Efficiency.. Electric motor comparison
1 - 6 of 6 Posts
Joined
·
297 Posts
EV mileage doesn't account for use of climate control, lighting, and battery temperature management, hydraulic/electric pumps for steering, brakes. (Climate control for the batteries) you already know that it takes lots of electricity to run electric AC and electric heat, in your house. So these will cost a lot of MPG in pure electric vehicles. High speed driving lacked braking regeneration energy and requires now energy per kilowatt than aloe speed driving. You might get 4mpge/kilowatt at 50mph, but half or less of that at 80mph. Mountainous driving will also affect it.
These lithium ion batteries have to be kept in a certain temp range to provide maxium range and prevent degradation.
The benefit of the Volt if that it can use the Internal Combustion Engine (ICE) to assist or completely perform those above tasks as needed. The system is able to select what is most efficient at any moment. The volt also allows you to lock out the gas engine or use only electric. For my 60 mile drive to work when cold, I use gas engine fire first 10-15 miles to provide efficient heating (and I'm on freeway at 75mph) then switch to electric .
I don't think anyone knows for sure. What we do know is that the Bolt EV motor is significantly more efficient than the Volt motor (at the least, the Gen 1 Volt) because it includes an additional stator winding ring. Look up Weber State videos by Professor Kelly. He does a good tear down and explanation if that's what you're looking for.
Outside of the motor efficiency, though, much of the real-world efficiency is due to other factors, such as the discharge rate relative to the battery capacity, rolling resistance of the tires, aerodynamics, and even gearing.
Joined
·
3,348 Posts
EPA testing allows the manufacturer to turn off all external power consumption, including Daytime Running Lights. So while the test cycle is realistic for about two thirds of the population, the creature features aren't used. The raw number becomes the CAFE value for the vehicle. Then the EPA uses a conversion factor to "account" for the creature features and this value ends up on the Mulrony sticker.
Except for automotive engineers who are designing vehicles, your question of which motor is more efficient is 100% useless. No one drives the base motor. You drive a vehicle which includes the base motor and a transmission as well as other friction inducing and mass (inertia) factors that need to be accounted for. What you can ask though, is which vehicle is more efficient.
A perfect example of these issues in the ICE world (there simply aren't comparable EVs yet) was the 1st generation Cruze LT and Cruze ECO Manual. These two Cruze trims have identical engines yet the ECO Manual trim was 4 to 5 MPG more efficient than the LT. The differences were in the transmission, aerodynamics (friction), and weight (inertia) and while none of the individual changes were that much they added up to a significant difference in efficiency from the same engine.
Tesla’s up until the Model 3 have had AC induction motors. The rear motor in the Model three is a variant of a reluctance motor with added permanent magnets on the rotor. Front motor on dual motor Model 3 is an induction motor. Volt and Bolt motors are permanent magnet motors.
There are power, efficiency, and cost trade offs with each motor type. Model 3s rear motor seems to be a real design breakthrough.
There are power, efficiency, and cost trade offs with each motor type. Model 3s rear motor seems to be a real design breakthrough.
Switched reluctance motors (SRM) have been around for a while, but I think Tesla is the first to scale them up to that much power. While they have similar to efficiency to typical PMAC motors (like those used in the Bolt EV and Volt), SRM tend to have a bit better power to weight ratio and are capable of higher rpm.
1 - 6 of 6 Posts
Join the discussion
Join now to ask and comment!