Power distribution system

Distributing higher 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. The power distribution system receives and distributes power from the power source to a power consuming load(s). The power distribution circuit is configured to limit current demand on the power source to not exceed a designed source current threshold limit. The power distribution circuit includes an energy storage circuit. The power distribution circuit is configured to charge the energy storage circuit with current supplied by the power source. Current demanded by the power consuming load(s) exceeding the source current threshold limit of the power source is supplied by the energy storage circuit. Thus, limiting current of the power source while supplying higher currents demanded by power consuming load(s) exceeding the source current limits of the power source can both be accomplished.

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.

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.

DETAILED DESCRIPTION

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 this regard,FIG. 2is a schematic diagram of an exemplary power distribution system200that includes a power distribution circuit202configured to receive power from a power source204of a source voltage VS and distribute the received power over power conductors206(+),206(−) to one or more remote units208(1)-208(N), which are power consuming loads and have capacitance loads CR(1)-CR(N). The remote units208(1)-208(N) use the received distributed power over the power conductors206(+),206(−) for powering operations of electronic circuits in the remote units208(1)-208(N). As a non-limiting example, the power distribution system200may be within a DCS, such as a DAS or small cell radio access network (RAN), where the remote units208(1)-208(N) are communications devices that are configured to distribute received communications signals to client devices. As will be discussed in more detail below, the power distribution circuit202includes a source PMC210that is configured to receive a source current ISfrom the power source204that results in remote current I2being distributed to the remote units208(1)-208(N) for powering their operations. To limit the source current ISsupplied by the power source204to not exceed a designed source current threshold limit, such as for safety or other design or regulatory limitations, the source PMC210includes a source current limiter circuit212to limit source current ISdemand by the remote units208(1)-208(N) on the power source204to not exceed a designed source current threshold limit. The source current limiter circuit212limits the source current ISto a limited source current I1, which is the source of a remote current I2being distributed to the remote units208(1)-208(N) for powering their operations. For example, the source current limiter circuit212may be a hot-swap circuit that includes its own current sensor and shut off circuit/switch. Hot-swap circuits are commonly used in some power supplies may also be employed in the power source204itself. The remote current I2is supplied to one or more remote PMCs214(1)-214(N) that are part of the power distribution circuit202, wherein each remote PMC214(1)-214(N) is associated with and coupled to a remote unit208(1)-208(N). The remote current I2demanded by the remote units208(1)-208(N) through the remote PMCs214(1)-214(N) is split between the remote units208(1)-208(N) according to their respective proportional impedances as a voltage divider in this example.

With continuing reference toFIG. 2, note that remote units208(1)-208(N) may have, from time to time, a higher current demand than the limited source current I1that can be demanded of the power source204and distributed by the source PMC210to the remote PMCs214(1)-214(N). For example, the remote units208(1)-208(N) may demand a higher current during an initial connection to the remote PMCs214(1)-214(N) of the power distribution circuit202or a power-up phase that creates an in-rush current demand on the source PMC210and the power source204. However, increasing the source current threshold limit of the source current limiter circuit212to meet these higher current demands of the remote units208(1)-208(N) to not risk interruption of power distribution to the remote units208(1)-208(N) may be undesired or not possible due to design or regulatory limitations.

In this regard, as shown in the power distribution system200inFIG. 2, the power distribution circuit202also includes an energy storage circuit216that is coupled in parallel to the power conductors206(+),206(−) between the source PMC210and the remote PMCs214(1)-214(N). In this example, the energy storage circuit216is a capacitor circuit219, which is capacitor Cs in this example. The energy storage circuit216is configured to store energy from the limited source current I1when the remote current I2representing the current demand by remote PMCs214(1)-214(N) is less than the limited source current I1in a charging phase (i.e., I2<I1). For example, as discussed in more detail below, the remote PMCs214(1)-214(N) may be configured to keep the remote units208(1)-208(N) electrically disconnected from the power distribution circuit202during the charging phase to prevent a current demand of the remote current I2higher than the source current threshold limit of the limited source current I1until the energy storage circuit216is sufficient charged. Then later, if the current demand for the remote current I2by the remote PMCs214(1)-214(N) is higher than the source current threshold limit of the limited source current I1that can be distributed by the source PMC210(e.g., an in-rush current demand), the higher demanded remote current I2can be satisfied by the limited source current I1distributed by the source PMC210and a current ICSthat is generated by the energy storage circuit216in a discharge phase based on a stored charge from the limited source current I1in the charge phase (e.g., remote current I2=limited source current I1+current ICS). The energy storage circuit216acts as a second power source to supplement the power supplied by the source PMC210. In this manner, the source current threshold limit of the power source204enforced by the source current limiter circuit212of the source PMC210is not exceeded, which may otherwise cause an interruption or discontinuation of power from the power source204. For example, the power source204may be designed to automatically shut off when the current demand on the power source204exceeds its internal current demand limits.

Thus, in the power distribution circuit202inFIG. 2, limiting the source current ISof the power source204while also being capable of supplying higher currents (e.g., short term in-rush currents) demanded by remote units208(1)-208(N) exceeding the source current limits of the power source204and the source current limiter circuit212in the source PMC210can be accomplished. The power distribution circuit202inFIG. 2is configured to supply a higher remote current I2demanded by the remote units208(1)-208(N) than the source current threshold limit of the limited source current I1without risking the shutting off (tripping) the power source and/or without having to choose a power source204that can supply a higher current for peak operations, when a lower current power source would be sufficient for nominal operations. Also, it may not be possible to choose a power source204for the power distribution system200that has increased current demand capability due to regulatory or other safety considerations.

More exemplary detail of the power distribution circuit202inFIG. 2will now be described. The source PMC210in the power distribution circuit202includes a source power input218configured to be coupled to the power source204. The source power input218has two terminals, a positive terminal220(+) and a negative terminal220(−). The source PMC210is configured to receive the source current ISof a source power PSof the power source204on the source power input218. The source current limiter circuit212of the source PMC210is coupled to the source power input218and a source power output222. The source current limiter circuit212is configured to limit the source current ISto a source current threshold limit to generate the limited source current I1. The source current limiter circuit212is configured to distribute the limited source current I1on the source power output222to be distributed to the remote PMCs214(1)-214(N). The remote PMCs214(1)-214(N) each include a respective remote power output224(1)-224(N) coupled to a respective remote unit208(1)-208(N) as power-consuming loads. The remote PMCs214(1)-214(N) are each configured to receive a respective remote current I2(1)-I2(N)split from the remote current I2on a respective remote power input226(1)-226(N) in the remote PMCs214(1)-214(N) coupled to the source power output222. The remote current I2is based on the limited source current I1as a source of current. The remote PMCs214(1)-214(N) are configured to distribute the respective remote currents I2(1)-I2(N)to the respective remote power outputs224(1)-224(N) to be distributed to coupled remote units208(1)-208(N).

