FIELD OF INVENTION:
The present invention generally relates to dual voltage LED lamps connectable to AC
as well 3S DC sources and specifically relates to such lamps which can work on three
sources viz photovoltaic (PV), AC mains and a Battery, in such a way that modulated
AC mains SMPS output decides the output voltage under loaded condition, as PV acts
as a current source around MPPT (Maximum Power Point Tracking) voltage. The
common output is connected to a common regulator which charges the battery as
well as feeds the LED lamp which is dimmable.
BACKGROUND OF INVENTION:
This invention is in continuation of the invention titled 'control circuit for reliable
dimmable high power led lamps' filed earlier against application no. 1495/KOL/2009.
The control circuit for dimming control has been designed using the inputs from the
same.
Another patent titled 'a modular led lighting system suitable for AC mains or solar
photo voltaic (spv) or both with dual voltage led lamps' addresses a multi PV panels
scenario with a common controller for multiple lamps using a common battery, which
also has been filed earlier against application no. 55/KOL/2010.
Prior art LED lamps either work only on the Mains, or on the Mains and a Battery
(emergency light), or PV and a Battery (Solar Lantern)-and are not connectable to all
three sources.
Existing technology of Solar Lantern is meant for off the grid use-hence Lanterns are
highly under utilized. PV just charges the battery, and if the lantern is not used due to
the availability of the grid power, PV power goes waste.
If Lantern is used in the day time its battery does not get charged. Also, during
prolonged monsoons, the lantern becomes useless.
All prior art lamps work on standard 12 V and 24 V Lead Acid batteries-resulting in to
higher losses, while the invention uses non standard 10 V and 20 V batteries (which
match better with Power LEDs characteristics), to reduce losses.
The present invention recognizes a fact that day time lighting is very much required in
the houses and the offices; hence PV power should be utilized on daily basis during
Sun hours even when grid power is available. It should also provide necessary back
up during non Sun hours. The invented lamp continues to work even during prolonged
monsoons if grid power is available unlike Solar Lantern. In villages where grid power
shall become available on a later date, only PV and battery based lamp can not be
utilized in future as it can not be connected to the Mains. Also, only the Mains based
or the Mains and battery based lamps as per existing technology can not tap PV
power to meet the emergency situation of very unreliable, and intermittent availability
of grid power.
SUMMARY OF INVENTION:
The main object of the present invention is to develop DUAL VOLTAGE, TRIPLE
SOURCE LED LAMP which can work on the AC mains and/or on a PV source and on a
Battery. It should be multi purpose and should work as day time light utilizing PV and
in the night like an emergency light. It should work like a Solar Lantern if a main is
not connected. It should work like AC mains fed lamp if neither PV nor battery is
connected.
The controller to be designed in such a way that PV power gets fully utilized near
MPPT point with or without AC mains.
As the power LED devices have standard characteristic, which get matched better with
non standard battery voltages. One object of the invention is to use Lamps with non
standard battery voltages 10 V (floating voltage 11.25 V) for 6 watt, 9 watt and 12
watt lamps 20 V (floating voltage 22.5 V) for 18 watt and 24 watt lamps, which shall
result in to higher efficiency of the lamps.
Another object of the invention is to ensure that the lamp should be dimmable
enabling minimization of the rating of PV and at the same time having flexibility of
getting higher light intensity from the lamp, whenever required.
Still another object is to have better efficiency and longer life by ensuring equal
sharing of current among the parallel strings, by using a control circuit designed as
per an earlier field patent.
The present invention also ensures that deep discharge of the battery is prevented.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1-12 watt and 24 watt dual voltage triple source lamps as per the invention.
Figure 2- Common Regulator (7), connections to other sub modules also depicted.

