U.S. patent application number 14/382612 was filed with the patent office on 2015-02-19 for lamp unit power supply system.
This patent application is currently assigned to TRIDONIC UK LTD. The applicant listed for this patent is TRIDONIC UK LTD. Invention is credited to Ian Wilson.
Application Number | 20150048685 14/382612 |
Document ID | / |
Family ID | 46003332 |
Filed Date | 2015-02-19 |
United States Patent
Application |
20150048685 |
Kind Code |
A1 |
Wilson; Ian |
February 19, 2015 |
LAMP UNIT POWER SUPPLY SYSTEM
Abstract
A power supply system for illuminating an LED lamp unit 5,
having a normal mode of operation in which a mains input 4 of a
driver 3 of the LED lamp unit is supplied by mains power 1, and an
emergency mode of operation, in which the LED lamp unit is supplied
by a charge storage device 19, is disclosed. The system includes an
emergency mode converter 21 operable to step-up the voltage from
the charge storage device and to supply the mains driver input for
illuminating the LED lamp unit.
Inventors: |
Wilson; Ian; (East
Herrington, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRIDONIC UK LTD |
Chineham Basingstoke |
|
GB |
|
|
Assignee: |
TRIDONIC UK LTD
Chineham Basingstoke
GB
|
Family ID: |
46003332 |
Appl. No.: |
14/382612 |
Filed: |
March 7, 2013 |
PCT Filed: |
March 7, 2013 |
PCT NO: |
PCT/EP2013/054591 |
371 Date: |
September 3, 2014 |
Current U.S.
Class: |
307/66 |
Current CPC
Class: |
H02J 9/061 20130101;
H05B 45/37 20200101; H02J 7/02 20130101; H05B 45/385 20200101; H05B
45/38 20200101; H02J 9/062 20130101; H05B 45/39 20200101 |
Class at
Publication: |
307/66 |
International
Class: |
H05B 33/08 20060101
H05B033/08; H02J 7/02 20060101 H02J007/02; H02J 9/06 20060101
H02J009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2012 |
GB |
1204106.7 |
Claims
1. A power supply system for illuminating an LED lamp unit (5),
having a normal mode of operation in which a mains input (4) of a
driver (3) of the LED lamp unit (5) is supplied by mains power (1),
and an emergency mode of operation, in which the LED lamp unit (5)
is supplied by a charge storage device (19), the system includes
comprising an emergency mode converter (21) configured to step-up
the voltage from the charge storage device (19) and to supply the
mains input (4) for illuminating the LED lamp unit (5).
2. The system of claim 1, wherein the emergency mode converter (21)
is configured to step-up the voltage from the charge storage device
(19) to a similar voltage to that of the mains power in the normal
mode or operation.
3. The system of claim 1, wherein the emergency mode converter (21)
comprises a: flyback; forward; push-pull; half-bridge; buck-boost
or SEPIC converter.
4. The system of claim 1, further comprising a controllable switch
(7, 9, 11) configured to selectively provide mains power (1) to the
mains input (4) of the driver (3) in the normal mode, and power
from the charge storage device (19) to the mains input (4) of the
driver (3) in the emergency mode.
5. A power supply method for illuminating an LED lamp unit (5),
having a normal mode of operation in which a mains input (4) of a
driver (3) of the LED lamp unit (5) is supplied by mains power (1),
and an emergency mode of operation, in which the LED lamp unit (5)
is supplied by a charge storage device (19), method comprising
providing an emergency mode converter (21) to step-up the voltage
from the charge storage device (19) and to supply the mains input
(4) to illuminate the LED lamp unit (5).
6. The method of claim 5, wherein the emergency mode converter (21)
steps-up the voltage from the charge storage device (19) to a
similar voltage to that of the mains power in the normal mode of
operation.
7. The method of claim 5, wherein the emergency mode converter (21)
comprises a: flyback; forward; push-pull; half-bridge; buck-boost
or SEPIC converter.
8. The method of claim 5, further comprising using a controllable
switch (7, 9, 11) to selectively provide mains power (1) to the
mains input (4) of the driver (3) in the normal mode and power from
the charge storage device (19) to the mains input (4) of the driver
(3) in the emergency mode.
Description
TECHNICAL FIELD
[0001] The present invention relates to power supply system and
method for illuminating an LED lamp unit, having a normal mode of
operation in which a mains input of a driver of the LED lamp unit
is supplied by mains power, and an emergency mode of operation, in
which the LED lamp unit is supplied by a charge storage device.
BACKGROUND TO THE INVENTION
[0002] Various arrangements for lighting systems are known which
provide both conventional and emergency lighting. Such emergency
lighting is intended to be activated when the conventional lighting
is no longer operative because the direct mains supply to the
conventional lighting is no longer available or malfunctions.
