High-speed capacitor leakage measurement systems and methods

Abstract

Systems and methods according to aspects of the present invention are described. The systems and methods enable charging, soaking, and measuring of capacitors to be conducted quickly. Charging and soaking typically occurs in parallel and certain embodiments facilitate the measuring of capacitor leakage by sequentially disconnecting each capacitor and measuring the time for voltage on the capacitor to reach a predetermined threshold. Further, all capacitors can be disconnected from a charging source simultaneously and voltages can be measured for each capacitor simultaneously. Monitoring can be periodic in nature. Substantial time savings in the calculation device of leakage values and parameters can be attained.

1 . A method for measuring capacitor leakage comprising:
 accessing a list of plurality of capacitors;   providing a charging current to the plurality of capacitors, wherein the current charges and soaks the plurality of capacitors;   selecting first and second capacitors from the plurality of capacitors;   disconnecting the charging current from the first and second selected capacitors;   connecting the first and second selected capacitors to a voltage sensor;   measuring first and second voltages of the first and second selected capacitors;   comparing first and second measured voltages of the first and second selected capacitors to a predetermined threshold voltage;   determining whether first and second measured voltages of the first and second selected capacitors have crossed the predetermined threshold voltage; and   adjusting the list of the plurality of capacitors as a function of determining whether first and second measured voltages of the first and second capacitors have crossed the predetermined threshold voltage.   
   
   
       2 . A method according to  claim 1 , wherein the step of disconnecting is performed simultaneously for all of the plurality of capacitors. 
   
   
       3 . A method according to  claim 1 , wherein the step of disconnecting is performed simultaneously for the first selected capacitor and the second selected capacitor. 
   
   
       4 . A method according to  claim 3 , wherein the step of determining is performed simultaneously for the first selected capacitor and the second selected capacitor. 
   
   
       5 . (canceled) 
   
   
       6 . A method according to  claim 5 , wherein the first and second selected capacitors are disconnected from the voltage sensor after voltage of the first and second selected capacitors are measured. 
   
   
       7 . A method according to  claim 6 , wherein voltages on each of the first and second selected capacitors are measured periodically until a corresponding time required to discharge the first and second selected capacitors has been determined. 
   
   
       8 . A method according to  claim 1 , wherein the step of adjusting comprises removing at least one of the first capacitor and the second capacitor from the list. 
   
   
       9 . A method according to  claim 1 , wherein the steps of disconnecting and determining are repeated for the second selected capacitor after the time to discharge the first selected capacitor is determined. 
   
   
       10 . A method according to  claim 1 , and further comprising calculating leakage values for the first and second capacitors as a function of time. 
   
   
       11 . A system for measuring capacitor leakage comprising:
 a plurality of charging switches, each charging switch controlling connection of one of a plurality of capacitors to a charging source;   a plurality of sensing switches, each sensing switch controlling connection of one of the plurality of capacitors to a voltage sensing device;   a controller operative to control the plurality of charging switches and the plurality of sensing switches wherein the controller is configured to cause all of the plurality of capacitors to be charged and soaked simultaneously, connect selected ones of the plurality of capacitors to the voltage sensing device according to a programmed sequence based on a list of the plurality of capacitors, and for each step in the programmed sequence, provide a measurement of voltage on a capacitor currently connected to the sensing device and determine whether a capacitor should remain on the list based on the measurement; and   a computing device programmed to determine leakage values for each of the plurality of capacitors based on a measurement of time after each capacitor is disconnected from the charging source.   
   
   
       12 . The system of  claim 11 , wherein the plurality of charging switches is provided by a switch matrix. 
   
   
       13 . The system of  claim 11 , wherein the plurality of sensing switches is provided by a switch matrix. 
   
   
       14 . The system of  claim 11 , wherein the plurality of charging switches and the plurality of sensing switches are provided by a switch matrix. 
   
   
       15 . The system of  claim 11 , wherein all capacitors of the plurality of capacitors are simultaneously disconnected from the charging source. 
   
   
       16 . The system of  claim 15 , wherein the controller is further configured to connect each of the plurality of capacitors to the sensing device periodically. 
   
   
       17 . The system of  claim 11 , wherein the controller is further configured to disconnect each of the plurality of capacitors from the sensing device sequentially. 
   
   
       18 - 20 . (canceled) 
   
   
       21 . A method for measuring capacitor leakage comprising:
 applying a current to a plurality of capacitors simultaneously, the current being applied for sufficient time to charge and soak each of the plurality of capacitors;   recording for each of the plurality of capacitors a first voltage obtained as a result of charging and soaking each of the plurality of capacitors;   discharging separately and simultaneously the plurality of capacitors;   after a predetermined period, measuring successively a second voltage for each of the plurality of capacitors as the plurality of capacitors discharges;   recording the second voltage and time duration, as measured from the start of the separate and simultaneous discharge of the plurality of capacitors; and   determining from the first and second voltages whether the capacitor leakage of a particular capacitor of the plurality of capacitors has reached a predetermined threshold value.