Isolated Power Supply System and Method For An Undersea Communication Cable

Abstract

An isolated power supply system for an undersea communication cable includes one or more power converters each including input circuitry responsive to an input current from a communication cable power conductor and in series with the communication cable power conductor of the undersea communication cable. One or more outputs are electrically isolated from the communication cable power conductor. A controller is coupled to each of the one or more power converters. The controller is configured to control the operation of the one or more power converters to provide the one or more outputs coupled to an external load located on a branch off of the undersea communication cable.

What is claimed is: 
     
         1 . An isolated power supply system for an undersea communication cable comprising:
 one or more power converters each including input circuitry responsive to an input current from a communication cable power conductor and in series with the communication cable power conductor of the undersea communication cable;   one or more outputs electrically isolated from the communication cable power conductor; and   a controller coupled to each of the one or more power converters, the controller configured to control the operation of the one or more power converters to provide the one or more outputs coupled to an external load located on a branch off of the undersea communication cable.   
     
     
         2 . The system of  claim 1  in which the one or more outputs includes one or more of: an output voltage, a programmable output voltage, a regulated DC output voltage, an output current, a programmable output current, and a desired regulated DC current. 
     
     
         3 . The system of  claim 1  in which the input circuitry of each of the one or more power converters includes a plurality of sections configured to divide the input voltage from the communication cable power conductor between the sections. 
     
     
         4 . The system of  claim 1  in which the controller is coupled to the input circuitry of each of the one or more power converters by magnetic isolation. 
     
     
         5 . The system of  claim 1  in which the controller is configured to control the operation of the input circuitry of each of the one or more power converters by pulse width modulation. 
     
     
         6 . The system of  claim 1  in which the one or more outputs are electrically isolated from the communication cable power conductor by an isolation transformer. 
     
     
         7 . The system of  claim 1  in which the input circuitry for each of the one or more converters includes a modulated converter followed by an inverter. 
     
     
         8 . The system of  claim 7  in which the inverter is configured to drive a transformer primary circuit including an isolation transformer, the transformer core, and a capacitor to allow switches of the inverter to open at low currents. 
     
     
         9 . The system of  claim 8  in which the inverter includes a square wave inverter. 
     
     
         10 . The system of  claim 8  in which the transformer core is gapped to allow switches of the inverter to close at zero voltage. 
     
     
         11 . The system of claim of  claim 1  in which the input circuitry of each of the one or more power converters includes a bypass capacitor. 
     
     
         12 . The system of  claim 7  in which the modulator converter includes one or more controllable switches and the inverter includes one or more controllable switches. 
     
     
         13 . The system of  claim 12  in which the controller is coupled to the one or more controllable switches of the inverter, an arbitrary and dynamically changing external load impedance located on the branch of the undersea communication cable, the controller configured to measure the input current communication cable power conductor, a regulated DC voltage output by the modulated converter, a desired regulated DC output voltage, a desired regulated DC current, and an external load impedance and configured to determine and adjust the duty cycle of switching of the controllable switches of the modulated converter and the inverter such that the desired regulated DC output voltage and/or the desired regulated DC current is provided to the external load impedance. 
     
     
         14 . The system of  claim 13  in which the switching of the controllable switches by the controller includes pulse width modulation. 
     
     
         15 . The system of  claim 12  in which the controllable switches of the modulated converter and the inverter includes one or more of: field effect transistors, silicon carbide metal oxide, field effect transistors (MOSFETs), insulated gate bi-polar transistors (IGBTs), field effect transistor controlled Thyristors (MCTs), gate runoff Thyristors (GTO), and power Darlingtons. 
     
     
         16 . The system of  claim 1  further including a voltage regulator coupled to the one or more power converters and the controller configured to provide power to the one or more power converters and the controller. 
     
     
         17 . The system of  claim 1  in which the one or more power converters includes a plurality of power converters. 
     
     
         18 . The system of  claim 1  in which the branching unit is housed in a pressure vessel. 
     
     
         19 . The system of  claim 2  in which the input circuitry and each of the one or more power converters includes an isolated variable DC-DC transformer circuit. 
     
     
         20 . The system of  claim 19  in which the controller is configured to control the operation of the variable DC-DC transformer circuit to provide current limiting. 
     
