BACKGROUND

The disclosure relates generally to distribution of power to one or more power consuming devices over power wiring, and more particularly to distributing higher (e.g., in-rush) current demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for a power source in a power distribution system, such as a remote power distribution system for distributing power to remote units in a distributed communications system (DCS) such as distributed antenna systems (DAS).

Wireless customers are increasingly demanding wireless communications services, such as cellular communications services and (Wireless Fidelity) Wi-Fi services. Thus, small cells, and more recently Wi-Fi services, are being deployed indoors. At the same time, some wireless customers use their wireless communication devices in areas that are poorly serviced by conventional cellular networks, such as inside certain buildings or areas where there is little cellular coverage. One response to the intersection of these two concerns has been the use of distributed antenna systems (DASs). DASs include remote antenna units (RAUs) configured to receive and transmit communications signals to client devices within the antenna range of the RAUs. DASs can be particularly useful when deployed inside buildings or other indoor environments where the wireless communication devices may not otherwise be able to effectively receive radio frequency (RF) signals from a source.

In this regard,FIGS. 1A and 1Billustrate a distributed communications system (DCS)100that is configured to distribute communications services to remote coverage areas102(1)-102(N), where ‘N’ is the number of remote coverage areas. The DCS100inFIG. 1Ais provided in the form of a wireless DCS, such as a DAS104. The DAS104can be configured to support a variety of communications services that can include cellular communications services, wireless communications services, such as RF identification (RFID) tracking, Wireless Fidelity (Wi-Fi), local area network (LAN), and wireless LAN (WLAN), wireless solutions (Bluetooth, Wi-Fi Global Positioning System (GPS) signal-based, and others) for location-based services, and combinations thereof, as examples. The remote coverage areas102(1)-102(N) are created by and centered on RAUs106(1)-106(N) connected to a central unit108(e.g., a head-end controller, a central unit, or a head-end unit). The central unit108may be communicatively coupled to a source transceiver110, such as for example, a base transceiver station (BTS) or a baseband unit (BBU). In this regard, the central unit108receives downlink communications signals112D from the source transceiver110to be distributed to the RAUs106(1)-106(N). The downlink communications signals112D can include data communications signals and/or communication signaling signals, as examples. The central unit108is configured with filtering circuits and/or other signal processing circuits that are configured to support a specific number of communications services in a particular frequency bandwidth (i.e., frequency communications bands). The downlink communications signals112D are communicated by the central unit108over a communications link114over their frequency to the RAUs106(1)-106(N).

With continuing reference toFIG. 1A, the RAUs106(1)-106(N) are configured to receive the downlink communications signals112D from the central unit108over the communications link114. The downlink communications signals112D are configured to be distributed to the respective remote coverage areas102(1)-102(N) of the RAUs106(1)-106(N). The RAUs106(1)-106(N) are also configured with filters and other signal processing circuits that are configured to support all or a subset of the specific communications services (i.e., frequency communications bands) supported by the central unit108. In a non-limiting example, the communications link114may be a wired communications link, a wireless communications link, or an optical fiber-based communications link. Each of the RAUs106(1)-106(N) may include an RF transmitter/receiver116(1)-116(N) and a respective antenna118(1)-118(N) operably connected to the RF transmitter/receiver116(1)-116(N) to wirelessly distribute the communications services to user equipment (UE)120within the respective remote coverage areas102(1)-102(N). The RAUs106(1)-106(N) are also configured to receive uplink communications signals112U from the UE120in the respective remote coverage areas102(1)-102(N) to be distributed to the source transceiver110.

Because the RAUs106(1)-106(N) include components that require power to operate, such as the RF transmitters/receivers116(1)-116(N) for example, it is necessary to provide power to the RAUs106(1)-106(N). In one example, each RAU106(1)-106(N) may receive power from a local power source. In another example, the RAUs106(1)-106(N) may be powered remotely from a remote power source(s). For example, the central unit108in the DCS100inFIGS. 1A and 1Bincludes a power source122that is configured to remotely supply power over the communications links114to the RAUs106(1)-106(N). For example, the communications links114may be cable that includes electrical conductors for carrying current (e.g., direct current (DC)) to the RAUs106(1)-106(N). If the DCS100is an optical fiber-based DCS in which the communications links114include optical fibers, the communications links114may by a “hybrid” cable that includes optical fibers for carrying the downlink and uplink communications signals112D,112U and separate electrical conductors for carrying current to the RAUs106(1)-106(N).

