Kia EV9’s Motor Does The Electric Equivalent Of Shifting Gears

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

Why ICE Automobiles (& Some EVs) Have Transmissions

If you recognize lots about combustion engines, transmissions, rear-ends, and wheel sizes, you possibly can 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 are able to examine it to what Kia’s electrical motor does.

In brief, an ICE automobile’s engine isn’t like an electrical motor the place you could have instantaneous torque obtainable proper from the get-go at zero RPM. An ICE doesn’t even work at zero RPM, and has to idle when the automobile stops to stop stalling out. At actually low or excessive RPMs, combustion engines need to work inside a reasonably slender band of effectivity, also known as the “power band.” Consider it like pedaling a motorcycle with just one gear ratio; you’d battle to begin shifting, and when you’re shifting, you’d both spin out if the gear is simply too low, otherwise you’d barely transfer if it’s too excessive. An ICE that’s at too low of an RPM will battle 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 automobile can go from standstill to freeway speeds. By having plenty of gears to select from, the combustion engine can at all times be within the vary of speeds the place it’s comfortable and doesn’t break.

However, to get one of the best efficiency and gasoline mileage, ICE automobiles are beginning to include increasingly gears. Fashionable engines do have some flexibility when it comes to excellent RPM because 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 objective of creating energy or getting good mileage is lots simpler if yow will discover the best tempo.

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

Some Electrical Automobiles Have Transmissions, & For Related Causes

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

However, an electrical motor’s versatility and suppleness doesn’t imply that it’s bought the identical energy and effectivity throughout its whole vary of RPMs and pedal positions (torque). There are specific 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 other people 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 fanatics.

The actual purpose most EVs don’t do that isn’t that it wouldn’t be good. It’s extra about price financial savings and retaining issues easy. Automakers constructing EVs with a number of drive items have even managed to supply the advantages of a transmission by giving the entrance motor a distinct 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” could 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 inventive workaround for the necessity to shift RPMs to maintain the electrical motor in a velocity vary the place it will get probably the most effectivity. And the corporate’s engineers did it with out including in any further shifting components, like gears or extra drive items.

You need to read the whole article at The Autopian if you want full detailshowever in brief, Kia’s motor is like two motors in a single. Ship the facility into one set of wires, and a you could have a “wye” motor. Ship the facility into a distinct set of wires, and you’ve got a “delta” motor. In brief, the wye configuration tends to work higher at low speeds, whereas the delta configuration is best for increased automobile speeds. It signifies that one motor can behave like two completely totally 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 facility down totally 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 thought something was taking place 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 increased voltages to cost the automobile sooner.

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

Featured picture by Jennifer Sensiba.