Abstract:
Some embodiments of the present invention provide a system that facilitates the operation of a supercapacitor. During operation, the system measures an electrical parameter of the supercapacitor using a set of conductor rings surrounding a capacitor seal of the supercapacitor. Next, the system determines the presence of a leak in the supercapacitor based on the electrical parameter. Finally, the system manages the operation of the supercapacitor based on the presence of the leak.

Description:
BACKGROUND 
     1. Field 
     The present embodiments relate to techniques for monitoring supercapacitors. More specifically, the present embodiments relate to a method and system for detecting and managing leaks in supercapacitors. 
     2. Related Art 
     Supercapacitors typically provide higher energy density than normal capacitors and a greater number of charge-discharge cycles than rechargeable batteries. For example, a supercapacitor may have a capacitance of several farads and may last through millions of charge-discharge cycles, compared with tens of millifarads for a comparably sized electrolytic capacitor and a few hundred charge-discharge cycles for a rechargeable battery. As a result, supercapacitors may be used in applications that bridge the gap between capacitors and batteries. For example, supercapacitors may be used in automotive systems as replacements for batteries in hybrid or electric cars. Along the same lines, a computer system may include supercapacitors to power the transfer of data from volatile memory to nonvolatile memory when the computer system is disconnected from a power source. 
     However, supercapacitors may be associated with a higher risk of fire than common capacitors. In particular, the increased energy density of a supercapacitor is often provided by a flammable electrolyte within the supercapacitor. If the electrolyte leaks from the supercapacitor, the electrolyte may ignite and cause a fire that damages components near the supercapacitor and/or the system containing the capacitor. For example, a supercapacitor may leak electrolyte onto a printed circuit board (PCB) in a computer system and create a short circuit that causes a fire in the computer system and in nearby computer systems. 
     Hence, what is needed is a mechanism for reducing the flammability risk associated with supercapacitors. 
     SUMMARY 
     Some embodiments of the present invention provide a system that facilitates the operation of a supercapacitor. During operation, the system measures an electrical parameter of the supercapacitor using a set of conductor rings surrounding a capacitor seal of the supercapacitor. Next, the system determines the presence of a leak in the supercapacitor based on the electrical parameter. Finally, the system manages the operation of the supercapacitor based on the presence of the leak. 
     In some embodiments, the supercapacitor is used within a computer system. 
     In some embodiments, determining the presence of the leak in the supercapacitor involves:
         (i) transmitting the electrical parameter to a leak-detection circuit coupled to the conductor rings;   (ii) providing the electrical parameter to a system controller in the computer system; and   (iii) analyzing the electrical parameter using the system controller.       

     In some embodiments, the electrical parameter is provided to the system controller using a system bus on the computer system. 
     In some embodiments, managing the operation of the supercapacitor based on the presence of the leak involves at least one of notifying a technician of the leak using the system controller and shutting down the computer system using the system controller. 
     In some embodiments, measuring the electrical parameter of the supercapacitor using the conductor rings involves measuring a first instance of the electrical parameter between an outer ring and a middle ring of the conductor rings and measuring a second instance of the electrical parameter between the middle ring and an inner ring of the conductor rings. 
     In some embodiments, the capacitor seal is larger than an outside diameter of the inner ring and smaller than an inside diameter of the outer ring. 
     In some embodiments, the first instance and the second instance of the electrical parameter are used to determine a direction of the leak from the supercapacitor. 
     In some embodiments, the electrical parameter corresponds to at least one of conductivity, capacitance, and resistance. 
     In some embodiments, the presence of the leak is associated with a change in the electrical parameter. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a computer system in accordance with an embodiment. 
         FIG. 2  shows a system for monitoring a supercapacitor in accordance with an embodiment. 
         FIG. 3  shows a flowchart illustrating the process of facilitating the operation of a supercapacitor in accordance with an embodiment. 
     
    
    
     In the figures, like reference numerals refer to the same figure elements. 
     DETAILED DESCRIPTION 
     The following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 
     The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. The computer-readable storage medium includes, but is not limited to, volatile memory, non-volatile memory, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or other media capable of storing code and/or data now known or later developed. 
     The methods and processes described in the detailed description section can be embodied as code and/or data, which can be stored in a computer-readable storage medium as described above. When a computer system reads and executes the code and/or data stored on the computer-readable storage medium, the computer system performs the methods and processes embodied as data structures and code and stored within the computer-readable storage medium. 
