US-20260129726-A1 - LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE

US20260129726A1US 20260129726 A1US20260129726 A1US 20260129726A1US-20260129726-A1

Abstract

A load control device for an electrical load is configured to operate in a normal mode and a burst mode to adjust the amount of power delivered to the electrical load. The load control device comprises a control circuit that operates in the normal mode to regulate an average magnitude of a load current conducted through the load between a maximum rated current and a minimum rated current. During the normal mode, the control circuit controls the operating period of a load regulation circuit between a high-end operating period and a low-end operating period. The control circuit operates in the burst mode to regulate the average magnitude of the load current below the minimum rated current. During the burst mode, the control circuit adjusts the low-end operating period to be less than or equal to a minimum on time of the load regulation circuit.

Inventors

Robert D. Stevens, JR.
Matthew R. Zartman

Assignees

LUTRON TECHNOLOGY COMPANY LLC

Dates

Publication Date: 20260507
Application Date: 20250707

Claims (18)

1 . A light-emitting diode (LED) lighting control apparatus, comprising: load regulation circuitry to generate a load current output between a minimum load current value and a maximum load current value; LED driver control circuitry operatively coupled to the load regulation circuitry, the LED driver control circuitry to: receive a target intensity; determine a target load current based on the received load target intensity; determine whether the target load current is less than the minimum load current value; and responsive to the determination that the target load current is less than the minimum load current value: cause the load regulation circuitry to output the minimum load current; cause the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state; wherein, in the ACTIVE state, the load regulation circuitry produces a load current output at the minimum load current value; and wherein, in the INACTIVE state, the load regulation circuitry does not produce a load current output.
2 . The LED lighting control apparatus of claim 1 wherein the LED driver control circuitry to further: responsive to the determination that the target load current is at or above the minimum load current value: cause the load regulation circuitry to operate in a NORMAL operating mode at a fixed duty cycle; and vary the load regulation circuitry current output to provide the target load current.
3 . The LED lighting control apparatus of claim 2 , wherein to cause the load regulation circuitry to operate in the NORMAL operating mode at the fixed duty cycle, the LED driver control circuitry to further: cause the load regulation circuitry to operate in a NORMAL operating mode at a 100% duty cycle.
4 . The LED lighting control apparatus of claim 1 , wherein to cause the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state, the LED driver control circuitry to further: cause the load regulation circuitry to periodically decrease the ACTIVE state duration by a predetermined amount until the ACTIVE state duration is less than or equal to a minimum on time.
5 . The LED lighting control apparatus of claim 1 wherein to determine the target load current based on the received target intensity, the LED control circuitry to further: retrieve data indicative of a relationship between output intensity and load current associated with an operatively coupled LED fixture from operatively coupled memory circuitry; and determine the target load current using the retrieved data indicative of the relationship between LED fixture intensity and load current.
6 . The LED lighting control apparatus of claim 5 , wherein to determine whether the target load current is less than the minimum load current value, the LED control circuitry to further: retrieve data indicative of a minimum load current associated with the operatively coupled LED fixture from the operatively coupled memory circuitry; and determine whether the target load current is less than the minimum load current associated with the operatively coupled LED fixture.
7 . A light-emitting diode (LED) lighting control method, comprising: receiving by light-emitting diode (LED) driver control circuitry, an input that includes information indicative of a target output intensity of an LED fixture; determining by the LED driver control circuitry, a target load current of the LED fixture based on the received target output intensity of the LED fixture; determining by the LED driver control circuitry, whether the target load current of the LED fixture is less than the minimum load current of the LED fixture; and responsive to the determination that the target load current is less than the minimum load current value: causing by the LED driver control circuitry, the load regulation circuitry to output the minimum load current; causing by the LED driver control circuitry, the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state; wherein, in the ACTIVE state, the load regulation circuitry produces a load current output at the minimum load current value; and wherein, in the INACTIVE state, the load regulation circuitry does not produce a load current output.