Some regulations, such as IEC 60950-21, may limit the amount of direct current (DC) that is remotely delivered by the power source122over the communications links114to less than the amount needed to power the RAUs106(1)-106(N) during peak power consumption periods for safety reasons, such as in the event that a human contacts the wire. One solution to remote power distribution limitations is to employ multiple conductors and split current from the power source122over the multiple conductors, such that the current on any one electrical conductor is below the regulated limit. Another solution includes delivering remote power at a higher voltage so that a lower current can be distributed at the same power level. The power source122may be equipped with an overcurrent protection circuit to shut down the power source122when current demand exceeds a given threshold current. For example, assume that the power source122is configured to shut down when delivered current I to the RAU106inFIG. 1Breaches 3 Amperes (A). When the power source122starts to provide power to the RAU106having an internal capacitance C as shown inFIG. 1B, the initially discharged capacitance C draws a higher current to charge from 0 V until the capacitance C is charged. If the power demand by the RAU106is 300 Watts and the voltage of the power source122is 60 Volts (V), the drawn current I from the power source122over the communications links114will be 5 Amperes (A) (i.e., 300 W/60 V). In this regard, being that the 3 A current threshold is exceeded in this example, the power source122will discontinue delivery of power as a safety precaution, and then may be configured to power-up again at a certain time. However, the cycle of current draw and charging of the capacitance C of the RAU106may then repeat again and again with repeated power shut downs. To address this issue, the power source122could be selected to have a higher supply voltage V to reduce current I. For example, if power source122had a higher supply voltage V of 400 V, the current I flowing through the wires of the communications links114for a 300 W power delivery would be 0.75 A (i.e., 300 W/400 V). However, delivering high voltage through electrical conductors may be further regulated to prevent an undesired current from flowing through a human in the event that a human contacts the electrical conductor. Thus, these safety measures may require other protections, such as the use of protection conduits, which may make installations more difficult and add cost.

No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.

SUMMARY

Embodiments of the disclosure relate to distributing higher (e.g., in-rush) currents demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for a power source in a power distribution system. Related methods are also disclosed. As a non-limiting example, such a power distribution system may be provided for distributed communications systems (DCS). For example, the DCS may be a wireless DCS, such as a distributed antenna system (DAS) that is configured to distribute communications signals, including wireless communications signals, from a central unit to a plurality of remote units over physical communications media, to then be distributed from the remote units wirelessly to client devices in wireless communication range of a remote unit. The remote units in the DCS are power consuming devices that require power to operate and can be powered by the power distribution circuit.

In exemplary aspects disclosed herein, the power distribution system includes a power distribution circuit that is configured to receive power from a power source and distribute the received power over electrical conductors (“power conductors”) to one or more remote power consuming loads (e.g., remote units) for powering their operations. To limit the current supplied by the power source to power consuming loads to not exceed a designed source current threshold limit, such as for safety or other design or regulatory limitations, the power distribution circuit includes a source power management circuit (PMC) coupled to the power source. The source PMC is configured to detect and limit current demand on the power source to not exceed a designed source current threshold limit. However, the remote power consuming load(s) may have, from time to time, a higher current demand (e.g., an in-rush current demand) than the source current threshold limit of the source power management circuit. For example, the remote power consuming load(s) may demand a higher current on the power source during an initial connection to the power source or a power-up phase. Instead of having to increase the source current threshold limit in the source power management circuit to not risk discontinuing power distribution to the remote power consuming load(s), which may be undesired or not possible due to design or regulatory limitations, an energy storage circuit (e.g., a capacitor circuit) and a remote PMC(s) are also included in the power distribution circuit. The energy storage circuit is coupled to a source power output of the source PMC that carries current from the power source. The remote PMC(s) is coupled between the energy storage circuit and the remote power consuming load(s). The remote PMC(s) is configured to decouple the remote power consuming load(s) from the source PMC so that the current distributed by the source PMC from the power source charges the energy storage circuit and is not distributed to the remote PMC(s) to be distributed to the remote power consuming load(s). In response to a power-up phase of the remote power consuming load(s), the remote PMC(s) is configured to couple the remote PMC(s) to the remote power consuming load(s) so that current supplied by the power source and distributed by the source PMC is distributed by the remote PMC(s) to the power consuming load(s). However, current demanded by the power consuming load(s) that exceeds source current threshold limit of the power source can be supplied by the stored charge in the energy storage circuit. In this manner, the source current threshold limit of the power source may not be exceeded, causing the source PMC to discontinue distribution of current from the power source, even though an instantaneous current demand of the remote power consuming load(s) exceeds the source current threshold limit of the power source. Thus, both desires of limiting the current of the power source while also being capable of supplying higher currents (e.g., short term in-rush currents) demanded by power consuming load(s) exceeding the source current limits of the power source can be accomplished.

