ULTRACAPACITOR MODULE WITH ACTIVE CAPACITOR CELL VOLTAGE CONTROL

An ultracapacitor module includes an ultracapacitor cell stack containing ultracapacitor cells connected in series and a bidirectional boost/buck DC/DC converter. The cell stack and the converter are configured to be connected in series with a voltage bus of a vehicle. The ultracapacitor module includes voltage sensors configured to determine a voltage value of each ultracapacitor cell. The ultracapacitor module includes electronically controlled switches connected in series with a bleed resistor. The electronically controlled switches and bleed resistors are connected in parallel with each of the ultracapacitor cells. The ultracapacitor module includes an electronic controller that communicates with the converter, the voltage sensors, and the switches. The electronic controller is configured to determine the voltage of each ultracapacitor cell via the voltage sensors and operate the switches to selectively discharge at least one of the ultracapacitor cells to bring the voltage of the discharged ultracapacitor cell closer to one of the other ultracapacitor cells.