Patent Publication Number: US-2006001398-A1

Title: Fuel cell-based charger for computer system

Description:
BACKGROUND  
      The usefulness of a mobile computing system often depends on how long the system can operate without being connected to a stationary power source, such as an AC outlet. Designers of mobile computing systems attempt to extend the length of this period by optimizing the power consumption of such systems. Since such mobile operation requires an attached, mobile power source, the period may also be lengthened by improving conventional or developing new mobile power sources.  
      Fuel cells have been proposed as one promising mobile power source. More particularly, a system consisting of one or more fuel cells, fuel, control elements and processing/delivery elements might provide mobile and renewable power to a mobile computing system. However, conventional mobile computing systems and fuel cell systems are not equipped for efficient interoperation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram of a system according to some embodiments.  
       FIG. 2  is a block diagram of a fuel cell system according to some embodiments.  
       FIG. 3  is a block diagram of a system charger voltage regulator according to some embodiments.  
       FIG. 4  is diagram of a process according to some embodiments.  
       FIG. 5  is a block diagram of a system according to some embodiments.  
       FIG. 6  is a block diagram of a system charger voltage regulator according to some embodiments.  
       FIG. 7  is diagram of a process according to some embodiments.  
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a block diagram of system  10  according to some embodiments. System  10  comprises mobile computing system  100 , fuel cell system  200 , and interface  300 . Mobile computing system  100  may comprise a notebook computer, a telephone, a personal digital assistant, a digital camera, a tablet PC, any system including electrical hardware and requiring a power source, and a system including any combination of the foregoing. Some embodiments will described below in the context of a notebook computer.  
      Mobile computing system  100  is configured to consume power provided by battery pack  110  and battery pack  120 . Battery pack  110  and battery pack  120  may be charged using current sense resistor  130 , and the battery power is delivered using decoupling capacitor  140 . Some embodiments include only one or more than two battery packs. As shown, the battery power is provided to and consumed by DC/DC converters and system loads  150 , which may include the primary functional elements (e.g., processor, hard drives, memory circuits) of mobile computing system  100 . Other arrangements may be employed in some embodiments.  
      Mobile computing system  100  may also receive power from system charger voltage regulator (VR)  210  of fuel cell system  200 . System charger VR  210  may convert fuel cell-generated power from a first voltage (and/or current) level to a second voltage (and/or current) level. According to some examples, the power is converted and output by system charger VR  210  at 8.7 to 12.6V. The power may be received by DC/DC converters  150 , which may then convert the power to different voltage levels suitable for use by various system loads  160  (e.g., 5V, 3.3V, 1V).  
      System charger VR  210  may also operate to selectively charge battery packs  110  and  120 . Battery packs  110  and  120  may comprise one or more of any currently- or hereafter-known rechargeable battery types suitable for use with mobile computing system  100 . These battery types may include, but are not limited to, Li-Ion, NiMH, Zn-Air, Li-Polymer, and Ag-ZN battery types. One or both of battery packs  110  and  120  may be mounted in a device-bay slot, a dedicated battery pack slot, and/or an external pack of mobile computing system  100 . Resistor  130  may be used in this regard as a current-sensing resistor to detect and control the voltage and current levels of charging power supplied to battery packs  110  and  120 .  
      The ability of system charger VR  210  to regulate fuel cell-generated power and to charge one or both of battery packs  110  and  120  with the regulated power may be advantageous, for example, in a case that mobile computing system  100  does not include a system charger VR having similar functionality. In some embodiments, however, mobile computing system  100  includes a system charger VR to regulate received power for system loads and to charge one or both of battery packs  110  and  120  with the regulated power. Details of system charger VR  210  according to some embodiments will be described with respect to  FIG. 3 .  