     Furthermore, methods and processes described herein can be included in hardware modules or apparatus. These modules or apparatus may include, but are not limited to, an application-specific integrated circuit (ASIC) chip, a field-programmable gate array (FPGA), a dedicated or shared processor that executes a particular software module or a piece of code at a particular time, and/or other programmable-logic devices now known or later developed. When the hardware modules or apparatus are activated, they perform the methods and processes included within them. 
     Embodiments provide a method and system for facilitating the operation of a supercapacitor. The supercapacitor may be used to provide power to components in a computer system (e.g., personal computer, server, workstation, etc.), portable electronic device, automotive system, and/or other system with electronic components. For example, the supercapacitor may be used in regenerative braking of a vehicle, or as a power source for a Real Time Clock (RTC) chip in an electronic device. 
     More specifically, embodiments provide a method and system for detecting and managing leaks in the supercapacitor. An electrical parameter corresponding to conductivity and/or capacitance may be measured from the supercapacitor using a set of conductor rings surrounding the capacitor seal of the supercapacitor. The presence of a leak in the supercapacitor may then be determined using the electrical parameter. In particular, a change in the electrical parameter may indicate a leak. The leak may then be managed by notifying a technician of the leak and/or by shutting down the system containing the leak. For example, a system controller in a computer system may manage a supercapacitor leak in the computer system by shutting down the computer system. 
       FIG. 1  shows a computer system  100  in accordance with an embodiment. As shown in  FIG. 1 , computer system  100  includes a number of supercapacitors  102 - 106 , three sets of conductor rings  112 - 116 , a leak-detection circuit  110 , a system controller  118 , and a system bus  124 . Each of these components is discussed in further detail below. 
     Supercapacitors  102 - 106  may provide energy to various components in computer system  100 . For example, supercapacitors  102 - 106  may provide power to a Real Time Clock (RTC) chip, nonvolatile memory, and/or one or more light-emitting diodes (LEDs) in computer system  100 . In addition, supercapacitors  102 - 106  may be used to facilitate the operation and/or maintenance of computer system  100 . For example, supercapacitors  102 - 106  may power the transfer of data from volatile memory to nonvolatile memory in computer system  100  if computer system  100  is disconnected from a power source. Along the same lines, supercapacitors  102 - 106  may illuminate LEDs next to failed components in computer system  100  during servicing of computer system  100 . In other words, supercapacitors  102 - 106  may be used in place of batteries and/or normal capacitors in computer system  100 . 
     Those skilled in the art will appreciate that supercapacitors  102 - 106  may be associated with a higher flammability risk than normal capacitors. In particular, each supercapacitor  102 - 106  may contain a flammable electrolyte that increases the energy density of the supercapacitor. If the electrolyte leaks from the supercapacitor, the electrolyte may slowly create a short circuit that starts a fire in computer system  100 . Alternatively, elevated temperatures inside computer system  100  may cause the electrolyte to leak from the supercapacitor and ignite instantaneously. 
     Fires that result from leaks in supercapacitors  102 - 106  may damage other components within computer system  100  and/or spread outside computer system  100 . For example, a fire caused by a leak in supercapacitor  102  may render computer system  100  inoperable and spread to other computer systems in the same data center as computer system  100 . Furthermore, haloalkane may be released within the data center to suppress the fire. As a result, fires caused by leaks in supercapacitors  102 - 106  may be costly with respect to both equipment damage caused by the fires and fire-extinguishing mechanisms used to put out the fires. 
     In one or more embodiments, computer system  100  includes functionality to detect and manage leaks in supercapacitors  102 - 106  before the leaks result in fires. As shown in  FIG. 1 , each supercapacitor  102 - 106  is monitored using a set of conductor rings  112 - 116  coupled to leak-detection circuit  110 . Leak-detection circuit  110  may use conductor rings  112 - 116  to measure an electrical parameter  108  from supercapacitors  102 - 106 . Each set of conductor rings  112 - 116  may surround the corresponding supercapacitor  102 - 106  and enable measurements of electrical parameter  108  as a capacitance and/or conductivity of the supercapacitor. Conductor rings  112 - 116  are discussed in further detail below with respect to  FIG. 2 . 
     After measuring electrical parameter  108  using conductor rings  112 - 116 , leak-detection circuit  110  may transmit the measurements to system controller  118  using system bus  124  (e.g., an Inter-Integrated Circuit (I 2 C) system bus). System controller  118  may be associated with and/or implemented using a service processor associated with computer system  100 . An analysis apparatus  120  within system controller  118  may analyze the measurements of electrical parameter  108  from leak-detection circuit  110  to determine the presence of leaks in each supercapacitor  102 - 106 . Alternatively, analysis apparatus  120  may be provided by leak-detection circuit  110 , which may transmit alerts to system controller  118  when leaks are detected in one or more supercapacitors  102 - 106  based on measurements of electrical parameter  108  obtained using conductor rings  112 - 116 . 
