Kia EV9’s Motor Does The Electrical Equal Of Shifting Gears

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A current article at The Autopian raised an attention-grabbing level in regards to the Kia EV9’s electrical motor. Not like most electrical motors, it might change its winding configuration on the fly, successfully doing the identical factor as shifting gears in an ICE automobile. However, to elucidate how wonderful this expertise is, we have to first clarify what transmissions in ICE automobiles (and a few EVs) do.

Why ICE Autos (& Some EVs) Have Transmissions

If you understand loads about combustion engines, transmissions, rear-ends, and wheel sizes, you’ll be able to in all probability skip this part. For everybody else, I’m going to elucidate within the easiest phrases attainable what a transmission does in order that we will examine it to what Kia’s electrical motor does.

Briefly, an ICE automobile’s engine isn’t like an electrical motor the place you could have instantaneous torque accessible proper from the get-go at zero RPM. An ICE doesn’t even work at zero RPM, and has to idle when the automotive stops to stop stalling out. At actually low or excessive RPMs, combustion engines must work inside a fairly slender band of effectivity, also known as the “energy band.” Consider it like pedaling a motorcycle with just one gear ratio; you’d wrestle to start out shifting, and when you’re shifting, you’d both spin out if the gear is just too low, otherwise you’d barely transfer if it’s too excessive. An ICE that’s at too low of an RPM will wrestle to maintain operating or get broken.

That is the place the transmission is available in. It’s just like the a number of gears in your bike, permitting the engine to function in its most effective vary whereas the automotive can go from standstill to freeway speeds. By having quite a lot of gears to select from, the combustion engine can all the time be within the vary of speeds the place it’s glad and doesn’t break.

However, to get one of the best efficiency and fuel mileage, ICE automobiles are beginning to include increasingly gears. Fashionable engines do have some flexibility when it comes to ideally suited RPM as a consequence of applied sciences like variable valve timing, however getting the entire symphony of pistons, rods, crank, cams, lifters, and injectors to all harmonize across the purpose of creating energy or getting good mileage is loads simpler if you could find the best tempo.

Some have as many as ten speeds in order that the engine may be not simply in a contented vary, however fairly near the perfect RPM. However, with all of those further gears comes further elements that may break, ultimately reaching the purpose of diminishing returns for upkeep, reliability, and value of operation.

Some Electrical Autos Have Transmissions, & For Comparable Causes

The typical EV nerd who isn’t acquainted with automotive expertise will let you know that EVs don’t want a transmission. The one-speed gear reducer does the job fairly properly as a result of fashionable electrical motors work properly throughout a really wide selection of speeds. They will work from zero RPM to properly over 10,000 RPM with out taking injury. Mechanically talking, they’re actually easy, and have solely two shifting elements (the rotor and the stator), so there isn’t a fancy symphony to search out the proper tempo for.

However, an electrical motor’s versatility and adaptability doesn’t imply that it’s obtained the identical energy and effectivity throughout its complete vary of RPMs and pedal positions (torque). There are particular torque and RPM conditions the place an EV’s motor makes energy much more effectively than others, offering for higher vary. There are additionally RPMs and torque conditions the place the motor tends to carry out higher than others.

Because of this, there’s actually no purpose EVs can’t profit from a transmission. Some automakers put easy 2-speed transmissions in manufacturing EVs (the Porsche Taycan is an effective instance), and folks changing ICE automobiles to electrical have usually mounted an electrical motor as much as a handbook transmission. Jeep has even constructed some electrical automobile prototypes with handbook transmissions, which might be enjoyable for fans.

The actual purpose most EVs don’t do that isn’t that it wouldn’t be good. It’s extra about value financial savings and preserving issues easy. Automakers constructing EVs with a number of drive items have even managed to offer the advantages of a transmission by giving the entrance motor a unique gear ratio than the rear one, after which having the pc “shift” between the motors to get higher vary in several conditions. So, the necessity to have the ability to “shift” may be very actual, even for Tesla.

Kia’s Motor Can Shift Its Effectivity Curve With out A Transmission Or A number of Drive Items

Kia managed to discover a artistic workaround for the necessity to shift RPMs to maintain the electrical motor in a velocity vary the place it will get essentially the most effectivity. And the corporate’s engineers did it with out including in any further shifting elements, like gears or extra drive items.

You must learn the entire article at The Autopian if you would like full particulars, however briefly, Kia’s motor is like two motors in a single. Ship the ability into one set of wires, and a you could have a “wye” motor. Ship the ability into a unique set of wires, and you’ve got a “delta” motor. Briefly, the wye configuration tends to work higher at low speeds, whereas the delta configuration is healthier for greater automobile speeds. It implies that one motor can behave like two completely completely different motors with out the price of an additional drive unit, further gears, or the rest.

“Shifting” the EV9’s motor is fairly easy: the automobile’s laptop sends the ability down completely different wires. Not solely would a driver not want to consider it, they’d in all probability not discover in any respect. Throughout my week with an EV9 press automobile, I had no concept something was occurring to ship higher efficiency or vary. It occurs at about 45 miles per hour, with no indication, controls, or shift shock.

The additional advantage is that, just like the Hyundai Ioniq 5 (made by the identical producer), the motor may also be used to transform 400 volt charging to greater voltages to cost the automobile quicker.

This idea of shifting between completely different modes has been round for industrial motors for a very long time, however till not too long ago, they weren’t very cost-effective to do in EVs. By working with the best suppliers and profiting from decreasing semiconductor prices, Kia has managed to carry the idea to the EV world and make it work even higher.

Featured picture by Jennifer Sensiba.