      Mobile computing system  100  further comprises system management controller  160 . In some embodiments, system management controller  160  provides low-level control over some aspects of system  100 . Such control may comprise input device control and control over a power consumption mode of system  100 . System management controller  160  may communicate with and/or control battery packs  110  and  120 , and DC/DC converters and system loads  150  via a system management bus (SMBus) in accordance with System Management Bus (SMBus) Specification, ver. 2.0, Aug. 3, 2000, ©2000 SBS Implementers Forum.  
      System management controller  160  may receive data from fuel cell system  200 . System management controller  160  may also or alternatively transmit data to fuel cell system  200  in some embodiments. As illustrated in  FIG. 1 , this data may be received and transmitted independently from the power received from system charger VR  210 . According to some embodiments, mobile computing system  100  receives a single signal that transmits both the data and the power using currently- or hereafter-known power line data transmission techniques.  
      The data received from fuel cell system  200  may indicate a presence of fuel cell system  200 . Such a feature may allow fuel cell system  200  to provide a smaller initial voltage to mobile computing system  100  than is otherwise required by some mobile computing systems. Specifically, a conventional mobile computing system may include a connector for receiving power from an external AC/DC adapter. The computing system holds the connector at a threshold voltage (e.g., 15VDC) that is lower than a supply voltage produced by a compatible external AC/DC adapter (e.g., 19VDC). The computing system therefore determines that an external AC/DC adapter is connected to the connector if it detects a voltage on the connector that is greater than the threshold voltage.  
      According to some embodiments, system management controller  160  transmits data to fuel cell system  200 . The data may indicate an amount of power that mobile computing system  100  desires from fuel cell system  200 . The data may be transmitted after controller  160  receives data from fuel cell system  200  indicating the presence of fuel cell system  200 .  
      Interface  300  may comprise any suitable physical coupling by which mobile computing system  100  may receive fuel cell system  200 . Interface  300  may comprise two or more components, with one or more components being located on each of system  100  and system  200 . In some embodiments, interface  300  is configured to removably couple mobile computing system  100  and fuel cell system  200  so that fuel cell system  200  may be swapped with another fuel cell system. Interface  300  may also include electrical connections for carrying one or more of the above-described signals and/or other signals between mobile computing system  100  and fuel cell system  200 .  
       FIG. 2  is a block diagram of fuel cell system  200  according to some embodiments. Fuel cell system  200  may transmit data and generated power to mobile computing system  100 . Some elements of fuel cell system  200  may comprise any currently- or hereafter-known system for converting chemical energy of a replenishable fuel source to electrical energy and for providing the electrical energy to a load.  
      Fuel cell system  200  according to the illustrated embodiment comprises system charger VR  210 , fuel cell stack  220 , fuel reservoir  230 , “balance of plant”  240 , and controller  250 . Each of elements  210  through  250  may be in communication with one or more of elements  210  through  250 .  
      Fuel cell stack  220  may comprise one or more fuel cells. According to some embodiments, fuel cell stack  220  comprises fifteen fuel cells connected in series to generate a voltage roughly equal to fifteen times the voltage generated by a single fuel cell. In some embodiments, each fuel cell generates electrical energy by stripping electrons from hydrogen, transmitting the electrons to an electrical circuit through an anode, transmitting the stripped hydrogen ions (H + ) to a cathode through a proton exchange membrane, receiving the electrons at the cathode, and recombining the received electrons with the stripped hydrogen ions (H + ) and with oxygen to produce water as exhaust. Many alternative implementations of the above process currently exist and will be created in the future. Elements of fuel cell stack  220  may vary across the alternative implementations, including but not limited to anode material, cathode material, catalyst used for the stripping and recombining procedures, and proton exchange membrane structure and composition.  
      Fuel reservoir  230  may comprise any currently- or hereafter-known fuel cell fuel reservoir. Fuel reservoir  230  stores fuel from which the hydrogen used to power fuel cell stack  220  is derived. Fuel reservoir  230  may be removable and replaced with a similar fuel reservoir once the fuel of fuel reservoir  230  is exhausted. In some embodiments, fuel reservoir  230  is refillable so the physical structure of fuel reservoir  230  need not be removed in order to replenish fuel cell system  200 .  
