Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
  • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
  • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
  • H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
  • H02J9/065—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads for lighting purposes

Definitions

• At least one embodiment in accordance with the present invention relates generally to switch mode power supplies and more particularly to systems and methods of providing a dual power Switch Mode Power Supply (SMPS) for a modular lighting system.
• SMPS Switch Mode Power Supply
• Solar, battery and electric grid lighting systems are well known, including those that use incandescent bulbs, fluorescent bulbs, and light emitting diodes (LEDs) as light sources.
• LEDs light emitting diodes
• the availability of reliable electric grid power systems remains spotty at best and alternate source systems can be expensive to install and operate and are not always compatible with available lighting sources.
• Efficient lighting systems may be used particularly in areas having unreliable and or prohibitively expensive electric grid systems.
• Designers of such lighting systems look for ways of reducing components in the lighting system while providing a reliable source of power to lighting modules.
• At least one embodiment discussed herein is directed to an efficient lighting system for use particularly in areas having unreliable and or prohibitively expensive electric grid systems.
• a first aspect of the invention is directed to a light assembly that includes a first input to receive power from a power source, a controllable power supply having a control input, a power input coupled to the first input, and an output to provide an output voltage having a voltage level controllable based on a control signal received at the control input, a battery input coupled to the output of the controllable power supply, and configured to couple to a battery, a light circuit coupled to the output of the controllable power supply and configured to provide output light in response to the output voltage, a feedback circuit configured to detect a current to the battery and a voltage across the battery and having an output coupled to the control input of the controllable power supply to provide the control signal to the controllable power supply based on at least one of the current to the battery input and the voltage across the battery.
• the controllable power supply may further include a PWM controller coupled to the power input.
• the PWM controller may be configured to generate a pulse width modulated signal having a duty cycle.
• the PWM controller may be further configured to decrease the duty cycle of the pulse width modulated signal based on the control signal having a first state indicating that at least one of the current to the battery input and the voltage across the battery is above a threshold.
• the PWM controller may be also configured to increase the duty cycle of the output voltage based on the control signal having a second state different from the first state.
• the controllable power supply may comprise a transformer, configured to receive power from the power input.
• the first input may be configured to receive power from an AC power source.
• the light assembly may further comprise a second input configured to receive power from a solar power source.
• the light assembly may additionally comprise a DC-DC converter having a converter control input, a power input coupled to the second input, and a converter output to provide a converter output voltage having a converter voltage level controllable based on a converter control signal received at the converter control input, a converter feedback circuit configured to detect a current to the battery and a voltage across the battery and having an output coupled to the converter control input of the DC-DC converter to provide the converter control signal to the DC-DC converter based on at least one of the current to the battery input and the voltage across the battery.
• the light circuit may be coupled the converter output and configured to provide output light in response to the converter output voltage.
• Another aspect of the invention is directed to a method of illuminating a room.
• the method includes receiving power from a power source, generating a DC voltage derived from the received power, the DC voltage having a voltage level, applying the DC voltage to a light circuit, applying the DC voltage to the battery, detecting a current to the battery, detecting a voltage across the battery, and controlling the voltage level based on at least one of the current to the battery and the voltage across the battery.
• the act of controlling the voltage level may further comprise generating a pulse width modulated signal having a duty cycle.
• the act of controlling the voltage level may further comprise decreasing the duty cycle of the pulse width modulated signal if at least one of the current to the battery and the voltage across the battery is above a threshold.
• the act of controlling the voltage level may further comprise increasing the duty cycle of the pulse width modulated signal until the current to the battery has reached a threshold or the voltage across the battery has reached a threshold.
• the act of generating a DC voltage may further comprise using a transformer to step down a voltage derived from the received power.
• the act of receiving power from a power source may further comprise receiving power from at least one of an AC power source and a solar power source.
• the method may further include providing power to the light circuit from the battery.
• Another aspect of the invention is directed to a light assembly that includes at least one input to receive power from a power source, a controllable power supply having a control input, a power input coupled to the at least one input, and an output, a battery input coupled to the output of the controllable power supply, a light circuit coupled to the output of the controllable power supply and configured to provide output light, and means for controlling the power supply to provide a regulated voltage to the light circuit and regulated charging current and charging voltage to a battery coupled to the battery input.
• the at least one input may include a first input configured to couple to an AC power source and a second input configured to couple to a solar power source.
• the controllable power supply may be configured to provide output DC power to the battery input and to the light circuit.
