The AC motor in the Tesla Model S uses a VFD controller to make use of simple abundant materials that do not rely on rare earth minerals to make remarkable AC power for insane acceleration!
The mining of rare earth materials represent one of the most toxic kinds of mining activity in terms of negative impacts on the Earths biosphere. Many electric motors in hybrid & electric cars use rare earth magnets that are toxic to manufacture. Tesla avoided the toxicity & elevated total costs of rare earth metal magnets in the Model S' innovative AC drive motors.
EV's Need Innovations
Limited single charge range, slow recharging, lack of electric outlets where people park their cars at home & work, along with battery fade are problems holding electric vehicles back from competing more directly with antique style piston engine gasoline & diesel burners.
-Tesla was able to address most of these EV problems using the following methods & innovative technologies!
-Huge battery pack of 85-100kWh, using Panasonic NCA 18650 by the thousands in a liquid cooled modern marvel pack design. This gives 200-300mi of range per charge.
-Super charging stations that pump 120,000w of power into the model S for 80% charge in 30min, though doing so will accelerate the capacity loss of the battery, reducing single charge range faster.
-Level 2 chargers at home using 240v at 40+ amps. Most Model S owners own single family homes with electrified garages where adding a Level 2 charger is relatively cost effective & simple.
-Battery fade was minimized using liquid cooling to keep the Tesla Battery pack cool during peak discharge & fast recharging at high rates.
-The NCA chemistry developed with Panasonic provides intrinsic thermal conductivity benefits, so the batteries can give up heat to the liquid cooling system more effectively. The NCA chemistry is also more robust because the Nickel & Aluminum add mechanic integrity to the anode, in sharp contrast to the fragile fade prone lithium cobalt carbon batteries used in smartphones, tablets & laptops.
Dirty Internal Combustion
Emissions control technologies like air injection, catalytic converters, and exhaust gas recirculation help to reduct tail pipe emissions in modern cleaner burning vehicles.
2003 Weed Wacker
My old 4 stroke carbureted air cooled 30cc gasoline powered weed-wacker lacks any kind of emissions controls technologies due to the manufacturing requirements to keep the unit light weight & cheap enough to be practical.
2013 Honda PCX150
With fewer cost & weight restrictions than those present in a weed wacker, Honda was able to make use of fuel injection and liquid cooling to get more than 13hp and 11ft lbs of torque (68MPH max) through a CVT, while returning ~90mpg in our PCX150. Honda was able to miniaturize advanced engine technologies into this relatively expensive $3500 scooter. Using better engine technology allows the PCX to get the same fuel economy as 50cc scooters that are 2x slower. I am not sure about the emissions control tech in the PCX, but it seems to burn its fuel relatively cleanly via smell analysis of the exhaust gases, even during cold start. Its a fuel sipper modern marvel of a scooter, but makes use of a very old and highly refined internal combustion piston engine technology, and correspondingly emits tail pipe pollution, and is not a future solution to transportation, just a fuel efficient alternative to driving in fair weather conditions, and a fun one that is simple to use with its automatic twist and go action.
46.4 MPG for the last 123,456mi : its got rare earth galore in the HV traction battery & two electric motor generators (MG1 & MG2) : For its day (2005) it was a modern marvel and still exists as one of the most fuel efficient cars on the road. Extension emissions controls help to keep the tail pipe emissions clean in this AT-PZEV vehicle. Idle Stop & brake regeneration for example help to reduce brake dust formation while almost eliminating idle emissions. MG1 is a permanent magnet 30kW AC motor generator used to start the engine & as the alternator to charge the HV battery, while MG2 is a 50kW power motor to drive the Prius at up to 60mph on electric power alone, but also acts as a generator when brake energy regeneration is activated, sending power to recharge the HV traction battery.
