge(s) and/or falling edge(s) of the pulse signal before feeding it to the transistor.

Claims

1. An emergency lighting driver device (1) for driving a lighting unit (10) comprising at least one emergency lighting source with a LED unit comprising at least one LED, wherein the emergency lighting driver device (1) comprises

a) an input terminal (2) being configured to be supplied with a supply voltage (11),

b) a battery (4) connected in series to a transistor (5), wherein the series connection (6) of the battery (4) and the transistor (5) is directly or indirectly connected in parallel to the input terminal (2), such that the battery (4) is chargeable starting from the supply voltage (11),

c) a LED driver (8) connected in parallel to the series connection (6) of the battery (4) and the transistor (5), the LED driver (8) having an output terminal (9) for driving a LED load (10), and

d) a control unit (7) being configured to feedback-control the current through the LED load (10) by controlling the LED driver (8) and being configured to apply a pulse signal to the transistor (5) for controlling the charging of the battery (4),

e) wherein the emergency lighting driver device (1) is configured to assume an operation mode in which:

the battery (4) is charged by applying the pulse signal to the transistor (5) from the control unit (7), while the LED load (10) is driven, and

the emergency lighting driver device (1) is configured to delay the pulse signal such that the rising edge(s) and/or falling edge(s) of the pulse signal have a transition time of at least 0.5 seconds.

2. An emergency lighting driver device (1) according to claim 1, wherein the emergency lighting driver device (1) comprises a low pass filter unit (12) configured to delay the transition time of the rising edge(s) and/or falling edge(s) of the pulse signal before feeding it to the transistor (5).

3. An emergency lighting driver device (1) according to claim 2, wherein the low pass filter unit (12) comprises at least one RC-element (R1, C3).

4. An emergency lighting driver device (1) according to claim 1, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the rising edge(s) and/or falling edge(s) of the pulse signal have a transition time of at least 1.0 seconds and less than 3 seconds.

5. An emergency lighting driver device (1) according to claim 1, wherein

the LED driver (8) comprises at least one switched converter (S2, L3, D2, C2), and

the control unit (7) is configured to feedback-control the current through the LED load (10) by adapting the switching of the at least one switched converter (S2, L3, D2, C2).

6. An emergency lighting driver device (1) according to claim 1, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the current through the LED load (10) being feedback-controlled by the control unit (7) is within 10% of the nominal value for the current through the LED load (10).

7. An emergency lighting driver device (1) according to claim 1, wherein the transistor (5) is a MOSFET and the control unit (7) is configured to apply the pulse signal to the gate-terminal of the MOSFET.

8. An emergency lighting driver device (1) according to claim 1, wherein

for charging the battery (4) the control unit (7) is configured to control the transistor (5) such that the transistor (5) is alternately switched between the conducting state and the non-conducting state,

the transistor (5) is in the conducting state for a predetermined conducting time and in the non-conducting state for a predetermined non-conducting time, and

the predetermined non-conducting time is longer than the predetermined conducting time.

9. An emergency lighting driver device (1) according to claim 8, wherein the predetermined conducting time corresponds to 4 minutes and the predetermined non-conducting time corresponds to 16 minutes.

10. An emergency lighting driver device (1) according to claim 8, wherein

for charging the battery (4) the control unit (7) is configured to control the transistor (5) such that the transistor (5) is in the conducting state for a predetermined initial conducting time before being alternately switched between the conducting state and the non-conducting state, and

the predetermined initial conducting time is longer than the predetermined non-conducting time.

11. An emergency lighting driver device (1) according to claim 10, wherein the predetermined initial conducting time corresponds to 20 hours.

12. An emergency lighting device comprising

an emergency lighting driver device (1) according to claim 1, and

a lighting unit (10) comprising at least one emergency lighting source with a LED unit comprising at least one LED,

wherein the emergency lighting driver device (1) is configured to drive the lighting unit (10) starting from a voltage supply (11) via its input terminal (2) in a normal operation mode and to drive the lighting unit (10) starting from the battery (4) in an emergency operation mode.

