Method of monitoring the internal impedance of an accumulator battery in an uninterruptible power supply, and an uninterruptible power supply
AssigneeFPS Power Systems OY AB
InventorLennart Jonsson
Life of this patent
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Abstract
A method of monitoring the internal impedance of an accumulator battery in an uninterruptible power supply, and a UPS. In accordance with the invention, during the discharge of the battery to the load, the load current induced by the load and passing through the battery is measured or calculated, and the corresponding AC voltage component obtained on the battery voltage is measured, the value for the internal impedance of the battery being calculated from these values. The obtained impedance value is compared to a predetermined reference value to determine the condition of the battery.
Claims11
A method of monitoring internal impedance of an accumulator battery in an uninterruptible power supply, said method comprising the steps of:
- determining a load current I.sub.L induced by a load connected to said battery and passing through said battery during discharge of said battery to said load;
- measuring a corresponding AC voltage component U.sub.R obtained on a battery voltage U.sub.BATT ;
- calculating a value of internal impedance Z.sub.B of said battery using said load current I.sub.L and said AC voltage component U.sub.R ;
- comparing said internal impedance value Z.sub.B with a predetermined reference value Z.sub.max ;
- and
- determining a condition of said battery in accordance with a result of said comparing step.
An uninterruptible power supply (UPS), comprising:
- a battery;
- an inverter connected between said battery and a load;
- a switch for selectively connecting said battery to said load;
- a charger connected to charge said battery;
- and
- a logic unit connected to control various control functions, wherein
- said logic unit monitors an internal impedance of said battery, determines a load current caused by said load and passing through said battery during a discharge of said battery to said load, measures a corresponding AC component of a battery voltage, calculates a value of internal impedance of said battery using said load current and said corresponding AC component and compares said internal impedance value to a predetermined reference value, a condition of said battery being determined on a basis of said comparison.
Dependencies are inferred from the claim text.