An Enhanced Dynamic Battery Model of Lead-Acid Batteries Using Manufacturers´ Data

Modeling and simulation of lead acid batteries is of utmost importance for transportation systems such as hybrid and electric vehicles, golf carts, electric scooters, and wheelchairs; and for battery backup systems such as UPS for computers and telecommunication systems. Considerable effort is put into the selection of the appropriate battery with specific regard to the battery´s state of charge (SOC) and battery reserve time during the discharge profile for the various loading conditions expected. The new enhanced model has increased accuracy; it includes voltage, current, and power monitoring functions and further permits modeling of the cycle-by-cycle charge/discharge characteristics which is imperative for regenerative applications. Furthermore, the operating features of this enhanced battery model are demonstrated for two regenerative simulations. The new battery model is interfaced to a full-bridge, bi-directional, PWM controller with bi-polar voltage switching. The load is a DC motor model with motor parameters such as load torque, viscous torque and inertia. The power converter/DC motor system presents bidirectional power flow to the battery model. The purpose of the first simulation is to demonstrate real-world operation of the battery model including regeneration. A second simulation has an ultra-capacitor bank connected across the battery terminals to compare the battery model charge/discharge parameters such as voltage, current and power when the ultra-capacitor bank is absent and when present in the system