With continuing reference toFIG. 2, the energy storage circuit216is also coupled to the source power output222. The energy storage circuit216is configured to store energy from the limited source current I1on the source power output222in response to the current demands by the one or more remote PMCs214(1)-214(N) being less than the source current threshold limit of the source current limiter circuit212. This situation can occur when the current demand by the remote PMCs214(1)-214(N) is less than the limited source current I1from the source current limiter circuit212. For example, this situation can occur when a remote unit208(1)-208(N) is physically or electrically disconnected from a remote PMC214(1)-214(N). Likewise, the energy storage circuit216is configured to not store energy from the limited source current I1on the source power output222when the current demand by the remote PMCs214(1)-214(N) is equal to or greater than the source current threshold limit of the source current limiter circuit212. This situation can occur when the current demands by the remote PMCs214(1)-214(N) is equal to or greater than the limited source I1from the source current limiter circuit212. For example, this situation can occur when one or more of the remote units208(1)-208(N) are electrically connected to a remote PMC214(1)-214(N). For example, when a remote unit208(1)-208(N) is initially connected to a remote PMC214(1)-214(N) and/or powered-up, the remote unit208(1)-208(N) may have an in-rush current situation wherein the total of the demanded remote currents I2(1)-I2(N)is greater than the source current threshold limit imposed by the source current limiter circuit212on the source current ISresulting in the limited source current I1. Thus, in the power distribution circuit202inFIG. 2, when the total of the demanded remote currents I2(1)-I2(N)is greater than limited source current I1such that the demand for the remote current I2is greater than the limited source current I1, the energy storage circuit216is configured to discharged stored energy in the form of current ICSon the source power output222to be added to the limited source current I1to provide the remote current I2. If the energy storage circuit216is a capacitor circuit219, the capacitor circuit219may be sufficiently sized to store enough energy to supplement the limited source current I1to meet the demand for the remote currents I2(1)-I2(N)by all of the remote units208(1)-208(N). Alternatively, the energy storage circuit216could be provided by individual energy storage circuits provided in each remote PMC214(1)-214(N) that are coupled between the respective remote power inputs226(1)-226(N) and the remote power outputs224(1)-224(N).

With continuing reference toFIG. 2, it may also be desired to limit the remote currents I2(1)-I2(N)as limited remote currents I2(1)-I2(N)that are distributed by the respective remote PMCs214(1)-214(N) to their electrically connected remote units208(1)-208(N). This may be desired for safety reasons for example. In this regard, the remote PMCs214(1)-214(N) include optional remote current limiter circuits228(1)-228(N) that are coupled to the respective remote power inputs226(1)-226(N). The remote current limiter circuits228(1)-228(N) are coupled to and between the respective remote power inputs226(1)-226(N) and the remote power outputs224(1)-224(N) of the remote PMCs214(1)-214(N). The remote current limiter circuits228(1)-228(N) are each configured to limit the received remote currents I2(1)-I2(N)to limited remote currents I2L(1)-I2L(N)according to a designed remote current threshold limit to be distributed to the remote units208(1)-208(N). For example, the source current limiter circuit212may be a hot-swap circuit that includes its own current sensor and shut off circuit/switch. Hot-swap circuits are commonly used in some power supplies.

With continuing reference toFIG. 2, the source PMC210may also include a touch safe circuit230that is configured to instruct the remote units208(1)-208(N) to electrically disconnect from their respective remote PMCs214(1)-214(N) in the event a current measured on the power conductors206(+),206(−) is greater than expected. This may occur for example in an event that causes a short circuit between the positive and negative terminals220(+),220(−) or the power conductors206(+),206(−) such as human touch on conductors coupled to positive and negative terminals220(+),220(−) or power conductors206(+),206(−) that causes an increased and unexpected current demand on the power source204. In this regard, the touch safe circuit230can include a current measurement circuit232that is coupled to the source power input218and configured to measure the source current ISat the source power input218. The current measurement circuit232generates a current measurement on a current measurement output234based on the measured source current ISat the source power input218. The touch safe circuit230also includes a safety control circuit236configured to receive the measured current measurement output234. The safety control circuit236is configured to determine if the measured source current ISexceeds a predefined current threshold level. In response to the measured source current ISexceeding the predefined current threshold level, the safety control circuit236is configured to generate a distribution power connection control signal238to the remote units208(1)-208(N) to cause the remote units208(1)-208(N) to electrically decouple from the respective remote PMCs214(1)-214(N). The remote units208(1)-208(N) can be instructed periodically to connect back to the remote PMCs214(1)-214(N) so that there is a current demand on the power source204for the current measurement circuit232measure the source current ISat the source power input218. If the source current ISagain exceeds the predefined current threshold level, the safety control circuit236can generate the distribution power connection control signal238to the remote units208(1)-208(N) to cause the remote units208(1)-208(N) to electrically decouple from the respective remote PMCs214(1)-214(N). Examples of touch safety circuits that can be included as the touch safety circuit230in the power distribution circuit202are disclosed in PCT Patent Application Publication No. PCT/IL18/050368 entitled “SAFETY POWER DISCONNECTION FOR POWER DISTRIBUTION OVER POWER CONDUCTORS TO POWER CONSUMING DEVICES,” filed on Mar. 29, 2018, which is incorporated herein by reference in its entirety.