In other exemplary aspects, the remote PMC(s) may also include a current limiting circuit that is configured to limit the current distributed to the power consuming load(s) to a remote current threshold limit to protect the power consuming load(s). However, the remote current threshold limit can be greater than the source current threshold limit limiting the current demand on the power source without risking discontinuation of power, because as discussed above, the energy storage circuit is configured to provide an additional current to the remote PMC to satisfy current demands by the power consuming load(s) that exceed the source current threshold limit. In yet other exemplary aspects, the remote PMC(s) may also include a bypass circuit that is configured to be activated to bypass the current limiting circuit in the remote PMC(s) to reduce energy loss. The remote PMC(s) can be configured to monitor the current level of power distributed to the power consuming load(s) and to deactivate the bypass circuit to limit the current distributed to the power consuming load(s).

In yet other exemplary aspects, the power distribution circuit may include a current detection circuit configured to disconnect the power source from the source PMC in response to detected load on the power conductors in excess of a current threshold level for safety reasons. For example, a human touching the power conductors is an unsafe condition that may be detected by a higher current detected on the power conductors.

For example, the current detection circuit may be included in the source PMC and/or the remote PMC(s). The current detection circuit can be configured to wait a period of time and/or until a manual reset instruction is received, before reconnecting the power source to the power conductors to once again allow current to flow from the power source to the power consuming load(s) serviced by the power distribution circuit.

In this regard, in one exemplary aspect, a power distribution circuit is provided. The power distribution circuit comprises a source PMC. The source PMC comprises a source power input, and a source current limiter circuit coupled to the source power input and a source power output. The source PMC is configured to receive source current of a source power on a source power input from a power source. The source current limiter circuit is configured to limit the source current to a source current threshold limit to generate a limited source current. The source PMC is further configured to distribute the limited source current on the source power output. The power distribution circuit also comprises one or more remote PMCs. The one or more remote PMCs each comprise a remote power output coupled to a remote unit among one or more remote units. The one or more remote PMCs also are each configured to receive a remote current on a remote power input coupled to the source power output based on the limited source current, and distribute the remote current to the remote unit coupled to the remote power output. The power distribution circuit also comprises an energy storage circuit coupled to source power output. The energy storage circuit is configured to store energy from the limited source current on the source power output in response to a current demand by the one or more remote PMCs being less than the source current threshold limit.

An additional aspect of the disclosure relates to a method of distributing power to one or more remote units in a power distribution system. The method comprises receiving a source current of a source power from a power source. The method also comprises limiting the source current to a source current threshold limit to generate a limited source current. The method also comprises distributing the limited source current to at least one remote PMC among one or more remote PMCs. The method also comprises receiving a remote current at each remote PMC among the at least one remote PMC based on the limited source current. The method also comprises distributing the remote current to a remote unit coupled to the remote PMC in response to a current demand by the at least one remote PMC among the one or more remote PMCs. The method also comprises storing energy from the limited source current in an energy storage circuit coupled to the at least one remote PMC in response to the current demand by the at least one remote PMC among the one or more remote PMCs being less than the source current threshold limit. The method also comprises discharging stored energy in the energy storage circuit in response to the current demand of the at least one remote PMC being greater than the source current threshold limit.

An additional aspect of the disclosure relates to a DCS. The DCS comprises a central unit configured to distribute one or more downlink communications signals over one or more of downlink communications links to a plurality of remote units, and distribute received one or more uplink communications signals from the plurality of remote units from one or more uplink communications links to one or more source communications outputs. The DCS comprises the plurality of remote units, wherein each remote unit among the plurality of remote units is configured to distribute at least one received downlink communications signal among the one or more downlink communications signals from the one or more downlink communications links, to one or more client devices, and distribute the one or more uplink communications signals from the one or more client devices to the one or more uplink communications links. The DCS also includes a power distribution circuit. The power distribution circuit comprises a source PMC comprising a source power input, and a source current limiter circuit coupled to the source power input and a source power output. The source PMC is configured to receive source current of a source power on a source power input from a power source. The source current limiter circuit is configured to limit the source current to a source current threshold limit to generate a limited source current. The source PMC is further configured to distribute the limited source current on the source power output. The power distribution circuit also comprises a plurality of remote PMCs each comprising a remote power output coupled to a remote unit among the plurality of remote units. Each of the plurality of remote PMCs is configured to receive a remote current on a remote power input coupled to the source power output based on the limited source current, and distribute the remote current to the remote unit coupled to the remote power output. The power distribution circuit also comprises an energy storage circuit coupled to source power output. The energy storage circuit is configured to store energy from the limited source current on the source power output in response to a current demand by the plurality of remote PMCs being less than the source current threshold limit.

Additional features and advantages will be set forth in the detailed description which follows and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework to understand the nature and character of the claims.

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.