DETAILED DESCRIPTION OF THE INVENTION:
The invention will now be described in an exemplary embodiment as depicted in the
accompanying drawing. There can however be other embodiments of the same
invention, all of which are deemed covered by this description.
Figure 2: AC Mains SMPS (4) out put is modulated to track the temperature
dependent maximum power point tracking (MPPT) voltage of PV panels (3) to enable
extraction of maximum power from PV. PV output and AC Mains SMPS output are
connected together in such a way that AC mains SMPS output decides the output
voltage under loaded condition, as PV acts as a current source around MPPT
(Maximum Power Point Tracking). The common output is connected to a common
regulator (7) (switch mode), which charges the battery (5), as well as feeds the LED
lamp through an earlier invented control circuit-ensuring that the lamp is dimmable
and maintains equal current sharing between the parallel strings. The controller (6)
ensures that the lamp is blocked under low battery condition, and that battery does
not attain over voltage. A non standard battery voltage is used which results in higher
efficiency due to better matching with the Power LED devices.
Figure i depicts a 12 watt, 10 V lamp (1) and also a 24 watt 20 volts lamp (2). 12
Watt lamp uses 12 nos. 3.3 V, 350 ma (milliampere) high power LEDs connected to
nodes 3- 13-31 (3 in series per strings and 4 such strings in parallel) and 24 watt
lamp uses 24 nos. LEDs (6 in series per strings and 4 such strings in parallel). As
typically three LEDs in series drop approx 10 volts, and 6 in series drop 20 volts, non
standard battery voltages viz. 10 V (floating voltage 11.25 V) and 20 V (floating
voltage 22.5 Volts) result in better efficiency according to this invention.

Similarly 6 watt lamp uses 6 LEDs (3 in series per string and 2 such strings in
parallel), 9 watt uses 9 LEDs (3 in series per string and 3 such strings in parallel) and
18 watt uses 18 LEDs (6 in series per string and 3 such strings in parallel).
Various sub modules used in the lamp have also been depicted in the Figure 1, and
the COMMON REGULATOR and its connections to other sub modules have been
depicted in Figure 2. In the following sections, salient features of various sub modules
have been described.
Each lamp uses a Mains operated SMPS (4) as per the following specifications:
Input: 230 V rms nominal (varation-100 volts to 300 volts rms), 50 or 60 HZ (can be
redesigned for 110 V rms nominal voltage also).
Out put: Constant Voltage DC, 16 V for 10 V system and 32 V for 20 V system at 25
degree Celsius, which has a temperature sensitive feedback circuit (using Negative
Temperature Coefficient resistor R 19 (NTC) as depicted in Figure 2) to change the
output voltage in approx. +/_ 10% range depending on the 0 to 70 degree Celsius
temperature variation of PV panel. This feature ensures that PV power is tapped near
about maximum power point tracking voltage (which is a function of PV panel's
temperature).
Current limit settable: 1.25 times to 1.5 times I normal of the lamp to enable
battery charging as well as for lighting the lamp.
Photovoltaic panel is depicted as 'PV (3). Its maximum power tracking voltage is
specified as approx. 16 V for 10 V system and 32 Volts for 20 volts system.

PV power can even be designed to deliver less than the rated current of the lamp as
lamp is dimmable and can normally be set at lesser light intensity. Output of PV is
connected in parallel with the out put of Mains SMPS through shottky diode Dl as
shown in the Figure 1 and Figure 2. A capacitor CI as per Figure 2 acts as a reservoir
of the common charge. Common regulator (7) uses an IC (Ul), which is a standard 5
pin regulator IC having built in switch mode control and built in MOSFET for power
delivery through inductor LI and shottky diode Dl and capacitor C2. Voltage across
capacitor C2 'Vout' is set using POT Rl and resistor R2 to a value equal to floating
voltage of 10 V battery i.e. 1.25 Volts (approx 22.5 V for 20 V battery). 'Vout' charges
the battery as well as supplies current to LEDs through CONTROL CIRCUIT MODULE.
Battery low condition is sensed through comparator U2A and control circuit (4) is
blocked to switch off LEDs to avoid deep discharge of the battery.
Input to common regulator is sensed through comparator U2B and Ul is blocked to
ensure that PV panel delivers power near MPPT voltage even when AC mains is not
available.
Each lamp uses a control circuit (6) specifically designed using the procedure in the
patent -1. It has following functions:
1. A POT switch is used to On or OFF the lamp.
2. Lamp intensity can be controlled by the POT.
3. Current sharing between the parallel strings is ensured-hence each parallel
string is individually connected to Pre regulator board.
4. Current limit can be adjusted manually.
5. It is blocked to avoid deep discharge of the battery on sensing battery low.