Emergency lighting is typically powered by a battery or other
energy storage device. Conventional lighting is controlled by an
on/off switch by means of which a user (or control system) can
control whether the lighting is illuminated or not. Generally,
emergency lighting is intended to be automatically illuminated when
the absence of mains power or the malfunction of mains power for
the conventional lighting is detected in some way. Emergency
lighting may be used to allow escape from buildings that would
otherwise be in darkness due to the inoperativeness of the
conventional lighting.
[0003] A lighting system comprising emergency lighting and
conventional lighting may be considered to have two operating
modes. In a normal mode, when the direct mains supply is operating
normally (within the normal voltage range), a switched mains input,
controlled by an on/off switch, is monitored, and the lamp is
illuminated or extinguished in dependence upon the switched mains
input In an emergency mode, when the mains supply is not available
or is malfunctioning (is outside the normal voltage range), the
lamp is illuminated automatically, irrespective of the status of
the switched mains input, using power from a battery or other
storage element.
[0004] Emergency lighting and conventional lighting may share
components. For example, the same lamp (such as an LED also called
Light Emitting Diode, lamp unit) may be used for both conventional
and emergency lighting. Other components may also be shared.
However, known arrangements, where the same LED lamp unit is used
in both the normal and emergency modes, require a separate driver
to drive the LED lamp unit from the battery in the emergency mode,
in addition to a mains driver for driving the LED lamp unit from
the mains in the normal mode. Separate drivers are used because the
battery and mains supplies have very different characteristics.
Providing two drivers is disadvantageous for cost and space
reasons. Also, the requirement for a separate driver to drive the
LED lamp unit from the battery in the emergency mode makes it
difficult to add emergency mode functionality to an existing
lighting system.
SUMMARY OF THE INVENTION
[0005] In one aspect, the present invention provides a power supply
system for illuminating an LED lamp unit, having a normal mode of
operation in which a mains input of a driver of the LED lamp unit
is supplied by mains power, and an emergency mode of operation, in
which the LED lamp unit is supplied by a charge storage device,
characterised in that the system includes emergency mode converter
means operable to step-up the voltage from the charge storage
device and to supply the mains driver input for illuminating the
LED lamp unit.
[0006] The charge storage device may be a battery or a
capacitor.
[0007] The emergency mode converter means may comprise a boost
converter, advantageously an isolated boost converter, that
provides a DC output at normal mains level so that it enables a
normal LED driver to be powered off the charge storage device for
the emergency duration. The emergency mode converter means may
comprise a boost converter, advantageously an isolated boost
converter, that provides a DC output at a level different to normal
mains level but which nevertheless enables a normal LED driver to
be powered off the charge storage device for the emergency
duration.
[0008] The emergency mode converter means may comprise instead of a
boost converter a fly-back or forward or push-pull or half-bridge
converter or buck-boost or a SEPIC (single-ended primary-inductor
converter) converter.
[0009] The system may include controllable switch means operable to
selectively provide mains power to the mains input of the driver in
the normal mode and power from the charge storage device to the
mains input of the driver in the emergency mode. In this way, the
driver and the lamp unit may be powered in both the normal mode and
the emergency mode. The emergency mode converter may be controlled
in a way that a fixed discharge current of the charge storage
device can be achieved.
[0010] Either signalling such as DALI or automatic detection of the
DC rail may be used to reduce the power in the mains LED driver if
desired, when power is supplied from the charge storage device. The
embodiment provides an advantage of flexibility and fast time to
market by using existing LED drivers (converters) during the
emergency mode.
[0011] In another aspect, the present invention provides a power
supply method for illuminating an LED lamp unit as defined in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a better understanding of the present invention an
embodiment will now be described by way of example, with reference
to the accompanying drawings, in which FIG. 1 shows schematically
the elements of a lighting arrangement that provides both a normal
mode and an emergency lighting mode.
DETAILED DESCRIPTION OF EMBODIMENT OF THE INVENTION
[0013] FIG. 1 shows schematically the elements of a lighting
arrangement that provides both a normal mode and an emergency
lighting mode. A direct mains AC supply 1 provides power in the
normal mode to a driver 3 optimised for use with the mains supply 1
(e.g. 230 volts, 50 Hz in the EU).
[0014] The driver 3 is supplied with power at a mains input 4 when
a mains relay 7 is closed. A control part 8 monitors the mains AC
supply 1. If the control part 8 detects that the mains AC supply 1
is interrupted, or if it is determined to be malfunctioning
(operating outside an acceptable range of values), the control part
8 may provide an appropriate signal to relay control line 9 to open
the mains relay 7 and to close an emergency relay 11. The emergency
relay 11 allows the lamp 5 to be driven in an emergency mode. The
driver 3 is preferably an independent driver which is only
connected to the mains AC supply through the mains relay 7 which is
closed when mains AC supply is available. In a preferred embodiment
there is no additional link between driver 3 and emergency lighting
module 12.
