Systems and methods for synchronizing subunits in a multi-unit power distribution network

Abstract

Systems and methods for synchronizing subunits a multi-unit power distribution network contemplate selectively opening and closing a switch at the power source to disconnect and reconnect the power source to power conductors to send a synchronization signal to one or more remote subunits. Once the remote subunits are synchronized and able to disconnect from the power conductors, leak detection at the power source may be enabled to detect inadvertent loads on the power conductors (e.g., a human touching the power conductors). Further, the remote subunits may power off and on based on the synchronization signal thereby ensuring that an end device may receive power concurrently from multiple remote subunits so as to meet the power requirements of the end device. Enabling the leak detection improves the safety features of the power distribution network and synchronized power delivery to the end device prevents improper shut downs.

What is claimed is: 
     
         1 . A method comprising:
 at a remote subunit, opening a switch to disconnect a load from a power conductor;   closing the switch to connect the load to the power conductor and receive a power signal therefrom;   detecting a first synchronization signal comprising a periodic voltage drop in the power signal; and   synchronizing opening the switch to the first synchronization signal.   
     
     
         2 . The method of  claim 1 , further comprising receiving a second synchronization signal having a frequency lower than the first synchronization signal. 
     
     
         3 . The method of  claim 2 , further comprising resetting an output port configured to be coupled to an end device based on the second synchronization signal. 
     
     
         4 . The method of  claim 1 , further comprising providing power from the remote subunit to a second cascaded remote subunit. 
     
     
         5 . A distributed communication system (DCS), comprising:
 a central unit configured to:
 distribute received one or more downlink communications signals over one or more downlink communications links to one or more remote subunits; and 
 distribute received one or more uplink communications signals from the one or more remote subunits from one or more uplink communications links to one or more source communications outputs; 
   a plurality of remote subunits, each remote subunit among the plurality of remote subunits comprising:
 a power input port configured to be coupled to a power conductor and receive a power signal from a power source therefrom; 
 a switch coupled to the power input port; 
 a first power output port configured to be coupled to a second power conductor to provide power from the remote subunit to a second cascaded remote subunit; and 
 a controller circuit configured to:
 detect a first synchronization signal comprising a periodic voltage drop in the power signal and time opening and closing of the switch based on the first synchronization signal; 
 
 the remote subunit configured to:
 distribute the received one or more downlink communications signals received from the one or more downlink communications links to one or more client devices; and 
 distribute the received one or more uplink communications signals from the one or more client devices to the one or more uplink communications links; and 
 
   a power distribution system comprising:
 one or more power distribution circuits each comprising:
 a distribution power input configured to receive current distributed by the power source; 
 a distribution power output configured to distribute the received current over a power conductor coupled to an assigned remote unit among the plurality of remote subunits;
 a distribution switch circuit coupled between the distribution power input and the distribution power output, the distribution switch circuit comprising a distribution switch control input configured to receive a distribution power connection control signal indicating a distribution power connection mode; 
 the distribution switch circuit configured to be closed to couple the distribution power input to the distribution power output in response to the distribution power connection mode indicating a distribution power connect state; and 
 the distribution switch circuit further configured to be opened to decouple the distribution power input from the distribution power output in response to the distribution power connection mode indicating a distribution power disconnect state; and 
 
 a current measurement circuit coupled to the distribution power output and comprising a current measurement output;
 the current measurement circuit configured to measure a current at the distribution power output and generate a current measurement on the current measurement output based on the measured current at the distribution power output; and 
 
 
 a controller circuit comprising:
 one or more current measurement inputs communicatively coupled to the one or more current measurement outputs of the one or more current measurement circuits of the one or more power distribution circuits; 
 the controller circuit configured to, for a power distribution circuit among the one or more power distribution circuits:
 generate the distribution power connection control signal indicating the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power connect state; 
 determine if the measured current on a current measurement input among the one or more current measurement inputs of the power distribution circuit exceeds a predefined threshold current level; and 
 in response to the measured current of the power distribution circuit exceeding the predefined threshold current level: 
 
 communicate the distribution power connection control signal comprising the distribution power connection mode to the distribution switch control input of the power distribution circuit indicating the distribution power disconnect state. 
 
   
     
     
         6 . The DCS of  claim 5 , wherein the controller circuit of the power distribution system is further configured to:
 lower a voltage level on the distribution power output from a first voltage level to a second voltage level distributing the received current over the power conductor coupled to the assigned remote unit;   raise the voltage level on the distribution power output from the second voltage level to the first voltage level distributing the received current over the power conductor coupled to the assigned remote unit; and   determine if the measured current on the current measurement input among the one or more current measurement inputs of the power distribution circuit exceeds the predefined threshold current level when the distribution switch circuit is closed to couple the distribution power input to the distribution power output in response to the raising of the voltage level on the distribution power output.   
     
     
         7 . The DCS of  claim 5 , wherein the central unit is configured to:
 distribute each of the received one or more downlink communications signals over a distribution communications output among a plurality of distribution communications outputs to a downlink communications link among the one or more downlink communications links; and   distribute each of the received one or more uplink communications signals from an uplink communications link among the one or more uplink communications links on a distribution communications input among a plurality of distribution communications inputs to the one or more source communications outputs.   
     
     
         8 . The DCS of  claim 5 , comprising a distributed antenna system (DAS). 
     
     
         9 . The DCS of  claim 5 , wherein:
 the one or more downlink communications links comprise one or more optical downlink communications links;   the one or more uplink communications links comprise one or more optical uplink communications links;   the central unit further comprises:
 one or more electrical-to-optical (E-O) converters configured to convert received one or more electrical downlink communications signals into one or more optical downlink communications signals; and 
 one or more optical-to-electrical (O-E) converters configured to convert received one or more optical uplink communications signals into one or more electrical uplink communications signals; 
   the central unit is further configured to:
 distribute the one or more optical downlink communications signals from the one or more E-O converters over a plurality of optical distribution communications outputs to the one or more optical downlink communications links; and 
 distribute the received one or more optical uplink communications signals from the one or more optical uplink communications links on a plurality of optical distribution communications inputs to the one or more O-E converters; 
   wherein each remote subunit among the plurality of remote subunits further comprises:
 one or more O-E converters configured to convert the received one or more optical downlink communications signals into one or more electrical downlink communications signals; 
 one or more E-O converters configured to convert the received one or more electrical uplink communications signals into one or more optical uplink communications signals; and 
   each remote subunit among the plurality of remote subunits is configured to:
 distribute the one or more electrical downlink communications signals from the one or more O-E converters to the one or more client devices; and 
 distribute the one or more optical uplink communications signals from the one or more E-O converters to the one or more optical downlink communications links. 
   
     
     
         10 . The DCS of  claim 5 , comprising a small cell system. 
     
     
         11 . The DCS of  claim 5 , wherein the remote subunit comprises a remote unit.