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@Henrik, I also googled When the Royal Society was formed in the 17th century they adopted the motto : Nullius in verba, which is Latin for "Take nobody's word for it". I would hope we have a policy of full disclosure at GCC that requires viewpoints to be qualified by vested interests. You have to take my word on my stockholdings. On the evidence it would be unlikely I would make contradictory statements re Tesla unless I was still holding on to some of the Tesla story. Despite the anachronisms Tesla is still the best game in town and likely to be for at least the next five years. I don't think you can come on here and make nonsense claims against me unless you supply the reasons. Otherwise it is you that is making the emotional response, I just call them as I see them. The remainder of response is just plain rude. If I was looking for rudeness I would just go on YouTube. As for the unsolicited advice to sell my stock , frankly that is none of your business.
I will look to see retail sales somewhere in 2019. It seems that so many Tesla personnel may have been thinking that Elon's company may be missing its mark and decided to jump ship. Certainly this is the right time. As a stockholder for Tesla I've seen the share price get whacked despite it producing gee whiz product. Wall Street is not happy with any company that tries to put fur on its back without rewarding stockholders. But in a growth phase all you can expect is high risk with no commensurate dividends. And to keep the "longs" from bailing you have to keep extending and embellishing the "story". Tesla is quite capable of meeting guidance on deliveries, the problem is that they don't win all their gambles and often times seem to be snatching failure from the jaws of success - I believe is the obvious cliche. Feature creep has caused production dislocations and the goal of an affordable car is reaching evermore into the future. The optics are that Tesla - in the name of progress - has been made more and more appealing in order to garner an even more upscale market. The argument presented is that there is more gross margin on those sales. What I am seeing on the blog postings etc, is more discontentment among those same customers because something isn't completely perfect on its first iteration. Precipitating comments like : "I paid good money for this and I am not receiving..." It is time for another company to enter the arena with a slightly modified strategy. Perhaps using the Nissan Leaf as the target vehicle to beat. First, the battery compartment should be the most thermally insulated and air tight enclosure on the market, it should share the cabin A/C equipment as Tesla has done. Because the Battery is the Car when it comes to electric vehicles. Second, the powertrain needs to be given a Top speed rating from the Engineering Dept not Marketing for the following reasons. The fact that aerodynamics at speeds above 60mph work severely against EVs as regards vehicle range. The fact that there is a financial compromise that has to be taken on motor size and gearing when an unrealistically high speed is chosen. The coarser gearing required to reach maximum speed will always impact bottom end acceleration negatively. You can have one or the other. Or you can have both by selecting a larger frame size motor but going that route will increase powertrain cost unless profitability is sacrificed while holding on to a previously set retail price target. Notice Prius limits out at 100mph and you don't hear complaints. The EV1 was initially 75mph. The EV1 proved that an EV with an 8 sec to sixty back in the 1990's coupled with instant throttle control was quite respectable, I saw no comments on its lack of top speed either, rather difficult unless you also condone road racing I would think. And that brings me to something that could have been trumpeted more often over at Tesla. Yes, these are quick cars, acceleration wise, but they were never intended to be used as track cars.
@Roger Regarding the gear train I agree with your description after having expanded the computer rendition which was a bit fuzzy on my monitor. You wrote : The changes are that the planetary gear reduction of the MG2 in the Gen 3 Prius is removed, as well as the drive chain from the power split device to the differential unit, replaced by a pair of simple helical spur gear sets to reduce drag, weight, and cost. Both the MG2 and the PSD are meshed to a larger spur gear of an intermediary gear set, the latter having a smaller spur gear meshed with the final gear of the differential unit. I can now see that the (yellow) intermediate gear rotates the (orange) pinion, keyed on its shaft obviously. This pinion then drives the (blue) final differential gear and (not shown) half shafts assembly. Your description is spot on. My understanding wasn't helped by the way Toyota described it on their website : "The transaxle also boasts a more compact design, and achieves approximately 20 percent loss reduction compared to the current Prius. This was made possible due to multi-shaft positioning of the motors, along with the relocation of the final drive reduction gear onto the same axis as the drive motor." It looks like the pinion drive permits the ~ 4:1 ratio to be accomplished in one step from the pinion to the final gear whereas it used to be accomplished in two steps consisting of two gearsets of 30/44 times 26/75. At least they haven't lengthened the critical path between MG2 and the PSD as I had originally thought. Incidentally, mesh efficiences for gear ratios of ~1:1 are known to be 95% and for ~1:3 they hover around 93%. The original transaxle had been known to have an efficiency of 22% so this is welcome news. The chain drive used to absorb 6% and now there is this 7% saving from eliminating yet another gear interchange. Back in 2005/6 some hypermiling enthusiasts were fitting electric pre-heaters to their transaxles to raise the transmission oil temperature to help reduce gear friction during the first two miles. In case any one is interested the PRIUS_TECHNICAL_STUFF thread documented this in Yahoo Groups. The question now concerns the longevity of the pinion that is fitted to MG2. In the previous design MG2 was sped up ~2.5 times in order to downsize it. At that time its motor pinion became the sun gear for the planetary reducer that is now removed. One advantage of a sun gear is that as it sits balanced between the gears of the planetary gearset it is protected from lateral bearing forces, as the forces from all those gear meshings are neutralised from top, below and the sides. When there is just a single point take-off as is now then this puts lateral pressure both on the motor bearing and on the bearing at the other side of the pinion. That there is some overhang on the pinion shaft because of its length can be observed. Not much more to be writ, there has been no rebuttal over the Virtual Power operation of the Prius and I take it that no-one has been offended by my description thereof.