8 . The LED lighting method of claim 7 , further comprising, responsive to the determination that the target load current is at or above the minimum load current value: causing by the LED driver control circuitry, the load regulation circuitry to operate in a NORMAL operating mode at a fixed duty cycle; and varying by the LED driver control circuitry, the load regulation circuitry current output to provide the target load current.
9 . The LED lighting method of claim 8 , wherein causing the load regulation circuitry to operate in the NORMAL operating mode at the fixed duty cycle, further comprises: causing by the LED driver control circuitry, the load regulation circuitry to operate in a NORMAL operating mode at a 100% duty cycle.
10 . The LED lighting method of claim 7 , wherein causing the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state, further comprises: causing by the LED driver control circuitry, the load regulation circuitry to periodically decrease the ACTIVE state duration by a predetermined amount until the ACTIVE state duration is less than or equal to a minimum on time.
11 . The LED lighting method of claim 7 , wherein determining the target load current based on the received target intensity, further comprises: retrieving by the LED driver control circuitry, data indicative of a relationship between output intensity and load current associated with an operatively coupled LED fixture from operatively coupled memory circuitry; and determining by the LED driver control circuitry, the target load current using the retrieved data indicative of the relationship between LED fixture intensity and load current.
12 . The LED lighting method of claim 11 , wherein determining whether the target load current is less than the minimum load current value, further comprises: retrieving by the LED driver control circuitry, data indicative of a minimum load current associated with the operatively coupled LED fixture from the operatively coupled memory circuitry; and determining by the LED driver control circuitry, whether the target load current is less than the minimum load current associated with the operatively coupled LED fixture.
13 . A non-transitory, machine-readable, storage device that includes instructions that, when executed by light-emitting diode (LED) driver control circuitry, cause the LED driver control circuitry to: receive an input that includes information indicative of a target output intensity of an LED fixture; determine a target load current of the LED fixture based on the received target output intensity of the LED fixture; determine whether the target load current of the LED fixture is less than the minimum load current of the LED fixture; and responsive to the determination that the target load current is less than the minimum load current value: cause the load regulation circuitry to output the minimum load current; cause the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state; wherein, in the ACTIVE state, the load regulation circuitry produces a load current output at the minimum load current value; and wherein, in the INACTIVE state, the load regulation circuitry does not produce a load current output.
14 . The non-transitory, machine-readable, storage device of claim 13 wherein the instructions, when executed by the LED driver control circuitry, further cause the LED driver control circuitry to: cause the load regulation circuitry to operate in a NORMAL operating mode at a fixed duty cycle; and adjust the load regulation circuitry current output to provide the target load current.
15 . The non-transitory, machine-readable, storage device of claim 14 wherein the instructions that cause the LED driver control circuitry to cause the load regulation circuitry to operate in the NORMAL operating mode at the fixed duty cycle, further cause the LED driver control circuitry to: cause the load regulation circuitry to operate in a NORMAL operating mode at a 100% duty cycle.
16 . The non-transitory, machine-readable, storage device of claim 13 wherein the instructions that cause the LED driver control circuitry to cause the load regulation circuitry to enter a BURST operating mode in which the load regulation circuitry operates at a variable duty cycle by alternating the load current output between an ACTIVE state and an INACTIVE state, further comprises: cause the load regulation circuitry to periodically decrease the ACTIVE state duration by a predetermined amount until the ACTIVE state duration is less than or equal to a minimum on time.
17 . The non-transitory, machine-readable, storage device of claim 13 wherein the instructions that cause the LED driver control circuitry to determine the target load current based on the received target intensity, further cause the LED driver control circuitry to: retrieve data indicative of a relationship between output intensity and load current associated with an operatively coupled LED fixture from operatively coupled memory circuitry; and determine the target load current using the retrieved data indicative of the relationship between LED fixture intensity and load current.
