In-wheel drive is not only energy efficient and compact, it is also proving to be reliable, durable and can operate in a wide range of harsh environmental conditions.

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This short video of Elaphe in-wheel vehicle winter testing is showing part of our Validation and Design verification activities carried out during this winter with a 4×4 iWD (4×4 in-wheel drive) and an RiWD (rear in-wheel drive) vehicle.

In order to demonstrate our vision of providing safe, reliable, high performance and cost efficient in-wheel motors, our technology development is based on carefully set design validation plans and is supported by a wide range of testing activities on both the component and vehicle level. As part of such activities, Elaphe recently conducted Winter testing of Elaphe™ M700 in-wheel motors on two test vehicles, a 2iWD sedan and a 4iWD SUV, both using in-wheel motors as their sole electric powertrain.

Elaphe in-wheel powertrain

Elaphe™ in-wheel technology in the toughest of conditions

Elaphe offers a wide range of in-wheel motor types that have been developed considering OEM requirements, international standards and legislation. Elaphe™ M700 motors that were used in winter testing activities are the most mature among the wide range of Elaphe™ in-wheel motors.

Elaphe M700 inside the wheel The automotive environmental and load requirements are among the toughest of any market for electric powertrains. When a direct-drive traction motor is placed inside the wheel of a vehicle, these requirements are amplified and the toughest testing conditions need to be selected in order to guarantee reliable operation throughout the motor lifetime.

The focus of winter testing were traction control validation tests on extreme surfaces, NVH tests and driving cycle tests. All tests were performed on different types of surfaces like compacted snow, smooth snow, ice, tarmac and their combinations.

Harsh, dirty and cold. In-wheel can take it.

The winter proving grounds are set up on a frozen river at the border between China and Russia (Siberia), where the temperatures in deep winter drop to less than -42°C. Extreme-cold endurance testing over a course of 3 months at down to -32°C along with multiple daily cold start tests sets an unprecedented performance benchmark for in-wheel propulsion technology.


Advanced traction control of multiple in-wheel drive vehicles – the Elaphe way

The traction control tests were focused on tuning and validation of the maximum transmissible torque algorithm implemented on the Elaphe™ “Propulsion control unit” (“PCU”). The tests revealed that the traction control system (TRC) successfully manages optimal traction and substantially increases the stability and controllability of the vehicle in low traction driving conditions. The TRC response for limiting wheel slip demonstrated extremely short response times from detection – on a mixed surface the slip was eliminated within 50 ms from detection.

Elaphe traction control system
Left: Acceleration on mixed surface (smooth ice parallel with high grip tarmac) with traction control disabled. Right: Acceleration on mixed surface with traction control enabled.

In addition to optimizing the acceleration on high-slip surfaces it is also paramount that the EM ARBS (Electro-magnetic Anti-lock Regenerative Braking System) also manages braking stability and distance in unstable traction conditions. Compared to regular braking, Elaphe™ EM ARBS system shortens the average braking time and stopping distance on compacted snow by at least 13% while greatly increasing directional stability of the vehicle.

The NVH section included testing the in-wheel motors on potholes, brick road, embedded rock and other NVH tracks, while the driving cycle testing focused on detection of functionality issues, learning about system behavior and gathering data about environmental impact on the system components.

winter NVH track


Among the multitude of tests performed over the course of the winter, several were designed to test real-world cold shock resistance of motors, validated previously in environmental chambers.

  • Extreme cold endurance (3 months, down to -32°C)
  • Cold start tests (-30°C environment and motor temperature and exerting immediate full torque)
  • Extreme cold shock resistance on NVH track (Recorded shocks of up to 40G on 8 different NVH surfaces)
  • Wet and freezing environmental influences on electrical components through the entire range of winter conditions from dry cold to damp melted river ice and snow (environmental temperatures from -32°C to +5°C)

Extreme Cold Shock Resistance

Winter testing of in-wheel electric motors has shown that the in-wheel motor propulsion system can be used reliably in the most demanding winter conditions, offers great potential in vehicle dynamics control and can bear the expected loads of a rough driving surface. Continuous testing, including summer conditions, provides an opportunity for systematical improvement of the system and system components.

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