The computer keeps the 201.6vdc 1.2kWh NiMH battery pack between 30 & 80% charged, with an average SOC ~60% to greatly enhance the battery pack cycle & calendar life. The 1.5 L 1NZ-FXE DoOCH I4 VVT-i engines makes 57kW (76hp) @ 5000 RPM & 115 N*m (85 lb*ft) torque @ 4200 RPM : The 500V electric system is rated at 50kW (67HP) @ 1200 RPM & 400 N*m (295 lb*ft) torque at 0rpm : giving a net system power of 82 kW (110hp) via the power split devices single speed planetary gear system that combines the 1NZ-FXE motors output shaft with the power shafts of electric motor/ generators MG1 & MG2. Rare earth metals in the NiMH battery & 2 electric motors make the environmental footprint of Prius manufacturing worse, though I will note that all of these rare materials are valuable, recyclable and desirable to recover during the scraping process at the end of the vehicles useful life, or when the battery becomes functionally less useful due to dramatic capacity loss after something like 400,000 mi or 20 years or ~50,000 cycles.
39.6 MPG for the last 12,873mi : it has a permanent magnet brushless DC IMA motor (15kw) sandwiched between the 6sp manual tranny & flywheel of the engine. The 144vdc Lithium Ion battery capture energy from the drive-train during hill descent braking events & other situations where excess energy is available for battery energy recovery, depending on which driving mode is selected (Eco, Normal or Sport). If the battery has more than 30% charge a Sport + button on the steering wheel can be activated to inject full electric assist for maximum acceleration.
The IMA battery was made by Blue Energy, a joint venture between Honda & GS Yuasa. Made of 40 EH4 batteries of 3.6vdc & 4.7ah in series, the 144v pack stores about 600 watt hours of energy, and weighs about 48 lbs. The EH4 batteries are a strong vehicle specific lithium ion design that Honda integrated into the 2013-2016 CR-z as an upgrade over the NiMH unit in earlier 2010-2012 models. I am curious how this battery will hold up over time & about the cost of a replacement should one become needed outside the warranty coverage period through 2022. Non-toxic, the Lithium Ion battery does not contain rare earth materials and can be easily recycled using existing infrastructure for recycling cell phone & laptop batteries. The IMA motor on the other hand has rare earth metals that are valuable & highly desirable for recovery at the end of the vehicles life.
2013 Nissan Leaf S
A 24 month lease for $200 per month with $2k due @ signing had me onboard. 14,000 mi of EV driving later I turned it back in, and purchase the 2014 Honda CR-z in spring of 2015, just before moving to our current home. Had I known we were going to move here, I might have purchased the Leaf S for $7800 at the end of the lease, though the limited single charge range & 12% capacity fade of the 24kWh battery caused me to abandon such an idea.
Like the Model S from Tesla, Nissan Leaf's use a highly responsive AC synchronous electric drive motor powered through a VFD controller from the 192 cell 24kWh laminated 48 aluminum 2P2S modules of 7.4v & ~66ah. The motor of the 13 Leaf S puts out 107 HP & 187 lb*ft of torque. Almost no rare earth materials in these first affordable highway capable lithium ion vehicles from Nissan. Woot woot Nissan Leaf. I only hope they continue to increase the single charge range of the Leaf with better aerodynamic design, lighter wheels & tires, less steel & more aluminum or light weight alternative materials, and improvements to the inverter controller & battery energy storage system.
I was able to go 123mi @ 16mph from 100% to 5% when testing the 13 Leaf S. I roughly empirically determined that ~16mph was the most efficient speed in terms of energy efficiency, netting something like 5.1mi/kWh. I was averaging more like 4.3-4.6mi/kWh most of the time. Roughly equivalent to over 100MPGe, the 24kWh battery holds less energy than 0.68 gallons of gasoline, though the inverter and motor combination achieve much greater efficiency ~90% than most gasoline motors 30%.