• the light assembly may further include means for detecting loss of AC power at the at least one input and for providing power to the light circuit from the battery.
• the means for controlling may include means for charging the battery in a first mode supplying substantially constant current to the battery, and means for charging the battery in a second mode supplying a substantially constant voltage across the battery.
• FIG. 1 shows a functional block diagram of a lighting system, in accordance with one embodiment
• FIG. 2A shows a functional block diagram of a dual power SMPS used in the embodiment of FIG. 1;
• FIG. 2B shows a more detailed functional block diagram of the dual power SMPS shown in FIG. 2A;
• FIG. 2C shows a functional block diagram of a DC-DC converter used in the embodiment of FIG. 1; ⁇ ⁇
• FIG. 3 shows an LED array used in the embodiment of FIG. 1 ;
• FIG. 4 shows an exploded view of a lighting assembly in accordance with one embodiment
• FIG. 5 shows a first perspective view of the lighting assembly of FIG. 4.
• FIG. 6 shows a second perspective view of the lighting assembly of FIG. 4.
• At least some embodiments disclosed herein are directed to modular, efficient lighting systems and methods, including LED lighting systems, operable from DC power sources including battery power sources, fuel cells, and solar power, and AC power sources including a utility electrical grid, generator or other AC power source. At least some embodiments are directed to LED lighting systems that are configurable for dual power mode operation to allow low power operation on battery power. At least some embodiments are directed to providing a dual power switch mode power supply configured to regulate the supply of power from both the AC power sources and DC power sources and to provide constant power to both the LED lighting sources and the battery to charge the battery.
• FIG. 1 is directed to a functional block diagram of a modular LED lighting system 100 in accordance with one embodiment.
• the lighting system 100 includes an array of LEDs 102, a dual power output control circuit 104, an LED driver circuit 106, a detection circuit 108, mode switches 110 and 112, a battery monitoring circuit 114, a DC-DC converter 118, a dual power Switch Mode Power Supply (SMPS) 120, a battery 122, a solar power source 124, and an AC power source 126.
• SMPS Switch Mode Power Supply
• functional circuits may be grouped differently than shown in FIG. 1.
• the LED array 102 is coupled between the dual power output control circuit 104 and the LED driver 106.
• Mode switches 110 and 112 are coupled between the LED driver circuit 106 and the battery 122, and the mode switches are also coupled to an output of the dual power SMPS 120.
• the DC-DC converter 118 is coupled between the solar power source 124 and the the mode switches 110 and 112. .
• the dual power SMPS 120 is coupled between the AC power source and the mode switches 110 and 112.
• the battery 122 is coupled to the dual power SMPS 120, mode switch 112 and the battery monitoring circuit 114.
• the detection circuit 108 is coupled to the dual power SMPS 120 output, DC-DC converter 118 output and the dual power output control circuit 104.
• the LED array In operation, light is provided by the LED array from power provided from one of the AC power source 126, the solar power source 124 and the battery 122.
• the dual power SMPS 120 When operated from the AC power source 126 or from the solar mode of operation, the dual power SMPS 120 provides one output of voltage to the LED driver 106 and LED array 102 and provides another output of voltage and constant current to the battery 122.
• mode switch 112 is open to isolate the battery, while mode switch 110 is configured to couple the output of the dual power SMPS 120 to the LED driver circuit 106.
• the LED driver circuit 106 receives the output of voltage of the dual power SMPS 120 and provides an output constant current for the LED array 102 to light the LEDs.
• mode switch 110 is configured to couple the output of the DC-DC converter 118 to the LED driver circuit 106.
• the DC-DC converter is configured to receive DC power from an external solar power system 124 having a voltage between 16 volts and 21 volts and to provide output DC power of 14.5 volts to the battery 112 and the LED driver circuit 106. In other embodiments, other voltages may be used to accommodate operation with other solar power systems.
• the dual power output control circuit 104 is used to provide a low power mode of operation of the lighting system 100 when operated from battery power. In the AC and solar modes of operation, the dual power output control circuit 104 is controlled to operate in normal, high power mode of operation.
• both mode switch 112 and mode switch 110 are configured to couple the output of the battery to the input of the LED driver.
• the lighting system is configured to operate with a battery having an output voltage of 11.5 volts to 13.5 volts, but in other embodiments, other battery voltages may be used. In at least one
• the lighting system is configured to operate with an external battery to
• an internal battery may be used in addition to an external battery or in place of the external battery.