FIG. 3is a flowchart illustrating an exemplary process300of the power distribution circuit202in the power distribution system200inFIG. 2distributing higher current demanded by the remote units208(1)-208(N) exceeding overcurrent limits of the source current limiter circuit212in the source PMC210. The exemplary process300inFIG. 3will be described with reference to the power distribution circuit202inFIG. 2. In this regard, a first exemplary step is that the source PMC210receives the source current ISof the source power PSfrom the power source204on the source power input218(block302inFIG. 3). A next exemplary step is that the source current limiter circuit212limits the source current ISto the source current threshold limit to generate the limited source current I1(block304inFIG. 3). A next exemplary step is for the source PMC210to distribute the limited source current I1to at least one remote PMC214(1)-214(N) among remote PMCs214(1)-214(N) (block306inFIG. 3). A next exemplary step is that the remote PMCs214(1)-214(N) receive remote currents I2(1)-I2(N)at each remote PMC214(1)-214(N) among the at least one remote PMC214(1)-214(N) based on a splitting of the limited source current I1(block308inFIG. 3). A next exemplary step is for the remote PMCs214(1)-214(N) to distribute the remote currents I2(1)-I2(N)to the remote units208(1)-208(N) coupled to the remote PMCs214(1)-214(N) in response to a current demand by the remote PMCs214(1)-214(N) (block310inFIG. 3). A next exemplary step is to store energy from the limited source current I1in the energy storage circuit216coupled to remote PMCs214(1)-214(N) in response to the current demand by the remote PMCs214(1)-214(N) being less than the source current threshold limit of the source current limiter circuit212(block312inFIG. 3). A next exemplary step is to discharge stored energy in the energy storage circuit216to remote PMCs214(1)-214(N) in response to the current demand by the remote PMCs214(1)-214(N) being greater than the source current threshold limit of the source current limiter circuit212(block314inFIG. 3).

FIG. 4is a schematic diagram of another exemplary power distribution system400that includes a power distribution circuit402configured to receive power from the power source204of a source voltage VS and distribute the received power over power conductors406(+),406(−) to one or more remote units208(1)-208(N), which are power consuming loads. Common components between the power distribution system400inFIG. 4and the power distribution circuit202inFIG. 2are shown with common element numbers betweenFIGS. 2 and 4and will not be re-described. Like the power distribution system200inFIG. 2, the power distribution system200may be within a DCS, such as a DAS, or small cell RAN, where the remote units208(1)-208(N) are communications devices that are configured to distribute received communications signals to client devices. As will be discussed in more detail below, the power distribution circuit402includes a source PMC410that is configured to receive a source current ISfrom the power source204that results in remote current I4being distributed to the remote units208(1)-208(N) for powering their operations. To limit the source current ISsupplied by the power source204to not exceed the designed source current threshold limit, such as for safety or other design or regulatory limitations, the source PMC410includes the source current limiter circuit212to limit source current ISdemand by the remote units208(1)-208(N) on the power source204to not exceed a designed source current threshold limit. The remote current I4is supplied to one or more remote PMCs414(1)-414(N) that are part of the power distribution circuit402, wherein each remote PMC414(1)-414(N) is associated with and coupled to a remote unit208(1)-208(N). The remote current I4demanded by the remote units208(1)-208(N) through the remote PMCs214(1)-214(N) is split between the remote units208(1)-208(N) according to their respective proportional impedances as a voltage divider in this example.

With continuing reference toFIG. 4, as shown in the power distribution system400inFIG. 4, the power distribution circuit402includes the energy storage circuit216that is coupled in parallel to the power conductors406(+),406(−) between the source PMC410and the remote PMCs414(1)-414(N). Like the power distribution circuit202inFIG. 2, the energy storage circuit216in the power distribution circuit402inFIG. 4is configured to store energy from a limited source current I3when the remote current I4representing the current demand by remote PMCs414(1)-414(N) is less than the limited source current I3in a charging phase (i.e., I4<I3). For example, as discussed in more detail below, the remote PMCs414(1)-414(N) may be configured to keep the remote units208(1)-208(N) electrically disconnected from the power distribution circuit402during the charging phase to prevent a current demand of the remote current I4higher than the source current threshold limit of the limited source current I3until the energy storage circuit216is sufficient charged. Then later, if the current demand for the remote current I4by the remote PMCs414(1)-414(N) is higher than the source current threshold limit of the limited source current I3that can be distributed by the source PMC410(e.g., an in-rush current demand), the higher demanded remote current I4can be satisfied by the limited source current I3distributed by the source PMC410and a current ICSthat is generated by the energy storage circuit216in a discharge phase based on a stored charge from the limited source current I3in the charge phase (e.g., remote current I4=limited source current I3+current ICS). The energy storage circuit216acts as a second power source to supplement the power supplied by the source PMC410. In this manner, the source current threshold limit of the power source204enforced by the source current limiter circuit212of the source PMC410is not exceeded, which may otherwise cause an interruption or discontinuation of power from the power source204. For example, the power source204may be designed to automatically shut off when the current demand on the power source204exceeds its internal current demand limits.

Thus, in the power distribution circuit402inFIG. 4, limiting the source current ISof the power source204while also being capable of supplying higher currents (e.g., short term in-rush currents) demanded by remote units208(1)-208(N) exceeding the source current limits of the power source204and the source current limiter circuit212in the source PMC410can be accomplished. The power distribution circuit402inFIG. 4is configured to supply a higher remote current I4demanded by the remote units208(1)-208(N) than the source current threshold limit of the limited source current I3without risking the shutting off (tripping) the power source and/or without having to choose a power source204that can supply a higher current for peak operations, when a lower current power source would be sufficient for nominal operations. Also, it may not be possible to choose a power source204for the power distribution system200that has increased current demand capability due to regulatory or other safety considerations.

More exemplary detail of the power distribution circuit402inFIG. 4will now be described. The source PMC410in the power distribution circuit402includes a source power input418configured to be coupled to the power source204. The source power input418has two terminals, a positive terminal420(+) and a negative terminal420(−). The source PMC410is configured to receive the source current ISof a source power PSof the power source204on the source power input418. The source current limiter circuit212of the source PMC410is coupled to the source power input418and a source power output422. The source current limiter circuit212is configured to limit the source current ISto a source current threshold limit to generate the limited source current I3. The source current limiter circuit212is configured to distribute the limited source current I3on the source power output422to be distributed to the remote PMCs414(1)-414(N). The remote PMCs414(1)-414(N) each include a respective remote power output424(1)-424(N) coupled to a respective remote unit208(1)-208(N) as power-consuming loads. The remote PMCs414(1)-414(N) are each configured to receive a respective remote current I4(1)-I4(N)split from the remote current I4on a respective remote power input426(1)-426(N) in the remote PMCs414(1)-414(N) coupled to the source power output422. The remote current I4is based on the limited source current I3as a source of current. The remote PMCs414(1)-414(N) are configured to distribute the respective remote currents I4(1)-I4(N)to the respective remote power outputs424(1)-424(N) to be distributed to coupled remote units208(1)-208(N).

