EP4721520A1

EP4721520A1 - A led driving arrangement, a led lighting device and a led lighting system

Info

Publication number: EP4721520A1
Application number: EP24726654.7A
Authority: EP
Inventors: Liang Shi; Kang Li; Zhengyu Wang
Original assignee: Signify Holding BV
Current assignee: Signify Holding BV
Priority date: 2023-06-05
Filing date: 2024-05-23
Publication date: 2026-04-08
Also published as: CN121241659A; WO2024251527A1

Abstract

A LED driving arrangement comprising an input to be connected to and receive a primary input power, an output to be connected to a LED load, a power conversion circuit adapted to convert the primary input power into a primary output power and to provide said primary output power to the LED load via the output in a first mode, said power conversion circuit comprising at least one energy exchanging component powered by the power conversion circuit in the first mode, and a controller adapted to switch the LED driving arrangement in the first mode, and further adapted to switch the LED driving arrangement in a second mode to at least partially stop from converting the primary input power into the primary output power and outputting to the LED load hereby at least partially stop powering the energy exchanging component. The LED driving arrangement further comprises a control interface to be connected with a remote/an external control node via a control network, and an auxiliary power supply circuit connected with the control interface and the power conversion circuit and adapted to, when in the second mode, retrieve an auxiliary power, via the control network, from the remote / external control node and supply the auxiliary power to the energy exchanging component.

Description

A LED driving arrangement, a LED lighting device and a LED lighting system

FIELD OF THE INVENTION

The present invention relates to the field of LED lighting, and in particular to LED drivers for LED lighting arrangements.

BACKGROUND OF THE INVENTION

LED lighting has an advantage of controllable power consumption to provide controllable output lumen/brightness. A dimming function is a common feature provided by a LED driver. Therefore, the LED driver/lighting device has a rated power at nominal power without dimming, and a reduced power at dimming. Nowadays the regulation on efficiency only regulates the device’s efficiency at the rated power. In electronics design, the driver is designed for its rated power and its efficiency is optimized at the rated power. When the LED driver power is dimmed down especially in deep dimming, the efficiency of the driving circuit usually drops significantly. Even though the present regulation does not regulate the efficiency at dimmed state, it is still very important to provide energy savings for the user. Besides, the future regulation may regulate efficiency at dimmed state. Thus the LED driver should be designed with better efficiency at the dimmed state.

Besides dimming, the LED lighting device may also operate in a non-light- emitting mode such as standby. A certain amount of power is still needed in the driving circuit even if the driving circuit does not output a substantial output power to turn on the LED. For example, the output buffer capacitor of the LED driver is pre-charged constantly to a level that is only slightly lower than the forward voltage of the LEDs, so the LED driver can quickly charge the output buffer above this level and turn on the LED when the LED driver switches from the standby to normal lighting. This pre-charging just needs a small amount of power, thus the LED driver has to work inefficiently to generate this small amount of power.

There is a need to provide a high efficiency for the LED lighting in case that the power consumed in the LED driver is small.

US2023108118A1 discloses a winding LI connected in parallel with the LED and energy from the winding LI is converted to an auxiliary power supply circuit 30. SUMMARY OF THE INVENTION

Lighting system has become connected via a wired network. Such a wired network is mainly for control. Hereafter it is called a control network wherein its original/ designed purpose is to transfer control signals. For example, 1-10V control/dimming network is very popular in lighting. A controlling device sends a 1-10V analog voltage to the lighting device via a 1-10V control network/bus. The voltage on control line changes from 1- 10V to indicate how much percent of output power is to be output by the lighting device. A voltage less <1V may command the lighting device into standby. Figure 1 schematically shows such as lighting system wherein the sensor is the controlling device. Traditionally, each driver needs still obtain the power in the dimmed mode and standby from the mains. Thus each driver has to output a power less than its rated power, at a efficiency lower that its rated efficiency. Alternatively, digital control protocols such as DALI. The control network is neither limited for dimming control network, but could also be a sensor network such as DALI Sensor-Ready (SR) network.

