Power converter systems for light emitting diode lighting fixtures

Abstract

A converter system for powering a plurality of LED lighting fixtures includes a centralized converter system coupled to the plurality of LED lighting fixtures and a plurality of DC-DC converters. The centralized converter system includes an AC-DC converter, a bidirectional DC-DC converter, and a controller. An input of each DC-DC converter of the plurality of DC-DC converters is coupled to the AC-DC converter and an output of each DC- DC converter is coupled to a grouping of LED lighting fixtures of the plurality of LED lighting fixtures to provide DC power to the grouping of LED lighting fixtures. The controller controls the AC-DC converter, the bidirectional DC-DC converter, and the plurality of DC-DC converters. A lighting system including the plurality of LED lighting fixtures and the converter system is also provided.

Description

1 ETN-096XINPCTP24-1260W001POWER CONVERTER SYSTEMS FOR LIGHT EMITTING DIODE LIGHTINGFIXTURESBACKGROUND

[0001] Electronic devices such as hazardous area lighting fixtures can be powered by centralized or decentralized control architectures. Lighting systems comprising LED (Light emitting diode) lighting fixtures can operate in harsh and hazardous environments where it can be difficult to control the temperature. These lighting systems are typically powered by an AC source which is converted to DC by an AC-DC converter to power the individual lighting fixtures. In a decentralized control architecture, there can be an AC-DC conversion unit for each LED lighting fixture which are co-located with one another. However, the AC-DC converters are sensitive to high temperatures, hence the components of the converter may fail or degrade prematurely in the high temperature environment. In a centralized control architecture, a centralized AC-DC conversion unit is provided to power the lighting fixtures and can be located in a more favorable and controlled environment. However, in the centralized control approach, a low-voltage DC distribution system that spans over a longer distance from the conversion unit to the lighting fixture can lead to excessive power loss and provide limited control.BRIEF SUMMARY

[0002] Power converter systems for LED lighting systems are described. Embodiments of the described power converter systems include a centralized converter system including an AC-DC converter, a bidirectional DC-DC converter, and a controller. In one embodiment, the centralized converter system includes a plurality of DC-DC converters, each DC-DC converter coupled to a grouping of lighting fixtures to provide DC power to the grouping of lighting fixtures. In another embodiment, the plurality DC-DC converters are decentralized such that the DC-DC converters are positioned locally with the lighting fixtures, each DC-DC converter coupled to a grouping of lighting fixtures to provide DC power to the grouping of lighting fixtures.

[0003] A converter system for powering a plurality of LED lighting fixtures includes a centralized converter system coupled to the plurality of LED lighting fixtures and a plurality of DC-DC converters. The centralized converter system includes an AC-DC converter, a bidirectional DC-DC converter, and a controller. An input of each DC-DC converter of the plurality of DC-DC converters is coupled to the AC-DC converter and an output of each DC-2 ETN-096XINPCTP24-1260W001DC converter is coupled to a grouping of LED lighting fixtures of the plurality of LED lighting fixtures to provide DC power to the grouping of LED lighting fixtures. The controller controls the AC-DC converter, the bidirectional DC-DC converter, and the plurality of DC-DC converters.

[0004] A lighting system includes a plurality of LED lighting fixtures, a centralized converter system coupled to the plurality of LED lighting fixtures and a plurality of DC-DC converters. The centralized converter system includes an AC-DC converter, a bidirectional DC- DC converter, and a controller. An input of each DC-DC converter of the plurality of DC-DC converters is coupled to the AC-DC converter and an output of each DC-DC converter is coupled to a grouping of LED lighting fixtures of the plurality of LED lighting fixtures to provide DC power to the grouping of LED lighting fixtures. The controller controls the AC- DC converter, the bidirectional DC-DC converter, and the plurality of DC-DC converters.

[0005] Advantageously, in some cases, centralized converter systems described herein can be disposed in a centralized location that is not necessarily within the harsh and hazardous location of the plurality of lighting fixtures facilitating easier maintenance on the components of the converter system.

