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Hybrid Vehicles Hybrid Vehicles - Archived Discussions How do Hybrids work? Newbie questions encouraged! 
139 messages, Last post on Aug 02, 2007 at 5:38 PM
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He thinks the ~200 volt hybrid car will somehow catch the house on fire... ...never mind that the house has LIVE 220 VOLT WIRES running through the walls! (shaking head) People are strange. |
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I am unclear as to the exact behavior of the regeneration function. Are there quantitative differences in regeneration between a) coasting; b) braking, and c) coasting in "B"? Also, when the display indicates that the ICE is supplying power to the wheels and also recharging the battery, is this a different level than the three modes mentioned above? Thanks for any clarification. jprice |
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Replying to: robertsmx (Dec 06, 2004 7:38 am) Since the "electric assist" of the Prius drive system is in fact an integral part of the drivetrain (unlike Honda IMA which is only supplemental) were the electric drive to fail, the car is basically out of operation. However, because the designers realized the critical nature of the electronic componentry of the THS/HSD system they took a lot of pains to make it as robust as possible. With the power split device, if you don't have control over the rotation of the motor/generators you don't have the ability to modulate the effective gear ratio of the drivetrain. So a better comparative question to ask is would your F-150 run if the transmission were to suddenly seize up or lose its fluid? |
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Do the friction brakes on the axle supplying regenerative braking stay off till regenerative braking fades or is it a blended system where both are active?
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Replying to: typesix (Dec 29, 2004 1:36 pm) In "motor" mode, the electric motor is providing torque to the wheels to turn. Now when you have to stop in a vehicle without regenerative braking, you must apply brakes sufficient to counter the torque (and energy is lost in the form of heat). With regenerative braking, the electric motor now becomes a generator (role reversal), converting mechanical energy to electrical energy. Some of the torque from the turning wheels now drives the generator which manages to capture some of the overall energy into useful form (electric charge). For the rest, you would still need to use conventional brakes. Regenerative braking simply reduces energy lost by minimizing the need for conventional braking (as much as possible). |
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Thanks for the answer. I was curious as to how the braking was setup, as many mass transit vehicles such as subways/streetcars are set up to hold off the friction brake till the dynamic/regenerative braking fades, usually 15 mph or down to 1 mph with electronic controls.
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Replying to: typesix (Dec 30, 2004 9:55 am) ___Except under a given higher then normal brake pedal pressure in which all Regenerative braking is overridden to allow ABS (Anti-lock Brakes) in the case of the HCH (Honda Civic Hybrid) and Insight, ABS, EBD (Electronic Brake Force Distribution), and TC (Traction Control) in the case of the AH (Accord Hybrid), and ABS, EBD, TC, VSC (Vehicle Stability Control), and BA (Brake Assist) in the case of the Prius II if so equipped. ___Good Luck ___Wayne R. Gerdes
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Replying to: xcel (Dec 30, 2004 10:17 am) This brings up an interesting perspective. Why would regenerative braking be overridden for ABS? ABS should be independent of the transformation of electric motor into an electric generator and monitor/impact wheel lockup during braking.
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Replying to: robertsmx (Dec 30, 2004 1:46 pm) Why would regenerative braking be overridden for ABS? ABS should be independent of the transformation of electric motor into an electric generator and monitor/impact wheel lockup during braking. ___The lowest rotational speed of any/all wheels during an impending ABS or other safety function is probably to slow or switching so fast from impending lockup to release and back again for regen to recover anything anyways so it’s best to remove the Regenerative braking functions for safety purposes. I am sure the engineers that designed the various regen and assist systems were given a design basis that under any emergency, all regen and assist functions are not to interfere with the safety engineered functions in any way shape or form. This is the case with the Insight and I have not read of anything different with the HCH, AH, or Prius II yet. ___I have read of future hybrid electric drives that will control all safety functions vs. locked out as is the case today. If the electric drives were designed to switch this fast, they probably could but I don’t think we are ready for brake by wire and electrics just yet  In the case of the Insight, the transition from regen to release or assist or assist to regen isn’t nearly fast enough for any emergency braking condition in my experience. The HCH, AH, and Prius should have improved upon this but the electrics are asked to perform a huge task to switch from regen to release and back so many times a second for such little M/G sets that it makes sense to me to leave them out of the equation. ___Good Luck ___Wayne R. Gerdes
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