DC power supply device, DC power receiving device, and operation method

Abstract

The present invention relates to a DC power supply device (400) for supplying operating DC power to one or more DC powered devices having corresponding DC power requirements, the DC power supply device comprising: a power interface (402) for providing DC output power via a single twisted pair wired bus (401); a DC power supply network communication unit (404) configured to receive DC power requirement information indicating a DC voltage requirement and a DC current requirement of each connected DC powered device; and a DC power supply control unit (406) configured to: drive delivery of an initialization DC output power amount in an initialization supply mode, the initialization supply mode being suitable for transmitting the corresponding DC power requirement information by the DC powered device; determine and provide operating DC output power using the DC power requirement information and a power determination rule for powering the at least one DC powered device for operation in its normal operating mode, thereby enabling powering a plurality of DC powered devices having different DC power requirements.

Description

Technical Field

[0001] The present invention relates to a DC power supply device, a DC powered device, an electrical apparatus, a method for operating a DC power supply device, a method for operating a DC powered device, and corresponding computer programs. Background Art

[0002] US 2017 / 0222436 A1 describes a power distribution system for distributing power from a power source to multiple electrical loads via outlets. The outlets receive power requests from the loads and transmit them to a master device, which controls the power provided by the respective outlets based on the received power requests. Because the master device receives all power requests from the outlets and therefore has an overview of the overall power demand, it can determine the power to be provided by the respective outlets based on this knowledge.

[0003] KR 20170085469 A discloses a power over data line (PoDL) system in which a single powered device (PD) is connected to a power sourcing equipment (PSE) via a twisted pair cable. Summary of the Invention

[0004] The inventors have recognised that it would be beneficial to provide improved flexibility when configuring a network comprising DC power sourcing devices and DC powered devices connected in parallel via a single wired bus.

[0005] The present invention is further based on the recognition that flexible configurability of an electrical installation (also referred to herein as a network) comprising a DC power supply device and DC powered devices connected in parallel via a single wired bus must provide the technical capabilities of the DC power supply device and the DC powered devices to enable normal operation of the DC powered devices while providing an operating DC voltage having an amount that depends on the number and corresponding requirements of the individual DC powered devices connected to the DC power supply device. According to the present invention, this is achieved by providing a DC power supply device according to the first aspect of the invention and a DC powered device according to the second aspect of the invention, both of which will be described further below. Further aspects of the invention will then be described.

[0006] Thus, according to a first aspect of the present invention, there is provided a DC power supply apparatus for supplying operating DC power to one or more DC powered devices. The DC power supply apparatus is for use in an electrical installation or network, wherein each DC powered device is operable in an initialization mode requiring a lower amount of DC power than in a corresponding normal operating mode of the DC powered device.

[0007] A DC power supply device includes a power interface for providing DC output power to a plurality of DC powered devices connected in parallel via a single twisted-pair wired bus. The DC power supply device also includes a DC power network communication unit configured to receive, via the power interface, corresponding DC power requirement information from the DC powered devices connected via the wired bus, the corresponding DC power requirement information indicating a DC voltage requirement and a DC current requirement for each DC powered device operating in its corresponding normal operating mode.

[0008] The DC power supply device further includes a DC power control unit configured to drive the DC power supply device to operate in an initialization supply mode, delivering a predetermined initialization DC output power amount via the power interface. The initialization DC output power amount is suitable for driving the connected DC powered devices in their initialization mode, wherein the initialization mode includes transmitting corresponding power requirement information for their respective normal operating modes to the DC power supply device via the wired bus. The DC power control unit is further configured to use the DC power requirement information received from the connected DC powered devices and a predetermined power determination rule to determine an operating DC output power amount to be output via the output power interface from a plurality of available DC output power amounts that the DC power supply device is configured to supply in the operational supply mode, the operating DC output power amount having an operating DC voltage amount suitable for powering the connected DC powered devices in their respective normal operating modes. The DC power control unit is further configured to subsequently drive the DC power supply device to operate in the operational supply mode, distributing the determined operating DC output power amount to the connected DC powered devices via the power interface.

[0009] A DC power supply device forms a network component that supplies operating DC power to one or more DC powered devices in a network configuration. In this network configuration, multiple DC powered devices can be connected in parallel to the DC power supply device via a single twisted-pair wired bus. In this network configuration, the DC power supply device and the DC powered devices form network nodes that share a physical medium for both power supply and data exchange. In this context, the physical medium is a single twisted-pair wired bus, also referred to herein as a wired bus. Typically, the wired bus takes the form of a single twisted-pair wired cable. However, in an alternative embodiment, the present invention is implemented using an alternative physical medium for both power supply and data exchange that is different from a single twisted-pair wired cable.

[0010] The DC power supply device of the first aspect of the present invention is advantageously configured to flexibly determine an amount of operating DC output power to be delivered to a connected DC powered device via the wired bus, using DC power requirement information provided by the DC powered device via the wired bus and received by the DC power supply device via its power interface during an initialization phase.

[0011] The DC power requirement information is provided by the DC powered device using a DC power supply control unit configured to operate the DC power supply device in an initialization supply mode and an operating supply mode. In the initialization supply mode, the DC power supply device is operated to provide a predetermined initialization DC output power amount to the connected DC powered device via the power interface. The initialization DC output power amount is suitable for operating the connected DC powered device in its initialization mode. As will be described in the context of the second aspect of the present invention, the initialization mode operation of the DC powered device includes the transmission of corresponding power requirement information for the corresponding normal operating mode of the given DC powered device. The transmission of the corresponding power requirement information from the DC powered device to the DC power supply device is performed via a wired bus.

[0012] Since the DC powered devices (each forming a load) are connected in parallel with the DC power supply device, the amount of DC voltage provided at the power interface of the DC power supply device will be the same for each DC powered device (not taking into account losses along the wired bus).

[0013] Typically, however, the connected DC powered devices have different respective DC voltage requirements and DC current requirements for operating in their respective normal operating modes.

[0014] The DC power supply control unit uses DC power demand information received from the connected DC powered devices and further uses a predetermined power determination rule to determine an amount of operating DC output power to be output via the output power interface. The predetermined power determination rule determines an amount of operating DC output power suitable for powering the connected DC powered devices in their respective normal operating modes. Thus, the power determination rule uses the collected information to determine, for example, an amount of DC voltage suitable for enabling each connected DC powered device to operate in its normal operating mode, and an amount of DC power that satisfies the power requirements of the connected DC powered devices in their normal operating modes. Thus, the DC power supply device is configured to determine the amount of operating DC output power from a plurality of available DC output power amounts that the DC power supply device is configured to supply in its operating supply mode (i.e., when delivering DC output power for normal operation of the DC powered devices).

[0015] Subsequently, the DC power supply control unit drives the operation of the DC power supply device in the operational supply mode, involving delivering the determined amount of operational DC output power, and in particular providing the determined amount of DC output voltage to the connected DC powered device via the power interface, which allows the connected DC powered device to operate in its corresponding normal operational mode.