[0006] In addition, having a centralized battery storage system enables easier maintenance of battery power as well as being able to provide backup power during a power outage of a grid connected to the converter system. The battery storage system can ensure that during an emergency situation, power is available to the lighting fixtures to aid in a safe evacuation of personnel in the harsh and hazardous environment.

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 illustrates an operating environment for a conventional architecture of a lighting system.

[0009] FIG. 2 illustrates an operating environment of an embodiment of a power converter system for a lighting system.

[0010] FIG. 3 illustrates an operating environment of a further embodiment of a power converter system for a lighting system.

[0011] FIG. 4 illustrates a representation of a controller.3 ETN-096XINPCTP24-1260W001DETAILED DESCRIPTION

[0012] Power converter systems for LED lighting systems are described. Embodiments of the described power converter systems include a centralized converter system including an AC-DC converter, a bidirectional DC-DC converter, and a controller. In one embodiment, the centralized converter system includes a plurality of DC-DC converters, each DC-DC converter coupled to a grouping of lighting fixtures to provide DC power to the grouping of lighting fixtures. In another embodiment, the plurality DC-DC converters are decentralized such that the DC-DC converters are positioned locally with the lighting fixtures, each DC-DC converter coupled to a grouping of lighting fixtures to provide DC power to the grouping of lighting fixtures.

[0013] Typically, a lighting system comprising a plurality of lighting fixtures are driven by a DC source that derives power from the grid (an AC source). Thus, a power converter system is needed to convert the AC power to DC power. To maintain high power factor, the LED lighting system uses power factor correction (PFC). The use of PFC ensures that the input current waveform closely matches the input voltage waveform in both shape and phase. In addition, power converter systems, including AC-DC converters and DC-DC converters, allow for use of dual voltage system electrical architectures.

[0014] The lighting fixtures described herein are LED luminaries that provide lighting for different applications such as harsh and hazardous environments, horticultural environments, and other commercial and industrial environments. In some cases, particularly in the harsh and hazardous environments, the LED lighting fixture can be enclosed in a housing and coupled to a DC-DC converter of the power converter system by a cable that passes through the housing. In other cases, communication between the controller and the lighting fixture(s) via the DC-DC converter can be wireless.

[0015] FIG. 1 illustrates an operating environment for a conventional architecture of a lighting system. Referring to FIG. 1, operating environment 100 includes a converter system 110 that includes an AC-DC converter 120 coupled to a DC-DC converter 130. The converter system 110 is coupled to an LED load 140 at its output. At its input, the converter system 110 is coupled to grid 150 that provides the converter system 110 with a three-phase AC power input. The AC-DC converter 120 receives the AC power from the grid 150 which it converts to DC power. The AC-DC converter 120 can include PFC circuitry 125 to improve the input power factor. DC-DC converter 130 converts the DC power received from the AC-DC converter 120 from a higher voltage level to a lower voltage level used by LED load 140. In4 ETN-096XINPCTP24-1260W001 some cases, an EMI filter can be positioned between grid 150 and AC-DC converter 120 to remove noise (unwanted frequencies) from the AC power signal. In some cases, LED load 140 can be a single lighting fixture. For example, the single lighting fixture can include a housing in which the lighting fixture and the converter system are co-located with one another so that the lighting fixture is powered by its own power source. The lighting system can include multiple converter systems, each converter system paired with a single lighting fixture. As described above, the arrangement described in FIG. 1 is considered a decentralized control architecture.

[0016] FIG. 2 illustrates an operating environment of an embodiment of a power converter system for a lighting system. Referring to FIG. 2, operating environment 200 includes a centralized converter system 210 coupled to a grid 250 and a battery 280 on its input side to provide power for conversion. At its output, centralized converter system 210 provides power to a plurality of LED lighting fixtures 240. The centralized converter system 210 includes a centralized AC-DC converter 220, a plurality of DC-DC converters 230, a controller 260, and a bidirectional DC-DC converter 270. Controller 260 provides control signals to the bidirectional DC-DC converter 270, centralized AC-DC converter 220, and each of the DC- DC converters 230. Centralized converter system 210 can be positioned remotely from the plurality of lighting fixtures 240.