Correction: The 3.6 is the effective planetary ratio between the sun gear and the planet carrier if the ring is stationary. I forgot to point out that the 17Hp (in this particular example) that is sent to MG2 mechanically from the PSD and then returned to MG1 electrically is the virtual power I was mentioning from an earlier post. There may be some who may be interested in the software that controls this system. I cannot comment on the coding of the ECU but I can say that the accelerator pedal controls the engine speed which represents power unlike other cars on the road which are motivated by variable torque demands. The Prius engine's torque is controlled by MG1. The system knows that MG1's line current should be 100 amps when MG1 is exerting 22 lbs-ft at the sun gear. And 3.6 times 22 = 80lbs-ft, the rated torque of the 1NZ-FXE engine. To keep the system in torque balance the ring gear takes remainder, in fact the lion's share of the torque which would be 2.6/3.6 of the engine's 80lbs-ft = 57.63lbs-ft to be exact. As I said ealier the power split device is more accurately described as a torque split device but outside the engineering power split is close enough. The fuel injection system delivers the amount of fuel to the engine that will cause MG1 to hold its speed when delivering or receiving 100 amps. A bit of a controversial statement but it is in one of the Prius' patents that engine torque is governed by monitoring MG1's line current. There is a rule pertaining to MG1. There must be a guard band around MG1's operating speeds when close to zero rpm requiring MG1 to rotate at a minimum of 100rpm in whichever direction it happens to be turning. May be something to do with low speed cogging. Naturally the engine speed will be adjusted away from optimum to accommodate this. There is a minimum engine speed also. My notes mention that the engine is parked at 1211 rpm for power delivery of up to 8.5kw @ 67n-m beyond which the engine speed must be raised to take advantage of 80lbs-ft. This is probably due to the effect of the Atkinson camming on this engine that limits low speed torque. The Prius is undoubtably the most complex car on the road. It is also the most reliable since it doesn't rely on an electro-hydraulically operated multi-ratio gearbox. Even those in the transmission repair industry have come out with statements that around fifty per cent of modern automatic gearboxes have faults which are uneconomic to repair. On the other hand the Prius system is alleged to lend itself to modular repair. Anyway that's enough with the commercials.
So I examined my charts and notes from nearly ten years ago and particularly the equation MG1 = 3.6 X ICE - 2.6 X MG2 and realised that under certain forward driving conditions MG1 does reverse its direction. So the finishing statement from my last post is incorrect and I need to do a reset on that post. What I should have said was: We have a small disagreement over the operating modes of MG1 and MG2. I think MG1 and MG2 under certain forward driving conditions swap roles and here's why. Let's say we accelerate the Prius to its electronic speed limit of 100mph. Just before it hits 100mph the ICE will be doing 5000rpm, MG2 will be doing 6000rpm and MG1 will be doing 2400rpm via the above equation. Two other facts the engine will always be made to run at max torque (80lbs-ft) where possible and it takes 49Hp to remain at 100mph (scan guage). Max output of the 1NZ-FXE engine is 76Hp @5000rpm so 49 Hp will require a new engine rpm of 49/76 X 5000 = 3223 rpm. Plugging this into the equation along with MG2 at 6000rpm reveals that : MG1 will need to rotate at (11603 - 15600 = - 3997) Yes that's minus 3997 rpm so it will need to go backwards as you suggested earlier Roger. MG1 @ its rated 22lbs-ft will drive as a motor ~17Hp into the PSD. Meanwhile the mechanical output of the PSD which remains steady at ~57lbs feet @ 6000 rpm representing ~ 66Hp. However Mg2 will no longer be augmenting this with 38HP but will now be swapping roles with MG1, MG2 now acts as a generator and will strip 17HP away from the PSD power just before it enters the 4.113 reducer to drive the wheels (23" dia). This will leave the requisite 49Hp going to the wheels needed to maintain the cruise speed at 100mph. The 17Hp from MG2 now converted to electricity is then supplied to MG1 that is needing it to drive into the PSD as I just mentioned. I think I can now come from out under table ! I apologise for not using metric but a US audience is more favorable towards imperial measurements. You might be wondering where that 38Hp came from. Well the full power of the MY2004 Prius is 104HP ( 76Hp from the engine and 28 Hp (21Kw) from the NiMH battery). 