Our Project

The Power Dynamics Group was formed in mid August 2000. However, our choice for a design project was made in July 2000. It was determined that the team would design and build a 3-Stage Battery Charger.

The concept originated from the teamís interest in Gas Electric Hybrid Vehicles. The design was laid out in a manner such that upon completion, the battery charger would be easily up-scaled to an Electric Vehicle Charging System.

In simplicity, the Battery Charger is designed in 3 stages. In stage 1, the idea is to draw a very small current until the battery is 20% charged. In stage 2, the current is doubled, and is drawn until the battery is 90% charged. At this point, stage 3 takes over. In this stage, current is no longer applied. The battery itself is fed a constant voltage source. The battery itself draws as much current as necessary to fully charge to 100%.

The 3 stages were agreed upon due to the life of the battery being taken into consideration. Since the main goal was to up-scale this version to an EV charging system, conserving the life of the battery was a design factor. By utilizing 3 stages, this could be achieved. Unlike the common 2-stage system found in many household chargers, a 3-stage design does not fry the battery. By drawing current in stages, the sudden, high, current intake is avoided. The 3 stages input different amounts of current, for different periods of time, thus avoiding sudden, long periods of high current intake.

The use of a Comparator Logic Feedback Control was initially adopted as the most ideal, efficient and simplest solution. Unfortunately, due to time constraints, the group was unable to finish this part and manual switching was used for testing and demonstration purposes. However, the group did eventually implement a Comparator Logic Feedback Control after the poster presentation. Even though the charger did successfully switch between stages, the desired results were not obtained. As a result, after further research, the group decided to modify the switching mechanism and use a Programmable Integrated Circuit, or PIC to do the desired switching action.

As a result, the PIC method was held as the better alternative. Currently, the group is actively working on this part and hopes to have it implemented in the near future.

© Power Dynamics Group, 2001