Scientific American Article on 2010 Prius

Discussion in 'Gen 3 Prius Main Forum' started by joe1347, Apr 18, 2009.

  1. joe1347

    joe1347 Active Member

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    Even Scientific American has a review of the new 2010 Prius. Not sure that I remember SciAm ever doing car reviews before.

    While the online article has the requisite annoying slide (advertisement) show, slide #5 has possibly some new information on the solar panel.

    [​IMG]
     
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  2. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Is that true about the interference? Can we aim that interference at kids with booming stereos and those who text while driving?

    Thanks for the SciAm heads up.
     
  3. SureValla

    SureValla Member

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    does this mean any solar panel connected to a battery will produce this interference? I've never heard of this, how is the prius a special case?
     
  4. HTMLSpinnr

    HTMLSpinnr Moderator
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    I imagine the sine waves generated by the inverter aren't your standard 50/60hz. Amplify that or any higher compliment and I'm sure you'd have some unhappy radios.

    Definitely gives us some things to consider if we choose to attempt to tie the panel into the battery for charging.
     
  5. donee

    donee New Member

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    Hi All,

    To match the voltage of the panel to the battery there will be a switiching power supply between the panel and the battery. To make these things small and light, yet high power, they operate in the 10 to 100 KHz range, and to avoid losses they switch quickly (square waves). Because, the more time a transistor is operating either not shorted or not open, the more power it disipates. The high frequency is neccassary to get the step-up transformers/inductors to a small size, and that is also the efficiency sweet spot of these devices (a combination of shorter wire in the winding, and the permeability losses in the ferrite magnetic loading materials).

    A square wave is composed of a many sin waves. Typically every third multiple of the square wave frequency out forever, but getting weaker and weaker. But in practice the highest socalled harmonics are tapering even further off till they are esentially zero amplitude as the edges on the square wave are not perfectly sharp.

    As the energy is going from the panel to to the battery, they should eventually be able to handle this.

    The panel would act like what is called a microstrip-patch antenna. And based on the size, I would guess it would be just about the perfect size for FM broadcast band (88 to 108 MHz). These antennas are a patch of metal suspended above a ground plane. Of ourse the car radio recieving antenna is right there next to the patch antenna, er solar panel.

    Remember, receivers are detecting power in the femtowatt (10to the minus 15 !) range. A panel hooked to a power supply handling 10 to 100 watts could have leakage easily in the microwatt range at 100 MHz. Which would be a million times stronger than the radio signals (60 dB stronger!). Now getting rid of this noise is straightforward for a guy who works on these kinda filters (me, besides other things).

    Indeed simple capacitors work well at 100 MHz, but up near 2 GHz (cell phone frequencies) the filtering devices that can do 60 dB of isolation become very fragile. Which besides making them expensive makes them prone to failure in a vibration enviorment. At the currents involved the ferrite filtering materials need to be pretty large. So, its not a standard product anybody makes. Microphone and headset filtering on radio used in the field typically can meet these requirements. But these are like $40 (even with all sorts of outsourced piece part manufacture). For the power involved, it might be $100 for the filter/connector (which includes a bulkhead connector body). And at the typical $2 car companies pay for such interconnects, its not going to happen yet.
     
  6. ronhowell

    ronhowell Active Member

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    This is ridiculous! I subscribe to Scientific American, and usually trust their comments on matters scientific, but I find this remark unbelievable. I have 19 200W solar panels on my roof generating a nominal 3.8kW of DC power and I get no radio or TV interference whatsoever.
    Just how could a 59W panel generating DC power to feed a battery cause radio interference. Details please?
     
  7. joe1347

    joe1347 Active Member

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    So is the shorter explanation - to charge the NIMH batteries, the Solar cell array would have to be connected to a DC-to-DC switching power supply that steps up the voltage to 600 Volts from the ~12 volts at the output of the solar cell panel. However, the DC-to-DC converter generates high frequency switching noise - that contains harmonics in both FM and cell bands - when then couples back via the 12 volt DC power line to the solar cell array and then radiates as an RF interference signal using the solar cell emitter (metal) grid as the antenna. Your solution would be to add an RF low pass filter (ferrite?) at the input side of the DC-to-DC converter. Are low pass filters that expensive - or would the DC-to-DC converter be the much higher cost component and since the solar cell array is fairly low powered - Toyota possibly figured that the added cost wasn't worth it (yet)?
     
  8. Flying White Dutchman

    Flying White Dutchman Senior Member

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    201,6 volts not 600
    600 is for the MG's

    o wait its not even 600 but 650
     
  9. HTMLSpinnr

    HTMLSpinnr Moderator
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    Any thoughts on an interconnect w/ the 12V battery instead? No switching power supply required.
     
  10. dogfriend

    dogfriend Human - Animal Hybrid

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    I see this as a potential product feature. Especially for the cell bands. Now if we can just make it directional so we can choose which cell phone(s) to jam. :madgrin:
     
  11. hill

    hill High Fiber Member

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    Well there's no sitching on our Duffy electric boat. Power goes from its batteries, through the rheostat/controller, to the DC motor. It still produces a ton of path noise, not completely canceled using a ferite onion.
     