      Fuel reservoir  230  may store pure hydrogen, methanol, reformed methanol, ethanol, and/or any other currently- or hereafter-known fuel suitable for fuel cells. Fuel reservoir  230  may include elements for extracting hydrogen from the stored fuel and/or for monitoring an amount of fuel stored in fuel reservoir  230 .  
      Balance of plant  240  may comprise elements used to facilitate the fuel cell process. Depending on the particular implementation of fuel cell system  200 , such elements may comprise one or more of sensors, pumps, compressors, control valves, heat exchangers, hoses, blowers, control systems, a power conditioner, a fuel reformer, an inverter, and other elements.  
      Controller  250  provides electronic monitoring and control over one or more other elements of fuel cell system  200 . Controller  250  may comprise one or more integrated circuits, which may be preprogrammed and/or capable of executing program code received from an external source and/or an internal memory. Controller  250  may transmit data to and receive data from system management controller  160  according to some embodiments. The transmitted data may indicate a presence of fuel cell system  200  and the received data may indicate an amount of power that mobile computing system  100  desires from fuel cell system  200 .  
      As described above, system charger VR  210  may receive power from balance of plant  240  at a first voltage (and/or current) level and generate regulated power having a second voltage (and/or current) level. The power may be transmitted to DC/DC converters  150  and/or to battery packs  110  and  120  for charging thereof. System charger VR  210  may regulate the power based on varying loads and/or instructions received by controller  250  from system management controller  160 . According to some embodiments, system charger VR  210  receives electrical energy from balance of plant  240  and outputs regulated power based on signals received from controller  250 .  
       FIG. 3  is a block diagram of system charger VR  210  according to some embodiments. The arrangement of  FIG. 3  may be characterized as a Buck converter, although other characterizations and configurations may be employed in some embodiments.  
      System charger VR controller  212  may receive control signals from controller  250 . Based on the control signals, system charger VR controller  212  controls MOSFETs  214  to regulate power that is received from balance of plant  240 . As illustrated, the regulated power may be transmitted to loads  150  and to battery packs  110  and  120  through resistor  130 . According to some embodiments, controller  250  transmits the control signals to system charger VR controller  212  based on data received from system management controller  160  that indicates a desired amount of power.  
       FIG. 4  is a flow diagram of process  400 . Process  400  illustrates procedures executed by mobile computing system  100  to utilize power from fuel cell system  200  according to some embodiments. Process  400  may be executed by any combination of discrete components, integrated circuits, and/or software.  
      Data indicating the presence of a fuel cell system is initially received at  401 . According to some examples, system management controller  160  receives the data from controller  250  of fuel cell system  200 . The data may comprise any data capable of indicating a presence of fuel cell system  200  to system management controller  160 .  
      Next, at  402 , data indicating a desired amount of power is then transmitted to the fuel cell system. System management controller  160  may transmit this data to controller  250  of fuel cell system  200 . Controller  250  may, in response, transmit control signals to system charger VR controller  212  in order to regulate power received from other elements of fuel cell system  200  and to output the regulated power to mobile computing system  100 .  
      The regulated power is received from the fuel cell system at  403 . The regulated power may be used for charging a local battery and for consumption by local system loads. In the present example, mobile computing system  100  receives the regulated power and the power is directed to DC/DC converters and system loads  150  as well as to battery packs  110  and  120 . Process  400  may therefore be useful at least in a case where mobile computing system  100  does not include elements to regulate received power for system loads and to charge a battery pack with the regulated power.  
       FIG. 5  is a block diagram of system  20  according to some embodiments. System  20  comprises fuel cell system  200  and interface  300  as described above and mobile computing device  1000 . System  20  may be used to execute process  400 . Except as noted below, the components of mobile computing device  1000  may be implemented and may function similarly to the identically-named components of mobile computing device  100  of  FIG. 1 .  
