It might increase the efficiency and range a little bit.
Electric cars – despite a long history of well over 100 years – still have tremendous potential for improvements aside from the batteries – simply because previously no one had a multi-billion dollar interest in developing new solutions and refining existing ones.
The recently unveiled, and very promising, Hyundai Motor Group Electric – Global Modular Platform (E-GMP) is a clear example of that. Let’s talk about the dual-motor all-wheel-drive system developed by the company.
At first sight, the E-GMP is like many other platforms – one motor for the rear axle, and another one for the front axle. It offers all-wheel-drive with independent control of each axle.
The entry-level models built on the E-GMP will be single-motor RWD, while the rest will be dual-motor AWD (no front-wheel-drive option).
In the AWD version, the rear motor is the primary one, responsible for most of the work, while the front motor is powered only when needed. Both motors are connected to the wheels by an individual single-speed transmission.
The new thing is that the front motor can be physically disconnected from the wheels by an EV transmission disconnector. The idea is to keep the front motor disconnected to improve efficiency in most driving scenarios.
“The all-wheel-drive system includes an EV transmission disconnector, which can control the connection between the additional motor and front wheels, and switch between two-wheel and all-wheel drive modes to enhance efficiency by offering the ideal level of power or performance for current driving conditions.”
Hyundai does not explain how much it will improve the efficiency and range, but we assume it must be noticeable if the company included it in the design. Maybe a few percent, like 2-3% on the highway (compared to the fixed AWD)?
The reason behind disconnecting the front motor is to eliminate the losses of an idle (not powered) electric motor with a permanent magnet rotor, which unfortunately probably has also some torque ripples.
We don’t know the details of how the electronics will control this new feature – whether there will be a “range mode” that keeps the front motor disconnected completely, a “sport mode” to engage it permanently and/or a “flexible mode” to connect/disconnected depending on conditions?
The flexible mode would engage the front motor for heavy acceleration, difficult driving conditions or regenerative braking.
One thing is sure, we are living at times when engineers working on EVs can be very creative and explore new things. In the internal combustion engine world, things are basically set and you can’t do much.
Time will tell whether other manufacturers also introduce a similar solution in their BEV platforms.
The rear transmission does not have this feature:
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