[0016] Thus, the DC power supply device of the first aspect advantageously implements an automatic power optimization scheme by flexibly determining and providing an operational DC output power having a DC voltage amount suitable for delivering power to a plurality of initially unknown DC powered devices connected via a wired bus.

[0017] Before turning to the description of an embodiment of the DC power supply device according to the first aspect of the present invention, the DC power receiving device according to the second aspect of the present invention will be disclosed and explained below. By directly juxtaposing the first and second aspects of the device, the complementary contributions of their features to the present invention will become particularly clear.

[0018] Therefore, according to a second aspect of the present invention, there is provided a DC powered device. The DC powered device includes a DC powered device control unit configured to control operation of the DC powered device in a normal operating mode and an initialization mode, the initialization mode requiring a predetermined initialization DC input power amount lower than the operating DC power amount required by the normal operating mode of the DC powered device.

[0019] The DC powered device further comprises an input power interface for receiving DC power from the DC power supply device via the single twisted pair wired bus.

[0020] The DC powered device further includes a storage unit configured to store DC power requirement information indicating a DC voltage requirement and a DC current requirement for operating the DC powered device in a normal operation mode.

[0021] The DC powered device further includes a DC powered device communication unit configured to provide DC power requirement information via the wired bus when the DC powered device is operated in the initialization mode.

[0022] Furthermore, the DC powered device has a power conversion unit connected to the input power interface and including a down-converter stage configured to receive DC power at an input DC voltage having an operating DC voltage amount from among a plurality of available DC output power amounts that the DC power supply device is configured to supply, and to provide converted DC power having a down-converted DC voltage amount for operation of the DC powered device in its normal operating mode, the down-converted DC voltage amount being equal to or less than the input DC voltage amount and complying with a DC voltage requirement.

[0023] Therefore, the DC powered device has two operating modes: an initialization mode and a normal operating mode. The initialization mode requires a predetermined initialization DC input power amount that is lower than the operating DC power amount required by the DC powered device's normal operating mode. As previously explained in the context of the first aspect of the present invention, when the DC power supply device operates in its initialization supply mode, the amount of DC power supplied to the connected DC powered device is lower than the amount of DC power supplied during the operating supply mode.

[0024] When a DC powered device first receives DC power from an external DC power supply device, the DC powered device control unit controls the operation of the DC powered device in an initialization mode. While operating in the initialization mode, DC power requirement information stored in the storage unit is provided to the DC power supply device via a wired bus. However, it should be noted that the operation of the DC powered device in its initialization mode is not necessarily coupled to the operation of the DC power supply device in its initialization supply mode. As will be explained in the context of the following embodiments, in some cases, the DC powered device operates in its initialization mode while the DC power supply device operates in its operational supply mode.

[0025] In any case, as explained in the context of the first aspect of the present invention, the DC power supply device then uses the DC power requirement information to determine an operating DC output power level to be output via the wired bus. This operating DC output power level has a higher DC voltage than the DC voltage of the DC power level provided during the initialization supply mode and is suitable for allowing the connected DC powered devices to operate in their normal operating mode. Because, in a parallel connection, the DC power supply device can only provide one DC voltage level to all connected DC powered devices, a given DC powered device may not receive a voltage level that complies with the transmitted DC power requirement information. However, even if the DC voltage of the operating DC output power level is higher than the DC voltage required to operate in the normal operating mode, the down-converter stage is appropriately configured to receive DC power having a higher DC voltage than the required input DC voltage and output the converted DC power at a down-converted DC voltage that is equal to or lower than the input DC voltage and complies with the DC voltage requirement. In this way, the DC powered device is able to operate in its normal operating mode despite receiving a variety of different voltage levels from the DC power supply device via the wired bus.

[0026] Thus, the DC power supply device of the first aspect of the present invention and the DC powered device of the second aspect of the present invention together enable operation by automatic power adjustment for a given configuration of DC powered devices in a network. The DC powered devices provide stored DC power demand information and are capable of flexibly operating in their normal operating mode while supplying DC power having an operating DC voltage amount determined from a plurality of available DC output power amounts that the DC power supply device is configured to supply in its operating supply mode.

[0027] As will be further explained below during the description of the embodiments, the present invention, with the aid of the devices of the first and second aspects, even enables the addition of additional DC powered devices to the network and the removal of one of the connected DC powered devices from the network while the connected DC powered device is in its normal operating mode. This additional capability is also referred to as hot swapping or hot plugging.

[0028] Now, the description turns to embodiments of the first and second aspects of the present invention. Hereinafter, embodiments of the DC power supply device of the first aspect of the present invention will be described.

[0029] The flexibility of the DC power supply device is enhanced both in the initialization phase of the electrical installation or network (ie when first powering up a connected DC powered device) and in the operational phase (ie when the DC powered device operates in its normal operating mode).

[0030] In one embodiment regarding the first aspect of the initialization phase, the DC power supply device further includes a DC powered device detection unit configured to detect connection of at least one DC powered device to the output power interface via the wired bus when the DC power supply device is operating in the initialization mode, and to provide an initialization detection signal indicating the connection to the DC power supply control unit. In this particular embodiment, upon receiving the detection signal, the DC power supply control unit is configured to drive delivery of a predetermined initialization DC output power amount via the power interface in the initialization mode.

[0031] In another embodiment regarding the second scenario of the operational phase, the DC powered device detection unit is further configured to detect a new connection event and a disconnection event when the DC power supply device is operating in the operational supply mode, the new connection event involving the connection of an additional DC powered device to the wired bus, and the disconnection event involving the disconnection of a previously connected DC powered device from the wired bus, and to provide a corresponding event detection signal indicating the new connection event or disconnection event. In this specific embodiment, the DC power control unit is further configured to maintain the currently provided operating DC voltage amount for providing the initialization DC power amount to the additional DC powered device when the DC power supply device is operating in the operational supply mode and upon receiving the event detection signal indicating a new connection event, and to redetermine the operating DC output power amount to be output via the power interface based on a predetermined power determination rule and the DC voltage and DC current requirements of the DC powered device currently connected to the wired bus upon receiving the event detection signal indicating a new connection event or disconnection event. Thus, this preferred embodiment is configured to enable "hot swapping" and "hot unswapping" of DC powered devices, i.e., the connection or disconnection of DC powered devices, while the DC power supply device is operating in the operational supply mode.

[0032] In this embodiment, the DC power supply dynamically adapts the provision of operating DC power to changes in currently connected DC powered devices. A newly connected DC powered device receives sufficient DC power from the DC power supply to provide its DC power requirement information, and the DC power supply uses this DC power requirement information and power determination rules to redetermine the amount of operating DC output power required by the connected DC powered device. To enable the addition of one or more DC powered devices to the network, the DC power supply is suitably configured to maintain a power margin available to power additional DC powered devices, at least in its initialization mode. However, depending on the DC power supply's technical specifications, the DC power supply's ability to supply additional newly added DC powered devices is limited, and thus, when a certain maximum number of connected DC powered devices is reached, the power margin will be exhausted.