[0015] To provide the emergency mode, an emergency lighting module
12 includes, in addition to the mains relay 7, relay control line 9
and emergency relay 11, a smoothing input filter 13, a rectifier 15
(typically a bridge rectifier), a battery charger 17 (a SELV,
Separated Extra Low Voltage, isolated DC-DC converter, a flyback
converter, for example), a battery 19 and a step-up converter 21.
The battery charger 17 may provide galvanic isolation between the
AC mains supply 1 and the battery 19 for safety reasons. The
converter 21 may likewise provide galvanic isolation of the battery
19 from the lamp 5.
[0016] The battery 19 may comprise a plurality of cells. Another
energy storage device may be used instead of the battery 19.
[0017] When the mains AC supply 1 is operating normally (and the
lamp 5 is powered by the AC supply 1), the battery 19 may be
charged (continuously or when required) by the battery charger 17.
The mains relay 7 is closed when mains AC supply 1 is operating
normally and the LED is fed by the Standard LED driver 3. When the
control part 8 detects that the AC supply 1 is interrupted (or
malfunctioning), the emergency relay 11 is closed (the mains relay
7 is opened), and the driver 3 illuminates the lamp 5 using power
from the battery 19.
[0018] As discussed above, the lighting arrangement shown in FIG. 1
includes the control part 8 which detects when the AC mains supply
1 is present and operating correctly--such as when the AC mains
supply 1 presents a voltage higher than a certain threshold (187
volts in a 230 volt nominal supply, for example). When the AC mains
supply 1 is present and operating correctly, the AC supply 1
provides power to illuminate the lamp via closed relay 7. Power
from the AC mains supply 1 is also provided to battery charger 17
to charge the battery 19 (or to keep the battery 19 fully charged).
The control part 8 is preferably a part of the emergency lighting
module 12.
[0019] The battery charger 17 is constituted, in this example, by a
so-called flyback converter which exhibits, on the one hand, a
transformer T with a primary winding L.sub.P and a secondary
winding L.sub.S and also, on the other hand, a controllable switch
S.sub.1. In known manner, by an appropriate alternating opening and
closing of the switch S.sub.1 the energy made available by the AC
mains supply 1 is transmitted to the secondary side of the flyback
converter and utilised for the purpose of charging the battery 19.
The transmission of energy takes place in the open state of the
switch S1, wherein for this purpose a diode D.sub.1 is furthermore
provided on the output side of the flyback converter. The battery
charger 17 is constituted by an isolated DC-DC converter. Instead
of a flyback converter other isolated converter topologies like a
forward converter or an isolated SEPIC converter may be used as
well.
[0020] The control part 8 also controls various aspects of
operation of the driver 3, including the power supplied to the LED
lamp 5--so that the level of illumination (dimming) can be
varied.
[0021] The control part 8 monitors switched mains input 20, and, in
the normal mode of operation, illuminates the LED lamp 5 (using the
driver 3) when the switched mains input 20 is on.
[0022] The control part 8 may determine the status of the switched
mains input 20 in any suitable manner. For example, it is known to
apply the switched mains input 20 to a potential divider, and then
to a voltage threshold detector with an isolation circuit, such as
an opto-coupler. Typically, the switched mains input 20 is
rectified by a rectifier before being applied to the voltage
threshold detector and the isolation circuit. When the switched
mains input 20 is on, the output of the isolation circuit will be a
pulsed signal, the presence of which can be detected by logic
within the control part 8. When the switched mains input 20 is off,
the output of the isolation circuit will be a constant value (zero
volts) and this can also be detected by logic of the control part
8. The control part 8 then operates the driver 3 and lamp 5 in
accordance with the state of the switched mains input 20.
[0023] The lighting system may optionally comprise an interface 25,
e.g. a DALI (Digital Addressable Lighting Interface), that is
connected to a bus 26 (e.g. DALI bus), for intensity control
(dimming) and/or for maintenance and service control. DALI is a
communication protocol widely used in lighting systems. A two wire
serial communication arrangement establishes a master/slave
communication between a central DALI controller (not shown) and the
lighting system control part 8 by setting low and high levels of
voltages. Data are transferred between the DALI controller and
lighting system control part 8, by means of an asynchronous,
half-duplex, serial protocol over a two-wire differential bus, with
a fixed data transfer rate of 1200 bit/s. The DALI data are
transmitted using Manchester encoding. The protocol standard sets
high levels as voltage differences high at 9.5V (either positive or
negative) between the two wires. Low levels are set as voltage
differences of less than 6.5V.
