Double-tiered capacitive shuttling method for balancing series-connected batteries

The auto industry is progressing towards hybrid and fully electric vehicles in their future car models. These vehicles need a power plant that is reliable during the lifetime of the car. Battery, capacity imbalances stemming from the cell manufacturer, ensuing driving environment, and operational usage affect voltage levels, which must follow adherence to strict limits to ensure the safety of the driver. A variation on an existing method of using a capacitor to shuttle charge from one battery to another to balance series strings of batteries is proposed in this paper. The advancement shown in this paper is to bridge every two balancing capacitors with an additional capacitor, allowing for a balance time that is drastically reduced when compared to the original method. Simulation using an idealized model shows a substantial improvement in balancing time using the new topology.