With continuing reference toFIG. 4, the energy storage circuit216is also coupled to the source power output422. The energy storage circuit216is configured to store energy from the limited source current I3on the source power output422in response to the current demands by the one or more remote PMCs414(1)-414(N) being less than the source current threshold limit of the source current limiter circuit212. This situation occurs when the current demand by the remote PMCs414(1)-414(N) is less than the source current threshold limit of the source current limiter circuit212. For example, this situation can occur when a remote unit208(1)-208(N) is physically or electrically disconnected from a remote PMC414(1)-414(N). Likewise, the energy storage circuit216is configured to not store energy from the limited source current I3on the source power output422when the current demand by the one or more remote PMCs414(1)-414(N) is equal to or greater than the source current threshold limit of the source current limiter circuit212. This situation occurs when the current demands by the remote PMCs414(1)-414(N) is equal to or greater than the source current threshold limit of the source current limiter circuit212. For example, this situation can occur when one or more of the remote units208(1)-208(N) is electrically connected to a remote PMC414(1)-414(N). For example, when a remote unit208(1)-208(N) is initially connected to a remote PMC414(1)-414(N) and/or powered-up, the remote unit208(1)-208(N) may have an in-rush current situation wherein the total of the demanded remote currents I4(1)-I4(N)is greater than the source current threshold limit imposed by the source current limiter circuit212on the source current ISresulting in the limited source current I3. Thus, in the power distribution circuit402inFIG. 4, when the total of the demanded remote currents I4(1)-I4(N)is greater than limited source current I3such that the demand for the remote current I4is greater than the limited source current I3, the energy storage circuit216is configured to discharge stored energy in the form of current ICSon the source power output422to be added to the limited source current I3to provide the remote current I4. If the energy storage circuit216is a capacitor circuit219which is shown as capacitor Cs, the capacitor Cs may be sufficiently sized to store enough energy to supplement the limited source current I3to meet the demand for the remote currents I4(1)-I4(N)by all of the remote units208(1)-208(N). Alternatively, the energy storage circuit216could be provided by individual energy storage circuits provided in each remote PMC414(1)-414(N) that are coupled between the respective remote power inputs426(1)-426(N) and the remote power outputs424(1)-424(N).

With continuing reference toFIG. 4, the source PMC410may also include the touch safe circuit230that is configured to instruct the remote units208(1)-208(N) to electrically disconnect from their respective remote PMCs414(1)-414(N) in the event a current measured on the power conductors406(+),406(−) is greater than expected. This may occur for example an event that causes a short circuit between the positive and negative terminals420(+),420(−) or the power conductors406(+),406(−) such as human touch on conductors coupled to positive and negative terminals420(+),420(−) or power conductors406(+),406(−) that causes and increased and unexpected current demand on the power source204. In this regard, the touch safe circuit230can include the current measurement circuit232that is coupled to the source power input418and configured to measure the source current ISat the source power input418. The current measurement circuit232generate a current measurement on a current measurement output234based on the measured current at the source power input418. The touch safe circuit230also includes the safety control circuit236configured to receive the measured current measurement output234. The safety control circuit236is configured to determine if the measured source current ISexceeds a predefined current threshold level. In response to the measured source current ISexceeding the predefined current threshold level, the safety control circuit236is configured to generate the distribution power connection control signal238to the remote units208(1)-208(N) to cause the remote units208(1)-208(N) to electrically decouple from the respective remote PMCs414(1)-414(N). The remote units208(1)-208(N) can be instructed periodically to connected back to the remote PMCs414(1)-414(N) so that there is a current demand on the power source204for the current measurement circuit232measure the source current ISat the source power input418. If the source current ISagain exceeds the predefined current threshold level, the safety control circuit236can generate the distribution power connection control signal238to the remote units208(1)-208(N) to cause the remote units208(1)-208(N) to electrically decouple from the respective remote PMCs414(1)-414(N). Examples of touch safety circuits that can be included as the touch safety circuit230in the power distribution circuit402are disclosed in PCT Patent Application Publication No. PCT/IL18/050368 entitled “SAFETY POWER DISCONNECTION FOR POWER DISTRIBUTION OVER POWER CONDUCTORS TO POWER CONSUMING DEVICES,” filed on Mar. 29, 2018, which is incorporated herein by reference in its entirety.

As discussed above, the energy storage circuit216in the power distribution circuit402inFIG. 4is configured to store energy from the limited source current I3on the source power output422in response to the current demands by the remote PMCs414(1)-414(N) being less than the source threshold current limit of the source current limiter circuit212. In this regard, in a charge phase, it may be desired to provide for the remote units208(1)-208(N) to be electrically disconnected from remote PMCs414(1)-414(N) so that there is no current demand by the remote PMCs414(1)-414(N) on the source PMC410and the power source204so that the energy storage circuit216is charged by the limited source current I3. Then, when the energy storage circuit216is charged, the remote PMCs414(1)-414(N) can electrically connect their respective remote units208(1)-208(N) so that their peak demand remote currents I4(1)-I4(N)can be satisfied, such as from in-rush current demands. However, a mechanism is needed to determine when remote PMCs414(1)-414(N) should electrically disconnect from and connect to the remote units208(1)-208(N). In this regard, in the power distribution circuit402, the source PMC410includes a source voltage sensing circuit440to the source power output422. The source voltage sensing circuit440coupled is configured to sense the source voltage VS on the source power output422and generate a source voltage state signal442on a source voltage state output444based on the sensed source voltage VS. Before the energy storage circuit216is fully charged, the voltage VCSacross the energy storage circuit216is increasing as charging occurs from limited source current I3. The source voltage sensing circuit440generates the source voltage state signal442indicating a charging state, meaning the energy storage circuit216is charging. When fully charged after time of capacitance CS*the source voltage VSdivided by the limited source current I3(i.e., CS*VS/I3), the voltage VCSacross the energy storage circuit216is approximately the source voltage VS, and the source voltage sensing circuit440generates the source voltage state signal442indicating a charged state, meaning the energy storage circuit216is charged.

