GB2584822A

GB2584822A - DALI power supply unit

Info

Publication number: GB2584822A
Application number: GB1906988.9A
Authority: GB
Inventors: Baynham Tom; Baynham Lawrence
Original assignee: INDO LIGHTING Ltd
Current assignee: INDO LIGHTING Ltd
Priority date: 2019-05-17
Filing date: 2019-05-17
Publication date: 2020-12-23
Anticipated expiration: 2039-05-17
Also published as: GB201906988D0; GB2584822B

Abstract

A power supply unit (PSU) for a Digital Addressable Lighting Interface (DALI) system, which may be incorporated in a DALI compatible device such as an LED driver, includes a microcontroller, a DALI bus input and a switchable power source that is connected to the DALI bus input. The power source can be switched on and off by the microcontroller. The microcontroller is configured to determine whether or not a DALI bus connected to the DALI bus input is energised by detecting a voltage on the DALI bus. If the DALI bus is energised, the microcontroller disables the switchable power source. If, on the other hand the DALI bus is not energised, the microcontroller enables the switchable power source to energise the DALI bus.

Description

Intellectual Property Office Application No. GII1906988.9 RTM Date:23 September 2019 The following term is a registered trade mark and should be read as such wherever it occurs in this document:

DALI

Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo

DALI POWER SUPPLY UNIT

TECHNICAL FIELD

The present invention relates generally to DALI power supply unit, for example for incorporation in an LED driver or other DALI compatible device.

BACKGROUND

The Digital Addressable Lighting Interface (DALI) is a protocol for lighting controls and dimming agreed by major manufacturers, set out in the technical standard IEC 62386. Standards conformance ensures that equipment from different manufacturers will interoperate.

A DALI network consists of a controller, a power supply and one or more slave devices (e.g., electrical ballasts, LED drivers and dimmers) that have DALI interfaces. The controller can monitor and control each device by means of a bi-directional data exchange. The DALI protocol permits devices to be individually addressed and it also allows multiple devices to be addressed simultaneously via multicast and broadcast messages.

A single pair of wires comprise the bus used for communication to all devices on a DALI network. The bus is used for both signal and power. While many devices are line-powered, low-power devices such as motion detectors may be powered directly from the DALI bus.

Each slave device typically has a bridge rectifier on its input so it is polarity-insensitive.

The bus is a wired-AND configuration where signals are sent by briefly shorting the bus to a low voltage level.

The power supply may be incorporated into the DALI controller. As an alternative, in a second generation of the DALI protocol, DALI-2, the DALI bus may be powered by one of the other components connected to the DALI bus, for example an LED driver. Typically, an LED driver designed for a DALI-2 system will not be appropriate for use in a DALI-1 system and vice versa. -1 -

SUMMARY

In general, embodiments of the present invention are concerned with providing a power supply unit (PSU) that can be used in a DALI system in a first mode in which the DALI controller (or any other external device) powers the DALI bus and in a second mode in which the PSU within the slave LED power supply powers the DALI bus. The PSU is preferably incorporated into a DALI compatible device, such as a DALI compatible LED driver, for example.

In a first aspect, the invention provides a power supply unit (PSU) for a DALI system, the PSU comprising: a microcontroller; a DALI bus input; and a switchable power source that can be switched on and off by the microcontroller and that is connected to the DALI bus input; wherein the microcontroller is configured: to determine whether or not a DALI bus connected to the DALI bus input is energized; in the event that the DALI bus is energized, to disable the switchable power source; and in the event that the DALI bus is not energized, to enable the switchable 20 power source to energize the DALI bus.

In some embodiments, the PSU further comprises a unidirectional signal block which allows DALI signals and power on the DALI system bus to pass through the unidirectional signal block in the event that the switchable power source is disabled. The PSU is configured, however, to cause signals and power on an internally generated bus to bypass the unidirectional signal block and reach the DALI system bus in the event that the switchable power source is enabled. The unidirectional signal block may be a DALI rectifier bridge. -2 -

In some embodiments, the PSU includes a power output separate from the DALI bus, which can be used to provide power to a connected unpowered DALI device.

In a second aspect, the invention provides a lighting control system comprising at least one DALI device (e.g.a DALI controller) and at least one PSU in accordance with the first 5 aspect above, the at least one DALI device and the PSU being connected by a DALI bus for transmitting DALI signals.

In a third aspect, the invention provides a DALI compatible device comprising a PSU in accordance with the first aspect above. The DALI compatible device may, for example, be an LED driver.

In a fourth aspect, the invention provides a method for operating a power supply unit for a DALI system, the power supply unit comprising a controller and a switchable power source and being connected to a DALI bus, the method comprising the microcontroller operating to: detect whether or not the DALI bus is energized; in the event that the DALI bus is already energized, disabling the switchable power source; and in the event that the DALI bus is not energized, enabling the switchable power source to energize the DALI bus.

The PSU of this aspect may be a PSU in accordance with the first aspect above.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 schematically illustrates PSU in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT

An embodiment is described below by way of example with reference to the accompanying drawing. -3 -

In general terms, embodiments of the invention provide a PSU that can be incorporated into a DALI compatible device so that it can power the DALI bus in the event that the DALI controller, or other external device is not powering the DALI bus. The example below uses the context of an LED driver incorporating the PSU but the skilled person will appreciate that the PSU may be incorporated in other DALI compatible devices.

