Upon completion of our model and final data collection, we made some very key observations that would drive the next phase of this project (if another team were to resume our work).
- The gasoline engine is incredibly inefficient. Most road legal gasoline vehicles are only 25-35% efficient when used to power a car. Employing the gasoline engine adds more energy usage to the system as a whole.
- Employing too much of an engine can lead to large amounts of overshoot. This overshoot is unnecessary and wastes energy and therefore fuel.
- Adding more energy to the system when it doesn’t require it leads to faster transient response time and can be beneficial on energy consumption. The system uses more energy when it takes the vehicle longer to reach the desired velocity.
These observations are all reasonable but were less obvious to us before we began testing our model. We already had clear ideas on which engine type would be most useful for specific performance measures: electric for optimizing acceleration, gas usage for maintaining a cruise velocity. Overall we learned that continuous optimization in a transmission is difficult. There are many factors to consider and it’s not as simple of an answer as percent X electric and percent X gasoline. However, the system that we are attempting to design is more efficient than the current hybrid car on the market. We included more inputs into our system (road grade for example) that most commercial systems do not account for and results in lower energy consumption.