[0017] The centralized AC-DC converter 220 receives the AC power from the grid 250 which it converts to DC power. Similar to the arrangement described above, an EMI filter can be positioned between grid 250 and the AC-DC converter 220 to remove noise and unwanted frequencies. In some cases, the AC-DC converter 220 can include PFC circuitry 225 to increase the power factor and reduce the harmonic currents that can be produced by a linear power supply. In other cases, the AC-DC converter 220 can be integrated with a boost converter having the PFC circuitry. The boost PFC converter uses a switching element to force the input AC current to be sinusoidal and in phase with the input voltage. The AC-DC converter 220 can output a high voltage DC power to power a plurality of DC-DC converters 230 via a common HV DC bus 290.

[0018] In the embodiment shown in FIG. 2, the DC-DC converters 230a, 230b, 230c are located remotely as part of the centralized converter system 210. Each of the DC-DC converters 230a, 230b, 230c converts the DC power received from the AC-DC converter 220 from a higher voltage level to a lower voltage level used by a respective LED load 240a, 240b, 240c. Each DC-DC converter 230a, 230b, 230c drives the respective LED load, e.g., a grouping of LED lighting fixtures 240a, 240b, 240c, through a LV distribution system, e.g., a low voltage5 ETN-096XINPCTP24-1260W001 cable, to achieve independent control over different sections of lighting. For example, DC-DC converter 230a drives grouping of LED lighting fixtures 240a via a LV cable. Each low voltage cable can be a short cable, e.g., up to 100 m in length. Cables longer than 100 m can have significant loss of the power signal.

[0019] Each grouping of LED lighting fixtures 240a, 240b, 240c can include one or more (e.g., up to 20 lighting fixtures). The number of LED lighting fixtures 240 that can be controlled by a single DC-DC converter 230 depends on the maximum current of the maximum output current of the respective DC-DC converter 230. However, to have better controllability, up to 20 lighting fixtures would be in a grouping of LED lighting fixtures. In some cases, each grouping of LED lighting fixtures 240 includes a range of 10-20 LED lighting fixtures.

[0020] Centralized converter system 210 includes a battery storage system. The battery storage system 210 includes a bidirectional DC-DC converter 270 coupled to a battery 280. The centralized battery storage system is connected to the common HV DC bus 290 through bidirectional DC-DC converter 270 for controlled charging / discharging operations. The bidirectional DC-DC converter 270 enables a bidirectional current flow between its input and output so that energy can be pulled back into the battery 280. In some cases, battery 280 includes a voltage in the range of 6 V - 60 V DC. The bidirectional DC-DC converter 270 can operate in two modes, a forward mode, and a reverse mode. In the forward mode, energy is transferred from battery 280 to the common HV DC bus 290. In the reverse mode, energy is transferred from the common HV DC bus 290 back into the battery 280. The controller 260 controls the bidirectional current flow between the bidirectional DC-DC converter 270 and the battery 280. For example, controller 260 can control the bidirectional current flow to charge or discharge the battery based on a measured current or a measured voltage at an output of the battery 280. When the battery is in a discharge mode, bidirectional DC-DC converter 270 operates to step-up the voltage from a lower voltage of the battery 280 to a higher voltage of the common HV DC bus 290. Conversely, when the battery is in a charging mode, bidirectional DC-DC converter 270 operates to step-down the voltage from a higher voltage of the common HV DC bus 290 to the lower voltage of the battery 280.