[0033] Therefore, the DC power supply device is configured to adapt the delivery of DC current within its specified practical limits to provide sufficient DC power to the newly connected DC powered device to operate at least in the initialization mode. If switching to normal operating mode is not possible due to limitations of the DC power supply device, the added DC powered device will not be allowed to switch to its normal operating mode through appropriate control signaling between the DC power supply device and the corresponding DC powered device in its initialization mode.

[0034] In another embodiment of the DC power supply device of the first aspect configured to detect new connection events and disconnection events, the DC powered device detection unit is additionally configured to determine the number of DC powered devices connected to the wired bus and, upon determining that no DC powered devices are currently connected, provide a disconnection signal indicating this. In this particular embodiment, the DC power supply control unit is configured to receive the disconnection signal and, upon receiving the disconnection signal, drive the power interface to cease supplying operational DC power via the wired bus.

[0035] In certain embodiments, determining the number of DC powered devices by the DC powered device detection unit is based on monitoring, by the DC powered device detection unit, the current amount of DC power provided via the power interface. In alternative embodiments, exchanging messages between the DC powered device and the DC power supply device under an OSI layer 2 communication protocol is used to determine the number of DC powered devices, as will be described in greater detail further below.

[0036] In another embodiment, the DC power supply control unit is configured to drive the DC power supply network communication unit to provide a shutdown request to one or more DC powered devices via a wired bus. In this embodiment, the shutdown request is provided based on the respective DC voltage and DC current demands received via the DC power supply network communication. This embodiment is particularly advantageous when the determined amount of operating DC power is insufficient to power all connected DC powered devices. Thus, the DC power supply network communication provides the shutdown request to those connected DC powered devices that, according to the DC power supply control unit, should cease the request and therefore no longer receive operating DC power.

[0037] DC power requirement information can take various forms. As described above, connected DC powered devices typically have different DC voltage and DC current requirements for operation in their respective normal operating modes. In some embodiments, the DC power requirement information associated with a single DC powered device includes information regarding a preferred DC voltage level and one or more suitable DC current levels for operating the given DC powered device in its normal operating mode. In some variations, the transmitted DC power requirement information further includes information regarding further compatible DC voltage levels, suitably combined with a corresponding maximum DC current level also required to operate the DC powered device in its respective normal operating mode.

[0038] In some network configurations, different DC powered devices have different priorities for power provision, typically depending on the degree of importance or necessity assigned to the functions performed by the DC powered devices. In one embodiment, the DC power demand information further includes power priority data indicating the hierarchical priority of each of the connected DC powered devices. In such embodiments utilizing power priority data, the power determination rules advantageously also utilize the hierarchical priorities of the DC powered devices connected via the wired bus. Therefore, in this particular embodiment, the DC power supply control unit is configured to further utilize the received priority data to determine the amount of operating DC power.

[0039] The receipt of this priority data and the inclusion of corresponding information in determining the operating DC power to be provided via the power interface enhances the adaptability of the DC power supply device in determining the allocation of negotiated operating DC power and providing operating DC power suitable for the intended application case in the best possible configuration.

[0040] In some embodiments, the DC power requirement information provided by the DC powered devices indicates different DC voltage requirements and different DC current requirements for operation of the respective DC powered devices in different respective normal operating modes. In a variation of this embodiment, the DC power supply network communication unit is further configured to receive power priority data, and the DC power supply control unit is further configured to drive the DC power supply network communication unit to provide a request to operate the DC powered device in a different normal operating mode, further based on the respective priorities received from the respective DC powered devices. In a specific variation, this also includes a request to shut down one or more of the DC powered devices via the wired bus.

[0041] A non-limiting example of a power determination rule suitable for any embodiment of the first aspect of the invention includes providing an amount of DC voltage at the power interface that is at least equal to the highest DC voltage value required by any DC powered device, and then adjusting the provided DC current to meet the DC current requirements of all connected DC powered devices, always within the configured current limits of the DC power supply device.

[0042] In a particularly suitable embodiment, the DC power network communication unit is configured to transmit and receive data in accordance with the IEEE 802.3bu standard. Furthermore, the DC power control unit is configured to drive the operation of the output power interface also in accordance with the IEEE 802.3bu standard. Furthermore, the DC power supply device is preferably configured to operate in accordance with the IEEE 802.3cg standard.

[0043] In a specific embodiment, the device complies with the IEEE 802.3bu standard and includes a DC powered device detection unit configured to perform a detection routine using a serial communication classification protocol according to the IEEE 802.3bu standard when operating in an initialization supply mode.

[0044] In particular, in an embodiment compliant with the IEEE 802.3bu standard, the power requirement information is included in a link layer discovery protocol packet, and preferably included in a non-routed link layer discovery protocol packet.

[0045] In the previously described embodiments involving detection of new connection and disconnection events, the re-determination of the amount of operational DC output power to be output via the power interface leverages the DC power supply device's compliance with the IEEE 802.3 family of Ethernet standards (particularly IEEE 802.3bu). More specifically, the DC powered device detection unit determines the number of DC powered devices by monitoring the corresponding MAC addresses of the connected DC powered devices. According to these standards, DC powered devices are assigned MAC addresses, which are provided to the DC power supply device via the wired bus.

[0046] In a particular embodiment, the received MAC address is additionally used by the DC powered device detection unit to determine the number of DC powered devices connected in parallel to the wired bus.

[0047] In a preferred embodiment, the initialization DC power has a DC voltage magnitude of at least 3 volts. Also in a preferred embodiment, the operating DC output power has a DC voltage magnitude equal to or greater than the DC voltage magnitude of the initialization DC power and less than or equal to 60 volts.

[0048] Any of the described embodiments of a DC power supply device may include multiple power interfaces for connecting a corresponding set of parallel-connected DC powered devices via corresponding wired buses. In this case, the DC power supply control unit is configured to independently operate each power interface. Thus, the DC power supply device is adapted to simultaneously provide an initialization DC output power amount to one set of connected DC powered devices and an operating DC output power amount to another set of connected DC powered devices, but via different wired buses.

[0049] Hereinafter, embodiments of a DC power receiving apparatus according to a second aspect of the present invention will be described.

[0050] In a preferred embodiment, the DC powered device control unit is further configured to operate the DC powered device in the initialization mode during the power-up process of the DC powered device, even when connection of the DC powered device to a wired bus is detected, and the wired bus currently provides an amount of DC power that is equal to or greater than the required predetermined initialization DC input power amount. Thus, this embodiment further enables the DC powered device to be hot-swapped, i.e., connected to the wired bus, when the DC power supply device is already delivering DC operating power and is therefore operating in the operating supply mode and is no longer in the initialization supply mode.

[0051] Preferably, in this embodiment, the power conversion unit for operating in the initialization mode is configured to receive DC power having an input DC voltage and output required initialization DC input power to the DC powered device communication unit and the DC powered device control unit.

[0052] In a specific embodiment, the DC power requirement information indicates a minimum required DC voltage and a corresponding DC current required for operation in a normal operating mode. Alternatively, in another embodiment, the DC power requirement information indicates a preferred DC voltage and a corresponding DC current for operation in the normal operating mode. In yet another embodiment, the DC power requirement information indicates the minimum required DC voltage and a corresponding DC current required for operation in different normal operating modes, as well as other acceptable DC voltages and acceptable DC currents compatible with operation of the DC powered device in different acceptable normal operating modes.