The source voltage state signal442is communicated to a respective remote voltage state input446(1)-446(N) of remote control circuits448(1)-448(N) in the respective remote PMCs414(1)-414(N). The remote control circuits448(1)-448(N) are configured to cause a remote switch450(1)-450(N) coupled to the remote power outputs424(1)-424(N) and located between the remote power inputs426(1)-426(N) and the remote power outputs424(1)-424(N) to be opened and closed based on the state of the source voltage state signal442. The remote control circuits448(1)-448(N) are configured to generate switch signals452(1)-452(N) to cause the respective remote switches450(1)-450(N) to be opened to decouple the distribution of the remote current I4(1)-I4(N)from the remote power outputs424(1)-424(N) in response to the source voltage state signal442indicating a charging state, meaning voltage level of the voltage VCSacross the energy storage circuit216is less than a source voltage VS. However, in response to the source voltage state signal442indicating a charged state, meaning voltage level of the voltage VCSacross the energy storage circuit216is approximately equal to the source voltage VS, the remote control circuits448(1)-448(N) are configured to generate the switch signals452(1)-452(N) cause the respective remote switches450(1)-450(N) to be closed to couple the distribution of the remote current I4(1)-I4(N)to the remote power outputs424(1)-424(N) to place loads on the source PMC410and power source204. Thus, if the total current demand by the remote units208(1)-208(N) is greater than the limited source current I3, the energy storage circuit216can discharge stored energy to cause a current ICSto flow to the source power output422to supplement and be additive to limited source current I3. For example, the remote switches450(1)-450(N) may be implemented as transistors, or alternatively SCRs of TRIACs.

It may also be desired to provide for the remote PMCs414(1)-414(N) to be able to open their respective remote switches450(1)-450(N) to protect the remote units208(1)-208(N) from a current overload situation like the functionality of the source current limiter circuit212provided in the source PMC410. This may be desired for safety reasons for example. In this regard, the remote PMCs414(1)-414(N) inFIG. 4also include respective remote current sensor circuits454(1)-454(N). The remote control circuits448(1)-448(N) along with their respective remote switches450(1)-450(N) and respective remote current sensor circuits454(1)-454(N) form remote current limiter circuits428(1)-428(N) in the respective remote PMCs414(1)-414(N). For example, the remote current limiter circuits428(1)-428(N) may be considered hot-swap circuits.

In this regard, as shown in the power distribution circuit402inFIG. 4, the remote PMCs414(1)-414(N) each include a respective remote current sensor circuit454(1)-454(N) coupled to their remote power inputs426(1)-426(N). The remote current sensor circuits454(1)-454(N) are configured to generate a respective remote current signal456(1)-456(N) on a respective remote current state output459(1)-459(N) coupled to the remote control circuits448(1)-448(N). The remote control circuits448(1)-448(N) are configured to cause the remote switches450(1)-450(N) to be opened to decouple the distribution of the remote currents I4(1)-I4(N)to the remote power outputs424(1)-424(N) in response to the remote current signals456(1)-456(N) indicating a current level greater than a designed or programmed remote current threshold as a overcurrent state. Likewise, the remote control circuits448(1)-448(N) are also configured to cause the remote switches450(1)-450(N) to be closed to couple the distribution of the remote currents I4(1)-I4(N)to the remote power outputs424(1)-424(N) in response to the remote current signals456(1)-456(N) indicating a current level less than or equal to the remote current threshold as a non-overcurrent state. In this regard, if the remote control circuits448(1)-448(N) have determined an overcurrent state, the remote control circuits448(1)-448(N) can periodically cause the remote switches450(1)-450(N) to be closed to allow the remote current sensor circuits454(1)-454(N) to measure the remote currents I4(1)-I4(N)to determine if the overcurrent state still exists. If the overcurrent state still exists, the remote control circuits448(1)-448(N) can cause the remote switches450(1)-450(N) to be opened again to decouple the distribution of the remote currents I4(1)-I4(N)to the remote power outputs424(1)-424(N).

It may also be desired to provide for the remote PMCs414(1)-414(N) to be able to limit the remote currents I4(1)-I4(N)to the remote power outputs424(1)-424(N) like the source current limiter circuit212in the source PMC410when the remote switches450(1)-450(N) are closed to protect the remote units208(1)-208(N). This can also protect an overcurrent demand on the source PMC410. For example, when the remote switches450(1)-450(N) are initially closed, the remote units208(1)-208(N) may have high initial current demands for the remote currents I4(1)-I4(N)that could damage the remote units208(1)-208(N) if not limited. In this regard, the remote current limiter circuits428(1)-428(N) also include current limiting resistor circuits458(1)-458(N) in this example. The current limiting resistor circuits458(1)-458(N) are configured to limit the remote currents I4(1)-I4(N)distributed to the remote power outputs424(1)-424(N) coupled to the remote units208(1)-208(N). Note that the total current of the limited remote currents I4L(1)-I4L(N)may still be greater than the limited source current I3, which can be accommodated by the energy storage circuit216as discussed above. The source PMC410can also be configured to progressively communicate the distribution power connection control signal238to the remote units208(1)-208(N) to cause the remote units208(1)-208(N) to electrically couple to their respective remote PMCs214(1)-214(N) progressively to minimize initial currents demands.

Energy loss occurs in the current limiting resistor circuits458(1)-458(N) through heat dissipation. To reduce this energy loss, the remote current limiter circuits428(1)-428(N) may also include remote current limiter bypass switches460(1)-460(N) that are coupled to remote power outputs424(1)-424(N) between the remote power outputs424(1)-424(N) and the remote current sensor circuits454(1)-454(N). The remote control circuits448(1)-448(N) are configured to cause the remote current limiter bypass switches460(1)-460(N) to be opened to cause the current limiting resistor circuits458(1)-458(N) to limit the received respective remote currents I4(1)-I4(N)to the limited remote currents I4L(1)-I4L(N), in response to the source voltage state signal442indicating a voltage level of the voltage VCSacross the energy storage circuit216and the remote current signals456(1)-456(N) indicating a non-overcurrent state. However, after a defined period of time has passed according to the design of the remote control circuits448(1)-448(N) of the remote PMCs414(1)-414(N), the remote control circuits448(1)-448(N) can cause the remote current limiter bypass switches460(1)-460(N) to be closed to bypass and short circuit the current limiting resistor circuits458(1)-458(N) to reduce energy loss. As an example, the current limiting resistor circuits458(1)-458(N) may be negative temperature coefficient (NTC) resistors. The use of NTC resistors can provide an additional current limiting mechanism on in-rush currents caused by current demand of the remote units208(1)-208(N). The initial resistance of the NTC resistors is high and therefore the initial limited remote currents I4L(1)-I4L(N)may is reduced. But after a short period of time, the NTC resistors warm up and their resistances decrease allowing the limited remote currents I4L(1)-I4L(N)to ramp up gradually. When remote current limiter bypass switches460(1)-460(N) are closed, the power consumption by the NTC resistors is reduced almost to zero, allowing the NTC resistors to cool down and get ready for the next operation. The use of NTC resistors for the current limiting resistor circuits458(1)-458(N) in combination with the remote current limiter bypass switches460(1)-460(N) can avoid the need for more costly higher current limiting transistors. For example, the remote current limiter bypass switches460(1)-460(N) may be implemented as transistors, or alternatively SCRs of TRIACs.