      Mobile computing device  1000  includes system charger VR  1700 . System charger VR  1700  may receive regulated power from system charger VR  210  of fuel cell system  200 , regulated the received power, transmit the regulated power to DC/DC converters and system loads  1500 , and charge battery packs  1100  and  1200  with the regulated power. System charger VR  1700  may include a circuit controllable to deactivate system charger VR  1700  and to pass the regulated power received from fuel cell system  200  to system loads  1500  and/or to battery packs  1100  and  1200 .  
      System management controller  1600  may communicate with and/or control system charger VR  1700 , battery packs  1100  and  1200 , and DC/DC converters and system loads  1500  via an SMBus. System management controller  1600  may control system charger VR  1700  to pass the regulated power received from fuel cell system  200  to system loads  1500  and/or to battery packs  1100  and  1200 .  
       FIG. 6  is a block diagram of system charger VR  1700  according to some embodiments. System charger VR  1700  of  FIG. 6  includes system charger VR controller  1710  and MOSFETs  1720 . As shown, system charger VR controller  1710  may deliver control signals to MOSFETs  1720  to regulate power received from system charger VR  210  of fuel cell system  200 . The regulated power may then be delivered to system loads  1500  and/or to battery packs  1100  and  1200 .  
      System charger VR controller  1710  may receive an instruction from system management controller  1600  via an SMBus. According to some embodiments, the instruction may instruct controller  1710  to “deactivate” system charger VR  1700  in order to pass regulated power received from system charger VR  210  to system loads  1500  and/or to battery packs  1100  and  1200 . In response, system charger VR controller  1710  may transmit signals to turn on its p-channel MOSFET and turn off its n-channel MOSFET. Any regulated power received from system charger VR  210  is thereby passed to system loads  1500  and to battery packs  1100  and  1200 .  
       FIG. 7  is a flow diagram of process  700 . Process  700  illustrates procedures executed by mobile computing system  1000  to utilize power from fuel cell system  200  according to some embodiments. Process  700  may be executed by any combination of discrete components, integrated circuits, and/or software.  
      Initially, at  701 , data indicating the presence of a fuel cell system is received. System management controller  1600  may receive the data from controller  250  of fuel cell system  200 . The data may comprise any data capable of indicating a presence of fuel cell system  200  to system management controller  1600 .  
      At  702 , data indicating a desired amount of power is then transmitted to the fuel cell system. System management controller  1600  may transmit this data to controller  250  of fuel cell system  200 . In response, controller  250  may transmit control signals to system charger VR controller  212  in order to regulate power received from other elements of fuel cell system  200  and to output the regulated power to mobile computing system  1000 .  
      The regulated power is received from the fuel cell system charger voltage regulator at  703 . Next, at  704 , it is determined whether to use system charger VR  1700  to regulate the received power. The determination at  704  may be performed by system management controller  1600 , and may be based on any factors, including but not limited to information regarding the operation of system  1000 . If the determination is positive, the received power is regulated at  705  by system charger VR  1700  and the thusly-regulated power is provided to DC/DC converters and local system loads  1500  and to battery packs  1100  and  1200 .  
      If the determination at  704  is negative, the local system charger is controlled at  706  to pass the power received from the fuel cell system charger VR to a local battery and to local system loads. According to some embodiments of  706 , system charger VR  1700  is deactivated as described with respect to  FIG. 6  so as to pass regulated power received from system charger VR  210  to DC/DC converters and system loads  1500  and/or to battery packs  1100  and  1200 .  
      The several embodiments described herein are solely for the purpose of illustration. Some embodiments may include any currently or hereafter-known versions of the elements described herein. Therefore, persons skilled in the art will recognize from this description that other embodiments may be practiced with various modifications and alterations.