  12. ronhowell

    ronhowell Active Member

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    Thank you Donee and Joe1347 for the explanations - on reflection I did jump to some premature conclusions, overlooking the fact that to charge the HV battery the panel output voltage would have to be boosted to something higher than the 201.6V of the traction battery pack. The solar panel output voltage is probably around 12V (open circuit), based on info I have on Sharp photovoltaic panels; any intermediate power inversion would obviously sap power, which is already low to begin with, quite apart from other considerations.

    Also I had entirely forgotten that my TV signal arrives via shielded cable, so external signal generators have to be really powerful to affect the input! (duh).
     
  13. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    #5 is interesting and the solar panels rooftop position and size is why inference would happen...

    personally #8 get more of my attention

    The fact that Toyota has reportedly slashed the Prius's price by as much as $4,000 to match the Insight's $20,000 price tag seems to confirm that view.

    also the 72 MPG by an albeit novice driver was also interesting. granted they used hypermiling to get those numbers; but as we all know, hypermiling is a work in progress. to get those numbers with minimal practice means that some here would get much more with experience, knowledge of the routes and perfection of the techniques
     
  14. efusco

    efusco Moderator Emeritus
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    This clearly makes the most sense to me. I have to believe one of the first mods we'll see will be someone tapping into the solar power supply and feeding it to the 12v. If one could find a way to preferentially use the solar power to recharge the 12v, rather than the DC-DC inverter from the HV, when it has power available then you would be using accessories like radio, computers, fans etc. totally free of energy drain from gas/battery. While this might not offer a huge MPG benefit, at least you're getting something out of those panels rather than just hauling the weight of them around for nothing.
     
  15. fuzzy1

    fuzzy1 Senior Member

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    Not much capacity in that tiny 12V battery to soak up that solar energy either. Like filling a teacup with a firehose, most of the available supply just has to be dumped.
     
  16. ronhowell

    ronhowell Active Member

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    I agree. Would be interesting to know Toyota's rationale for selecting the option they did, as opposed to simply tying the solar panel output to the 12V battery. The small fan that the panel operates presumably uses a 12V motor.
     
  17. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    I suspect that they gave up on charging at the first hint of unplanned trouble. The batteries have to work 100% of the time without the solar panel, so there is no battery need. The energy of the solar output is not going to make much of an mpg improvement if it did. Yet dumping excess energy is not the mindset of Prius engineers if excess energy is available to charge. What to do?

    Answer-Charge the battery if it does not add to the price of the car or delay the delivery. One the EMI noise showed up, it was an easy decision.
     
  18. Rybold

    Rybold globally warmed member

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    Hahaha! Brilliant ! :D

    I've been reading SciAm on and off for the past two decades. I'm not positive, but I think they did a feature on solar cars once. Transitioning from ICE to hybrids to PHEVs to EVs is SCIENCE that will effect the entire human race and the entire planet. I can very well see why SciAm would have an article on hybrids. But ... why the Prius ? (I think that is what your question is asking. hmmm. I see your point). Perhaps it is because the Prius is pushing the limits and innovating science in numerous areas. Is this the first time ever that a production car has had an EPA rating of over 50mpg? Straight from the beginning of the article "The big benefit is, of course, striking fuel efficiency—the best among sedans on the market." Additionally, through the "ten things" they mention science in all but two. This is not a car review, this is a "Hey, look at this cool new science" article. The first MASS PRODUCTION vehicle to feature SOLAR PANELS, include plant-based materials. And it's a mass production vehicle (aka: for the masses). This is SCIENCE, and it is happening right now, before our very eyes.

    Also, did you notice the bottom of the article? There are several other articles on hybrids, new crash-test safety devices, and eco-friendly houses. It appears that SciAm covers the science aspects of automobiles just as much as they cover the science aspects of everything else.

    ** "Despite the introduction of the new version, Toyota will continue to sell the earlier, second-generation Prius, as well." --I know they are doing this in Japan, but has this been confirmed for the U.S. ?
     
  19. donee

    donee New Member

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    Hi Ron,

    Your welcome.

    In your case, the cable signal is usually the source of the interferance when people inside their houses create a cross connecto to an antenna. That happens all the time around here. When Channel 7 gets jammed by a signal with a carrier frequency within KHz of Channel 7, that is almost for sure cable TV leakage some place.

    Our local Channel 7 ABC will be switching to Channel 7 for the HD broacast, and taking down the Channel 52 broadcast. At that time, it will be easy to track down the house with the cross connect. Because the HD signal looks completely different on a spectrum analyzer than the NTSC signal coming out of the cable.
     
  20. PriusSport

    PriusSport senior member

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    The most interesting thing about the 2010 Prius I've read about is how easy it is to make pulse-glide work compared to the earlier models. Reviewers are getting 60-70 mpg on test drives. Somehow, Toyota has made pulse-glide easier to work. I wonder if some of you experts on the technique are willing to comment.

    I use it in local driving of my 08. On the highway, I've noticed that going 70-75 mph can induce more battery, increasing effective mpg--at least on the readout. I wonder if that is real?
     
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