Nissan greatly increased the battery capacity of newer Leaf models to 30kWh, and the next major revision is slated to get a 60kWh battery. That means 200+ mi per charge in the ~2018 2nd gen Nissan Leaf. Time will tell ^^
Engineering Tradeoffs in EV Design
The Nissan Leaf is smaller & lighter but has more aerodynamic resistance than a Tesla Model S. Made of mostly Steel the Nissan Leaf is less expensive & easier to repair than the mostly Aluminum Tesla Model S. The Tesla Model 3 will compete against the 2018+ Nissan Leaf 60kWh version and other 200mi per charge EV's like the GM/ Chevy Bolt, 2019 BMW i5, 2019Audi ETron and other new longer range electric vehicles from other manufacturers.
200mi Affordable Key
200 mi range @ 70mph is the key for electric vehicles to compete against conventional fossil fueled vehicle. I can add 400mi of driving range gasoline to my Prius II in under 5 min at a gas pump. Thats tough competition for electric vehicle charging, though Qualcomm seems intent on building a 400kW charging station standard for something better than 3x faster than a Tesla Super Charger. That sounds like a dangerous amount of energy to pump into the charging port on a car with realistic battery cable sizes. Unless they make use of sodium cooled wiring or something exotic.
Rational High Speed Charging
I think charging a Lithium EV at 400kW sounds a little batty! Lithium ion batteries are prone to venting with flame if abused by over charging, shorting, overheating, punctures, dendrite perforations, side chain reaction thermal runaway, extreme discharge rates, freezing temperatures and other operating parameters possible to encounter in the real world. Lithium ion battery fires became a public topic of widespread though after the hover-board fire debacles and Galaxy Note 7 fires hit the news channels ^^
We want safe electric vehicles, so next generation battery technology needs to bring fire proof concepts to the forefront of EV battery design philosophy. Gasoline cars catch fire all the time, so much that it never makes the news anymore. Since electric vehicles with lithium ion batteries are a relatively new technology, any EV that catches fire tends to make news headlines.
Alloy Wheels & Better Tires
Tires are the most important thing on a vehicle. Tires are where the power to move the vehicle meets the road surface, the mechanical interface between the vehicle and the road. Alloy wheels afford less unsprung rotating weight, which reduces gyroscopic inertial effects that reduce corning performance, and acceleration while elongating stopping distances. All of the vehicles that Meg & I use today have aluminum alloy wheels. I also research tires extensively before purchasing them, and have gone with LRR Michelin tires as OEM replacements so far, and plan to use high quality LRR Micheline tires to replace the OEM tires on the CRZ, PCX and possibly even the Subaru if Michelin produces a 14 inch tire.
Modern vehicle tires are a modern marvel of materials science & manufacturing technological improvements. The tire compounds have to balance cost, strength, endurance, ride quality, grip, safety, solar energy loading, dynamic friction heating, acceleration sheer forces and breaking sheer forces, water channeling for rain safe operation and ride quality. Thats a lot to consider for the tire scientists!
Electric vehicles achieve greater range with lower rolling resistant tires. Look at the narrow tires on the BWM i3 for example. The first BMW i3 went about 89 miles per charge, the revision achieves 114 miles and the next version in 2018 will likely get enough battery for 200mi of range per charge ^^
The Electromotive Platforms of Honda 2017 onward
Electric, Fuel- Cell Electric & Plug-in Hybrid : they send me email updates because I am the owners of a 2014 Honda CR-z ex that I purchased new directly from Honda of North America, through their dealer/ distributor at the Smoky Point Honda. They hooked me up with a fantastic deal as this specific CR-z sat on their lot for more than 5 months. I learned from a sticker on the underside of the hood that it must be driven for 30 minutes every 30 days in order to prevent the hybrid IMA battery from experience over-discharge damage. I suspect that the stated required use cycling of the battery is also important for its longevity given that parking a battery at a higher state of charge causes accelerated capacity loss.
Store Lithium 50% full @ 50 deg F
If you do need to store a lithium-ion battery, it will hold up better if it is kept at ~50% charged at ~50 deg. F. Lithium ion batteries are damaged by freezing temperatures and by temperatures greater than 77 deg. F. High heat, freezing, fully charging & deep discharging are all things that damage lithium ion batteries.