[0024] The converter 21 may comprise a flyback or forward or
push-pull or half-bridge or isolated boost converter with a step-up
characteristic and a SELV isolation barrier, whose input is
connected directly to the battery 19. The converter 21 may comprise
as an alternative variant a non-isolated topology as for example a
buck-boost converter.
[0025] The converter 21 comprises an input part X. The input part X
comprises a switch S.sub.2 and a primary winding section N.sub.1
which is connected in parallel across the battery 19. By operation
of the switch S.sub.2, the input part produces a rectangular output
voltage. The time for which each of the switch is closed and the
frequency of operation (opening/closing) of the switch is
controlled by a driver controller (not shown).
[0026] The input part X of the converter 21 supplies an output part
Y. The output part Y includes a secondary winding N.sub.2 with a
rectifier unit and a smoothing filter, e.g. a L (inductor) series C
(capacitor) parallel filter, connected to it. The rectifier unit
may be formed by a single diode or by full wave rectifier. The
converter 21 may provide a DC voltage or an AC voltage on its
output. In case of an DC output the output part Y may comprise a
rectifier and smoothing filter as shown in the example. When the
control part 8 detects that the AC mains supply 1 is interrupted or
malfunctioning--such as when the mains AC supply 1 presents a
voltage lower than a certain threshold (145 volts in a 230 volt
nominal supply, for example) the control part 8 opens the mains
relay 7, closes the emergency relay 11, and activates the converter
21. The converter 21 provides power to illuminate the lamp 5 from
only the battery 19 via the closed emergency relay 11.
[0027] In accordance with an important feature of the embodiment,
the converter 21 may provide an output at normal mains level so
that the output can be applied to the same mains input 4 of the
driver 3 as the AC mains supply 1 in the emergency mode. It is also
possible that the converter 21 provides an output at a level
different from the normal mains level but which is nevertheless
sufficient so that the output can be applied to the same mains
input 4 of the driver 3 as the AC mains supply 1 in the emergency
mode. The same components of the driver 3 may be used in both the
normal and emergency modes. The converter 21 may provide a DC
voltage or an AC voltage to the mains input 4 of the driver 3.
Optionally, the AC mains supply 1 may be applied to a rectifier
unit and a smoothing filter (not shown) so that a smoothed DC
voltage is applied to the mains input 4 of the driver 3 in the
normal mode.
[0028] This has the advantage that a separate driver for driving
the LED light unit 5 is not required in the emergency mode. Because
the output of the converter 21 is at (or near) the normal mains
level, it can be applied to the driver 3 as if it was the AC mains
supply 1. No modification to the driver 3 is required to allow an
emergency mode to be possible. This is advantageous if it is
desired to add emergency mode functionality to an existing light
installation. The emergency module 12 can be added to the existing
installation (comprising the driver 3, which is normally powered by
the AC mains supply 1, and the LED light unit 5)--and the existing
driver 3 can be used in the emergency mode without
modification.
[0029] The converter 21 may be controlled in a way that a fixed
discharge current of the charge storage device 19 can be achieved.
The discharge current of the charge storage device 19 can be
controlled by the converter 21. Preferably the converter 21 is
operated in a way where the discharge current of the charge storage
device 19 is fixed or is depending on a given curve depending on
the voltage or status of the charge storage device 19. Such control
of the converter 21 of the discharge current of the charge storage
device 19 can offer an optimised utilization of the charge storage
device 19 according to the given capacity of this charge storage
device 19 and/or depending on the expected or intended duration of
the emergency mode.
[0030] Depending on the type of mains voltage detected on the
direct mains input 1, the control part 8 may put the driver 3 into
different operation modes, e.g. to illuminate the lamp 5 at a given
intensity level. For example, if it is detected that the direct
mains input 1 is absent or malfunctioning (emergency mode), the
control unit may cause the driver 3 to lower the light intensity
level of the lamp unit 5 (dimming) in order to reduce power
consumption.
[0031] It is also possible the there is no DALI bus 26 and no
control part 8. In such case the driver 3 can be formed to be able
to monitor the voltage on the mains input 4 of the driver 3 and to
detect a change of the mains input 4 by a detection of the type of
voltage or amplitude of the voltage detected on the mains input 4
of the driver 3. For example the operation mode of the driver 3 can
be changed to emergency mode in case where a DC voltage is detected
on the mains input 4 of the driver 3. The driver 3 may be able to
detect that it is supplied with a voltage at a level different from
the normal mains level and may be able to automatically reduce the
current or power supplied to the LED 5 in such case as can be
detected as operation in emergency mode.
[0032] The dimming level may also be varied by signalling via the
DALI interface 25 and DALI bus 26.
[0033] Although the embodiment uses a forward converter as
emergency mode converter means 21, several other converter
arrangements, e.g. a push-pull converter, are able to provide a
suitable voltage output, and may be used in accordance with the
invention.
* * * * *