• the detection circuit 108 detects the present of AC and solar power, and in one embodiment, selects operation from the solar power source when both AC power and solar power is available to operate the lighting system 100 in a more economical manner.
• the detection circuit 108 also provides a signal to the dual power output control circuit 104 to control the circuit for high power operation if either AC power or solar power is available. If neither AC power nor solar power is available, then the detection circuit 108 controls the dual power output control circuit to operate in low power mode. Operation of the lighting system at low power in battery mode of operation allows the battery to operate for a longer period of time.
• the dual power output control circuit 104 is implemented using parallel resistors in series with the LED array, and a switch (such as a transistor) is used to alter the value of the resistance in series with the LED array to limit the drive current to the LED array.
• a switch such as a transistor
• the total current through the LED array is 580mA in high power mode of operation and is reduced to 500mA in low power mode of operation.
• mode switch 110 is a pull cord switch that may be used by a user to power the lighting system 100 on and off.
• the pull cord switch is connected between the dual power SMPS 120 output, internal switch 112 and LED driver 106.
• the internal switch 112 is a controllable switch, such as a diode.
• the switch may be controlled by forward biasing or reverse biasing the diode.
• the diode is reverse biased when the power is available either from dual power SMPS 120 and/or DC -DC converter 118 thereby disconnecting the LED driver 106 from the battery 122.
• the diode is forward biased when the power is not available either from dual power SMPS 120 or from DC -DC converter 118 and the lighting system 100 is powered from the battery 122.
• switch 112 is controlled to be in the open position if solar or AC power is available, and if neither is available, the switch 112 is closed to couple the battery 122 to the LED driver 106.
• the battery monitoring circuit 114 is coupled to output of battery 122 and LED driver 106. This circuit monitors remaining charge of the battery and gives a signal to the driver 106 to cut off the power supply to LED array 102 when the battery drains to 50 % of its full charge level. In other embodiment the battery may be drained to 80% of its full charge level. The RED indication LED is ON, when the battery drains to 50% of its full charge capacity and the pull switch 110 is ON position.
• the dual power SMPS 120 includes a PWM (Pulse Width Modulation) controller 202, a transformer 204, a feedback circuit 206, a rectifier and filter 214 and a multiplexer 208.
• the load 210 in one embodiment, is a light circuit that includes the LED driver 106 and the LED array 102.
• the dual power SMPS When operated from the AC power source 126, the dual power SMPS receives the input AC power and converts the AC power to DC power.
• the input AC power may be filtered by an EMI (Electro-Magnetic Interference) filter, converted to DC power by a rectifier and smoothed by a capacitor filter,
• EMI Electro-Magnetic Interference
• the resultant DC power has a relatively high voltage of 230 volts.
• other input voltages may be used and single phase or multi-phase power may be used.
• the PWM controller 202 receives the high voltage DC power and provides high frequency pulse width modulated output power to transformer 204. In one embodiment, a switching frequency of 62 kHz is used by the PWM controller 202.
• the transformer 204 receives power from the PWM controller 202 and steps down the high voltage to provide a lower voltage.
• the dual power SMPS 120 provides the lower voltage to the load 210 to power the LED array 102.
• the SMPS 120 may have one or more rectifier and filter circuits 214 that are made of smoothing components that rectify AC power to DC power and filter components that filter the DC power to provide, in one embodiment, a controlled output voltage to charge the battery and power to the lighting system 100.
• the dual power SMPS 120 also provides power to charge the battery.
• the battery 122 may be charged from either AC power, or if AC power is not available from the solar power provided by the DC-DC converter 118.
• the battery is charged in two modes: a constant current mode and a constant voltage mode. The two charging modes protect the battery from overcharging at the end of the charging cycle and provide better charge termination at the end of the charge. If the battery is discharged, the dual power SMPS will charge the battery in constant current mode at a constant current until the charge on the battery reaches a battery current charging threshold. Once the voltage on the battery reaches the battery current charging threshold, the dual power SMPS 120 will charge the battery in constant voltage mode at a constant voltage. The dual power SMPS 120 will charge the battery at the constant voltage until the battery reaches a battery voltage charging threshold indicating that the battery is fully charged.
• the dual power SMPS 120 determines the current and the voltage on the battery.
• the feedback circuit 206 receives the voltage from the transformer 204 and provides a voltage indication of the sensed current output to the multiplexer 208.
