Solid-State Lighting With A Control Gear Cascaded By A Luminaire

Abstract

A light-emitting diode (LED) lighting system comprising a luminaire and an LED luminaire control gear is used to replace the luminaire operated with alternate-current (AC) mains. The luminaire coupled to the LED luminaire control gear comprises LED arrays and a power supply. The LED luminaire control gear comprises a rechargeable battery, a current-fed inverter, and a relay switch. When a line voltage from the AC mains is unavailable, the LED luminaire control gear is automatically started to provide a high output voltage within an input operating voltage range of the luminaire and a low direct-current (DC) voltage to control the power supply to provide an LED driving voltage greater than a forward voltage across the LED arrays, eliminating operating instability of the power supply. The relay switch is configured to couple either the line voltage or the high output voltage to the power supply to operate thereon.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present disclosure is part of a continuation-in-part (CIP) application of U.S. patent application Ser. No. 16 / 458,823, filed 1 Jul. 2019, which is part of CIP application of U.S. patent application Ser. No. 16 / 432,735, filed 5 Jun. 2019 and issued as U.S. Pat. No. 10,390,396 on 20 Aug. 2019, which is part of CIP application of U.S. patent application Ser. No. 16 / 401,849, filed 2 May 2019 and issued as U.S. Pat. No. 10,390,395 on 20 Aug. 2019, which is part of CIP application of U.S. patent application Ser. No. 16 / 296,864, filed 8 Mar. 2019 and issued as U.S. Pat. No. 10,390,394 on 20 Aug. 2019, which is part of CIP application of U.S. patent application Ser. No. 16 / 269,510, filed 6 Feb. 2019 and issued as U.S. Pat. No. 10,314,123 on 4 Jun. 2019, which is part of CIP application of U.S. patent application Ser. No. 16 / 247,456, filed 14 Jan. 2019 and issued as U.S. Pat. No. 10,327,298 on 18 Jun. 2019, which is part of CIP application of ...

AI Technical Summary

Benefits of technology

[0007]An LED lighting system comprising a luminaire and an LED luminaire control gear cascaded by the luminaire is used to replace a fluorescent or an LED lamp normally operated with the AC mains. The luminaire comprises one or more LED arrays with a forward voltage across thereon and a power supply unit that powers the one or more LED arrays. The LED luminaire control gear comprises a rechargeable battery, a line voltage detection and control circuit, and a current-fed inverter configured to receive power from the rechargeable battery and to generate at least one high output voltage, VH, and at least one low direct-current (DC) output voltage, VL, when the line voltage from the AC mains is unavailable. The at least one high output voltage, VH, is compatible to a voltage in an input operating voltage range of the power supply unit whereas the at least one low DC output voltage is compatible to a voltage in a range of 0-to-10 volts. The line voltage detection and control circuit comprises a relay switch configured to couple either the line voltage from the AC mains or the at least one high output voltage, VH, to the power supply unit to operate thereon. The line voltage detection and control circuit further comprises a transistor circuit configured to enable the current-fed inverter.