Thus in summary, in one exemplary operation of the power distribution circuit402inFIG. 4, the remote switches450(1)-450(N) and the remote current limiter bypass switches460(1)-460(N) are initially caused to be opened by the respective remote control circuits448(1)-448(N) in the remote PMCs414(1)-414(N). This decouples the loads of the remote units208(1)-208(N) from the remote PMCs414(1)-414(N) to cause the limited source current I3to charge the energy storage circuit216. The source current limiter circuit212in the source PMC410limits the source current ISto the limited source current I3. Once the voltage VCSacross the energy storage circuit216reaches the source voltage VS, the source voltage sensing circuit440in the source PMC410voltage generates the source voltage state signal442to the remote control circuits448(1)-448(N) indicating a voltage level of the voltage VCSacross the energy storage circuit216reaches the source voltage VS. In response, the remote control circuits448(1)-448(N) cause their respective remote switches450(1)-450(N) to be closed to allow the remote currents I4(1)-I4(N)to flow to the remote current limiter circuits428(1)-428(N) to provide the limited remote currents I4L(1)-I4L(N)to the remote units208(1)-208(N). The remote control circuits448(1)-448(N) cause their respective remote current limiter bypass switches460(1)-460(N) to be opened or are left open to allow the remote currents I4(1)-I4(N)to flow to the current limiting resistor circuits458(1)-458(N) to generate the limited remote currents IL4(1)-IL4(N). After a defined period of time, remote control circuits448(1)-448(N) cause their respective remote current limiter bypass switches460(1)-460(N) to be closed to bypass the current limiting resistor circuits458(1)-458(N) to avoid heat loss through the current limiting resistor circuits458(1)-458(N). The remote control circuits448(1)-448(N) are configured to determine from the remote current sensor circuits454(1)-454(N) if the remote currents I4(1)-I4(N)are in a current overload condition. If so, the remote control circuits448(1)-448(N) can cause the respective remote switches450(1)-450(N) and remote current limiter bypass switches460(1)-460(N) to be opened, and then cause remote switches450(1)-450(N) to be closed to check the current overload condition. If the current overload condition still exists, the remote control circuits448(1)-448(N) can again can cause the respective remote switches450(1)-450(N) and remote current limiter bypass switches460(1)-460(N) to be opened, and the process repeated.

Power distribution systems that include a power distribution circuit configured to receive power from a power source and distribute the received power over power conductors to one or more remote power consuming loads for powering their operations, wherein the power distribution circuit is further configured to distribute higher current demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for the power source in the power distribution system, can be provided is a distributed communications system. For example,FIG. 5is a schematic diagram of a distributed communications system500in the form of a DAS502that includes a power distribution system504. The power distribution system504can include, for example, the power distribution systems200,400inFIGS. 2 and 4as examples. A DAS, including DAS502inFIG. 5, is a system that is configured to distribute communications signals, including wireless communications signals, from a central unit506to a plurality of remote units508(1)-508(X) over physical communications media, to then be distributed from the remote units508(1)-508(X) wirelessly to client devices in wireless communication range of a remote unit508(1)-508(X). The power distribution system504includes a power distribution circuit510that includes a source PMC512and a remote PMC514. The source PMC512is configured to receive power from a power source516and distribute the received power over power conductors to the remote units508(1)-508(X) for powering their operations. The power distribution circuit510is further configured to distribute higher current demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for the power source516in the power distribution system504.

With reference toFIG. 5, the DAS502in this example is an optical fiber-based DAS that is comprised of three (3) main components. One or more radio interface circuits provided in the form of radio interface modules (RIMS)518(1)-518(T) are provided in the central unit506to receive and process downlink electrical communications signals520D(1)-520D(S) prior to optical conversion into downlink optical communications signals. The downlink electrical communications signals520D(1)-520D(S) may be received from a base transceiver station (BTS) or baseband unit (BBU) as examples. The downlink electrical communications signals520D(1)-520D(S) may be analog signals or digital signals that can be sampled and processed as digital information. The RIMS518(1)-518(T) provide both downlink and uplink interfaces for signal processing. The notations “1-5” and “1-T” indicate that any number of the referenced component, 1-S and 1-T, respectively, may be provided.

With continuing reference toFIG. 5, the central unit506is configured to accept the plurality of RIMS518(1)-518(T) as modular components that can easily be installed and removed or replaced in a chassis. In one embodiment, the central unit506is configured to support up to twelve (12) RIMs518(1)-518(12). Each RIM518(1)-518(T) can be designed to support a particular type of radio source or range of radio sources (i.e., frequencies) to provide flexibility in configuring the central unit506and the DAS502to support the desired radio sources. For example, one RIM518may be configured to support the Personal Communication Services (PCS) radio band. Another RIM518may be configured to support the 700 MHz radio band. In this example, by inclusion of these RIMS518, the central unit506could be configured to support and distribute communications signals, including those for the communications services and communications bands described above as examples.

The RIMs518(1)-518(T) may be provided in the central unit506that support any frequencies desired, including but not limited to licensed US FCC and Industry Canada frequencies (824-849 MHz on uplink and 869-894 MHz on downlink), US FCC and Industry Canada frequencies (1850-1915 MHz on uplink and 1930-1995 MHz on downlink), US FCC and Industry Canada frequencies (1710-1755 MHz on uplink and 2110-2155 MHz on downlink), US FCC frequencies (698-716 MHz and 776-787 MHz on uplink and 728-746 MHz on downlink), EU R & TTE frequencies (880-915 MHz on uplink and 925-960 MHz on downlink), EU R & TTE frequencies (1710-1785 MHz on uplink and 1805-1880 MHz on downlink), EU R & TTE frequencies (1920-1980 MHz on uplink and 2110-2170 MHz on downlink), US FCC frequencies (806-824 MHz on uplink and 851-869 MHz on downlink), US FCC frequencies (896-901 MHz on uplink and 929-941 MHz on downlink), US FCC frequencies (793-805 MHz on uplink and 763-775 MHz on downlink), and US FCC frequencies (2495-2690 MHz on uplink and downlink).

