APU Performance Modeling & Testing

       To verify the potential improvement made by installing an electronic speed governor, a mathematical model was developed. The model predicts the steady-state velocity of the HEV given a certain battery pack voltage. All of the power to the road is modeled as being drawn from the auxiliary power unit (APU). The development of this model allowed the velocity of the HEV to be compared at different engine speeds. The results were used in a proposal to demonstrate the improvements the speed governor would make to the HEV’s performance.

       Following the purchase and installation of the electronic speed governor, the APU was tested to verify the mathematical model. A load bank was used to vary the resistance and test for a full current range. The results are shown in graphs 1 and 2. As already predicted by the model, the ability to electronically govern the speed of the Kohler engine to 3600 rpm had a substantial effect on the maximum power output and the steady-state velocity that could be achieved by the HEV.

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