[0021] FIG. 3 illustrates an operating environment of a further embodiment of a power converter system for a lighting system. Referring to FIG. 3, operating environment 300 includes a centralized converter system 310 coupled to a grid 350 and a battery 380 on its input side to provide power for conversion. Similar to the power converter architecture described in FIG. 2, the AC-DC converter 320 with PFC circuitry 325 is part of the centralized converter system 310 along with bidirectional DC-DC converter 370 and controller 360. However, the6 ETN-096XINPCTP24-1260W001 power converter system illustrated in FIG. 3 includes decentralized DC-DC converters 330 so the power converter architecture is a hybrid power converter architecture having both centralized and decentralized components.

[0022] Centralized converter system 310 can be positioned remotely from the LED lighting fixtures while the plurality of DC-DC converters 330 can be positioned locally with LED lighting fixtures 340. When the centralized converter system 310, while being positioned remotely, is within a harsh or hazardous environment, one or more of the components, e.g., controller 360, AC-DC converter 320, and / or battery 380 can be enclosed in a housing such as an explosion-proof housing. In some cases, each of the locally positioned DC-DC converters 330 are positioned within the housing of a grouping of LED lighting fixtures powered by the respective DC-DC converter 330. In other cases, the locally positioned DC-DC converters 330 are located within a harsh and hazardous facility or near to the harsh and hazardous facility in which the plurality of lighting fixtures are disposed which are disposed in their own respective housing. Each of the plurality of DC-DC converters 330 can be an isolated or non-isolated type of conversion system. Controller 360 provides control signals to the bidirectional DC-DC converter 370, centralized AC-DC converter 320, and each of the DC-DC converters 330.

[0023] AC-DC converter 320 includes features similar to those described above with respect to AC-DC converter 220, however, the common HV DC bus 390 coupling the AC-DC converter 320 can comprise long high voltage cables, e.g., a length in a range of 100 m to 1000 m (1 km) or longer, to carry the converted DC power to the plurality of DC-DC converters 330 which are co-located with the plurality of LED lighting fixtures. Similar to the plurality of DC- DC converters 230 described with respect to FIG. 2, each of the plurality of DC-DC converters 330, converts the DC power received from the AC-DC converter 320 from a higher voltage level to a lower voltage level used by LED load 340. Each DC-DC converter 330a, 330b, 330c drives the respective LED load 340, e.g., agrouping of LED lighting fixtures 340a, 340b, 340c, through a LV distribution system, e.g., a low voltage cable, to achieve independent control over different sections of lighting. Centralized converter system 310 includes a battery storage system that includes a bidirectional DC-DC converter 370 coupled to a battery 380. Bidirectional DC-DC converter 370 includes similar features as those described above with respect to bidirectional DC-DC converter 270. Controller 360 controls the bidirectional current flow between the bidirectional DC-DC converter 370 and the battery 380.

[0024] FIG. 4 illustrates a representation of a controller. Referring to FIG. 4, controller 460 can be representative of controller 260 and controller 360 from the presented embodiments of converter system architectures illustrated in FIG. 2 and FIG. 3, respectively. Controller 4607 ETN-096XINPCTP24-1260W001 can be implemented using one or more processors (executing suitable software instructions), state machines, and / or logic circuits. Controller 460 can independently control each of the plurality of DC-DC converters 330a, 330b, 330c so that one or more groupings of LED lighting fixtures of the plurality of lighting fixtures 340a, 340b, 340c are illuminated for a time period.

[0025] Controller 460 can receive various inputs from sensed signals within the operating environment of the respective power converter system. The various inputs can include an LED current from one or more of the LED lighting fixtures received from respective current sensors measured at each LED lighting fixture, a DC link voltage, e.g., HV DC voltage, received from a voltage sensor at the output of the AC-DC converter, temperature at various locations within the operating environment received from temperature sensors, remaining battery life of a battery connected to the power converter system received from voltages, currents, and / or temperature from respective sensors measuring these parameters at the battery, and motion within a facility housing the power converter system and / or the lighting fixtures from motion sensors.