13. An emergency lighting driver device (1) for driving a lighting unit (10) comprising at least one emergency lighting source with a LED unit comprising at least one LED, wherein the emergency lighting driver device (1) comprises

a) an input terminal (2) being configured to be supplied with a supply voltage (11),

b) a battery (4) connected in series to a transistor (5), wherein the series connection (6) of the battery (4) and the transistor (5) is directly or indirectly connected in parallel to the input terminal (2), such that the battery (4) is chargeable starting from the supply voltage (11),

c) a LED driver (8) connected in parallel to the series connection (6) of the battery (4) and the transistor (5), the LED driver (8) having an output terminal (9) for driving a LED load (8), and

d) a control unit (7) being configured to feedback-control the current through the LED load (10) by controlling the LED driver (8) and being configured to apply a pulse signal to the transistor (5) for controlling the charging of the battery (4),

e) wherein the emergency lighting driver device (1) is configured to assume an operation mode in which:

the battery (4) is charged by applying the pulse signal to the transistor (5) from the control unit (7), while the LED load (10) is driven, and

the pulse signal is fed through a low pass filter unit (12) of the emergency lighting driver device (1) delaying the transition time of the rising edge(s) and/or falling edge(s) of the pulse signal before feeding it to the transistor (5).

14. An emergency lighting driver device (1) according to claim 13, wherein the low pass filter unit (12) is configured to delay the pulse signal such that the rising edge(s) and/or falling edge(s) of the pulse signal have a transition time of at least 0.5 seconds.

15. An emergency lighting driver device (1) according to claim 13, wherein the low pass filter unit (12) comprises at least one RC-element (R1, C3).

16. An emergency lighting driver device (1) according to claim 13, wherein

the LED driver (8) comprises at least one switched converter (S2, L3, D2, C2), and

the control unit (7) is configured to feedback-control the current through the LED load (10) by adapting the switching of the at least one switched converter (S2, L3, D2, C2).

17. An emergency lighting driver device (1) according to claim 13, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the current through the LED load (10) being feedback-controlled by the control unit (7) is within 10% of the nominal value for the current through the LED load (10).

18. An emergency lighting driver device (1) according to claim 13, wherein the transistor (5) is a MOSFET and the control unit (7) is configured to apply the pulse signal to the gate-terminal of the MOSFET.

19. An emergency lighting driver device (1) according to claim 18, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the MOSFET is driven through its active region during the transition time of the rising edge(s) and/or falling edge(s) of the pulse signal.

20. An emergency lighting driver device (1) according to claim 18, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the MOSFET is driven through its active region during the transition time of the rising edge(s) and/or falling edge(s) of the pulse signal.

21. An emergency lighting driver device (1) according to claim 13, wherein

for charging the battery (4) the control unit (7) is configured to control the transistor (5) such that the transistor (5) is alternately switched between the conducting state and the non-conducting state,

the transistor (5) is in the conducting state for a predetermined conducting time and in the non-conducting state for a predetermined non-conducting time, and

the predetermined non-conducting time is longer than the predetermined conducting time.

22. An emergency lighting driver device (1) according to claim 21, wherein the predetermined conducting time corresponds to 4 minutes and the predetermined non-conducting time corresponds to 16 minutes.

23. An emergency lighting driver device (1) according to claim 21, wherein

for charging the battery (4) the control unit (7) is configured to control the transistor (5) such that the transistor (5) is in the conducting state for a predetermined initial conducting time before being alternately switched between the conducting state and the non-conducting state, and

the predetermined initial conducting time is longer than the predetermined non-conducting time.

24. An emergency lighting driver device (1) according to claim 23, wherein the predetermined initial conducting time corresponds to 20 hours.

25. An emergency lighting device comprising

an emergency lighting driver device (1) according to claim 13, and

a lighting unit (10) comprising at least one emergency lighting source with a LED unit comprising at least one LED,

wherein the emergency lighting driver device (1) is configured to drive the lighting unit (10) starting from a voltage supply (11) via its input terminal (2) in a normal operation mode and to drive the lighting unit (10) starting from the battery (4) in an emergency operation mode.

26. An emergency lighting driver device (1) according to claim 13, wherein the emergency lighting driver device (1) is configured to delay the pulse signal such that the rising edge(s) and/or falling edge(s) of the pulse signal have a transition time of at least 1.0 seconds and less than 3 seconds.