The basic idea of the invention is that generating all of the power, needed by the power converting circuit in each lighting load at small power mode, at a center device with a high efficiency, and distributing this power to each node via the control network. At each node, instead of generating the small power from the mains at a high power loss, the node retrieves this power from the control network and apply the retrieved power to the energy exchanging component of the power converting circuit. Thus the power converting circuit do not operate from the mains at high power loss and the efficiency is increased. Here the term control network means a network whose major purpose is for communicating control signal, and it preferably excludes a network whose major purpose is for distributing power signal, such as AC mains grid or DC grid, and it even more preferably also excludes power line communication network.

In a first aspect of the invention, it is provided a LED driving arrangement comprising an input to be connected to and receive a primary input power, an output to be connected to a LED load, a power conversion circuit adapted to convert the primary input power into a primary output power and to provide said primary output power to the LED load via the output in a first mode, said power conversion circuit comprising at least one energy exchanging component powered by the power conversion circuit in the first mode. It further comprises a controller adapted to switch the LED driving arrangement in the first mode, and further adapted to switch the LED driving arrangement in a second mode to at least partially stop from converting the primary input power into the primary output power and outputting to the LED load thereby at least partially stop powering the energy exchanging component. Most notably, it comprises a control interface to be connected with a remote/an external control node via a control network, and an auxiliary power supply circuit connected with the control interface and the power conversion circuit and adapted to, when in the second mode, retrieve an auxiliary power, via the control network, from the remote/extemal control node, and supply the auxiliary power to the energy exchanging component.

In this aspect, in the second mode, the power conversion circuit is at least partially stopped from powering the energy exchanging component so as to reduce its power loss, and the power needed by the energy exchanging component is retrieved from the control network. This effectively reduces the power loss on the LED driving arrangement. Moreover, the power is generated in a centralized way thus with a higher efficiency. The cable loss for the power transmitted over the control network is neglectable. Therefore the efficiency of the whole lighting system is improved.

In a further embodiment, the controller is adapted to switch the LED driving arrangement in the second mode to completely stop from converting the primary input power into the primary output power and outputting to the LED load.

In this embodiment, the power loss of the power conversion circuit at small power is avoided.

In a further embodiment, the energy exchanging component is adapted be charged and discharged by a power being converted by the power conversion circuit so as to provide the power to the load.

In this embodiment, the energy exchanging component is a substantial power conversion component by being charged and discharged. The power conversion circuit can be stopped from supplying this energy exchanging component thus avoid power loss. The energy exchanging component is supplied by the auxiliary power thus it can still manipulate the auxiliary power for the second mode purpose.

In a further embodiment, the energy exchanging component comprises any one of a buffer capacitor in the power conversion circuit; and a power inductor of the power conversion circuit wherein the power conversion circuit comprises a switched mode power supply.

This embodiment provides two implementations for the energy exchanging component.

The power conversion circuit has various implementations, and therefore there are also many ways to stop the power conversion circuit for avoid power loss thereof. In one embodiment, the power conversion circuit comprises multiple conversion stages comprising a first stage and at least one later stage, and the energy exchanging component is at one of the later stage and the stages before this later stage is adapted to be stopped whereas the later stage and thereafter are adapted to convert the auxiliary power.

In another embodiment, the energy exchanging component is at the output and the power conversion circuit is adapted to be stopped.

In this embodiment, the power conversion circuit could either be a multiple stage converter or a single stage converter, and the portion thereof before the energy exchanging component can be stopped and power loss avoided.

In a further embodiment, the later stage and thereafter comprises an integrated circuit for driving the later stage and thereafter, and the auxiliary power supply circuit is also adapted to supply the auxiliary power to the integrated circuit for driving the later stage and thereafter.

In this embodiment, the integrated circuit for driving the later stage is also supplied by the auxiliary power thus does not need the LED driving arrangement to supply the integrated circuit from the primary input power, and this further reduces power loss for supplying the integrated circuit.

The second mode, namely the low power mode, have many implementations / usages. In one implementation, the second mode is a standby mode wherein the auxiliary power supply circuit is adapted to supply the auxiliary power to the energy exchanging component and regulate a power at the output not sufficient to turn on the LED load but is higher than a threshold. This embodiment archives both a low power loss standby and a quick start-up time.