• a voltage signal indication of the voltage across the battery 122 is also provided to the multiplexer 208.
• the multiplexer 208 triggers a feedback signal to the PWM controller 202 if the current through the battery reaches the battery current charging threshold or if the voltage on the battery reaches the battery voltage charging threshold.
• the feedback provided to the PWM controller is described in more detail with reference to FIG. 2B. As shown in FIG.
• the transformer 204 includes a primary winding, a secondary winding and an auxiliary winding.
• the PWM controller 202 modulates power supplied to the primary winding of the transformer 204.
• the primary winding induces AC voltage in the secondary winding to produce AC voltage of lower amplitude as the secondary output.
• the primary winding also induces AC voltage in the auxiliary winding to produce AC voltage of lower amplitude as the auxiliary output.
• the auxiliary output is used to provide bias voltage to an optocoupler switch 212, which is used to isolate the feedback to the PWM controller 202.
• the controlled output voltage range from 11.5 volts to 14.3 volts depending on the charge state of the battery.
• the solar power will be used to charge the battery 122.
• DC power from the DC- DC converter 118 is provided at node 224.
• voltage from the DC-DC converter 118 is 14.5 volts, while voltage from the rectifier and filter circuit 214 is 14.3 volts.
• the feedback circuit 206 comprises a current sense resistor 3 placed between the SMPS 120 ground and the battery 122 ground and in one example, has resistance of 0.03 Ohms.
• the feedback circuit has an op-amp comparator 216 that compares the voltage drop across . the current sense resistor R3, as a voltage indication of the current across the battery, with a reference voltage 218 and outputs the sensed current to the
• the multiplexer 208 is comprised of two diodes, D4 and D5.
• the diode D4 receives output from the op-amp comparator 216 and the diode D5 receives voltage sensed across the battery, which is scaled down by a voltage divider 220.
• the multiplexed feedback signal from D4 and D5 is applied to a shunt regulator 220.
• the shunt regulator 220 is a zener diode with internal reference voltage of 2.5 volts.
• the function of the dual mode charging circuit will now be described in accordance with one embodiment.
• the voltage, current and resistance values used herein are for the purpose of example only and other values according to different characteristics of the battery can be used. According to one embodiment, if the battery is 80% discharged, the battery voltage will be approximately 11.5 volts. The voltage near the full charge is 13.5 volts and the full charge voltage is approximately 14.1 volts. However, other batteries may have other charging characteristics. In one embodiment, the constant current supplied to the battery is 3 amps, but other constant currents may also be used.
• a discharged battery connected to the dual power SMPS 120 will result in a high current to the battery, because of the potential difference between the SMPS voltage and the battery voltage.
• the high current to the battery will generate a voltage across the sense resistor R3, which is connected to the non-inverting input of the op- amp comparator 216.
• a reference voltage generated by the reference voltage circuit 218 is 0.09 volts and is applied to the inverting input of op-amp 216.
• the op-amp output voltage will forward bias the diode D4.
• the voltage at the shunt regulator 222 provided by D4 diode will be more than the internal reference voltage of 2.5 volts and the shunt regulator 222 will provide a feedback control signal to the PWM .
• Diode D4 will stay forward biased until the current to the battery is reduced to 3 amps.
• the PWM controller 202 will increase the duty cycle of the PWM controller voltage pulse absent a feedback signal from the optocoupler 212. In this manner, the battery current is maintained at 3 amps during constant current mode.
• FIG. 2C there is illustrated a block diagram of one example of the use of a feedback scheme to control power of the solar power input 124 to power the load and to charge the battery. Similar to the feedback scheme for the AC power discussed with reference to FIGs. 2A and 2B, the feedback scheme in FIG. 2C can be used to regulate solar power to the battery 122 and the load 210. As shown in FIG. 2C, the feedback scheme includes the use of the DC-DC converter 118, which includes a PWM (Pulse Width
• the DC-DC converter 118 receives the DC power from the solar power source 124.
• the PWM controller 226 receives the DC power from the solar source and provides high frequency pulse width modulated output power to transformer 228.
• the DC power has . a voltage level between 16 volts and 21 volts.
• the transformer 228 receives power from the PWM controller 226 and steps down the received DC voltage to provide output AC voltage.
• the output AC voltage of the transformer 228 may be rectified, filtered and smoothed by the rectifier and filter circuit 230, to provide output DC power of 14.5 volts to the battery 112 and the load 210.
