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New e-bike motor (2)

New E-bike motor concept

The project is a continuation of a project that was done in the fall of 2021. The previous group investigated a new linear motor design for an E-bike. The idea is to improve on the traditional motor design of E-bikes. Existing E-bike motors need to be quite powerful to produce the required torque. Such powerful motors require large currents. If it is possible to have the same amount of torque using lower currents, the lifetime of the battery and the range of the E-bike can be improved.

Project description

The main goal of our project is to research two different concepts for an E-bike rim motor. One using a current-carrying wire in the rotor and the other using permanent magnets. Calculations were done on the current-carrying wire concept which gave definitive proof that the current-carrying wire is not a realistic concept.

Then, the pole-slot combination was researched to find the combination causing the least amount of cogging torque whilst still being easy to manufacture for the prototype. A pole-slot combination of eight magnets and six coils was found to be the optimum solution; it would fit the bicycle and it did not require to many coils to produce.

In the design of the permanent magnets and coils we used a Halbach array for maximum magnetic field density.

E-bike coil holder
Design of coil holder for E-bike rim motor

Project results

The E-bike motor has been completely realized. But the realization is quite crudely done due to time constraints. There were a few challenges during the realization of the wheel and the coils.

E-bike wheel prototype
Wheel prototype for E-bike rim motor

The making of the coils was difficult and also very inconsistent, causing the coils to have different resistance values. This was solved by balancing the coils, such that the resistance values on both sides of the wheel are about the same. The second challenge during the complete project was the planning of not only the individual parts, but especially the integration. The final design has been tested and the results were shared with the project’s stakeholders.

Acknowledgement

The student team would like to thank the company IDbike, located in Riel – the Netherlands, for their involvement in this project.

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