In another implementation, the second mode is a dimming mode wherein the auxiliary power supply circuit is adapted to supply the auxiliary power to the energy exchanging component so as to regulate a power at the output sufficiently to turn on the LED load but is less than a threshold. This embodiment archives a low power loss deep dimming.

In one embodiment, the control network is a communicating network.

The control interface / control communicating network can also be implemented by various technologies. In some embodiments, the control interface comprises any one of

- a dimming interface; and

- a sensor interface. In a more specific implementation, the dimming interface comprises any one of: a 1-10V analog dimming interface wherein the controller is adapted to switch the LED driving arrangement into the second mode when an analog voltage on the 1-10V dimming interface is lower than a certain level, and the auxiliary power supply comprises at least one stage of boost circuit to boost the analog voltage and supply the boosted analog voltage to the energy exchanging component; and a DALI digital interface.

In another specific implementation, the sensor interface comprises a DALI Sensor-Ready digital interface.

A second aspect of the invention provides a LED lighting device comprises the LED driving arrangement according to the first aspect, and a LED load.

A third aspect of the invention provides a LED lighting system comprising at least one of the LED lighting devices according to the second aspect, a remote control node and the control network interconnecting the LED lighting devices and the control node, wherein the remote control node is adapted to send the auxiliary power to the LED lighting devices via the control network.

In a further embodiment, the remote control node is adapted to send a command, for controlling the LED lighting devices to switch into the first mode and the second mode, to the LED lighting devices via the control network.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Fig. 1 shows the structure of the lighting system including lighting devices, a sensor as a control device and a control network.

Fig. 2 is a known circuit schematic of a LED lighting device;

Fig. 3 is a circuit schematic of a LED lighting device according to an embodiment of the invention; and

Fig. 4 is a circuit schematic of a LED lighting device according to an alternative embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS The invention will be described with reference to the Figures.

It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

Fig. 2 schematically shows the known LED lighting device with a 1-10V dimming interface. Its components and operation will be described.

The power conversion circuit of the LED lighting device is a two stages converter with a first stage flyback converter and a second stage buck converter. The AC mains is rectified by a rectifier bridge (not shown) into a bus voltage Vbus. The Vbus is connected to the flyback converter, and it provides a supply power VCC at start up for the control block of the flyback converter before the flyback converter starts normal high frequency switching. The control block controls the flyback power switch SI in series with the primary side flyback winding. An auxiliary winding at the left side also provides a supply power VCC for the control block, in response to normal high frequency switching of the flyback converter.

At the secondary side, the secondary side flyback winding is connected to a buffer capacitor via a diode DI. The buffer capacitor is an intermediate power exchanging component and the second stage buck converter draws the energy on the buffer capacitor and convert it into the LED power/current to the LED load.

At the secondary side, there is another auxiliary winding connected with a diode D2 to provide another supply power for secondary side. More specifically, this supply power is supplied to the 1-10V dimming control block/interface. This supply power is also provided to the MCU, optionally via a buck conversion into 3.3V by another buck converter. The MCU converts the dimming command from the 1-10V control network into a certain waveform such as a PWM signal and transmits this waveform to the control block on the primary side via a photocoupler. The control block on the primary side can adjust the power generated by the flyback converter accordingly. The MCU may also controls the second stage buck converter according to the dimming command. Notably,

In a deep dimming mode, a low voltage a little higher than IV is transmitted on the 1- 10V interface. The MCU converts this signal into a corresponding PWM signal to the control block. And the control block controls the flyback converter to output a small power to the secondary side, effectively to the LED. But the flyback converter, operating at this power, has a low efficiency. And

In a standby mode, a low voltage smaller than IV is transmitted on the 1-10V interface. The MCU converts this signal into a corresponding PWM signal to the control block. And the control block controls the flyback converter to output an even smaller power to the secondary side. This smaller power is used for pre-charge the buffer capacitor to a certain level but insufficient to turn on the LED. This precharged energy helps to shorten the start-up duration in the future since the flyback converter does not need to charge the buffer capacitor from zero voltage when it switches from the standby mode to the operation mode. Similarly, in the standby mode, the flyback converter, operating at this even smaller power, has a low efficiency. The MCU may instruct the buck converter at the secondary side to either stop operating or just regulating the voltage on the output capacitor slightly lower than the forward voltage of the LED.