[0053] In another embodiment, the DC powered device control unit is further configured to receive a shutdown request via the wired bus and the DC powered device communication unit, and upon receiving the shutdown request, to stop supplying operating DC power to the load device. This is particularly suitable for enhancing power negotiation capabilities between the DC power supply device and multiple DC powered devices having corresponding, but not necessarily identical, DC power requirements.

[0054] In a preferred embodiment, the storage unit is further configured to store power priority data as part of the DC power demand information, the power priority data indicating the priority of power requests from the DC powered device. In this embodiment, the DC powered device communication unit is further configured to provide the power priority data via the wired bus upon receiving at least a predetermined initialization DC input power amount.

[0055] Different DC powered devices may have different priorities for power requests, depending on how necessary the DC powered device is to operate in its normal operating mode. Providing this power priority data to the appropriate DC power supply device further enhances power negotiation capabilities and ensures that those DC powered devices with higher priority receive the power they need, even at the expense of not powering DC powered devices with relatively lower priority.

[0056] In a preferred embodiment, the DC powered device control unit is configured to control the operation of the DC powered device communication unit when transmitting and receiving data via the wired bus in accordance with the IEEE 802.3bu standard. Preferably, in this embodiment, power requirement information, including power priority, is included in a link layer discovery protocol packet. In a specific embodiment, the link layer discovery protocol packet is a non-routable link layer discovery protocol packet.

[0057] The down-converter stage is preferably configured to allow operation within a DC voltage range (i.e., a range of DC voltage levels of the DC output power), which is suitably between 3.3 V and 60 V. For example, a 3.3 V amount is provided during the initialization supply mode. During the operational supply mode, the nominal DC voltage value of the operational DC output power amount ranges from 4.41 V in a Class 1 PSE to 60 V in a Class 9 PSE, where the PSE classification corresponds to the PoDL standard known per se.

[0058] In another embodiment, the storage unit is further configured to store MAC address data indicating a MAC address of the DC powered device, and wherein the DC powered device communication unit is further configured to provide the MAC address data via the wired bus according to the IEEE 802.3bu standard.

[0059] As is clear from the above description, a DC powered device forms and includes an electrical load that requires DC power for normal operation. In one application example forming a preferred embodiment of the second aspect, the powered device is a lighting device, such as a luminaire. In normal operating mode, the luminaire operates according to a predefined lighting function to emit light. Different lighting functions can be predefined to implement different normal operating modes with different power requirements.

[0060] According to a third aspect of the present invention, an electrical device (network) is provided. The electrical device includes a DC power supply device according to the first aspect of the present invention or one of its embodiments, and a group of one or more parallel-connected DC powered devices according to the second aspect of the present invention or one of its embodiments.

[0061] A DC power supply device and a group of DC powered devices are connected via a single twisted-pair wired bus that connects a power interface of the DC power supply device to power input interfaces of one or more DC powered devices. The wired bus is configured to transmit DC power and data packets according to a predetermined communication protocol.

[0062] The electrical apparatus of the third aspect of the present invention is adapted to introduce a power distribution scheme for use on a single twisted pair wired bus to which one or more DC powered devices can be dynamically connected and disconnected.

[0063] Hereinafter, embodiments of the electric device of the third aspect of the present invention are described.

[0064] This electrical device is particularly advantageous in that it does not require separate wired bus lines to transmit DC power and data communications. This reduces installation complexity and also reduces weight. In this regard, Power over Ethernet technology, which requires at least two twisted pairs to operate, does not offer comparable results. Therefore, preferably, in an embodiment, the electrical device is configured to use a single twisted pair wired bus and operate in accordance with the IEEE 802.3 (Ethernet) family of standards (i.e., IEEE 802.3cg standard). Also preferably, the electrical device includes a DC power source and a DC powered device, both of which comply with the IEEE 802.3bu standard.

[0065] An embodiment of an electrical device includes a DC power supply device, a wired bus, and a plurality of DC powered devices connected in parallel to the wired bus. Each DC powered device may have different DC power requirements and, in certain embodiments, be powered at different power priorities. The DC power supply device uses information provided by the DC powered devices during an initialization supply mode to determine an amount of operational DC output power required to operate at least some of the DC powered devices connected in their respective normal operating modes.

[0066] In a preferred embodiment, when the DC power supply device is operating in an operational supply mode, a DC powered device detection unit is provided to the DC power supply device, enabling hot plugging or connecting a previously unconnected DC powered device to a wired bus, as well as hot plugging or disconnecting a previously connected DC powered device. The DC powered device detection unit is configured to detect a new connection event (connection of an additional DC powered device to the wired bus) and a disconnection event (disconnection of a previously connected DC powered device from the wired bus) when the DC power supply device is operating in the operational supply mode. The DC powered device detection unit is further configured to provide a corresponding event detection signal indicating a new connection event or a disconnection event. In this embodiment, the DC power supply control unit is further configured to maintain the currently supplied operating DC voltage level for supplying initialization DC power to the additional DC powered device when the DC power supply device is operating in the operational supply mode and upon receiving the event detection signal indicating a new connection event. Further, upon receiving an event detection signal indicating a new connection event or a disconnection event, the DC power supply control unit is configured to redetermine an amount of operating DC output power output via the power interface based on a predetermined power determination rule and based on a DC voltage demand and a DC current demand of a DC powered device currently connected to the wired bus.

[0067] According to a fourth aspect of the present invention, there is presented a method for operating a DC power supply apparatus for supplying operating DC power to one or more DC powered devices, each DC powered device being operable in an initialization mode requiring a lower amount of DC power than in a corresponding normal operating mode of the DC powered device. The method comprises:

[0068] - driving delivery of a predetermined initialization DC output power via the power interface and the wired bus when operating the DC power supply device in the initialization supply mode, wherein the amount of the initialization DC output power is suitable for driving the connected DC powered devices in their initialization mode, the initialization mode comprising transmitting respective power requirement information for their respective normal operating modes to the DC power supply device via the wired bus;

[0069] - receiving, via the power interface, respective DC power requirement information from DC powered devices connected via the single twisted pair wired bus, the respective DC power requirement information indicating a DC voltage requirement and a DC current requirement for the respective DC powered devices to operate in their respective normal operating modes;

[0070] - using DC power demand information received from the connected DC powered device and a predetermined power determination rule, determining an operating DC output power amount to be output via the output power interface from a plurality of available DC output power amounts that the DC power supply device is configured to supply in the operational supply mode, the operating DC output power amount having an operating DC voltage amount suitable for powering operation of the connected DC powered device in its corresponding normal operating mode; and

[0071] - The DC power supply device is then driven to operate in an operational supply mode, distributing the determined amount of operational DC output power to the connected DC powered device via the power interface.

[0072] The method of the fourth aspect of the invention shares the advantages of the DC power supply of the first aspect of the invention.