     As described above, electrical parameter  108  may correspond to conductivity and/or capacitance. As a result, an change in a measurement of electrical parameter  108  may indicate a leak in the supercapacitor (e.g., supercapacitors  102 - 106 ) from which the measurement is obtained. For example, conductor rings  114  may be used to measure electrical parameter  108  as a capacitance associated with supercapacitor  104 . Because the dielectric between conductor rings  114  includes air and/or printed circuit board (PCB) substrate, the capacitance of supercapacitor  104  under normal conditions may be measured as a relatively low value. However, if electrolyte with a high dielectric constant leaks from supercapacitor  104  and spreads between two or more conductor rings  112 , the measured capacitance may increase sharply. 
     In one or more embodiments, analysis apparatus  120  includes functionality to detect leaks in different types of supercapacitors based on measurements of electrical parameter  108  from each type of supercapacitor. For example, analysis apparatus  120  may include a threshold value for electrical parameter  108  for each type of supercapacitor in computer system  100 . If a measurement of electrical parameter  108  for a supercapacitor exceeds the threshold value for that type of supercapacitor, analysis apparatus  120  may determine that electrolyte has leaked from the supercapacitor. 
     In one or more embodiments, leaks in supercapacitors  102 - 106  detected by analysis apparatus  120  may be managed by a leak-management apparatus  122  in system controller  118 . For example, analysis apparatus  120  may observe a sharp change in electrical parameter  108  measured by conductor rings  112 . In response to the change, leak-management apparatus  122  may notify a technician of a leak in supercapacitor  102  and/or shut down computer system  100  to prevent the leak from starting a fire in computer system  100 . 
     Those skilled in the art will appreciate that functionality associated with detecting and managing leaks in supercapacitors  102 - 106  may be implemented in a variety of ways. As mentioned previously, analysis apparatus  120  may be provided by leak-detection circuit  110  and/or system controller  118 . Similarly, leak-detection circuit  110  may reside on the same PCB as supercapacitors  102 - 106 , or leak-detection circuit  110  may be placed on a separate plug-in board and/or a Peripheral Component Interconnect (PCI) card in computer system  100 . As a result, leak-detection circuit  110  may be coupled to conductor rings  112 - 116  using one or more vias, traces, and/or buses (e.g., system bus  124 ) within computer system  100 . Moreover, multiple leak-detection circuits may be used to monitor supercapacitors in computer system  100 . For example, different leak-detection circuits may be used to monitor supercapacitors in different parts of computer system  100 . 
     Those skilled in the art will also appreciate that leaks in supercapacitors outside computer system  100  may also be detected using one or more components in  FIG. 1 . For example, leak-detection circuit  110  and conductor rings  112 - 116  may be used to detect leaks in supercapacitors within automotive systems, portable electronic devices, avionics systems, and/or other systems with electronic components. 
       FIG. 2  shows a system for monitoring a supercapacitor  200  in accordance with an embodiment. As mentioned previously, supercapacitor  200  may be used to supply power within a computer system, automotive system, portable electronic device, and/or other system with electronic components. Supercapacitor  200  is mounted on a PCB  220  containing at least two layers  222 - 224 . A capacitor seal of supercapacitor  200  may contact PCB  220  along the perimeter of the bottom surface of supercapacitor  200 . As a result, electrolyte may leak from supercapacitor  200  through the capacitor seal directly onto PCB  220 . 
     A set of conductor rings surrounding the capacitor seal may be used to detect leaks in supercapacitor  200 . The conductor rings may correspond to exposed traces on PCB  220  and include an outer ring  202 , a middle ring  204 , and an inner ring  206 . As shown in  FIG. 2 , middle ring  204  is placed directly underneath the capacitor seal, while outer ring  202  is larger than the capacitor seal and inner ring  206  is smaller than the capacitor seal. 
     To assess the presence of leaks in supercapacitor  200 , an electrical parameter corresponding to capacitance and/or conductivity may be measured using outer ring  202 , middle ring  204 , and inner ring  206 , with middle ring  204  as the electrical ground. A first instance of the electrical parameter may be measured between outer ring  202  and middle ring  204 , and a second instance of the electrical parameter may be measured between middle ring  204  and inner ring  202 . 