[0026] Based on the various inputs controller 460 can analyze the state of the operating environment of the power converter system and provide control signals to the various components of the system. The control signals, e.g., outputs of controller 460, can include illumination (dimming control) of the LED lighting fixtures, the output of the AC-DC converter (HV voltage control), overheating protection control, battery state of charge estimation, and smart illumination for emergency evacuation.

[0027] The described power converter systems can operate with or without the battery storage system. When the grid is operational and providing AC power to the respective power converter system, power provided by the battery may not be needed. However, in some cases, e.g., in a no power situation when power is not being received from the grid, the power converter system can utilize energy stored within the battery via the bidirectional DC-DC converter for power. The no power situation can be sensed by a voltage sensor measuring the DC link voltage at the output of the AC-DC converter. The measured DC link voltage is received by the controller 460 which can then control the bidirectional current flow between the bidirectional DC-DC converter and the battery through a control signal to the bidirectional DC-DC converter.

[0028] In addition, based on a measured current or a measured voltage at an output of the battery, the controller 460 can control the bidirectional current flow to charge or discharge the battery. In some cases, e.g., when there is a no power situation, the controller 460 controls the bidirectional flow to discharge the battery providing power to the DC-DC converters. In8 ETN-096XINPCTP24-1260W001 other cases when the grid is providing power to the power converter system, the controller 460 can use the available HV DC power on the HV DC bus to charge the battery.

[0029] In some cases, the controller 460 can identify critical and non-critical groupings of LED lighting fixtures and can independently control each of the plurality of DC-DC controllers so that only the critical groupings of LED lighting fixtures are illuminated. For example, in order to extend the backup time of the available power from the battery, the controller 460, using sensed voltages, currents, and / or temperature of the battery, can limit power to only critical sections of the facility. For example, referring to FIG. 3, controller 460 can control the grouping of LED fixtures 340a via DC-DC converter 330a to remain on while turning off the grouping of LED fixtures 340b and the grouping of LED fixtures 340c to save power. In addition, in order to save power, the controller 460 can enable a dimming feature of the LED fixtures 340 via control signals to the corresponding DC-DC converter 330. By enabling the dimming feature, the controller 460 controls an illumination level of one or more groupings of LED lighting fixtures to a lower illumination level thus saving power.

[0030] In some cases, the controller 460 can detect occupancy at the facility housing the lighting fixtures based on motion sensed by motion sensors. An emergency situation warranting an evacuation of occupants of the facility can be triggered through various inputs including an input voltage, e.g., a grid voltage or a DC link voltage, high temperatures at the facility, etc. During the emergency situation, any occupants at the facility will need to be evacuated safely from the facility to safety. After detecting occupancy during the emergency situation, controller 460 can then control illumination of the lighting fixtures via the DC-DC converters to provide an illuminated path for occupant evacuation. Based on where the motion is detected, and in some cases, where the emergency situation was initiated, e.g., an uninhabitable temperature sensed from a temperature sensor, the controller 460 can determine a shortest, safest path for evacuation and illuminate the determined evacuation path with corresponding grouping(s) of lighting fixtures. In some cases, the controller 460 can control the corresponding grouping(s) of lighting fixtures for the determined evacuation path to selectively blink providing the occupants with a distinctive visual representation of the evacuation path.

[0031] Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and9 ETN-096XINPCTP24-1260W001 other equivalent features and acts that would be recognized by one skilled in the art are intended to be within the scope of the claims.

Claims

10 ETN-096XINPCTP24-1260W001CLAIMSWhat is claimed is:

1. A converter system for powering a plurality of LED lighting fixtures, comprising: a centralized converter system coupled to the plurality of LED lighting fixtures, the centralized converter system including: an AC-DC converter; a bidirectional DC-DC converter; and a controller; and a plurality of DC-DC converters, wherein an input of each DC-DC converter of the plurality of DC-DC converters is coupled to the AC-DC converter and an output of each DC-DC converter is coupled to a grouping of LED lighting fixtures of the plurality of LED lighting fixtures to provide DC power to the grouping of LED lighting fixtures, wherein the controller controls the AC-DC converter, the bidirectional DC-DC converter, and the plurality of DC-DC converters.