[0073] According to a fifth aspect of the present invention, there is presented a method for operating a DC powered device operable in a normal operating mode and an initialization mode, the initialization mode requiring a predetermined initialization DC input power amount lower than the operating DC power amount required by the normal operating mode of the DC powered device. The method comprises:

[0074] - storing in a storage unit DC power requirement information indicating a DC voltage requirement and a DC current requirement for operating the DC powered device in a normal operating mode;

[0075] - Receive DC power from a DC power supply device via a single twisted pair wired bus;

[0076] - providing DC power requirement information via the wired bus when the DC powered device operates in initialization mode; and

[0077] -When the DC powered device operates in a normal operating mode, receiving DC power at an input DC voltage having an operating DC voltage amount from among a plurality of available DC output power amounts that the DC power supply device is configured to supply, and providing converted DC power having a down-converted DC voltage that is equal to or less than the input DC voltage and meets a DC voltage requirement using the received DC power.

[0078] The method of the fifth aspect of the present invention shares the advantages of the DC powered device of the second aspect of the present invention.

[0079] According to a sixth and seventh aspect of the present invention, there is provided a computer program comprising respective instructions which, when executed by a respective computer, cause the computer to carry out the method of the fourth and fifth aspect of the present invention, respectively.

[0080] It should be understood that the DC power supply device according to the first aspect, the DC powered device according to the second aspect, the electrical apparatus according to the third aspect, the method for operating a DC power supply device according to the fourth aspect, the method for operating a DC powered device, the computer program and the computer program have similar and / or identical preferred embodiments, in particular as defined in the dependent claims.

[0081] It shall be understood that a preferred embodiment of the present invention may also be any combination of the dependent claims or the above embodiments with the corresponding independent claim.

[0082] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In the following figures:

[0084] Figure 1 A schematic block diagram of an embodiment of an electrical apparatus is shown, the electrical apparatus comprising a DC power supply device and a plurality of DC powered devices connected to a single twisted pair wired bus.

[0085] Figure 2 A schematic block diagram of an embodiment of a DC powered device is shown.

[0086] Figure 3 A schematic block diagram of another embodiment of a DC powered device connected to a DC power supply device via a single twisted pair wired bus is shown.

[0087] Figure 4 A schematic block diagram of an embodiment of a DC power supply device connected to a single twisted pair wired bus is shown.

[0088] Figure 5 A schematic flow chart of a method for operating a DC power supply device is shown.

[0089] Figure 6 A schematic flow chart of a method for operating a DC powered device is shown. DETAILED DESCRIPTION

[0090] Figure 1An electrical installation 100 is shown, comprising a DC power supply device 110 and multiple DC powered devices 120, 130, and 140 connected to a single twisted-pair wired bus 101. In this specific, non-limiting example, the electrical installation is a connected lighting system, wherein connectivity is achieved via a multi-point bus, such as that currently being standardized in the IEEE 803.2cg consortium known as 10SPE. The DC powered devices 120, 130, and 140 are light network PDs (powered devices) with corresponding lamps as load devices 121, 122, and 123, and are strategically located to connect to the single twisted-pair wired bus 101. The electrical installation includes only one DC power supply device, also known as power source equipment (PSE), which provides DC power to the DC powered devices, also known as nodes of the electrical installation. Only three nodes 120, 130, and 140 are depicted here. However, more or fewer nodes may be connected to the wired bus 101. The location of the PSE node 110 at one end is intentionally chosen, but may be located anywhere on the wired bus.

[0091] An exemplary electrical device is a connected lighting system, where connectivity is achieved via a multi-point bus, such as the one currently being standardized in the IEEE 803.2cg consortium known as 10SPE. Preferably, it is configured to implement a power supply scheme according to 10SPE, which requires the use of the so-called PoDL standard (802.3bu). The same principles are applicable to other areas such as, but not limited to, industry, building automation, heating, ventilation, and air conditioning (HVAC), and automotive.

[0092] Among the goals of the 10SPE standard (IEEE 802.3cg) is that power delivery through the network should be part of the considerations and should be standardized. Currently, only the 10SPE peer-to-peer network topology has a power supply option, through the so-called Power over Data Line (PoDL) standard (IEEE 802.3bu).

[0093] The voltage and amount of power delivered can be negotiated between the PSE 110 and the nodes 120, 130, 140. However, for multi-point configurations using PoDL, no hot-plug and hot-replace actions are supported. PoDL does not include a power negotiation protocol suitable for negotiating power when operational DC output power is already being delivered. PoDL can negotiate power, but only before DC output power is provided because the negotiation used in PoDL is done via the Serial Communication Classification Protocol (SCCP). SCCP only works when power is not applied to the low-impedance wired bus because data transfer from the client to the host is done over an open-drain short circuit of the bus.

[0094] For multi-point networks such as electrical installation 100, with the flexibility to dynamically add or remove connected DC powered devices, different negotiation techniques are established. This not only supports hot-plugging and hot-removal of DC powered device nodes, but also enables additional optimization freedom for system power usage during operation.

[0095] The key principle is to establish an input power interface at each DC powered device that can adapt to the potential DC voltages that the DC power supply device according to the present invention can provide. The DC powered devices 120, 130, and 140 must be able to minimally boot their microcontrollers from this initial DC voltage level and inform the PSE that they will require or prefer different DC voltage levels and how much power they intend to draw. This is contained in the DC power requirement information transmitted via the wired bus when the DC powered devices are configured to operate in initialization mode. Based on power determination rules, the DC power supply device 101 uses the DC power requirement information of the nodes 120, 130, and 140 connected to the wired bus 101 to determine an operational DC output power amount to be output via the output power interface. This operational DC output power amount is suitable for powering the connected DC powered devices in their respective normal operating modes.

[0096] Figure 2 An embodiment of a DC powered device 200 connected to a single twisted-pair wired bus 201 is shown. The DC powered device 200 includes a DC powered device control unit 202 configured to control the operation of the DC powered device 200 in a normal operating mode of an electrical load device 204 and in an initialization mode, the initialization mode requiring a predetermined initialization DC input power amount that is lower than the operating DC power amount required by the DC powered device's normal operating mode. The device also includes an input power interface 206 for receiving DC power from a DC power supply device (not shown) via the single twisted-pair wired bus 201. The DC powered device includes a storage unit 208 configured to store DC power requirement information indicating a DC voltage requirement and a DC current requirement for operating the DC powered device in the normal operating mode. The DC powered device further includes a DC powered device communication unit 210 configured to provide DC power requirement information via a wired bus when the DC powered device is operated in the initialization mode, and a power conversion unit 212 including a down-converter stage configured to receive DC power having an input DC voltage and output converted DC power having a down-converted DC voltage that is equal to or lower than the input DC voltage and meets the DC voltage requirement when the DC powered device is operated in the normal operation mode.

[0097] The down-converter stage is configured to operate over the entire PoDL DC voltage range (i.e., the range of DC voltage levels for DC output power), which is typically between 3.3 V and 60 V. 3.3 V is typically provided during the initialization supply mode. During the operational supply mode, the nominal DC voltage value for the operational DC output power level ranges from 4.41 V in a Category 1 PSE to 60 V in a Category 9 PSE, where the PSE category classification corresponds to the PoDL standard.