     
         21 . The system of  claim 19  in which the controller is configured to control the operation of the variable DC-DC transformer circuit to provide the output current. 
     
     
         22 . The system of  claim 19  in which the controller is configured to control the operation of the variable DC-DC transformer circuit to provide voltage limiting. 
     
     
         23 . The system of  claim 22  in which the controller is configured to control the operation of the variable DC-DC transformer circuit to provide the output voltage. 
     
     
         24 . The system of  claim 19  in which the isolated DC-DC transformer circuit includes a programmable voltage regulator. 
     
     
         25 . The system of  claim 19  in which the controller is configured to control the operation of the isolated DC-DC transformer circuit to provide power to the branch off the undersea communication cable. 
     
     
         26 . The system of  claim 19  in which the controller is configured to control the operation of the isolated DC-DC transformer circuit to provide power to a load off the undersea communication cable. 
     
     
         27 . The system of  claim 1  further including a fault protection circuit coupled to the communication cable power conductor and the isolated DC-DC transformer circuit configured to bypass fault current around the input circuitry of one or more power converters. 
     
     
         28 . The system of  claim 19  further including an output voltage clamp coupled to the isolated DC-DC transformer circuit and the communication cable power conductor configured to limit the output voltage to a maximum desired output voltage. 
     
     
         29 . The system of  claim 19  in which the output voltage clamp includes a controllable switch and a diode. 
     
     
         30 . The system of  claim 29  in which the maximum desired output voltage is about 10 V when the controller is not energized. 
     
     
         31 . The system of  claim 19  in which the input circuitry includes a current divider coupled between the communication cable power conductor and the isolated DC-DC transformer circuit configured to direct a &action of the input current to the isolated DC-DC transformer circuit. 
     
     
         32 . The system of  claim 19  in which the current divider is configured as a boost regulator including one or more of a diode, an inductor, a controllable switch, and an isolated gate driver circuit. 
     
     
         33 . The system of  claim 19  in which the controller is configured to control the input circuitry and the one or more outputs by pulse width modulation. 
     
     
         34 . The system of  claim 19  in which the controller is configured to provide a large DC ripple current for toning. 
     
     
         35 . A method for providing isolated power from a current carrying undersea communication cable to a branch located off the undersea communication cable, the method comprising:
 providing one or more power converters each including input circuitry responsive to input current from an undersea communication cable power conductor;   providing one or more outputs electrically isolated from the communication power conductor; and   controlling the operation of the one or more power converters to output the one or more outputs coupled to an external load located off a branch of the undersea communication cable.   
     
     
         36 . The method of  claim 35  in which the controlling including controlling the operation of the variable DC-DC transformer circuit to provide current limiting. 
     
     
         37 . The method of  claim 35  in which the controlling includes controlling the operation of the variable DC-DC transformer circuit to provide the output current. 
     
     
         38 . The method of  claim 35  in which the controlling includes controlling the operation of the variable DC-DC transformer circuit to provide voltage limiting. 
     
     
         39 . The method of  claim 35  in which the controlling includes controlling the operation of the variable DC-DC transformer circuit to provide the output voltage. 
     
     
         40 . The method of  claim 35  in which the controlling includes controlling the operation of the isolated DC-DC transformer circuit to provide power to the branch off the undersea communication cable. 
     
     
         41 . The method of  claim 35  in which the controlling includes controlling the operation of the isolated DC-DC transformer circuit to provide power to a load off the undersea communication cable. 
     
     
         42 . The method of  claim 35  further including providing a fault protection circuit coupled to the communication cable power conductor and the isolated DC-DC transformer circuit configured to bypass fault current around the input circuitry of one or more power converters. 
     
     
         43 . The method of  claim 35  further including providing an output voltage clamp coupled to the isolated DC-DC transformer circuit and the communication cable power conductor configured to limit the output voltage to a maximum desired output voltage. 
     
     
         44 . The method of  claim 35  in which the input circuitry includes a current divider coupled between the communication cable power conductor and the isolated DC-DC transformer circuit configured to direct a fraction of the input current to the isolated DC-DC transformer circuit. 
     
     
         45 . The method of  claim 35  in which the controlling includes controlling the input circuitry and the one or more outputs by pulse width modulation.