It can be seen that for both cases, since the flyback converter still operates to generate a small power, its power loss is unavoidable.

Figure 3 shows one embodiment of the present invention. There are many similar components between figure 2 and figure 3 and those similar components/operations would not be described again.

The most significant improvement in figure 3 is the auxiliary power supply circuit 300 connected with the 1-10V control interface and the power conversion circuit, and adapted to retrieve an auxiliary power from the control network, and supply the auxiliary power to the energy exchanging component when the LED driving arrangement is in the second mode.

In this embodiment, the energy exchanging component is the buffer capacitor intermediate between the secondary side flyback winding and the buck converter.

In a deep dimming mode, a low voltage a little higher than IV is transmitted by the remote control node on the 1-10V interface. This voltage is optionally boosted by a boost converter 300 as the auxiliary power supply circuit and supply to the buffer capacitor. The second stage buck converter draws the energy on the buffer capacitor and convert it into the LED power/current to the LED load. Notably, the first stage / flyback converter does not operate and avoids power loss thereof. The MCU on the secondary side provides enable (disable) signal to the boost converter 300. In an alternative embodiment that the power on the 1-10V interface is not sufficient for the LED, the first stage/flyback converter can be activated but works at very low power just to provide the difference between the LED power and the power retrieved on the 1-10V interface. Since the provided power is very limited, the power loss on the flyback converter can be accepted. Optionally, the MCU is also supplied from the power on the 1-10V interface. This could be via a further boost regulator block as shown.

In an alternative embodiment, the boost converter 300 as the auxiliary power supply circuit may supply the boosted voltage directly into a power inductor of the second stage buck converter.

In still an alternative embodiment, the buck converter may be driven by an integrated circuit controller and the boost converter 300 of the auxiliary power supply circuit 30 may supply the boosted voltage directly to the IC controller of the buck converter.

Similarly, in standby mode, a low voltage smaller than IV, such as 0.9V, is transmitted by the remote control node on the 1-10V interface. This voltage is optionally boosted by a boost converter 300 of the auxiliary power supply circuit 30 and supply to the buffer capacitor. In one example, the buffer capacitor’s voltage is maintained at a certain level and the second stage buck converter is not operating thereby the LED is not turned on, wherein the MCU sends a disable signal to the second stage buck converter. In another example, the second stage buck converter is operating and draws the energy on the buffer capacitor and convert it to charge the output capacitor to a voltage lower than the LED forward voltage so the LED is not turned on, wherein the MCU sends an enable signal to the second stage buck converter. In this example, the start-up time of the LED is minimized since the output capacitor has a voltage, but the second stage buck converter has operation power loss. Notably, in both cases, the first stage / flyback converter does not operate and avoids power loss of the first stage / flyback converter.

Even more, if the MCU senses the voltage drops lower than 0.9V (for example), that means the system has no power supply on control network. The MCU will disable the boost converter from generating any power for the second mode. The LED lighting device may act in the known way above mentioned with respect to in figure 2. In an alternative embodiment shown in fig. 4, the power conversion circuit is a single stage wherein the second stage buck converter in fig. 3 is taken away. The boost converter 300 is connected between the 1-10V interface and the LED load directly.

In this embodiment,

• for a deep dimming mode, the boost converter can be used as a current regulator to provide the deep dimming current to the LED load.

Similar as above, the flyback converter can be completely deactivated, or only partially deactivated to provide a very small power. The power loss of the flyback converter is minimized.

• for a standby mode, the boost converter can be used as a voltage regulator to regulate the voltage on the output capacitor lower than the LED forward voltage so the LED is not turned on. Notably, the flyback converter does not operate and avoids power loss.