66Hp comes directly from the PSD (57lbs-ft@6000rpm) and the balance of 38Hp is supplied by MG2 which draws electrical power from the battery (28Hp) and MG1 (10 Hp). Bear in mind that MG1 is only able to rotate at 2400 rpm at this time so generates but a fraction of its 42.2Hp (@ 10,000rpm) in this case just 10.2Hp. The important thing is that I was assisted in being able to prove the power balance electrically in terms of the volts and amps of the thing thanks to the Oak Ridge National Laboratory posting the PDF of their tear down in the spring of 2004. It is useful to know that with the pedal to the metal from rest, MG1 eclipses 10,000 rpm as soon as the ICE has zipped up to 2777 rpm. MG1 stays at that rpm until 51 mph. At 51mph the ICE - until then having been mechanically constrained by road wheel rpms through the PSD gearing equation - is able to finally attain 5000rpm and its max power. The ICE remains at constant max rpm and full rated torque until it reaches 100mph the electronic limit. This gives the Prius a performance more akin to a 2.4L engine than its actual 1.5L would suggest. From 51mph MG1 begins ramping down to 2400 rpm @ 100mph. It should be noted that the fact that traction motor MG2 is only assisting with 38HP as the 100mph is approached is solely a limitation of the HV battery supply. However because the generated power from MG1 0-51mph is 42Hp and merged with the 28Hp from the battery means that the 67Hp motor is well provided for during that initial half of the acceleration ramp. When you understand the constraints of the Prius Synergy Drive you realise how much better a pure series hybrid could be without those constraints. One last thing the PSD is really a TSD (Torque Split Device) The 57 lbs ft is the ICE torque times 2.6/3.6 where 80 X 2.6/3.6 =57.63 lbs-ft The Sun gear torque of MG1 = ICE Torque X 1/3.6 =22.37 lbs-ft The 2.6 is the tooth ratio of the PSD = Ring gear / Sun gear = 78/30 The 3.6 is from the effective planetary ratio between the ring and the carrier if the ring is stationary. Planetary gear ratio = tooth ratio + 1
I agree that initially, OTA should be free, like roadside assistance with Lexus. However I am suspicious of companies that want you to pay for ongoing service when the value added turns out to be minimal. OTA service with a car like the Tesla is pretty much essential and somebody has to pay for that access but with an $80k car there is going to be some space in the sales price to carry this cost. I haven't seen that agreement but it is probably limited to the original owner to reduce ongoing liability to the manufacturer. All businesses desire to get into the automated payments business. First they lowball you to start with and then, when their cash register is effectively joined to your bank account they can make those periodic "adjustments" whenever they feel like it, but just small ones. So you don't notice it. I came across this sales brochure from a CHP company in the states. When they had installed a system the homeowner was required to pony up for a monthly internet fee, so that they could monitor the health of the system. "If we see anything wrong with your system we will call and notify you". I got to thinking what if the homeowner could be privy to this information why would he need a third party to do it for him ? Bearing in mind that most heating equipment is unlikely to fail for a very long time. And then, when it does, well the service call is going to be chargeable anyways.
Roger I am sure that you don't want to spend much time on this either. I'll agree that Toyota has not made any changes to its original concept regarding the PSD operation, so explanatory arguments should remain unchanged. Incidentally I found a small error in your second paragraph. The chain drive was in fact removed going to the third generation while your statements make it appear to be still present on the third generation. Anyway I think we both agree that MG2's planetary first appeared on gen three and has now been removed going to gen four. In my recap I apologise for omitting to mention anything at all regarding the sprockets and gear chain because their removal doesn't change the geartrain direction in the same way that knocking out a shaft with two gears on it would have done and besides the ratio was close to 1:1. ( a 35 tooth to a 36 tooth I believe). Tyring to keep things simple that's all. We have a small disagreement in the direction change of MG1. I think it doesn't and here's why ... to be continued
Hi Emily, listen, could I ask a favor on behalf of all of us and get you to divide your posts into paragraphs or at least spread blank lines liberally around in your posts ? I appreciate your concern with waste but as a programmer I can confidentally tell you that a blank line doesn't waste eighty bytes consisting of space codes, it replaces them instead with carriage return and line feed codes respectively which take up just two bytes. Yes I agree with your sequestering argument. In fact we should have teams going out and culling old growth forests and planting saplings. The old growth is responsible for those forest fires we had in Alberta this summer and was entirely preventable in my opinion. Disposal of the old growth would require it to be chipped to make it suitable for transport and its subsequent underground storage in decommissioned mine shafts. However getting back to cars. I don't see the economics of autonomous vehicles even for taxi services unless they are designed as two seat grocery getters with a top speed capability of 40mph which should be enough for local city to suburbs transport. They could well be used as a replacement for public transport vehicles particularly during off peak hours. Public transport authorities insist on adhering to the same model of chauffeuring a couple of people around late at night in an eight ton vehicle which has been my experience. Of course, as Sirkulat points out in the third paragraph from his post above, corporate interests will ignore this. The gross margins per car from those downsized vehicles purposed primarily for taxi service won't allow them to grow their business. They clearly - from the TV advertising I most see - want you in the largest SUV or pickup that low interest money can buy. It is the EPA and other air quality organisations with clout which will make the biggest alteration to Toyota's aspirations in the years to come. Certainly not Toyota itself.
This being the fourth generation of Prius and inline with those previous releases, Toyota policy once again requires a one year delay before introducing it to North American shores in order that the new manufacturing tooling can benefit from the experience as well as any possible vehicle improvements that may be forthcoming from the thousands of early-adopter Japanese motororists. An insider once told me that as a rule new model designs, as opposed to yearly refreshes, are an opportunity for Toyota to discard all their machine tools, robots etc and bring in new computers with the latest operating systems. This ensures their manufacturing environment remains both current and maintainable being that it is often difficult to obtain spare parts for legacy equipment that is more than five years old. The computer generated model of the transaxle doesn't agree with the photograph. Seems to be upside down and back to front ! So what's new in real terms ? Well what I noticed is that the traction motor, referred to as MG2, is directly geared onto the final (differential) gear which, as we know, rotates at the same speed as the wheel axle. The previous model (MY2010) coupled MG2 to the power-split device (PSD) speed using a planetary gear arrangement similar to the PSD itself. This particular planetary gave a 2.5 ratio step down allowing the motor to rotate as fast as its 15000 rpm limit but able to be coupled to the PSD output which maxxes out at 6000rpm. The PSD then transmits the power through a two stage reducer to give an overall 4.11 stepdown to the wheels, where the ~1500 rpm approximates to about 100mph. But now, that is all changed. The topology of the new generation gear path is to route MG2's power directly onto the final gear thus avoiding the more tortuous path through the motor planetary and the two stage reducer. Obviously this allows elimination of the motor planetary altogether as well as eliminating the 6% torque loss from that component and the 7% loss through at least one of those stages of the existing 4.11 reducer. From the photograph the relative sizes of the final gear and motor pinion suggest a 10:1 stepdown ratio may be in effect so expect MG2's rpms to continue to be as high as before. MG2 acts as a motor while accelerating in the forward direction, it also acts as a motor when vehicle operation is required in reverse. And of course MG2 acts as a generator when acting as a brake in regen mode. At all other times it is acting as a generator which includes travelling at a constant forward speed on a level road. It is required to behave as an electronic brake to strip off surplus power coming from the PSD and feed it to MG1 (the generator) which acts as a motor and assists the engine to provide maximum torque through the PSD. This is the true Prius action, its purpose is to make the engine think it is always climbing a steep hill at 18mph or whatever when reality is that it is travelling at 60mph,say, on a level road. The engine is made to run at full torque,wideopen throttle, but at the lowest rpm that will provide the power to move the vehicle at whatever roadspeed is desired. These extra low rpms are commensurate with obtaining exceptionally low frictional losses in the engine which equals great mileage. There is going to be some debate about this latest design move which will include lots of talk about virtual power. Virtual power that can always be made to exist when two electrical machines are connected back to back with their shafts coupled together. The problem here is that virtual power does not accrue virtual losses. That would be nice. On the contrary it generates real losses. In this case even more losses than the earlier designs since the virtual power loop extends from the PSD right down through the two stage reducer to the final gear iself and then comes back to MG2 through MG2's pinion. To recap. In the first two North American generations of Prius (MY1999 and MY2004) MG2 was coupled directly to PSD planetary ring gear. Zero mechanical loss in this path obviously. But MG2 limited to 6000rpm meant a high torque motor with large frame size required. In MY 2010, MG2 was coupled in via its own planetary. (the planetary carrier being locked stationary with gearbox frame) The ring gears of the two planetaries were joined together. A real loss attributed to virtual power would now occur when the virtual power passed through the motor planetary when MG2 was in its generating mode. In MY2017 as stated above .....virtual power loop extends from the PSD right down through the two stage reducer to the final gear iself and then comes back to MG2 through MG2's pinion.
Vupilla wrote the braking power of the Genset can be easily increased to 20 KW, even 30KW. Recently I was speaking to a Toyota mechanic who was understandably very familiar with Prius service issues. I mentioned I had seen brake rotor discs that seemed like brand new despite tens of thousands of kilometers of use. He responded whether I had seen what the brake calipers look like ? Normally the heat from the rotors is enough to dry out the calipers and prevent rusting. Everywhere, that is, except on the Prius where the recuperation of kinetic energy into electrical power interferes with that process causing brake systems to rust badly. So having as little as the 10Kw braking allowed by Prius software already has quite an effect. I somehow doubt raising this to 20/30Kw will be any more propitious unless we can raise it significantly to a value that would allow removal of the front brakes entirely. I can see that if lobbying by those with EV interests can get to a point where side mirrors can be replaced by cameras (for aerodynamic reasons) then I can see elimination of some mechanical braking equipment being next on the agenda. Finally we have to accept that except for the extreme cases - there will always be those living in underserved regions to whom gasoline vehicles make sense - the fact is the majority of the population will benefit from pure electrics supported by some form of reliable supercharger network.
ARPA-E also announced funding for SBIR/STTR projects under its GENSETS program which aims to design, build and test improved electric-power generators for use in residential combined heat and power systems. The GENSETS SBIR/STTR program aims to develop 1 kWe (electric) sized generators that are highly efficient (40% or greater); long lasting (10 years or more); low cost ($3,000 or less); and clean. The projects fall under three areas of technology focus: Stirling engines, internal combustion engines, and microturbines. It is good to see ARPA proposing a model which does not align with the old school method of distributed electrical power. It's probably safe to assume that the electric power generators here are undoubtedly intended for running on natural gas. To most of us it should be irrelevant how efficient megascale generating plants can be made when at the same time the residential buildings they supply happen to have their space heating provided by open flame natural gas furnaces and as we all know these forced air systems have a thermodynamic efficiency of ZERO per cent. I wrote this about six months ago and not sure whether I got around to posting it, my apologies if this is a repost. IT is an obvious but important fact that when consuming natural gas there is but one chance to obtain electricity from this process by the appropriate use of thermodynamics. Since both electricity and mechanical power are both needed in a residence besides space heating it would seem unwise to waste this one time opportunity by the almost callous misuse of burning this non renewable energy source in the typical open flame gas furnace without considering a thermodynamic option. Methods are available with alternative equipment to allow the capture of a portion of the results of this combustion for conversion to electricity generation with the overflow providing heat for the home. The simplest method is to use a single cylinder engine. There would be an emphasis to extract heat from the exhaust gas by a heat exchanger system before the spent gas is expelled up the flue. The operation of the heat exchanger would be governed by the amount of home heating required before the gas is expelled. If insufficient thermal heat is available the electrical power being generated could be increased by dissipating it in an electrical heating element located in the forced-air heating plenum. The increased load on the engine would require the consumption of an increasing amount of gas the combustion of which will yield an even greater amount of exhaust gas. The multiplying effect of this electrical load by the plenum heater would amount to approximately a threefold output in the thermal heat expelled for an engine of 25% efficiency. A relatively small electrical load can therefore leverage a much greater amount of space heating. The use of a small engine can be magnified further by the assistance of lead-acid or lithium ion batteries. In this stationary applicaton neither space nor weight is of a premium, lead acid has the price advantage at the moment. The safe storage voltage is suggested to be around 24V DC. Lighting and most electronics could be found to suit this voltage as well as most kitchen counter appliances although some of the latter may need fitting with suitable plugs rated at 30Amps in order to be acceptable. Further consideration is required for the more extreme demand devices consisting mainly white goods like clothes dryers and cooking ranges which will probably need be operated at conventional voltages. In each case an electronic inverter with an output of 220vAC with a 6Kw rating should be installed. Additionally these particular inverters would need to be located adjacent to the battery system. Since each inverter could be drawing as much as 250 amps from the 24Volt supply then clearly some power management involving the interleaving of a multiplicity of these devices will need be in place. Some of this peak current demand from the storage battery will be offset by the current supplied from the engine generator assuming a reasonable expectation of it having a continuous rating of around 100 amps. Dryers rarely run for more than an hour and even the peak load of an electric range is usually less than 20 minutes and that normally occurs whenever the oven is needed to be brought up to temperature. Inverters should be arranged in a hierachy so that the least essential item will be the first to be disabled. In lieu of a direct gas heater for domestic hot water a secondary heat exchanger loop of de-ionised water at low pressure could be sent over to a remote domestic hot water heater with insulated piping. It could circulate around or even through the hot water tank depending on the design before returning to the heat recovery unit of the exhaust cooling system. As with the previously described forced-air plenum and its electrical heating element an immersion heater for the hot water tank would have similar effect on the electrical generating system with the increased load on the engine requiring the consumption of an increasing amount of gas. As before the element could have a reduced rating owing to the thermal assist boost from the heat recovery unit. Summer would differ from winter operation by arranging for the forced air flow in the plenum to bypass the heat recovery unit.
the car can also generate electricity directly from hydrogen stored outside the vehicle. You know, when I see a hydrogen storage tank being installed by my neighbour, the next thing that will go up is a "my home is for sale" sign. Most around here will not even take the time to prune their trees and now they are going to be entrusted with hydrogen tanks on their property ? Heck I am not even allowed to store my BBQ propane tank indoors.
First I am not familiar with Schaeffler from this project it sounds like they are an engineering school. It is nice to see an Audi involved in yet another "green" concept car while some of their diesels are less than "golden" right now. It's hard to be positive on belt drive assisted systems. Is this ever likely to grab the attention of the average Audi TT buyer ? I think not. It kind of shows the mindset of these legacy auto companies or whoever, hanging on for the sake of an obsolete technology particularly when there is some government handout somewhere along the road. Meanwhile, in other news, the first Model X officially rolled off the production line yesterday evening from you-know-who. In a way this too is a concept car. But the concept here being that you can go online, assuming you have the wherewithal, and actually order this car today. Wow ! What a concept ! But to continue, the above article does not specify the battery capacity or motor therefore it is difficult to comment on perceived performance. For anyone doubting the facility of providing electric-only driving on city roads with only 48 Volts, well there was a time when I was involved with the design of a controller for a street legal EV which achieved 45mph pulling about 80 amps from a 36 volt Pb-acid 18Kwh pack electronically limited to 400amps. Of course, that was more than 30 years ago and we were doing it with our own money. An electric rear transaxle will need to be similar to that fitted to the Lexus RX450h with two ratios and a clutching mechanism. It would be expected that a small motor geared initially for low speed driving must be able, later on, to avoid the major motor rpms that would otherwise be imposed on it when the gas engine pushes the vehicle above 100mph, which a TT might be expected to do.
Marshall wrote: Electric is not there yet. Also, if you're driving in Africa, your odds of finding, say, a level 2 charging station is pretty low. About the same odds as finding UREA in Toronto I would think. Although any place where they decide that having 500 miles between gas stations is OK then I guess worrying about pollution would be the least of your worries when you run out of it.
I have always been enthusiastic about series hybrids as a superior way to use gasoline power. Sometime in 1979 I was made aware of the 1914 GALT located in Ontario at the Oshawa motor museum. It used a two cylinder engine along with an identical pair of 5Kw motors. The museum staff allowed access to photograph the underside that's how I know. The nameplate is marked 90Vdc 900rpm Shunt Wound Motor. Schematics were not stored at the museum so exactly how the motorist was meant to control the MG set is not available. Only one was ever built however. Today I am convinced this idea could be made to work efficiently with an AC motor drive system along with a small engine similar to the turbocharged parallel twin from Fiat's Panda. Originally known as the Aria concept engine when introduced in 2007 this powerplant is now optioned for the iconic Fiat 500 in Europe and the UK where its performance earned it a spot on a Top Gear. Meanwhile Toyota's Prius models and the GM's Volt continue to cling to four cylinder engines even though it is known that less cylinders equate to less emissions. That said, the problem continues to remain, however successful this newer transitional technology could become, it is still supporting personal mobility at the expense of urban pollution and that is something we have to stop. In the meantime the landscape has been changed by Tesla's Supercharger Network which today offers an alternative to gasoline in the dispensing of energy. I think the real challenge for manufacturers is not to be seeking alternative powertrains or providing EVs with longer range at lesser cost, rather it should be to target affordable ~$30k cars able to take advantage of fast charging from other than Tesla's propriety system.
Need to hear more about what active temperature control - both heating & cooling - has been built into the battery pack enclosure. IMO consideration should be given to providing significant underside insulation to guard against overwhelming the cooling system during summer driving particularly on sunbelt roads as has been reported. I write this because it is becoming increasingly recognised that the battery is the car if strong residual values are to be realised. Otherwise it is possible that leasing of EVs will become the predominate mode in areas that frequently experience extreme temperatures.
Evolute last week now Bosch. God there is so much wrong here I don't know where to start. Unlike conventional ~400-volt full hybrids, the 48V system can utilize less expensive components. So first, what are these full hybrids that run on ~400V ? I personally don't know of any full hybrids on 400V but if they meant full electrics then Model S from Tesla fits that bill. They certainly can't be referring to the Prius because from 2004 that vehicle has been employing 500V with a 650v Sport upgrade arriving in 2010. So you could say that Toyota's collective experience has not made them averse to the use of high voltage semicons when over the years they have manufactured more than 8 million Prius. That last million being produced in the past eight months, or so I believe. That said, I would think that the adoption of 48V by Bosch probably has a lot to do with the powering of other ancillary equipment on board that could benefit from a higher voltage than 12V. History has not been kind to belt-assisted hybrids. The Malibu hybrid lasted just two model years being marketed mostly to rental fleets at the end. It didn't produce the expected fuel savings and the driving experience was was also less than stellar. History has not been kind to non belt-assisted hybrids either. Honda produced an inline-assist with 15Kw motor for the Honda Civic and the V6 Accord to take on the Prius which has two motor/generators. If they had just released the Civic with its specialised 1.3L engine without the battery assist it would have done fine IMO. However the inadequate battery charge management system hardware including insufficient battery insulation and of course the lack of battery temperature environmental control meant that oft times the Civic was operating as a Hybrid in name only. Amost inevitably in early 2012 a court case was won by an owner whose car did not provide the advertised savings and by 2015 Honda dropped their hybrid owing to the poor showing in sales. The future for the Malibu now includes mechanical solutions in the form of 6-speed transmissions. The future for the Civic Hybrid is that Honda is going to re-introduce their hybrid with a downsized version of the two motor configuration as equipped by the 2014 Accord Hybrid.
What you found in catalogs are probably not high performance motors, for cost reasons they may have used the same stator. Alex, the motors in a Eurotherm catalog are Premium Effcy with copper rotors - aluminum is being phased out as more and more newly installed motors are being inverter fed. I refer you to the catalog to see first hand that 460Vac 10Hp 2-pole and 4-pole weigh the same even though the former puts out only half the torque of the latter. It gives a more poignant look at the situation. I know I am repeating an earlier post, perhaps I wasn't clear enough, but an intelligent person like yourself may opt for a 230Vac 5Hp 4-pole which makes the exact same torque as a 10 Hp 2-pole (but will naturally weigh and cost a whole lot less) and drive it with a 460Vac inverter at 120Hz to reach ~3600rpm and thus match the performance of the larger 2-pole. Hopefully these facts and ideas will lessen your enthusiasm for the use of 2-pole motors which today is now a dead end as far as I am concerned. You are probably already aware that catalog motors are unsuitable anyway since their windings have a V/Hz of 480/60Hz = 8.0V/Hz Automobile inverter motors are more likely to be 0.25V/Hz. Just need 32X more current to reach the same torque. That's where the 1500Amp IGBT's come in. Their use completely changed the picture as they effectively extend the useful voltage range because the adoption of an extra low V/Hz motor winding allows the motor to spin 8X faster before the inverter runs out of voltage headroom. Tesla was among the first to use them with the legendary 2.8sec to 60 ramp with fixed gear P85D. So I am thinking how much more proof do you need ? Anway congrats on figuring out what is basically turns out to be the equivalent of the cube root of two, it looks like the generic formula is the cube root of the number of divisions you make of the original motor. As you discovered, the utility of two motors suggests 26% better cooling/or more power. From that perspective I think you will find that four motor systems begin to look even more interesting.
See if I've got this right. 20,700rpm to 9000rpm in 80mSecs. So you're thinking you can regen a rotor the size of a 1lb coffee can to give up 75% of its rotational energy in less than a tenth of a second. Sorry, not possible, the physics is just not with you. Do you think is a hypothetical question. 4-pole (2pole-pair/phase) induction motors have twice the torque per unit mass so 2-poles are rarely used except to avoid an inverter. Examine a motor catalog for specs, a 10Hp 2-pole and 4-pole will be seen to have the exact same weight, although the 2-pole will have smaller dia rotor. How do I know ? Compare their rotor inertia constants. Actually the best way is to run a 230Vac 4-pole on 460Vac @120Hz. The motor will develop twice its nameplate power and run cooler. Has it been done ? Yes. The Tesla system takes the idea further by winding for @480Hz (~14,000rpm), in this case the stator lams would be made thinner of course and the rotor would be finely balanced to enable it to run with low vibration at that speed.