A sealed non standard maintenance free 10 V lead acid battery (5) is used for 12 W
lamp and 20 V battery is used for 24 watt lamp. Amp-hr capacity of the battery is
selected based on the back up time required.
Following embodiments of the multipurpose DUAL VOLTAGE TRIPLE SOURCE LED
LAMPS for 12 w (1) and 24 w (2) ratings (just for illustration, but other power ratings
are also possible using the same process as described in a) and b) below) - are
invented as per the specific characteristics detailed out in subsequent claims.
a) 10 volt, 6 watt/9watt/12 watt using 3 nos. 3.3 V, 350 ma LEDs in series with
2,3, and 4 such strings in parallel respectively.
b) 20 V, 18 watt and 24 watt using 6 nos, 3.3.V, 350 ma LEDs in series with 3 and
4 such strings parallel respectively.
To get over the invention, a person well versed in the state of art may do the
packaging differently e.g. a hybrid PCB can be made combining the functions of AC
Mains SMPS (4), common regulator (7) and control circuit (6). However, the following
unique claims are made with respect to this invention-whatever be the packing
method adopted. The claims, through described for 10 V, 12 W (1) and 20 V 24 W
lamps (2), are applicable to other lamps which can be designed using the techniques
disclosed in this invention.
The invented lamp is multipurpose and has a very high utilization factor as it is meant
for continuous usage (even during day time). If the lamp is connected to the Mains
SMPS and a battery (without connection to PV panel), it works in day time also (unlike
an Emergency Light which is not meant for day time use), at the same time it works
like an Emergency Light if Mains goes off.
If connected to PV without the Mains connection, it works like a solar Lantern. It is
flexible in usage especially in rural areas as grid power can be also be connected to
the lamp as and when it comes to that particular village (in that situation, normal PV
type lamp would have become redundant).
This invention recognizes a fact that day time lighting is very much required in the
houses and the offices, hence PV power should be utilized on daily basis during day
time even when grid power is available. It should also provide necessary back up
during non Sun hours. Unlike a solar Lantern, the invented lamp continues to work
even during prolonged monsoons if grid power is available. The invented lamp utilizes
the PV power to the maximum possible extent, and PV power rating can be minimized
as lamp is dimmable, at the same time the lamp can be used to deliver higher light
intensity whenever required.
Lamps can work with AC mains SNIPS (4), PPV (3) and non standard battery (5), 10 V
and 20 V respectively instead of standard voltages 12 V and 24 V -thereby works at
higher efficiency due to better matching of LED device characteristics.
Input to the lamp can be either 230 V rms, 50/60 HZ nominal (case 1) or 110 V rms
nominal (case 2) with variations as wide as 100 V to 300 V in case 1 and 50 V to 150
V in case 2. A mains SNIPS (1) is designed as per the specifications given under
DESCPJPTTON-SN1, in a way to give constant voltage current limited output of
apparox. 16 V for 6, 9 and 12 watt lamps and approx. 32 V for 18 watt and 24 watt
lamps, which are settable to match PV characteristics and deliver a voltage which
tracks the temperature dependent MPPT voltage of the PV using a NTC resistor.
Output of Mains SMPS is connected to the PV using shottky diodes Dl and the net
ourt put is connected to a common regulator (7).

A common regulator (7) is used to deliver 11.25 volts for 12 w lamp and 22.5 volts for
24 watt lamp using resistors R2 and R1 POT. It ensures that control circuit (6) input
voltage and battery voltage never exceeds the safe limit of 11.25 volts (22.5 V for 20
V system).
Battery low condition is sensed through comparator U2A and control circuit (4) is
blocked to switch off LEDs to avoid deep discharge of the battery.
Input tc common regulator is sensed through comparator U2B and Ul is blocked to
ensure that PV panel delivers power near MPPT voltage even when AC mains is not
available.
Each lamp uses a control circuit (6) specifically designed using the procedure in the
patent- 1 referred under 'BACKGROUND' above. The control circuit has following
functions;
1. A POT switch is used to ON or OFF the lamp,
2. Lamp intensity can be controlled by the POT,
3. Current sharing between the parallel strings is ensured hence each parallel
string is individually connected to Pre-regulator board.
WE CLAIM:
1. A LED lamp connectable to AC as well as DC source and capable of working on
three sources viz Photovoltaic (PV), AC mains and a battery, the said AC mains
driven SMPS output modulated to track the temperature dependent maximum
power point tracking (MPPT) voltage of PV panels, to enable extraction of
maximum Power from PV, and the PV output so extracted and the AC mains
output taken together forming essential inputs to the said lamp where AC
mains output decides the output voltage under loaded condition, as PV acts as
current source around MPPT; the common output being connected to a
common regulator (7), charges the battery (5) and feeds the said lamps
through a control circuit (6) ensuring that the lamp is dimmable.
2. The LED lamps as claimed in claim 1 are in 10 V or 20 volts rating having
6/9/12 watts or 18/24 watts respectively.
3. The LED lamps as claimed in claim 1 are powered from 230 V rms (root mean
square), 50/60 HZ (case 1) or 110 V rms 50/60 HZ (case 2) AC mains.
4. The LED lamps as claimed in claim 4 may have variations of input voltage
within a range of 100 V to 300 V in case 1 and 50 V to 150 V in case 2.
5. The LED lamps as claimed in claim 1 are powered through SMPS (4) and gives
constant voltage current limited output of 16 V for 6/9/12 watt lamps and 32 V
for 18/24 lamps.
6. The output of the SMPS (4) as claimed in claim 6 is connected to the PV (3)
using schottky diodes D1 and the net output is connected common regulator
(7).