[0098] The following table (Table 1) shows a categorized power requirement matrix according to the PoDL standard.

[0099]

[0100] Where V PSE(max) It is the maximum allowable DC voltage of the DC power supply device for the amount of DC output power it can operate.

[0101] V PSE_OC(min) It is the minimum allowable open circuit voltage measured at the power interface of the DC power supply device.

[0102] V PSE(min) The minimum DC voltage allowed for the DC power supply device to operate at the DC output power level.

[0103] I PI(max) Is the maximum DC current flowing through the power interface under normal operating conditions (i.e. excluding special conditions such as inrush or overload). During inrush or overload conditions, this value can be exceeded and the user is reminded of the limitations of the system and local rules and regulations.

[0104] P Class(min) is the minimum average operating DC output power at the power interface of the DC power supply device,

[0105] V PD(min) is the minimum DC voltage required for a DC powered device to operate in normal operating mode, and

[0106] P PD(max) It is the maximum average available DC operating power at the input power interface of the DC powered device.

[0107] Figure 3Another exemplary DC powered device 300 is shown connected to a DC power sourcing device 302, known as a power sourcing equipment (PSE), via a single twisted-pair wired bus 301. PSE 302 is configured to supply DC power via the wired bus and can operate in two different operating modes. In an initialization supply mode, PSE 302 delivers a predetermined initialization DC output power amount to the wired bus, where the initialization DC output power amount is suitable for driving the connected DC powered devices in their initialization modes, which includes transmitting corresponding power requirement information for their respective normal operating modes to the DC power sourcing device via the wired bus. It is further operable in an operational supply mode, where the DC power sourcing device delivers the determined operational DC output power amount to the connected DC powered devices via a power interface. In this example, PSE 302 also acts as a wired bus master for the Serial Communication Classification Protocol (SCCP). DC powered device 300 includes SCCP initialization negotiation circuitry 328, an 10SPE client 326, and a power conversion unit 323. In this example, the 10SPE client 326 includes a microprocessor and a memory unit 322. Thus, the 10SPE client is configured to function as a DC powered device communication unit and a DC powered device control unit. It advantageously includes 10SPE PHY and MAC functionality combined with microcontroller functionality and interconnects 324, 325, 327, as well as an access point 321.

[0108] The exemplary PSE 302 is configured to provide sufficient DC power in initial provisioning mode to detect that at least one compatible network node is installed. This identification can be accomplished using the Serial Communication Classification Protocol (SCCP) of the PoDL standard, which also allows for the collection of information about multiple nodes connected in parallel. If the PSE has not yet detected the presence of any individual nodes in this step, no power is applied, and SCCP is used to detect when the first node (i.e., a DC powered device) is connected. If at least one node is detected, a base DC voltage (the startup voltage selected by SCCP in the corresponding power class, see Table 1) is applied to the wired bus. This functionality is part of the PoDL standard.

[0109] After applying a base DC voltage to the wired bus, thereby providing an initial DC output power level via the power interface of PSE 302, all connected nodes (such as node 300) activate their respective DC powered device control units and their respective DC powered device communication units, or, in the case of node 300, activate the 10SPE client 326, which includes both the DC powered device control unit and the DC powered device communication unit. Each node then provides DC power requirement information, including the preferred voltage and resulting current requirement, as well as all compatible voltages and associated maximum current values. Communication between the DC powered devices and PSE 302 is optimally accomplished using LLDP packets (preferably non-routed LLDP packets).

[0110] The PSE 302 collects all DC power requirement information for the connected DC powered devices and determines an amount of operating DC output power suitable for powering at least one of the connected DC powered devices in its corresponding normal operating mode. This determination is based on predetermined power determination rules. In a non-limiting example, one of the connected DC powered devices requires a certain DC voltage to function, and all other connected DC powered devices are capable of functioning at that DC voltage.

[0111] Figure 4 An exemplary DC power supply device 400 is shown connected to a single twisted-pair wired bus 401. The DC power supply includes a power interface 402 for providing DC output power to a plurality of DC powered devices connected in parallel via the wired bus via the single twisted-pair wired bus. The DC power supply also includes a DC power supply network communication unit 404 configured to receive, via the power interface, corresponding DC power requirement information from the DC powered devices connected via the wired bus 401. The corresponding DC power requirement information indicates the DC voltage requirement and DC current requirement of each DC powered device when operating in its corresponding normal operating mode. The DC power supply device also includes a DC power supply control unit 406 configured to:

[0112] - driving the DC power supply device 400 to operate in an initialization supply mode, delivering a predetermined initialization DC output power amount via the power interface, wherein the initialization DC output power amount is suitable for driving the connected DC powered devices in their initialization modes, the initialization mode comprising transmitting respective power requirement information for their respective normal operating modes to the DC power supply device via the wired bus 401,

[0113] - using DC power requirement information received from the connected DC powered devices and predetermined power determination rules to determine an amount of operational DC output power to be output via the output power interface, the amount of operational DC output power being suitable for powering operation of at least one connected DC powered device in its respective normal operating mode, and

[0114] The DC power supply device is then driven to operate in an operational supply mode, delivering the determined amount of operational DC output power to the connected DC powered device via the power interface 402 .

[0115] Optionally, the DC power supply device 400 may further include a DC powered device detection unit 408, shown in dashed lines, configured to detect the connection of at least one DC powered device to the output power interface via the wired bus when the DC power supply device is operating in the initialization mode, and to provide an initialization detection signal indicating this to the DC power supply control unit. In this DC power supply device, the DC power supply control unit is configured to drive the delivery of a predetermined initialization DC output power amount via the power interface in the initialization mode upon receiving the detection signal.

[0116] Preferably, the DC powered device detection unit 408 is further configured to detect a new connection event, involving the connection of an additional DC powered device to the wired bus, and a disconnection event, involving the disconnection of a previously connected DC powered device from the wired bus 401, when the DC power supply device is operating in the operational supply mode, and to provide a corresponding event detection signal indicating the new connection event or disconnection event. In this particular DC power supply device, the DC power supply control unit 406 is further configured to, when the DC power supply is operating in the operational supply mode:

[0117] - upon receiving an event detection signal indicating a new connection event, maintaining a currently supplied amount of operating DC voltage for supplying an initialization amount of DC power to the additional DC powered device; and

[0118] - upon receiving an event detection signal indicating a new connection event or a disconnection event, re-determining the amount of operating DC output power to be output via the power interface based on a predetermined power determination rule and a DC voltage requirement and a DC current requirement of a DC powered device currently connected to the wired bus.

[0119] Therefore, such a DC power supply device is also suitable for negotiating power transfer when operating in an operational supply mode, in particular in the event of a new connection or disconnection of a DC powered device.

[0120] When a new DC powered device is connected, it must be able to be powered up from all possible voltage levels that the DC power sourcing device can provide. Assuming the DC power sourcing device is within its limitations regarding the maximum DC current to be provided, it maintains a margin of available power for the newly connected DC powered device to ensure that an overcurrent condition is not detected, which would result in a power outage of all DC powered devices and, in turn, a network restart.