     The first and second instances of the electrical parameter may be used to detect the direction of a leak in supercapacitor  200 . If the leak moves outward from the capacitor seal (e.g., away from supercapacitor  200  onto PCB  220 ), the first instance of the electrical parameter may change while the second instance may remain the same. On the other hand, if the leak moves inward (e.g., underneath supercapacitor  200  onto PCB  220 ), the second instance of the electrical parameter may change while the first instance may remain the same. Consequently, outer ring  202 , middle ring  204 , and/or inner ring  206  may be used to detect leaks in supercapacitor  200  regardless of the orientation of PCB  220  (e.g., vertical, horizontal, etc.). For example, an outward leak from the capacitor seal may be detected as an increase in the conductivity between outer ring  202  and middle ring  204 , or conversely as a decrease in the resistance between outer ring  202  and middle ring  204 . 
     Outer ring  202 , middle ring  204 , and inner ring  206  are connected to a set of traces  214 - 218  using a set of vias  208 - 212  in PCB  220 . Vias  208 - 212  and traces  214 - 218  may allow signals to be transmitted from outer ring  202 , middle ring  204 , and inner ring  206  to another component in PCB  220  and/or a component coupled to PCB  220 , such as a leak-detection circuit (e.g., leak-detection circuit  110  of  FIG. 1 ). In particular, vias  208 - 212  may connect the exposed traces of outer ring  202 , middle ring  204 , and inner ring  206  to traces  214 - 218  on the surface of layer  224  of PCB  220 . Alternatively, traces  214 - 218  may be placed on other layers of PCB  220  and/or on different layers of PCB  220 . Traces  214 - 218  may also connect to input pins on the component and/or to a bus that connects to the component. The component may thus measure the electrical parameter using differences in signals transmitted from outer ring  202 , middle ring  204 , and inner ring  206 . 
       FIG. 3  shows a flowchart illustrating the process of facilitating the operation of a supercapacitor in accordance with an embodiment. In one or more embodiments, one or more of the steps may be omitted, repeated, and/or performed in a different order. Accordingly, the specific arrangement of steps shown in  FIG. 3  should not be construed as limiting the scope of the technique. 
     Initially, an electrical parameter of the supercapacitor is measured using a set of conductor rings surrounding a capacitor seal (operation  302 ) of the supercapacitor. The electrical parameter may be measured as conductivity, capacitance, and/or resistance. The conductor rings may include an outer ring, middle ring, and inner ring disposed around the capacitor seal such that the capacitor seal is larger than an outside diameter of the inner ring and smaller than an inside diameter of the outer ring. 
     Next, the electrical parameter is transmitted to a leak-detection circuit coupled to the conductor rings (operation  304 ). The leak-detection circuit may obtain the electrical parameter as a difference in signals transmitted by pairs of the conductor rings. For example, the leak-detection circuit may measure a first instance of the electrical parameter between the outer ring and the middle ring and a second instance of the electrical parameter between the middle ring and the inner ring. 
     The electrical parameter is then provided to a system controller in a computer system (operation  306 ) containing the supercapacitor. For example, the electrical parameter may be transmitted from the leak-detection circuit to the system controller using a system bus in the computer system. Alternatively, the electrical parameter may be provided to a different controlling mechanism if the supercapacitor is used within an automotive system, a portable electronic device, an avionics system, and/or other system containing electrical components. 
     The system controller and/or controlling mechanism may analyze the electrical parameter (operation  308 ) to determine the presence of a leak (operation  310 ) in the supercapacitor. In particular, a leak may be detected as a change in the electrical parameter measured between a pair of conductor rings. For example, if a change is observed in the electrical parameter measured between the outer ring and the middle ring, a leak that moves outward from the capacitor seal may be detected. On the other hand, if a change is found in the electrical parameter measured between the middle ring and the inner ring, a leak that moves inward from the capacitor seal may be detected. As a result, the outer ring, middle ring, and inner ring may be used to determine the direction of the leak from the supercapacitor and may allow leaks to be detected regardless of the orientation of the supercapacitor. 
     If a leak is present, the operation of the supercapacitor is managed based on the leak (operation  312 ). For example, the system controller and/or controlling mechanism may notify a technician of the leak and/or shut down the system (e.g., computer system) containing the supercapacitor. If no leak is found, the supercapacitor may continue to be monitored (operation  314 ). If monitoring is to continue, the electrical parameter is measured from the supercapacitor using the conductor rings (operation  302 ), and the presence of a leak in the supercapacitor is determined based on the electrical parameter (operations  304 - 310 ). If a leak is found, the operation of the supercapacitor is managed based on the leak (operation  312 ). The supercapacitor may continue to be monitored (operation  314 ) until the supercapacitor is no longer used. Also, if it can be determined how much material leaks from the supercapacitor and if the amount of leakage exceeds a predetermined threshold value, the system controller can cause the computer system to shut down. 
     The foregoing descriptions of various embodiments have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention.