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Safer, Better Batteries Ahead…Maybe
What's All This Fuzzy Logic Stuff, Anyhow? (Part VI)
Recently, I have been riding on various trains—BART in San Francisco, CalTrans trains, various people-movers in airports, plus the London Underground. I've even been on some ferry boats. At one time, claims were made that Fuzzy Logic could help a subway train, such as the Sendai train, use less energy,
go faster and smoother, and stop at exactly the right place in less time. Well, I punctured that bogus baloney back in "What's All This Acceleration Stuff, Anyhow?" (Electronic Design, Analog Applications Issue, Nov. 7, 1994, p. 63). I showed that the claims were based on faulty computer simulation. The report claiming all those advantages was published before the trains were running. No updates or corrections were published after the trains were running—until I punctured the myth.
Claims were made that trains could be stopped in exactly the right place, which was not possible with conventional controllers. I have recently seen trains on the London Underground that stopped very smoothly and crisply, with less than an inch of position error. This is because the track-side door had to align with the door of the train, within less than an inch of tolerance. The London trains could stop perfectly and consistently. And these trains were old. FL had not been invented when they started running, so I doubt FL is being used.
Other "people-movers" at airports—little trams such as the ones at Minneapolis, SFO, DFW, and ORD—do seem to stop at the right place, but only by slowing to a crawl and then creeping up the last few inches. This, of course, wastes seconds. BART seems to stop within about two feet of its target. Maybe the "Sendai Train" can do better, but hey, good enough is good enough. I realized that stopping a train from 60 mph (88 ft/s), with precision of 1/12 ft, would require putting on the brakes with millisecond precision. Obviously, no subway train can justify the precision of train location within an inch at 88 ft/s. This would require hitting the brakes at the exact correct millisecond.
Then I realized that every good racecar driver has to hit the brakes, when coming down the straightaway at 120 mph, with millisecond precision. If the driver brakes 0.1 s too late, he will swing about 17 ft too wide at the corner and will be at a serious disadvantage. If he brakes 0.2 s (34 ft) too late, he will overrun the corner badly and risk wrecking his car in the hay bales. If he starts braking 0.1 s too early, he will waste about 0.08 s. So racecar drivers have to be very precise in their time to start braking.
So do ferry pilots. It is very important that a ferry boat not "overshoot" its goal. Claims were made that a Fuzzy Logic controller could dock a ferry without even knowing the variables of the system. "A fully loaded ferry could be docked just as fast as an empty ferry" without anybody telling the FL controller what the mass of the boat was, nor the wind, nor the tide. Sure... In view of the recent ferry accident on Staten Island, we really have to be suspicious about human-controlled systems, as well as computer-controlled systems.
After I published "Fuzzy Logic Stuff (Part IV)" (Electronic Design, Nov. 6, 2000, p. 146), I sent copies to several FL experts. I asked them, "Okay, I have just punctured the myth that FL is always better than conventional control systems. Do you see any place where I am wrong? Is FL really not better than conventional systems, unless conventional systems are misapplied, or artificially crippled?"
I not only got zero arguments from the dozen experts, I never even got any reply from any of them. So if Fuzzy Logic is kaput, maybe that is just as well.
Comments invited!
rap@galaxy.nsc.com —or:
Mail Stop D2597A, National Semiconductor
P.O. Box 58090, Santa Clara, CA 95052-8090
What you’ll learn:
- Attempt by Lotus to have a hot-swappable-battery-capable EV available for LeMans by 2030.
- Success of automaker NIO’s battery-as-a-service (BaaS) model.
- China’s standardization efforts regarding battery swapping.
Lotus unveiled a design study focused an electric endurance racer—the goal is to have it compete at Le Mans and other tracks for the 2030 season. Among the Lotus E-R9’s projected innovations is an electric motor for each wheel and aircraft-like body panels that can change their shape as needed to deliver minimum drag on the straights and maximum downforce in the corners.
Of all the proposed features, it was most curious that the Lotus engineers chose to employ a hot-swappable battery that could be changed out by a pit crew, with a little mechanical help, in a similar manner to which fuel is replenished.
Lotus’s ER-9 Le Mans concept racer has movable aero surfaces and a fully swappable battery pack.
During a Le Mans race, a car will stop for fuel approximately every 45 minutes, around 30 times in all. This means a car needs to be able to do about 100 miles before refueling to be competitive. However, battery tech has only advanced to the point where it makes sense for shorter (about 45 minute) races, as in the current Formula E series. By 2030, Lotus reckons that the problem will be solved.
“Battery energy density and power density are developing significantly year on year. Before 2030, we’ll have mixed cell chemistry batteries that give the best of both worlds, as well as the ability to ‘hot-swap’ batteries during pitstops," said Louis Kerr, a member of the E-R9 development team and principal platform engineer for the Lotus Evija, a limited production electric sports car and the first EV to be introduced and manufactured by the company.
The notion that a car can be designed around the idea of hot-swappable batteries to allow for much faster “refueling” isn’t new. Indeed, in 2013, Elon Musk showed off Tesla's battery-swapping technology on its Model S. However, when Tesla opened a battery-swapping station in California, prepared to exchange a vehicle's energy cells for fully charged ones rather than rely on fast-charging stations, owners rejected the swapping-out battery concept. Only a small number of cars were being brought in to swap out batteries.
Successful Swapping in China
Nonetheless, the idea seems to be working in China, the largest EV market in the world with 3.1 million electric vehicles in active use. NIO, a publicly traded automaker founded in 2014 and based in Shanghai, is succeeding with a battery-swap business model. Clients of the Chinese brand can buy only the vehicle, choose BaaS (Battery as a Service), and select the best battery pack for their need: 70 kWh or the newer 100-kWh pack, for example.
Battery-swapping also raises the possibility that, as consumers will not own the battery—it will be leased until it’s swapped—automakers can reduce the overall cost of the EV. Batteries are one of the most expensive portions of an electric vehicle. For instance, NIO’s BaaS subscription model decouples the battery costs from the purchase price of its vehicles. Using the BaaS model, customers can buy the NIO ES8, ES6, or EC6 vehicles without a battery, rent batteries of different capacities, and pay the battery fee on a monthly basis in accordance with their actual needs.
Shown is a NIO battery in the company’s battery-exchange station.
NIO’s batteries-not-included program for its 70-kWh battery can save buyers $10,000 off the price of a vehicle. Currently, a 70-kWh pack is priced at about $145 per month.
Powered by a 100-kWh battery, the range of NIO models can now reach up to 615 km (382 miles). Purchasing a NIO car with the 100-kWh battery using BaaS results in an RMB 128,000 ($19,732) subtracted from the car’s price with a battery subscription fee of RMB 1,480 ($228) per month.
NIO has succeeded in a way no other automaker in the world has to date. Its EV battery-swap service in China, dubbed NIO Power, has surpassed 1.1 million exchanges. NIO has also expanded the size of its battery-swap network to 158, with plans to build 300 more in 2021 as the automaker has signed several agreements designed to expand this number even further.
For instance, NIO has an agreement with State Grid EV Service, a unit of China’s state-owned electricity distributor, to build 100 stations across China and a strategic cooperation agreement with a leading Chinese furniture retailer, Red Star Macalline, to jointly build EV charging and battery-swapping stations. Under the latter agreement, the two parties will co-build 60 such stations this year.
NIO built its first battery-swap station in May 2018. Each station has five spots for swappable batteries. It takes an average of three to five minutes to replace drained batteries with fully charged ones at a NIO Power Swap station. That's about the same time it takes to fill up on gasoline at a service station.
The Latest from NIO
At its NIO Day held in early January, the company launched its 150-kWh battery pack and second-generation battery swapping station.
The new battery pack boosts energy density to 360 Wh/kg thanks to a hybrid electrolyte, an inorganic Si/C composite anode, and a nano-coated high-nickel cathode. This battery would increase the range of the new ES8 to 850 km, the ES6 to 900 km, the EC6 to 910 km, and the ET7 to 1,000 plus km.
NIO's second-generation battery-swapping station can accommodate 13 batteries, allowing for up to 312 swap services per day. NIO said it expects the number of its battery-swapping stations in China to total 500 by the end of 2021. BaaS now covers 64 cities in China and NIO is building a new battery-swapping station in China every week.
Apart from NIO, BAIC BJEV, the electric-vehicle unit of Beijing Automotive Group (BAIC) and State Grid EV, a Chinese state-owned electric utility, are collaborating on the battery-swapping business with the aim of jointly setting up 100 battery-swapping stations and serving not fewer than 10,000 vehicles powered by swappable batteries before June 2021.
Governmental Role
One of the holdups on a full-blown attempt to make battery swapping widespread in China is that China's Ministry of Finance this year cut subsidies for EVs by 20%; the standard amount reimbursed to buyers last year was roughly RMB 18,000 ($2,800). That discount will now be reduced to around $2,220. Beijing’s subsidy support has a phase-out deadline of 2022.
To ensure a safe battery-swapping process, the Chinese government has been working on standardizing battery-swapping services, aiming to establish common industry standards for the procedure. This is important since the Chinese EV makers that provide battery-swapping services, including BJEV and NIO, have different battery models, which means that EV owners can only swap their batteries in their own brand's station.
The technical compliance required to serve multiple types of battery-powered vehicles is difficult. However, it can be overcome working with something like a taxi fleet in which all of the taxis are the same.
As a result, industry observers expect to see battery swapping take hold with robo-taxi and shared ownership fleets. For example, China's biggest maker of purely electric cars, BAIC BJEV, owns 206 battery-swap stations in 19 cities in China. The stations mainly serve the company's taxi fleet.
Similarly, Bluepark Intelligence Energy Technology Company, itself a battery-technology spinoff of the BAIC group of companies, is reported to have 187 battery-swap stations in 15 Chinese cities. The Bluepark battery-swapping operation caters mainly to the taxi population as well as to car sharing networks; it serves 16,000 electric powered taxis. One of the investors in BluePark Intelligence is SK Future Energy Shanghai, a wholly owned subsidiary of SK Innovation from Korea, which, in turn, is part of the Korean conglomerate SK Group.