[0121] When a new suitable DC powered device or node is connected to the wired bus, it is configured to operate in initialization mode and provide DC power requirement information, typically via LLDP communications. The DC power sourcing device receives the DC power requirement information from the newly connected node and re-determines the amount of DC output power for operation.

[0122] Exemplary DC power supply devices are also configured to monitor for disconnection of DC powered devices from the wired bus. For example, monitoring can be performed by detecting changes in the DC power consumption of a connected set of DC powered devices. Alternatively or additionally, suitable DC power supply devices can monitor for loss of the MAC address of a connected network device based on MAC address-related information. Otherwise, unless an intention to disconnect is announced, there is no explicit signaling of the DC powered device disconnection. According to the PoDL standard, a DC power supply device periodically checks the impedance at the power interface and can therefore detect that no nodes are connected to the wired bus, thereby ceasing to provide operational DC output power via the power interface.

[0123] Preferably, any DC powered device or node that is not capable of continuous operation in normal operating mode at a given operational DC output power level should be shut down. This can occur, for example, at high wired bus DC voltages for low-power nodes not supplied by linear regulators. Such regulators may not be able to sustainably deliver DC power to the node with the associated high linear losses.

[0124] In many applications, a high DC voltage applied to a wired bus means low DC current and, therefore, low losses in cables and filters. This is especially true for long wired buses and / or high-power DC-powered devices. However, for ultra-low-power nodes, such as motion detectors based on the PIR effect, a low bus voltage may be optimal. This is because supplying these voltages from a high rail voltage implies high losses in any linear regulator, while using an SMPS supply can often result in switching losses that are easily higher than the sensor's DC power requirement.

[0125] Therefore, if many nodes require only low wattage, some power determination rules may result in the DC voltage for the amount of operational DC output power allowed in PoDL being reduced to the lowest level that still adequately supplies nodes with large power consumption (such as cameras, IR, or RF nodes). A table can be used to evaluate and determine the optimal amount of operational DC output power to be delivered and the corresponding optimal DC voltage.

[0126] Furthermore, the DC power supply device can preferably request that some DC powered devices reduce their power usage to allow the newly added DC powered device to use the prioritized power. For this action, the added DC powered device sends DC power demand information indicating that it requires DC power that is currently unavailable, and uses power priority data to signal a higher priority. The DC power supply device uses power determination rules (which may include, for example, a budget table) to find the connected DC powered device with the lowest priority currently being supplied with DC power. If this node has a lower priority than the newly connected DC powered device, it will request that it be shut down. If the available DC power level is still insufficient, the DC power supply device will repeat the search as described above.

[0127] Figure 5 A flow chart illustrating an embodiment of a method 500 for operating a DC power supply for supplying operating DC power to one or more DC powered devices, each of the DC powered devices being operable in an initialization mode requiring a lower amount of DC power than in a corresponding normal operating mode of the DC powered devices, the method comprising, in step 502, driving, when operating the DC power supply device in the initialization mode, via a power interface, delivery of a predetermined initialization DC output power amount, wherein the initialization DC output power amount is suitable for driving the connected DC powered devices in their initialization modes, the initialization mode including transmitting respective power requirement information for their respective normal operating modes to the DC power supply device via a single twisted pair wired bus. The method further comprises, in step 504, receiving, via the power interface, respective DC power requirement information from the DC powered devices connected via the single twisted pair wired bus, the respective DC power requirement information indicating a DC voltage requirement and a DC current requirement for each DC powered device operating in its corresponding normal operating mode. The method includes: in step 506, using DC power demand information received from a connected DC powered device and a predetermined power determination rule, determining an operational DC output power amount to be output via an output power interface from a plurality of available DC output power amounts that the DC power supply device is configured to supply in an operational supply mode, the operational DC output power amount having an operational DC voltage amount suitable for powering operation of the connected DC powered device in its corresponding normal operating mode; and in step 508, subsequently driving the DC power supply device to operate in the operational supply mode, distributing the determined operational DC output power amount to the connected DC powered device via the power interface.

[0128] Figure 6 A flowchart illustrates an embodiment of a method 600 for operating a DC powered device operable in a normal operating mode and an initialization mode, the initialization mode requiring a predetermined initialization DC input power amount lower than the DC power amount required by the DC powered device's normal operating mode. The method includes, in step 602, storing DC power requirement information in a memory unit indicating a DC voltage requirement and a DC current requirement for operating the DC powered device in the normal operating mode. The method includes, in step 604, receiving DC power from a DC power supply device via a single twisted-pair wired bus. The method also includes, in step 606, providing the DC power requirement information via the wired bus while the DC powered device is operating in the initialization mode. The method further includes, in step 608, receiving DC power at an input DC voltage having an operating DC voltage amount from a plurality of available DC output power amounts that the DC power supply device is configured to supply while the DC powered device is operating in the normal operating mode; and, in step 610, providing converted DC power having a down-converted DC voltage that is equal to or less than the input DC voltage and meets the DC voltage requirement.

[0129] Other 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.

[0130] 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.

[0131] A single unit or device may fulfill the functions of several items recited in the claims. 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.

[0132] The computer program may be stored / distributed on an appropriate medium (such as an optical storage medium or solid-state medium), provided together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0133] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A DC power supply device for supplying operating DC power to a plurality of DC powered devices via a single twisted pair wired bus, each DC powered device being operable in an initialization mode requiring a lower amount of DC power than in a corresponding normal operating mode of the DC powered device, the DC power supply device comprising: - a power interface (402) for providing DC output power via a single twisted pair wired bus to a plurality of DC powered devices connected in parallel via the wired bus; a DC power network communication unit (404) configured to receive corresponding DC power requirement information from DC powered devices connected via a wired bus via a power interface by means of LLDP communication, the corresponding DC power requirement information indicating a DC voltage requirement and a DC current requirement of each DC powered device operating in its corresponding normal operation mode, wherein the DC power requirement information includes a preferred voltage and a resulting current requirement, and further includes all compatible voltages and associated maximum current values; and - A DC power supply control unit (406) configured as follows: - driving the DC power supply device to operate in an initialization supply mode, delivering a predetermined initialization DC output power amount via the power interface, wherein the initialization DC output power amount is suitable for driving the connected DC powered devices in their initialization modes, the initialization modes comprising communicating respective power requirement information for their respective normal operating modes to the DC power supply device via the wired bus; - using DC power demand information received from each of the plurality of DC powered devices and a predetermined power determination rule, determining an operating DC output power amount to be output via the power interface from a plurality of available DC output power amounts that the DC power supply device is configured to supply in the operational supply mode, the operating DC output power amount having an operating DC voltage amount suitable for powering operation of the plurality of DC powered devices in their respective normal operating modes; and - subsequently driving the DC power supply device to operate in an operational supply mode, distributing the determined amount of operational DC output power to the plurality of DC powered devices via the power interface such that a single twisted pair wired bus is provided with an amount of DC voltage for powering each of the plurality of DC powered devices; and - a DC powered device detection unit (408) configured to detect a new connection event and a disconnection event when the DC power supply device is operated in the operation supply mode, the new connection event involving the connection of an additional DC powered device to the wired bus and the disconnection event involving the disconnection of a previously connected DC powered device from the wired bus, and configured to provide a corresponding event detection signal indicating the new connection event or the disconnection event; and wherein - the DC power supply control unit is further configured to, when operating the DC power supply device in the operation supply mode: - upon receiving an event detection signal indicating a new connection event, maintaining a currently supplied amount of operating DC voltage for supplying an initialization amount of DC power to the additional DC powered device; and - upon receiving an event detection signal indicating a new connection event or a disconnection event, re-determining the amount of operating DC output power to be output via the power interface based on a predetermined power determination rule and a DC voltage requirement and a DC current requirement of a DC powered device currently connected to the wired bus.