[0008]The power supply unit comprises at least two electrical conductors, a main full-wave rectifier, and an input filter. The at least two electrical conductors are configured to couple to the LED luminaire control gear, receiving either the line voltage from the AC mains or the at least one high output voltage, VH. The main full-wave rectifier is coupled to the at least two electrical conductors to convert either the line voltage from the AC mains or the at least one high output voltage, VH, into a fourth DC voltage. The input filter is configured to suppress electromagnetic interference (EMI) noises. The power supply unit further comprises a power switching converter comprising a main transformer and a power factor correction (PFC) and power switching circuit. The PFC and power switching circuit is coupled to the main full-wave rectifier via the input filter and configured to improve a power factor, to reduce voltage ripples, and to convert the fourth DC voltage into a fifth DC voltage. The fifth DC voltage is configured to couple to the one or more LED arrays to operate thereon. The power switching converter further comprises a pulse width modulation (PWM) control circuit and a pair of input ports configured to receive a 0-to-10 V signal, a 1-to-10 V signal, a PWM signal, or a signal from a variable resistor for luminaire dimming applications. The PFC and power switching circuit is generally a current source, in which when the one or more LED arrays require more current than a predetermined maximum, the fifth DC voltage drops accordingly to maintain power conservation. In other words, when the LED luminaire control gear is cascaded by the luminaire powered by the LED luminaire control gear that only provides a fraction of power compared with a rated power of the luminaire, there exists an operating uncertainty that a driving voltage and current provided by the LED luminaire control gear to drive the one or more LED arrays may fall into an unstable operating situation. That is, when the one or more LED arrays require more current than a predetermined maximum, the fifth DC voltage drops below the forward voltage of the one or more LED arrays, resulting in an operating failure of the one or more LED arrays. When the power supply unit recovers to start tracking current, the fifth DC voltage recovers to an original level, thereby temporarily operating the one or more LED arrays. Such a voltage and current competition continues, creating a phenomenon called luminaire strobing. Therefore, the LED luminaire control gear must provide an additional signal to control the power supply unit to operate stably and efficiently the one or more LED arrays at low power conditions.

[0009]The LED luminaire control gear further comprises a full-wave rectifier and a charging circuit. The full-wave rectifier is coupled to the AC mains and configured to convert the line voltage from the AC mains into a first DC voltage. The charging circuit comprises a first transformer, a feedback control circuit, a control device, a first electronic switch, a diode, a first ground reference, and a second ground reference electrically isolated from the first ground reference. The first electronic switch comprises a metal-oxide-semiconductor field-effect transistor (MOSFET) or a transistor. The charging circuit is coupled to the full-wave rectifier and configured to convert the first DC voltage into a second DC voltage that charges the rechargeable battery to reach a third DC voltage. The feedback control circuit is configured to monitor the second DC voltage and to regulate the control device in response to various charging requirements. The current-fed inverter comprises a second transformer having a primary side and a secondary side. The secondary side comprises at least two windings. The current-fed inverter is configured to receive the third DC voltage from the rechargeable battery and to convert the third DC voltage into the at least one high output voltage, VH, and the at least one low DC output voltage, VL, when the line voltage from the AC mains is unavailable. The at least one low DC output voltage, VL, is coupled to the PWM control circuit via the pair of input ports and configured to control the fifth DC voltage to be greater than the LED forward voltage for the one or more LED arrays to operate, avoiding instability of the fifth DC voltage due to the voltage and current competition in a constant current-limiting operation of the power switching converter. The secondary side further comprises a rectifier and at least one capacitor, the rectifier and the at least one capacitor configured to couple to one of the two windings and to generate the at least one low DC output voltage, VL, when the line voltage from the AC mains is unavailable. The at least one low DC output voltage, VL, is configured to control the power switching converter to operate with a fraction of power consumed when the line voltage from the AC mains is available, whereas a combination of the at least one low DC output voltage, VL, and the at least one high output voltage, VH, is configured to maintain stability of the power switching converter in a way that the one or more LED arrays are operated without strobing. The primary side comprises a second electronic switch, a third electronic switch, an upper portion of a center-tapped winding, a lower portion of the center-tapped winding, and a center-tapped port coupled between the upper portion of the center-tapped winding and the lower portion of the center-tapped winding. The center-tapped port is coupled to a high-potential electrode of the rechargeable battery. The upper portion of the center-tapped winding is driven in one direction of a current flow with the second electronic switch activated, whereas the lower portion of the center-tapped winding is driven in the opposite direction of the current flow with the third electronic switch activated. Each of the second electronic switch and the third electronic switch comprises a metal-oxide-semiconductor field-effect transistor (MOSFET) or a transistor.