7. The constant output of the SMPS (4) as claimed in claim 7 are settable to
match PV characteristics and deliver a voltage which tracks the temperature
dependant MPPT voltage of the PV using a NTC resistor.
8. The LED lamps as claimed in claim 1 are connected to common regulator (7)
which is used to deliver 11.25 volts for 12 w lamp and 22.5 volts for 24 watt
lamps using resistors R2 and R1 POT and also ensures that control circuit (6) in
put voltage and battery voltage never exceeds the predetermined safe limit.
9. The LED lamp as claimed in claim 1 is connected to a control circuit (6) is
which used for switching purpose of the lamp, controlling intensity by the POT
and ensuring current sharing between the parallel strings.
10. A system for using multipurpose dual voltage, triple sources dimmable LED
lamp comprising:
a. An array of LED lamps connectable to AC as well as DC and can work on
PV, AC mains and batteries (1) and (2),
b. AC main driven SMPS (4),
c. Photovoltaic cell (PV) (3),
d. Common regulator (7),
e. Control circuit (6),
f. Battery (5).
11. The system as claimed in claim 10 has provision for arrangement of a 10 V/6
Watt/9 Watt/12 Watt combination 350 ma (milliampre) LED devices in series
with suitable number of such strings in parallel.
The system as claimed in claim 10 has also provision for arrangement of a 20
V/18 Watt/24 Watt combination 350 ma (milliampre) LED devices in series with
suitable number of such strings in parallel.
12. The system as claimed in claim 10 has provision for a common regulator (7)
which delivers 11.25 V for 12 Watt lamps and 22.5 volts for 24 Watt lamps
using R2 and R1 POT.
13. The system as claimed in claim 10, wherein the common regulator (7) ensures
that the control circuit (6) in put voltage and battery voltage never exceeds the
sage limit of 11.25 volts for 10 V system and 22.5 V for 20 V system.
14. The system as claimed in claim 10, wherein the in put the common regulator
(7) is sensed through comparator U2B and U1 is blocked to ensure that PV
panel delivers power near MPPT voltage even when AC man is not available.
15. The system as claimed in claim 10 has provision for control circuit (6) for each
lamp.
16. The control circuit (6) as claimed in claim 16 switches the lamps through a
POT switch controls intensity of the lamp ensures current sharing between
parallel strings in a way such that each parallel string is individually connected
to pre regulator board.
17. The battery as claimed in claim 10 is provided with a sensing device to sense
low battery condition through comparator U2A and control circuit (6) is blocked
switch off LEDs to avoid deep discharge of the battery.

A LED lamp connectable to AC as well as DC source and capable of working on three
sources viz. Photovoltaic (PV), AC mains and a battery, the said AC mains driven
SNIPS output modulated to track the temperature dependent maximum power point
tracking (MPPT) voltage of PV panels, to enable extraction of maximum Power from
PV, and the PV output so extracted and the AC mains output taken together forming
essential inputs to the said lamp where AC mains output decides the output voltage
under loaded condition, as PV acts as current source around MPPT. The common
output being connected to a common regulator (7), charges the battery (5) and feeds
the said lamps through a control circuit (6) ensuring that the lamp is dimmable.