18 . The non-transitory, machine-readable, storage device of claim 13 wherein the instructions that cause the LED driver control circuitry to determine whether the target load current is less than the minimum load current value, further cause the LED driver control circuitry to: retrieve data indicative of a minimum load current associated with the operatively coupled LED fixture from the operatively coupled memory circuitry; and determine whether the target load current is less than the minimum load current associated with the operatively coupled LED fixture.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/663,255 filed May 14, 2024; which is a continuation of U.S. patent application Ser. No. 18/296,407, filed Apr. 6, 2023, now U.S. Pat. No. 12,022,582, issued Jun. 25, 2024; which is a continuation of U.S. patent application Ser. No. 17/394,073 filed Aug. 4, 2021, now U.S. Pat. No. 11,653,427, issued May 16, 2023; which is a continuation of U.S. patent application Ser. No. 16/808,098, filed Mar. 3, 2020, now U.S. Pat. No. 11,109,456, issued Aug. 31, 2021; which is a continuation of U.S. patent application Ser. No. 16/446,601, filed Jun. 19, 2019, now U.S. Pat. No. 10,609,777, issued Mar. 31, 2020; which is a continuation of U.S. patent application Ser. No. 16/127,163, filed Sep. 10, 2018, now U.S. Pat. No. 10,356,868, issued Jul. 16, 2019; which is a continuation of U.S. patent application Ser. No. 15/583,425, filed May 1, 2017, now U.S. Pat. No. 10,104,735, issued Oct. 16, 2018; which is a continuation of U.S. patent application Ser. No. 15/186,254, filed Jun. 17, 2016, now U.S. Pat. No. 9,655,180, issued May 16, 2017; which claims the benefit of Provisional U.S. Patent Application No. 62/182,110, filed Jun. 19, 2015, the disclosures of all of which are incorporated herein by reference in their entireties. BACKGROUND Light-emitting diode (LED) light sources (i.e., LED light engines) are often used in place of or as replacements for conventional incandescent, fluorescent, or halogen lamps, and the like. LED light sources may comprise a plurality of light-emitting diodes mounted on a single structure and provided in a suitable housing. LED light sources are typically more efficient and provide longer operational lives as compared to incandescent, fluorescent, and halogen lamps. In order to illuminate properly, an LED driver control device (i.e., an LED driver) must be coupled between an alternating-current (AC) source and the LED light source for regulating the power supplied to the LED light source. The LED driver may regulate either the voltage provided to the LED light source to a particular value, the current supplied to the LED light source to a specific peak current value, or both the current and voltage. LED light sources are typically rated to be driven via one of two different control techniques: a current load control technique or a voltage load control technique. An LED light source that is rated for the current load control technique is also characterized by a rated current (e.g., approximately 350 milliamps) to which the peak magnitude of the current through the LED light source should be regulated to ensure that the LED light source is illuminated to the appropriate intensity and color. In contrast, an LED light source that is rated for the voltage load control technique is characterized by a rated voltage (e.g., approximately 15 volts) to which the voltage across the LED light source should be regulated to ensure proper operation of the LED light source. Typically, each string of LEDs in an LED light source rated for the voltage load control technique includes a current balance regulation element to ensure that each of the parallel legs has the same impedance so that the same current is drawn in each parallel string. It is known that the light output of an LED light source can be dimmed. Different methods of dimming LEDs include a pulse-width modulation (PWM) technique and a constant current reduction (CCR) technique. Pulse-width modulation dimming can be used for LED light sources that are controlled in either a current or voltage load control mode/technique. In pulse-width modulation dimming, a pulsed signal with a varying duty cycle is supplied to the LED light source. If an LED light source is being controlled using the current load control technique, the peak current supplied to the LED light source is kept constant during an on time of the duty cycle of the pulsed signal. However, as the duty cycle of the pulsed signal varies, the average current supplied to the LED light source also varies, thereby varying the intensity of the light output of the LED light source. If the LED light source is being controlled using the voltage load control technique, the voltage supplied to the LED light source is kept constant during the on time of the duty cycle of the pulsed signal in order to achieve the desired target voltage level, and the duty cycle of the load voltage is varied in order to adjust the intensity of the light output. Constant current reduction dimming is typically only used when an LED light source is being controlled using the current load control technique. In constant current reduction dimming, current is continuously provided to the LED light source, however, the DC magnitude of the current provided to the LED light source is varied to thus adjust the intensity of the light output. Examples of LED drivers are described in greater detail in commonly-assigned U.S. Pat. No