Application of amorphous alloy to high speed motors for electric vehicles
Final Report Abstract
In this project, the electromagnetic and mechanical properties of an amorphous magnetic metal (AMM) material 2605SA1 were studied and tested in depth. It was found that the higher the stacking factor (stacking stress), the higher the core losses. It is recommended to use a medium stacking factor around 0.9 to avoid high core losses. The temperature plays a major role on the saturation flux density of AMM. The higher the temperature, the lower the saturation flux density. The saturation flux density is reduced by about 9 % at 150 °C compared with room temperature. Similar to the conventional silicon steel, at a higher temperature, the core losses can be reduced. Annealing treatment can help to improve the performance of AMM ribbon to some extent. However, after stacking and solidification of AMM cores, this improvement might disappear because of the cores’ degradation. As annealing treatment leads to high brittleness, it might not always necessary to anneal the AMM cores. The cutting method also cause core degradation in terms of electromagnetics and mechanics. Laser may cause the AMM layers melt together and leads to short circuit between layers, which results in core losses increase. The mechanical strength of AMM cores might be significantly decreased because transverse cracks occur during cutting. In ideal case, the ultimate tensile strength of AMM ribbon can reach higher than 1000 MPa based on the experimental results. However, due to the influence of cutting, this value might be lower than 200 MPa. Hence, when AMM cores are going to be used for high-speed rotors, the mechanical strength of the rotor core cut by a specific method should be tested. Based on the experimental results, it is recommended to use wire electrical discharge machining method. According to the multi-physics analysis and experimental results, it was found that by using AMM for high-speed SRMs, the power density and efficiency of this type of motors can be significantly increased. The maximum power/volume and power/weight ratios of the designed demonstrator motor can reach about 14 kW/L and 2 kW/kg, respectively. They are comparable to the permanent-magnet synchronous motors used in electric vehicles. The feasibility of the proposal has been experimentally proved. In order to fully take the advantages of low core losses and high mechanical strength of AMM, a high-speed sleeve-free interior permanent-magnet synchronous rotor made from AMM was proposed. Based on the tested results of a 125,000 /min demonstrator motor, it was found that the surface velocity of the rotor and the power density as well as the efficiency of the motor can be significantly increased. The major challenge of this application is to ensure the high mechanical strength of AMM cores during mechanical machining. Nevertheless, AMM has high potential in the application of high-speed high-power-density motors.
Publications
- Application of amorphous cores to DC-excited flux-modulated motors used for electric vehicles. 2018 IEEE Int. Conf. on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles & Int. Transportation Electrification Conf. (ESARS-ITEC), Nottingham, 2018, pp. 1-7
J. Ou, Y. Liu, M. Schiefer, P. Breining, M. Doppelbauer, and F. Chai
(See online at https://doi.org/10.1109/ESARS-ITEC.2018.8607428) - Application of an amorphous core to an ultra-high-speed sleeve-free interior permanent-magnet rotor. IEEE Transactions on Industrial Electronics, vol. 65, no. 11, pp. 8498-8509, Nov. 2018
Y. Liu, J. Ou, M. Schiefer, P. Breining, F. Grilli and M. Doppelbauer
(See online at https://doi.org/10.1109/TIE.2018.2807418) - (2019) Experimental study of the amorphous magnetic material for high-speed sleevefree PM rotor application. IEEE Transactions on Industrial Electronics, vol. 67, no. 6, pp. 4422-4432, Jul. 2020
J. Ou, Y. Liu, P. Breining, M. Schiefer, and M. Doppelbauer
(See online at https://doi.org/10.1109/TIE.2019.2931282) - (2019) Investigation of PM eddy current losses in surface-mounted PM motors caused by PWM. IEEE Transactions on Power Electronics, vol. 34, no. 11, pp. 11253-11263, Nov. 2019
J. Ou, Y. Liu, D. Liang, and M. Doppelbauer
(See online at https://doi.org/10.1109/TPEL.2019.2895679) - (2020) Experimental Characterization and Feasibility Study on High Mechanical Strength Electrical Steels for High-speed Motors Application. IEEE Transactions on Industry Applications
J. Ou, Y. Liu, P. Breining, T. Gietzelt, T. Wunsch and M. Doppelbauer
(See online at https://doi.org/10.1109/TIA.2020.3033262) - Comparison Study of a Surface-mounted PM Rotor and an Interior PM Rotor Made from Amorphous Metal of High-speed Motors. IEEE Transactions on Industrial Electronics
J. Ou, Y. Liu and M. Doppelbauer
(See online at https://doi.org/10.1109/TIE.2020.3026305)
