Development of an air conditioning compressor for a 2-in-1 electric motor for electric vehicles
N. Satheesh Kumar
Date of Issue2017
Interdisciplinary Graduate School (IGS)
Energy Research Institute @ NTU
Electric Vehicles (EVs) are gaining popularity over gasoline powered vehicles due to its eco-friendly appeal. However, the market penetration of EVs is comparatively low, owing to its poor cruise range, cost and performance characteristics. Part of the reason for rapid battery drainage leading to poor cruise performance is due to the large electrical load contributed by the air-conditioning system. Data published by Mitsubishi Motors reveals that the air-conditioning system reduces the cruise-range of the EV by as much as 50% when operated at full capacity. Keeping this in focus, the objective of the present thesis is to design a new 2-in-1 motor electric motor for EVs that integrates the air-conditioning compressor, its motor and the traction motor in a single system. Thereafter the focus shifts to the design and development of a suitable compressing mechanism that suits the 2-in-1 motor design. The 2-in-1 motor uses a coaxial shaft to achieve concentric placement of the traction and compressor drives. This arrangement provides the flexibility of independent torque and speed control of the motor drives and enables the drivetrain to operate at six unique modes never before achieved in conventional drivetrain architecture. A simulation based study has been performed on the 2-in-1 motor drivetrain architecture and the analysis point that cruise range of EV can be improved by 3.2%. Based on the findings, it is evident that the integration of the air-conditioning compressor with the traction drive results in enhancing the energy capturing capacity of the regenerative braking mechanism and decreases the power consumed from the battery. Further, the integrated unit boosts other advantages such as reduced material cost, improved reliability, a compact and light weight design. The thesis also explores a new design variant of the fixed vane compressor. Significant reduction in re-expansion losses is the primary highlight of the newly designed compressor. Mathematical models of the conventional swing vane compressor and the new fixed vane compressor design are quantitatively assessed. The theoretical study shown that the new compressor is 6.2% more efficient than the conventional swing vane compressor. Following that, experimental investigations has been performed on the new fixed vane compressor design to validate the compressor models. In general, there is a close agreement between the predicted and experimental mechanical power requirements. In general, this research project shows that the 2-in-1 motor design is a practical solution that is expected to enhance the performance of EVs. In addition, the newly developed fixed vane compressor has the potential to outperform the existing state of the art rotary compressors.
DRNTU::Engineering::Mechanical engineering::Motor vehicles