Fig. 1 schematically shows the components of the PSU and illustrates two different operating states. In a first operating state, an unpowered DALI controller or device (labelled "Un-Powered signal source" in the figure) is connected to the DALI bus, and the PSU must provide power to the DALI bus. In a second operating state, a powered DALI controller or device (labelled "Powered signal source" in the figure) is connected to and provides power to the DALI bus. In this state.the PSU must refrain from powering the DALI bus.

The PSU includes a microprocessor, a "unidirectional signal block" (for example a rectifier bridge), a path that bypasses the unidirectional signal block, and a switchable power source (e.g. a Buck power supply).

The microprocessor is configured to detect whether the PSU is connected to a powered DALI device (e.g. a powered DALI controller) or an unpowered DALI device by detecting whether or not there is a voltage on the DALI bus.

For example, the microcontroller can have a DALI-receive pin connected to the DALI bus and this pin can be polled shortly after power-up of the PSU (or the LED driver in which it is incorporated). If the pin is high, then the microprocessor determines that an unpowered DALI device is connected. If, on the other hand, the pin is low, this means that the DALI bus is already energized, and the microcontroller can determine that a powered DALI device is connected to the bus.

In the case where the microcontroller determines that the DALI bus is already energized by a powered DALI device (e.g. a DALT controller), i.e. the second state noted above, the PSU need not provide any power and the switchable power source remains disabled by the microcontroller. The DALI control signals are passed in a normal fashion through the unidirectional signal block (e.g. DALI rectifier bridge). -4 -

In this case, the powered DALI device may also provide power to the PSU (or the LED driver in which it is incorporated), in particular to power the microprocessor (or additional microprocessors).

On the other hand in the case corresponding to the first state noted above, where the 5 microcontroller determines that an unpowered DALI device (e.g. an unpowered DALI controller) is connected to the DALI bus, it falls on the PSU to power the bus and, typically, also to power the connected DALI device.

In this case, the microcontroller will turn on the switchable power source to energise the DALI bus. The microprocessor will also switch the path so that the unidirectional signal block is bypassed allowing signal and power current to flow from the PSU to the system DALI bus. For example, where a DALI rectifier bridge is used, the microcontroller can bypass the rectifier bridge by turning on a transistor that shorts a lower diode in the bridge and turning on a second transistor that bypasses the upper diode in the bridge In some cases, the unpowered DALI device will draw power from the DALI bus. In other 15 cases, however, the DALI device may require more power than can be drawn from the DALI bus. In such cases, the PSU may also provide power at a higher voltage than the DALI bus (e.g. 24v) to the unpowered DALI device via a separate power supply connection.

In this way, the PSU, which as noted above can be incorporated into an LED driver or other DALI compatible device, can be used with either powered or unpowered DALI controllers (or other DALI devices) and functions to automatically select an appropriate operating state based on whether the connected DALI controller (or other device) is powering the DALI bus or not. This offers significant advantages over the known DALI LED drivers, for example, where different devices are required for the two different types of DALI system.

The skilled person will understand that various modifications and additions can be made to the example described above without departing from the spirit and scope of the present invention. -5 -

Claims

CLAIMS: A power supply unit (PSU) for a DALI system, the PSU comprising: a microcontroller; a DALI bus input; and a switchable power source that can be switched on and off by the microcontroller and that is connected to the DALI bus input; wherein the microcontroller is configured: to determine whether or not a DALI bus connected to the DALI bus input is energized; in the event that the DALI bus is energized, to disable the switchable power source; and in the event that the DALI bus is not energized, to enable the switchable power source to energize the DALI bus.
2. The PSU of claim 1, further comprising a unidirectional signal block, the microcontroller being further configured: in the event that the switchable power source is disabled, to pass DALI signals on the DALI bus through the unidirectional signal block; and in the event that the switchable power source is enabled, to cause signals on the DALI bus to bypass the unidirectional signal block.
The PSU of claim 2, wherein the unidirectional signal block is a DALI rectifier bridge.
4. The PSU of any one of the preceding claims, comprising a power output separate from the DALI bus, which can be used to provide power to a connected unpowered DALI device.
5. A lighting control system comprising at least one DALI device and at least one PSU in accordance with any one of claims Ito 4, the at least one DALI device and the PSU being connected by a DALI bus for transmitting DALI signals. -6 -
The lighting system of claim 5, wherein the DALI device is a DALI controller.
The lighting system of claim 5 or claim 6, wherein the PSU is part of a DALI compatible device.
The lighting system of claim 7, wherein the DALT compatible device is an LED driver.
A DALI compatible device comprising a PSU in accordance with any one of claims 1 to 4.
10. The device of claim 9, wherein the device is an LED driver.
11. A method for operating a power supply unit for a DALI system, the power supply unit comprising a controller and a switchable power source and being connected to a DALI bus, the method comprising the microcontroller operating to: detect whether or not the DALI bus is energized; in the event that the DALI bus is already energized, disabling the switchable power source; and in the event that the DALI bus is not energized, enabling the switchable power source to energize the DALI bus.
12. The method according to claim 11, wherein the power supply unit is a PSU in accordance with any one of claims 1 to 4. -7 -