CHARGE BALANCING CIRCUIT FOR ULTRACAPACITORS AND LITHIUM BATTERIES

摘要

A device (10) for balancing the charge of a series connection of a first (11) and a second (12) rechargeable energy storage device, such as an ultracapacitor or lithium battery, is provided. The device for balancing comprises a voltage divider (R1, R2) comprising an output (104) for outputting half of the total voltage across the first and second energy storage devices. It further comprises a feedback connection providing a voltage feedback of the voltage (U11) across the first energy storage device and a circuit (U1) comprising a first input (105) coupled to the output of the voltage divider, a second input (106) coupled to the voltage feedback and an output (107) for outputting a signal in function of the difference between the first input and the second input. The output of said circuit is coupled to means for reducing a charge unbalance between the first and the second energy storage devices. The device for balancing further comprises a low-pass filter for limiting the bandwidth of said circuit.A method of reducing the charge unbalance between the two energy storage devices is also provided.