2. The DC power supply device according to claim 1, wherein - the DC powered device detection unit (408) is further configured to detect connection of at least one DC powered device to the power interface via the wired bus when the DC power supply device is operated in the initialization supply mode, and to provide an initialization detection signal indicating the connection to the DC power supply control unit; wherein The DC power supply control unit is configured to drive the delivery of a predetermined initialization DC output power amount via the power interface in an initialization supply mode upon receipt of the detection signal.

3. The DC power supply device according to claim 1, wherein: - a DC powered device detection unit (408) configured to determine the number of DC powered devices connected in parallel to the wired bus, and when it is determined that no DC powered device is currently connected, provide a no connection signal indicating the same; and in The DC power supply control unit is configured to receive a no connection signal and, upon receiving said no connection signal, to stop providing the operating DC power via the wired bus.

4. The DC power supply device according to any one of claims 1 to 3, wherein: According to the corresponding DC voltage demand and DC current demand, the DC power control unit (406) is further configured to drive the operation of the DC power network communication unit (404) for providing a shutdown request to one or more DC powered devices via a wired bus.

5. The DC power supply device according to any one of claims 1 to 3, wherein: - the DC power demand information additionally comprises power priority data indicating a hierarchical priority of individual ones of the connected DC powered devices; wherein - The DC power control unit (406) is configured to further use the received priority data to determine an operating DC power amount.

6. The DC power supply device according to any one of claims 1 to 3, wherein: - the DC power network communication unit is configured to transmit and receive data according to the IEEE 802.3bu standard; and wherein - The DC power control unit is configured to drive the operation of the power interface according to the IEEE 802.3bu standard.

7. The DC power supply device according to claim 2, wherein: The DC powered device detection unit is configured to perform a detection routine using a serial communication classification protocol according to the IEEE 802.3bu standard when operating in the initialization mode.

8. An electrical device (100), comprising: - A DC power supply device according to claim 1; - Multiple DC powered devices connected in parallel; - a single twisted pair wired bus connecting a power interface of a DC power supply device and an input power interface of one or more DC powered devices, said wired bus being configured to - transmit DC power provided by the DC power supply device; as well as - transmit DC power demand information according to a predetermined communication protocol, Each DC powered device includes: a DC powered device control unit (202) configured to control the operation of the DC powered device in a normal operating mode and an initialization mode requiring a predetermined initialization DC input power amount lower than an operating DC power amount required by the normal operating mode of the DC powered device; - an input power interface (206) for receiving DC power from a DC power supply device via a single twisted pair wired bus; - a storage unit (208) configured to store DC power requirement information indicating a DC voltage requirement and a DC current requirement of the DC powered device operating in a normal operation mode; - a DC powered device communication unit (210) configured to provide DC power requirement information via the wired bus by means of LLDP communication when the DC powered device is operated in an initialization mode, wherein the DC power requirement information includes a preferred voltage and a resulting current requirement, and further includes all compatible voltages and associated maximum current values; and - a power conversion unit (212) connected to the input power interface and comprising a down-converter stage configured to receive DC power at an input DC voltage having an operating DC voltage amount from a plurality of available DC output power amounts that the DC power supply device is configured to supply, and to provide converted DC power having a down-converted DC voltage amount for operation of the DC powered device in its normal operating mode, the down-converted DC voltage amount being equal to or less than the input DC voltage amount and conforming to a DC voltage requirement.

9. The electrical device (100) according to claim 8, wherein The DC powered device control unit is configured, during a power-on process of the DC powered device, to operate the DC powered device in an initialization mode even when connection of the DC powered device to a wired bus currently providing a DC power amount equal to or greater than a required predetermined initialization DC input power amount is detected.

10. The electrical device (100) according to any one of claims 8 or 9, wherein: The DC power requirement information indicates minimum required DC voltage amounts and corresponding DC current amounts required for operation in different normal operating modes, and other acceptable DC voltage amounts and acceptable DC current amounts compatible with operation of the DC powered device in different acceptable normal operating modes.

11. A method (500) for operating a DC power supply device for supplying operating DC power to a plurality of DC powered devices via a single twisted pair wired bus, each DC powered device being operable in an initialization mode requiring a lower amount of DC power than in a corresponding normal operating mode of the DC powered device, the method comprising: - driving delivery of a predetermined initialization DC output power amount via the power interface and the wired bus when operating the DC power supply device in an initialization supply mode, wherein the initialization DC output power amount is suitable for driving a plurality of DC powered devices in their initialization mode, the initialization mode comprising communicating respective power requirement information for their respective normal operating modes to the DC power supply device via the single twisted pair wired bus; - receiving, via the power interface, respective DC power requirement information from each of a plurality of DC powered devices connected via a single twisted-pair wired bus by means of LLDP communication, the respective DC power requirement information indicating a DC voltage requirement and a DC current requirement for the respective DC powered device to operate in its respective normal operating mode, wherein the DC power requirement information includes a preferred voltage and a resulting current requirement, and further includes all compatible voltages and associated maximum current values; - using DC power demand information received from the plurality of DC powered devices and a predetermined power determination rule, determining an operating DC output power amount to be output via the power interface from a plurality of available DC output power amounts that the DC power supply device is configured to supply in an operational supply mode, the operating DC output power amount having an operating DC voltage amount suitable for powering operation of the plurality of DC powered devices in their respective normal operating modes; - subsequently driving the DC power supply device to operate in an operational supply mode, distributing the determined amount of operational DC output power to the plurality of DC powered devices via the power interface such that a single twisted pair wired bus is provided with an amount of DC voltage for powering each of the plurality of DC powered devices; and detecting a new connection event and a disconnection event when the DC power supply device is operating in an operational supply mode, the new connection event involving connection of an additional DC powered device to the wired bus and the disconnection event involving disconnection of a previously connected DC powered device from the wired bus, and providing a corresponding event detection signal indicating the new connection event or the disconnection event; and upon receiving the event detection signal indicating the new connection event, maintaining the currently provided operating DC voltage amount for providing the initialization DC power amount to the additional DC powered device; and upon receiving the event detection signal indicating the new connection event or the disconnection event, redetermining the operating DC output power amount to be output via the power interface based on a predetermined power determination rule and the DC voltage demand and DC current demand of the DC powered device currently connected to the wired bus.

12. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the method of claim 11.

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