Alex, no I hadn't heard, but a somewhat less sophisticated alternative to avoid rotor overheat is to cut the rotor in half so to speak and then use the two resulting downsized motors to separately power each axle. Theoretically the effect is to increase surface to volume ratio by 26%. That opens up the possibilities of more power per motor but with the same motor case temperature as the original single motor drive system. Splitting the drive unit like this also confers AWD something the Evolute isn't offering I notice.
SJC , I'll give one more kick of the can to this. electric motors are not always 90% efficient Not at slow speed and full torque, I'll grant you your point which is exactly as you stated in your first post earlier in this thread. But these occurences of slow speed operation (<20mph)do not present a significant loss, in total, of battery energy for several reasons. They are usually of very short duration when accelerating from rest, sub 3 seconds. They exist during prolonged slow speed operation where the motor demand is bound to be very low so electrical losses are going to be expected to be proportionally low as well. Finally within this low speed region, the vehicle may actually be slowing down with or without regen braking. No losses at all. Aerodynamic losses, which I consider the biggest battery killer, are almost zero in all these scenarios. If this was an industrial machine then a CVT may be a good idea if considerable high torque while running continuously at low speed was required. BUT for a road vehicle any heavy demand is only transitory as the motor drives the inertia of the vehicle up to cruise speed. I don't see the need for any further mechanical complication to be added here. If I haven't convinced you by now then at least you are in good company with Evolute Drives they don't see it either.
I seem to have a complete earlier post wiped thanking Mahonj for the Chrome suggestion, and then SJC reposting a link I could use. Plus comments on the content of that link. ?? Of course that would be the post that I didn't save, because the system told me it had been posted. I began my response to Yoatman almost directly after.
Yoatman, The bigger the e-motor is, the more current it'll draw under load from the battery. Look, current is not the issue here, rather it is the ability of the motor to deliver power to the load. At low rpms there can be 1000 amps in the motor but no more than 75 amps being pulled from the battery. So motor current is not a problem to the battery when accelerating from rest. As the vehicle gathers speed the voltage to the motor is increased proportionally to maintain torque. I think that makes sense. As the controller applies more voltage while still supplying 1000 amps clearly the battery, for its part, has to supply more current. Simply put the battery voltage times battery draw must equal motor current times motor voltage. In this case since the battery voltage is fixed and we have decided to fix the motor current at 1000 amps, then as the motor voltage rises so must the battery current in order to balance the power IN equal power OUT equation. Yoatman, I could go on and on because there is considerably more to be written for a complete understanding of the all the issues and I have only touched on one of them here. There are other issues involved. These issues concern motor V/Hz, Fixed gear ratio. Max motor rpm and max vehicle speed. The first issue is when to allow motor voltage to hit the battery voltage. The second issue is how soon should the battery current be limited before the first issue takes effect. Finally my personal favorite "How much do max road speed bragging rights impair system performance with fixed gear systems ?"
SJC , understand that although my "Vista" browser is said to be all knowing and all powerful but Just not able to find attachments. Would you mind a cut and paste here so that us lesser mortals can see what smug village has produced in Teslamotor land, please and thank you. By the way in case there is misunderstanding about the P85D. It does entirely achieve the 2.8 sec to 60mph ramp as promised but the 85Kwh battery causes the reigning in above that speed. A larger 90kwh is in the offing(at a price) which will significantly improve subsequent acceleration beyond 60mph.
I suppose if you make gearboxes, every problem looks like a gearbox problem. Yes, Evolute Drives clearly know little about induction motors or must be reading from 30year old textbooks. Induction motors can be operated at constant rated torque over their complete speed range providing the inverter voltage is made sufficiently high. For short time durations induction motors can output a Peak torque of up to 350%, perhaps as high as 420%, before electrical constraints step in. Durations are also limited to avoid rotor meltdowns. Forget about efficiences quoted at 60Hz since automotive grade 4-pole induction motors don't usually spend much time there (~15mph). The fact is that induction motors are more efficient the faster they spin, perhaps as high as 99%. The reason is simple, it takes a certain power to establish the stator field. With the setting up of the magnetic flux needed for rated torque, power output becomes simply proportional to the spin rate. No more power is needed to maintain that torque. Think of it as a fixed tax that has to be paid following which conversion of power from electrical to mechanical is 100% efficient. Theoretically, unlimited power lasts for as long as the rotor can survive the rpms but in practice, and it's usually somewhere below 60mph, the motor output has to be constrained electrically by the controller in order to prevent thermal distress to the battery pack. This is the problem faced by the Tesla P85D that has some owners riled up. To recap, since both efficiency and power increase with rpm it should never be necessary to spin down the motor as you would do with an ICE powered car. This should make the need for a multi-ratio gearbox somewhat moot.