With continuing reference toFIG. 5, the received downlink electrical communications signals520D(1)-520D(S) are provided to a plurality of optical interfaces provided in the form of optical interface modules (OIMs)522(1)-522(W) in this embodiment to convert the downlink electrical communications signals520D(1)-520D(S) into downlink optical communications signals524D(1)-524D(S). The notation “1-W” indicates that any number of the referenced component 1-W may be provided. The OIMs522(1)-552(W) may include one or more optical interface components (OICs) that contain electrical-to-optical (E-O) converters526(1)-526(W) to convert the received downlink electrical communications signals520D(1)-520D(S) into the downlink optical communications signals524D(1)-524D(S). The OIMs522(1)-552(W) support the radio bands that can be provided by the RIMs518(1)-518(T), including the examples previously described above. The downlink optical communications signals524D(1)-524D(S) are communicated over a downlink communications link528D to the plurality of remote units508(1)-508(X) provided in the form of remote antenna units in this example. The notation “1-X” indicates that any number of the referenced component 1-X may be provided. One or more of the downlink optical communications signals524D(1)-524D(S) can be distributed to each remote unit508(1)-508(X). Thus, the distribution of the downlink optical communications signals524D(1)-524D(S) from the central unit506to the remote units508(1)-508(X) is in a point-to-multipoint configuration in this example. The power distribution system504may also be configured to provide power signals529(1)-529(X) based on power received from the power source516over electrical conductors over the downlink communications link528D. For example, the downlink communications link528D may be a hybrid cable that includes electrical conductors and optical fibers.

With continuing reference toFIG. 5, the remote units508(1)-508(X) include optical-to-electrical (O-E) converters530(1)-530(X) configured to convert the one or more received downlink optical communications signals524D(1)-524D(S) back into the downlink electrical communications signals520D(1)-520D(S) to be wirelessly radiated through antennas532(1)-532(X) in the remote units508(1)-508(X) to user equipment (not shown) in the reception range of the antennas532(1)-532(X). The remote units508(1)-508(X) may also include power interfaces533(1)-533(X) to receive the power signals529(1)-529(X) distributed by the central unit506to provide power for operations. For example, the downlink communications link528D may be a hybrid cable that includes electrical conductors and optical fibers. The OIMs522(1)-522(W) may also include O-E converters534(1)-534(W) to convert received uplink optical communications signals524U(1)-524U(X) from the remote units508(1)-508(X) into uplink electrical communications signals536U(1)-536U(S) as will be described in more detail below.

With continuing reference toFIG. 5, the remote units508(1)-508(X) are also configured to receive uplink electrical communications signals538U(1)-538U(X) received by the respective antennas532(1)-532(X) from client devices in wireless communication range of the remote units508(1)-508(X). The uplink electrical communications signals538U(1)-538U(X) may be analog signals or digital signals that can be sampled and processed as digital information. The remote units508(1)-508(X) include E-O converters540(1)-540(X) to convert the received uplink electrical communications signals538U(1)-538U(X) into the uplink optical communications signals524U(1)-524U(X). The remote units508(1)-508(X) distribute the uplink optical communications signals524U(1)-524U(X) over an uplink optical fiber communication link528U to the OIMs522(1)-522(W) in the central unit506. The O-E converters534(1)-534(W) convert the received uplink optical communications signals524U(1)-524U(X) into uplink electrical communications signals542U(1)-542U(X), which are processed by the RIMs518(1)-518(T) and provided as the uplink electrical communications signals542U(1)-542U(X) to a source transceiver such as a base transceiver station (BTS) or baseband unit (BBU).

Note that the downlink communications link528D and the uplink optical fiber communications link528U coupled between the central unit506and the remote units508(1)-508(X) may be a common optical fiber communications link, wherein for example, wave division multiplexing (WDM) may be employed to carry the downlink optical communications signals524D(1)-524D(S) and the uplink optical communications signals524U(1)-524U(X) on the same optical fiber communications link. Alternatively, the downlink communications link528D and the uplink optical fiber communications link528U coupled between the central unit506and the remote units508(1)-508(X) may be single, separate optical fiber communications link, wherein for example, wave division multiplexing (WDM) may be employed to carry the downlink optical communications signals524D(1)-524D(S) on one common downlink optical fiber and the uplink optical communications signals524U(1)-524U(X) carried on a separate, only uplink optical fiber. Alternatively, the downlink communications link528D and the uplink optical fiber communications link528U coupled between the central unit506and the remote units508(1)-508(X) may be separate optical fibers dedicated to and providing a separate communications link between the central unit506and each remote unit508(1)-508(X).

The DCS500inFIG. 5can be provided in an indoor environment as illustrated inFIG. 6.FIG. 6is a partially schematic cut-away diagram of a building infrastructure600employing the DCS500. With reference toFIG. 6, the building infrastructure600in this embodiment includes a first (ground) floor602(1), a second floor602(2), and a Fth floor602(F), where ‘F’ can represent any number of floors. The floors602(1)-602(F) are serviced by the central unit506to provide antenna coverage areas604in the building infrastructure600. The central unit506is communicatively coupled to a signal source606, such as a BTS or BBU, to receive the downlink electrical communications signals520D(1)-520D(S). The central unit506is communicatively coupled to the remote units508(1)-508(X) to receive the uplink optical communications signals524U(1)-524U(X) from the remote units508(1)-508(X) as previously described inFIG. 5. The downlink and uplink optical communications signals524D(1)-524D(S),524U(1)-524U(X) are distributed between the central unit506and the remote units508(1)-508(X) over a riser cable608in this example. The riser cable608may be routed through interconnect units (ICUs)610(1)-610(F) dedicated to each floor602(1)-602(F) for routing the downlink and uplink optical communications signals524D(1)-524D(S),524U(1)-524U(X) and power signals529(1)-529(X) to the remote units508(1)-508(X). The ICUs610(1)-610(F) may alternative include power distribution circuits612(1)-612(F) like the power distribution system504inFIG. 5that include power sources and are configured to distribute power remotely to their respective remote units508(1)-508(X) to provide power for operations. For example, array cables614(1)-614(F) may be provided and coupled between the ICUs610(1)-610(F) that contain both optical fibers to provide respective downlink and uplink optical fiber communications links528D(1)-528D(F),528U(1)-528U(F) and power conductors616(1)-616(F) (e.g., electrical wire) to carry current from the respective power distribution circuits612(1)-612(F) to the remote units508(1)-508(X).