[0010]The relay switch comprises a power sensing coil with a pick-up voltage and a drop-out voltage and is configured to couple either the at least one high output voltage, VH, or the line voltage from the AC mains to the power supply unit to operate thereon, subsequently powering up the one or more LED arrays connected with the power supply unit. The relay switch further comprises a first pair of input electrical terminals, a second pair of input electrical terminals, and a third pair of input electrical terminals. The first pair of input electrical terminals are configured to couple to the line voltage from the AC mains, whereas the second pair of input electrical terminals are configured to couple to the at least one high output voltage, VH. The third pair of input electrical terminals are configured to receive the pick-up voltage to operate the power sensing coil. The relay switch further comprises a pair of output electrical terminals configured to relay either the line voltage from the AC mains or the at least one high output voltage, VH, to the power supply unit to operate thereon. In this case, the relay switch comprises a double-pole double-throw (DPDT) configuration, in which either the at least one high output voltage, VH, and the line voltage from the AC mains can be coupled to the power supply unit with a return current to respectively operate thereon without crosstalk. The at least one high output voltage, VH, is within an input operating voltage range of the power supply unit to guarantee that an under-voltage lockout will never occur.

[0011]The line voltage detection and control circuit further comprises a flyback module comprising a diode and a resistor connected in parallel with the diode, in which the diode is with a reverse polarity from the second DC voltage. The flyback module is connected in parallel with the power sensing coil. When the second DC voltage is greater than the third DC voltage, the pick-up voltage is built up for the power sensing coil to operate. The transistor circuit comprises a first transistor, a first resistor, and at least one diode and is configured to couple to the second DC voltage and the third DC voltage and to determine whether the line voltage from the AC mains is available or not. The first transistor is turned on or off to allow or forbid a discharge current from the third DC voltage to flow into the current-fed inverter to enable and disable thereon. The transistor circuit further comprises a second transistor, a second resistor, a voltage regulator, and a resistor-capacitor (RC) circuit. The second transistor, the second resistor, the voltage regulator, and the RC circuit are configured to couple to the first transistor to operate thereon. The transistor circuit further comprises a pair of electrical terminals coupled between the first resistor and the second resistor. The pair of electrical terminals are configured to couple the first transistor to the second transistor to operate the transistor circuit when the pair of electrical terminals are short-circuited. The pair of electrical terminals may be short-circuited by using a jumper, a jumper wire, or a switch. The transistor circuit further comprises a test switch coupled between the second DC voltage and the third DC voltage. When the test switch is pressed, the drop-out voltage is reached, thereby disabling the power sensing coil. In this case, the first transistor is turned on to enable the current-fed inverter. The line voltage detection and control circuit further comprises a first current guiding diode and a second current guiding diode. The first current guiding diode and the second current guiding diode are configured to conduct a charging current in one direction and a discharging current in another direction such that the second DC voltage is distinct from the third DC voltage.

Problems solved by technology

But the fact is that total cost of ownership for this approach is high regardless of very low initial cost.

If the existing ballast is not compatible with the ballast-compatible LED lamp, the consumer will have to replace the ballast.

Some facilities built long time ago incorporate different types of fixtures, which requires extensive labor for both identifying ballasts and replacing incompatible ones.

Maintenance will be complicated, sometimes for the lamps and sometimes for the ballasts.

The labor costs and long-term maintenance costs will be unacceptable to end users.

In this sense, any energy saved while using the ballast-compatible LED lamps becomes meaningless with the constant energy use by the ballast.

In the long run, the ballast-compatible LED lamps are more expensive and less efficient than self-sustaining AC mains-operable LED lamps.

Meeting OSHA requirements takes time and investment, but not meeting them could result in fines and even prosecution.

In other words, when the LED luminaire control gear is cascaded by the luminaire powered by the LED luminaire control gear that only provides a fraction of power compared with a rated power of the luminaire, there exists an operating uncertainty that a driving voltage and current provided by the LED luminaire control gear to drive the one or more LED arrays may fall into an unstable operating situation.

That is, when the one or more LED arrays require more current than a predetermined maximum, the fifth DC voltage drops below the forward voltage of the one or more LED arrays, resulting in an operating failure of the one or more LED arrays.

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