• the resistor R3 allows the DC- DC converter 118 to sense the current to the battery 122 and the voltage across the battery 122.
• the multiplexer 208 triggers a feedback signal to the PWM controller 202 if the battery reaches the battery charging threshold.
• the LED array 102 is implemented using a 3 x 30 array of closely spaced LEDs as shown in FIG. 3.
• the 3 rows are spaced 6.985 mm with the LEDs of each row spaced at 8.6mm intervals, and with each LED having a 5 mm diameter.
• the LEDs have a forward voltage of 3.0 to 3.5 volts, a peak forward current of 20 mA, a reverse voltage of 5 volts, reverse current of 10 microamps, a luminous intensity of 1500 - 2000 mod, and are white with a wavelength of 5800K. In other embodiments, LEDs having different characteristics may be used.
• a green LED, a red LED and a yellow LED are also provided, and in this embodiment, illumination of the green LED indicates that the power from the grid supply or the solar panel is available and is charging the battery, illumination of the yellow LED indicates that the battery is FULL, and illumination of the red LED indicates that the battery is drained and load is cut off from the battery.
• FIG. 4 shows an exploded view of an LED light assembly 400 in accordance with one embodiment, while FIGS. 5 and 6 show perspective views of the LED light assembly 400.
• the components of the functional block diagram of the lighting system 100 are contained within the LED light assembly 400, except that the AC power source, the solar power source and the battery are all external to the LED light assembly and are not shown in FIG. 4.
• the light assembly 400 includes a front cover 402, a case 404, an LED strip 406, a switch mode power supply board 408, an LED driver board 410, a solar board 411, a back cover 412, a solar power input terminal 414, a battery power input terminal 415, and an AC power input terminal 416.
• the LED light assembly also includes the pull switch 418 and the three LED indicator lights 419. In one embodiment, the LED light assembly 400 is fastened together using screws 417 as shown in FIG. 4.
• the LED light assembly 400 is a modular, upgradeable assembly, having several versions, and the specific electronics contained in the assembly can be varied based on the particular version of the assembly. More specifically, the SMPS board and the solar board may be removed or upgraded to change the version of the LED light assembly. To easily accommodate changing the SMPS board and the solar board, connection between the boards is accomplished in one embodiment using flexible cables between the boards with terminal block connectors coupling the cables to the boards. As shown in FIG. 4, the LED driver board, the solar board and the SMPS board are mounted to the back cover 412.
• the LED strip in one embodiment contains the LED array 102 mounted on a printed circuit board with the board electrically coupled to the LED driver board 410. When assembled, the LED is mounted to the front of the case 404.
• the case 404 and the back cover 412 in one embodiment are made form plastic (ABS Abstron ⁇ 17A) while the front cover 402 is made from transparent plastic (PMMA 876G). In other embodiments, other plastic material can be used for the front cover 402, the case 404 and the back cover 412.
• FIG. 5 the front cover is shown in an operational, closed position, while in FIG. 6, the front cover is shown in an open position that allows cleaning of any dust buildup on the front cover.
• the input terminal 414 provides for connection to a solar power source
• the input terminal 415 provides for connection to a battery
• input terminal 416 provides for connection to an AC source.
• a PWM controller is used as part of a controllable SMPS to provide regulated voltage and current to a battery and a load. In other embodiments other types of controllable power supplies may be used. .
• Embodiments of the dual power SMPS may be used in other applications, including computers and computer peripherals, consumer electronics, such as, mobile phones, as well as, battery chargers.
• an SMPS provides regulation of the battery charger and voltage to a load using a single PWM controller.
• light assemblies may be configured for operation with other power sources as well, including fuel cells and wind power.
• any embodiment disclosed herein may be combined with any other embodiment, and references to "an embodiment,” “some embodiments,” “an alternate embodiment,” “various embodiments,” “one embodiment” or the like are riot necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment. Such terms as used herein are not necessarily all referring to the same embodiment. Any embodiment may be combined with any other embodiment in any manner consistent with the aspects and embodiments disclosed herein. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms.

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• 2012
  • 2012-06-29 EP EP12751374.5A patent/EP2727214A1/de not_active Withdrawn
  • 2012-06-29 WO PCT/IN2012/000462 patent/WO2013001548A1/en active Application Filing
  • 2012-06-29 AU AU2012277331A patent/AU2012277331B2/en not_active Ceased
  • 2012-06-29 CN CN201280040187.7A patent/CN103765723A/zh active Pending

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