George DavisMechanical Engineering BEng
Design and Build of a Mobile Motor Test Bench for Electric Drivetrains
The following project details the investigation into the design and build of a test bench for high performance electric drivetrains. The scope of this study was to investigate the criteria needed to test high performance motors and from this, design and build a test bench to enable testing. The major aim of this dissertation project was to design & build a mobile test bench capable of testing high performance electric motors. The project involved two months of researching electric drivetrains and the inner components. Along side this research an iterative process of designing the test bench was achieved. This process focused on achieving the maximum features for the test bench. The iterative design process reached a conclusion from a Pugh's method of analysis and from the quantitative method clearly illustrating the final design, giving the best balance of features. Within the Pugh's method, the criteria were given a weighting in order of importance, which then created a weighted total ensuring that the most important criteria had the largest impact on the design choice. This final design incorporated the use of aluminium extrusion, which is anodised aluminium cast into an unusual cross-section providing similar material characteristics to high strength steel. The unusual cross-section enables vast modularity due to the attachments that can be fitted, which enable anything to be bolted to the frame. The majority of non-aluminium extrusion parts were manufactured within the Brunel university machine shop by qualified technicians. However an external supplier cut all of the aluminium extrusion material to length. This did not include the machining and fitting that enable the innovative fasteners to attach. Therefore all three hundred taps were made and one hundred and fifty holes drilled for the frame to attach. In order to validate the effectiveness of the new design and utilise it with a high performance electric motor, the test bench was used to test the effect of changing gear ratio for Brunel University on their Agni motor 95 series, in an attempt to optimise for their drivetrain for the Isle of Man race in June 2013. The test bench was also validated against a previous test bench with a control test under the same conditions and with the same apparatus, bar the new test bench itself. This resulted in the new test bench having the following attributes. • Secure and easy attachment of two motors • Easy attachment due to toggle clamp quick release • Efficient and safe transfer of drivetrain • High mobility due to integrated casters • Seamless connection to rolling road due height adjustment • Greater stability ensuring better safety • More accessibility to attach components • High modularity enabling re-design and packaging of all components _ To summarise the design and build of this mobile motor test bench, the test bench has met all the set out criteria. Furthermore, the original aims have been exceeded by the validation of testing its purpose and by confirming the numerical data of a control test versus the data of a previous test bench. The design has successfully enabled the testing of high-powered electric motors and facilitated the complete disassembly/modularity of the frame for future development.