What makes axial flux motors a better solution for electric vehicles?

This QnA with Ramesh Lakra was first published as a part of EVreporter e-magazine for April 2021. Check out our magazines here.

How are axial flux motors different from the regular EV motors we have today? 

Axial flux motor (figure B) has Electromagnetic (EM) interaction parallel to the axis, whereas the traditional radial flux motor has rotor and stator interacting radially as shown in the figure (A) – see the cover image.

Axial flux motors are more suitable for EV applications due to multiple advantages it has over radial.

What are the advantages of axial flux motors for EVs? What benefits can be expected in terms of efficiency and cost?

The inherent shape of the axial flux motors allows them to be wheel-hub- mounted. Axial flux technology allows for 7-times higher flux interaction vis-à-vis radial flux leading to better torque and power densities. Also, the efficiencies are much better due to use of CRGO, shorter flux path, better flux path and no end turn windings. Overall axial flux are more suitable for EVs and any mobile applications.

What are the advantages of in-wheel motors for EVs?

Traditional ICE based vehicle architecture does not exploit the full benefits that EVs can offer.

Implementing EV design through conventional ICE based powertrain mind-set introduce inefficiencies of gear boxes, transmission lines and axle which consume nearly 15% energy and add to weight and volume of EV, which all are undesirable. A distributed powertrain provides much better grip and torque distribution which is not only efficient but also gives natural advantages at no extra cost like torque vectoring, better regenerative capabilities and better driving ranges.

Motors have an import dependency for permanent magnets. Can SRM motors present a long term solution to overcome this dependency for different segments of EVs?

SRM motors or Rare Earth Free (REFREE) motors can meet most of the functionalities of the EVs. SRM motors do not suffer from back emf and can have better efficiencies as the rpm goes up. We have developed SRM motors and trying to find partners for matching controller as controls remains sticky points in SRM configurations. We are also working on REFREE motors and have found ferrite based PMSM / BLDC yielding excellent results for certain applications. We are working with some of the established ACMA member suppliers to use these motors. We are also in discussions with certification agencies to jointly develop motors and drives for SRM motors.

What type are your motors at Quanteon Powertrain?

We have completed PoC for a modular axial flux 2 wheeler motor covering entire power range of upto 5 Kw for scooters and upto 15 Kw for Bikes. Start of production is likely by end of the year. Similar axial flux direct drive motors are also completed upto 95 Kw, but the production will take some time based on the numbers. We are also developing eAxle in collaboration with Ghaziabad Precision Products for LCV and 3W auto. The motors in eAxle are going to be radial flux induction / Axial flux PMSM or SRM. Going forward, we are trying every possible configuration in axial flux motors like SRM, Ferrite based PMSM / BLDC and SynRel motor.

In terms of technology readiness, what is the current status? How soon will these motors be used in any segments of EVs?

Axial flux motors are ready and we have proved them on test bed. We are testing these motors in the vehicles. We are in touch with the OEMs to test these on their platform from homologation point of view. Meanwhile, we are trying to sort out tooling and other aspects of the production. We should be production ready with various motors and eAxle by the end of the year. We are collaborating with OEMs and automobile component suppliers for joint development of powertrain components.

Ramesh Lakra is the CEO and Co-founder of Quanteon Powertrain. He has 23 years of experience of Motor & Generator whilst serving in Indian Navy. He, along with his team in IIT Delhi, TBIU have developed efficient motors for electric vehicles.