In case that the 1-10V interface is replaced by DALI or DALI Sensor-Ready (SR) interfaces which has a higher voltage on the control network, the above boost converter and boost regulator can be adapted or even removed since the voltage on the control interface may also be applicable for the second stage buck converter, the LED load and the MCU.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. For example, the cool white LED channel and the warm white LED channel can also be replaced by or added with red, green and blue LED channels.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A LED driving arrangement comprising an input to be connected to and receive a primary input power, an output to be connected to a LED load, a power conversion circuit adapted to convert the primary input power into a primary output power and to provide said primary output power to the LED load via the output in a first mode, said power conversion circuit comprising at least one energy exchanging component powered by the power conversion circuit in the first mode, and a controller adapted to switch the LED driving arrangement in the first mode, and further adapted to switch the LED driving arrangement in a second mode to at least partially stop from converting the primary input power into the primary output power and outputting to the LED load thereby at least partially stop powering the energy exchanging component, a control interface to be connected with a remote /an external control node via a control network, and an auxiliary power supply circuit (300) connected with the control interface and the power conversion circuit and adapted to, when in the second mode, retrieve an auxiliary power, via the control network, from the remote / external control node and supply the auxiliary power to the energy exchanging component.

2. The LED driving arrangement of claim 1, wherein the controller adapted to switch the LED driving arrangement in the second mode to completely stop from converting the primary input power into the primary output power and outputting to the LED load.

3. The LED driving arrangement of claim 1, wherein the energy exchanging component is adapted be charged and discharged by a power being converted by the power conversion circuit so as to provide the power to the load.

4. The LED driving arrangement of claim 2, wherein the energy exchanging component comprises any one of a buffer capacitor in the power conversion circuit; and a power inductor of the power conversion circuit wherein the power conversion circuit comprises a switched mode power supply.

5. The LED driving arrangement of claim 1, wherein the power conversion circuit comprises multiple conversion stages comprising a first stage and at least one later stage, and the energy exchanging component is at one of the later stage and the stages before this later stage is adapted to be stopped whereas the later stage and thereafter are adapted to convert the auxiliary power.

6. The LED driving arrangement of claim 4, wherein the later stage and thereafter comprises an integrated circuit for driving the later stage and thereafter, and the auxiliary power supply circuit (300) is also adapted to supply the auxiliary power to the integrated circuit for driving the later stage and thereafter.

7. The LED driving arrangement of claim 1, wherein the energy exchanging component is at the output and the power conversion circuit is adapted to be stopped.

8. The LED driving arrangement of claim 1, wherein the second mode is a standby mode wherein the auxiliary power supply circuit (300) is adapted to supply the auxiliary power to the energy exchanging component and regulate a power at the output not sufficient to turn on the LED load but is higher than a threshold.

9. The LED driving arrangement of claim 1, wherein the second mode is a dimming mode wherein the auxiliary power supply circuit (300) is adapted to supply the auxiliary power to the energy exchanging component so as to regulate a power at the output sufficiently to turn on the LED load but is less than a threshold.

10. The LED driving arrangement of claim 1, wherein the control network is a communicating network.

11. The LED driving arrangement of claim 1 , wherein the control interface comprises any one of

- a dimming interface; and

- a sensor interface.

12. The LED driving arrangement of claim 10, wherein the dimming interface comprises any one of:

- a 1-10V analog dimming interface wherein the controller is adapted to switch the LED driving arrangement into the second mode when an analog voltage on the 1-10V dimming interface is lower than a certain level, and the auxiliary power supply comprises at least one stage of boost circuit to boost the analog voltage and supply the boosted analog voltage to the energy exchanging component; and

- a DALI digital interface; and the sensor interface comprises

- a DALI Sensor-Ready digital interface.

13. A LED lighting device comprises the LED driving arrangement according to any one of claim 1 to 12, and a LED load.

14. A LED lighting system comprising at least one of the LED lighting devices according to claim 13, a remote control node and the control network interconnecting the LED lighting devices and the control node, wherein the remote control node is adapted to send the auxiliary power to the LED lighting devices via the control network.

15. The LED lighting system according to claim 14, wherein the remote control node is adapted to send a command, for controlling the LED lighting devices to switch into the first mode and the second mode, to the LED lighting devices via the control network.