DC Motor Selection for Hybrid and Electric Vehicles Using an Infinitely Variable Transmission
Demand for more fuel efficient and less polluting vehicles has motivated development of the electric and hybrid power-trains. Unfortunately, some components used in these vehicles are expensive and complex. This research summarizes DC motor types, DC speed control methods and the use of an Infinitely Variable Transmission (IVT) to reduce the cost of the vehicle. A safe, low cost and repeatable laboratory setup was designed and documented for educational use. Motor testing revealed that field weakening can be a low-cost speed-control method but has limited range of control and must be supplemented. Additionally it was determined that a mechanical differential can be used as an IVT by varying the speed of the input motors. An innovative concept is presented using one DC motor as a power or traction motor, while another motor acts as a vehicle speed controller. This concept eliminates the need for expensive complex AC motor controllers, improves safety and efficiency, and reduces battery management requirements by lowering the operating voltage of the system.