FIG. 7is a schematic diagram of another DCS700in the form of a small cell radio access network (RAN)702that includes small cell radio access nodes704(1)-704(C) communicatively connected to an evolved packet core (EPC)706and Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)708arranged under Long Term Evolution (LTE) for a mobile telecommunications environment. The small cell RAN702includes a services node710that can include a power distribution system712configured to receive power from a power source714and distribute the received power over power conductors716to one or more small cell radio access nodes704(1)-704(C) for powering their operations, wherein the power distribution system712is further configured to distribute higher current demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for the power source in the power distribution system712. The power distribution system712may be, without limitation, the power distribution systems200,400,504inFIGS. 2, 4, and 5.

With reference toFIG. 7, the small cell RAN702forms an access network (i.e., an E-UTRAN under 3GPP. There is no centralized controller in the E-UTRAN708, hence an LTE network architecture is commonly said to be “flat.” Macrocells718(1)-718(M) are typically interconnected using an X2 interface720. The macrocells718(1)-718(M) are also typically connected to the EPC network702by means of an S1 interface722. More particularly, the macrocells718(1)-718(M) are connected to a Mobility Management Entity (MME)724in the EPC network706using an S1-MME interface726, and to a Serving Gateway (SGW)728using an S1-U interface730. An S5 interface732couples the SGW728to a Packet Data Network Gateway (PGW)734in the EPC network706to provide user mobile communications devices736with connectivity to the Internet738. A user mobile communications device736can connect to the small cell radio access nodes704(1)-704(C) in the small cell RAN702over an LTE-Uu interface739.

The macrocells718(1)-718(M) and the small cell RAN702are connected to the MME724and SGW728in the EPC network706using the appropriate S1 interface connections722. Accordingly, as each of the small cell radio access nodes704(1)-704(C) in the small cell RAN702is operatively coupled to the services node710over a LAN connection740, the communications connections from the small cell radio access nodes704(1)-704(C) are aggregated to the EPC network706. Such aggregation preserves the flat characteristics of the LTE network while reducing the number of S1 interface connections722that would otherwise be presented to the EPC network706. Thus, the small cell RAN702essentially appears as a single Evolved Node B (eNB)742to the EPC network706, as shown.

A user mobile communications device736will actively or passively monitor a cell in a macrocell718(1)-718(M) in the E-UTRAN708in the communications range of the user mobile communications device736as the user mobile communications device736moves throughout the small cell RAN702. Such a cell is termed the “serving cell.” For example, if user mobile communications device736is in communication through an established communications session with a particular small cell radio access node704(1)-704(C) in the small cell RAN702, the particular small cell radio access node704(1)-704(C) will be the serving cell to the user mobile communications device736, and the small cell RAN702will be the serving RAN. The user mobile communications device736will continually evaluate the quality of a serving cell as compared with that of a neighboring cell in the small cell RAN702. A neighboring cell is a cell among the small cell RAN702and the macrocells718(1)-718(M) that is not in control of the active communications session for a given user mobile communications device736, but is located in proximity to a serving cell to a user mobile communications device736such that the user mobile communications device736could be in communications range of both its serving cell and the neighboring cell. Both small cell radio access nodes704(1)-704(C) and the macrocells718(1)-718(M) can identify themselves to a user mobile communications device736using a respective unique Physical Cell Identity (PCI) and a public land mobile network (PLMN) identification (ID) (PLMN ID) that are transmitted over a downlink to the user mobile communications device736. Each of the small cell radio access nodes704(1)-704(C) and the macrocells718(1)-718(M) can assign a physical channel identity (PCI) that allows user mobile communications device736to distinguish adjacent cells.

FIG. 8is a schematic diagram representation of additional detail illustrating a computer system1200that could be employed in any component of a power distribution system configured to receive power from a power source and distribute the received power to one or more remote units for powering their operations, wherein the power distribution system is further configured to distribute higher current demanded by a power consuming load(s) exceeding overcurrent limits of a current limiter circuit for the power source in the power distribution system. The power distribution system may be, without limitation, the power distribution systems200,400,504,712inFIGS. 2, 4, 5 and 7. In this regard, the computer system1200is adapted to execute instructions from an exemplary computer-readable medium to perform these and/or any of the functions or processing described herein.

The computer system800inFIG. 8may include a set of instructions that may be executed to program and configure programmable digital signal processing circuits in a DCS for supporting scaling of supported communications services. The computer system800may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the term “device” shall also be taken to include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The computer system800may be a circuit or circuits included in an electronic board card, such as, a printed circuit board (PCB), a server, a personal computer, a desktop computer, a laptop computer, a personal digital assistant (PDA), a computing pad, a mobile device, or any other device, and may represent, for example, a server or a user's computer.

The exemplary computer system800in this embodiment includes a processing device or processor802, a main memory804(e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM), such as synchronous DRAM (SDRAM), etc.), and a static memory806(e.g., flash memory, static random access memory (SRAM), etc.), which may communicate with each other via a data bus808. Alternatively, the processor802may be connected to the main memory804and/or static memory806directly or via some other connectivity means. The processor802may be a controller, and the main memory804or static memory806may be any type of memory.

The processor802represents one or more general-purpose processing devices, such as a microprocessor, central processing unit, or the like. More particularly, the processor802may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or other processors implementing a combination of instruction sets. The processor802is configured to execute processing logic in instructions for performing the operations and steps discussed herein.

The computer system800may further include a network interface device810. The computer system800also may or may not include an input812, configured to receive input and selections to be communicated to the computer system800when executing instructions. The computer system800also may or may not include an output814, including but not limited to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device (e.g., a keyboard), and/or a cursor control device (e.g., a mouse).

The computer system800may or may not include a data storage device that includes instructions816stored in a computer-readable medium818. The instructions816may also reside, completely or at least partially, within the main memory804and/or within the processor802during execution thereof by the computer system800, the main memory804and the processor802also constituting computer-readable medium. The instructions816may further be transmitted or received over a network820via the network interface device810.

Unless specifically stated otherwise and as apparent from the previous discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing,” “computing,” “determining,” “displaying,” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data and memories represented as physical (electronic) quantities within the computer system's registers into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission, or display devices.

The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatuses to perform the required method steps. The required structure for a variety of these systems will appear from the description above. In addition, the embodiments described herein are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the embodiments as described herein.

It is also noted that the operational steps described in any of the exemplary embodiments herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actually be performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary embodiments may be combined. Those of skill in the art will also understand that information and signals may be represented using any of a variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips, that may be references throughout the above description, may be represented by voltages, currents, electromagnetic waves, magnetic fields, or particles, optical fields or particles, or any combination thereof.