2. The converter system of claim 1, wherein the centralized converter system includes the plurality of DC-DC converters.

3. The converter system of claim 2, wherein the centralized converter system is positioned remote from the plurality of LED lighting fixtures.

4. The converter system of claim 1, wherein the plurality of DC-DC converters are decentralized to be positioned locally with the plurality of LED lighting fixtures.

5. The converter system of claim 4, wherein each of the plurality of DC-DC converters are coupled to the AC-DC converter by a high voltage cable.

6. The converter system of claim 1, wherein the AC-DC converter includes PEC circuitry.

7. The converter system of claim 5, wherein a length of the high voltage cable is in a range of 100 m to 1000 m.

8. The converter system of claim 1, wherein the bidirectional DC-DC converter is coupled to a battery to provide a battery storage system.11 ETN-096XINPCTP24-1260W0019. The converter system of claim 8, wherein the controller controls a bidirectional current flow between the bidirectional DC-DC converter and the battery.

10. The converter system of claim 9, wherein based on a measured current or a measured voltage at an output of the battery, the controller controls the bidirectional current flow to charge or discharge the battery.

11. The converter system of claim 8, wherein the battery is a battery having a voltage in a range of 6 V to 60 V DC.

12. The converter system of claim 1, wherein the controller independently controls each of the plurality of DC-DC converters so that one or more groupings of LED lighting fixtures of the plurality of LED lighting fixtures are illuminated for a time period.

13. The converter system of claim 12, wherein the controller identifies critical and non- critical groupings of LED lighting fixtures of the plurality of LED lighting fixtures and independently controls each of the plurality of DC-DC converters so that only the critical groupings of LED lighting fixtures are illuminated.

14. The converter system of claim 12, wherein the controller, based on detection of occupancy from a motion sensor, controls each of the plurality of DC-DC converters so that the one or more groupings of LED lighting fixtures are illuminated to define a path to safety during an emergency situation.

15. The converter system of claim 14, wherein the one or more groupings of LED lighting fixtures are controlled by the controller via the corresponding coupled DC-DC converter to selectively blink during the emergency situation.

16. The converter system of claim 1, wherein the plurality of LED lighting fixtures are disposed in a harsh and hazardous environment, and wherein each grouping of LED lighting fixtures of the plurality of LED lighting fixtures is enclosed in a housing and coupled to a corresponding DC-DC converter by a cable that passes through the housing.

17. The converter system of claim 1, wherein the plurality of LED lighting fixtures are disposed in a harsh and hazardous environment, and wherein each grouping of LED lighting fixtures of the plurality of LED lighting fixtures communicate to the controller via a corresponding DC-DC converter wirelessly.12 ETN-096XINPCTP24-1260W00118. A lighting system, comprising: a plurality of LED lighting fixtures; a centralized converter system coupled to the plurality of LED lighting fixtures, the centralized converter system including: an AC-DC converter; a bidirectional DC-DC converter; and a controller; and a plurality of DC-DC converters, wherein an input of each DC-DC converter of the plurality of DC-DC converters is coupled to the AC-DC converter and an output of each DC-DC converter is coupled to a grouping of LED lighting fixtures of the plurality of LED lighting fixtures to provide DC power to the grouping of LED lighting fixtures, wherein the controller controls the AC-DC converter, the bidirectional DC-DC converter, and the plurality of DC-DC converters.

19. The lighting system of claim 18, wherein the controller, based on detection of occupancy from a motion sensor, controls each of the plurality of DC-DC converters so that one or more groupings of LED lighting fixtures are illuminated to define a path to safety during an emergency situation.

20. The lighting system of claim 19, wherein the one or more groupings of LED lighting fixtures are controlled by the controller via the corresponding coupled DC-DC converter to selectively blink during the emergency situation.

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