Old article on 'Prius Classic' - NHW11
#1
Old article on 'Prius Classic' - NHW11
http://www.autospeed.com/cms/A_1450/...popularArticle
Yes, I know it is an older article, 2002, it is well written and may be new to some folks.
Bob Wilson
. . .
Toyota Hybrid System (THS)
The Prius is propelled by a parallel hybrid system, in which two drive sources are employed either separately or simultaneously - a petrol engine and an electric motor.
The electric motor - drawing from a large hybrid battery - serves as the sole power source in instances when the petrol engine is relatively inefficient; this includes driving conditions such as slow-moving traffic jams, sitting stationary, deceleration, light acceleration and low speed cruise. Under these conditions, the electric motor is relied upon for drive, and the petrol engine is automatically switched off - completely eliminating fuel consumption and tailpipe emissions.
. . .
Toyota Hybrid System (THS)
The Prius is propelled by a parallel hybrid system, in which two drive sources are employed either separately or simultaneously - a petrol engine and an electric motor.
The electric motor - drawing from a large hybrid battery - serves as the sole power source in instances when the petrol engine is relatively inefficient; this includes driving conditions such as slow-moving traffic jams, sitting stationary, deceleration, light acceleration and low speed cruise. Under these conditions, the electric motor is relied upon for drive, and the petrol engine is automatically switched off - completely eliminating fuel consumption and tailpipe emissions.
. . .
Bob Wilson
#2
Re: Old article on 'Prius Classic' - NHW11
Thank you for the good article, but there are some errors need to be corrected.
Toyota says it is series/parallel hybrid system.
http://www.toyota.co.jp/en/tech/envi...ths2/what.html
The maximum engine power and the maximum motor power don't perform at the same time, therefore we can't add two of them.
The maximum system power is 65kW.
http://www.toyota.co.jp/en/tech/envi...hs2/speci.html
None can supply such huge 351 amperes, probably approx 100 ampares.
The VVT-i engine does not change the exhaust valve timing, therefore the expansion stroke is as same as a conventional engine.
So, the expansion stroke is nothing related to the Atkinson cycle.
The specification paper says the compression ratio is 13.0:1, but it never goes to the real 13.0:1 ratio.
The intake valles closed very late during the compression cycle, and some intake air blew back to intake manifold.
Then, the real compression ratio becomes approx 9.5:1 or so.
That's how the Atkinson cycle and the VVT-i work!
Ken@Japan
Originally Posted by Article
The Prius is propelled by a parallel hybrid system
http://www.toyota.co.jp/en/tech/envi...ths2/what.html
Originally Posted by Article
Maximum power from the petrol engine is 53kW and the electric motor gives 33kW - total output is 86kW.
The maximum system power is 65kW.
http://www.toyota.co.jp/en/tech/envi...hs2/speci.html
Originally Posted by Article
At maximum torque, the motor draws 351 amperes.
Originally Posted by Article
The Atkinson cycle sees the exhaust valves closed until the end of the expansion stroke - this extends the expansion stroke, enabling more combustion energy to be applied to the piston.
So, the expansion stroke is nothing related to the Atkinson cycle.
Originally Posted by Article
Its pentroof type combustion chambers deliver a high 13.0:1 compression ratio, yet - partially thanks to a knock sensor
The intake valles closed very late during the compression cycle, and some intake air blew back to intake manifold.
Then, the real compression ratio becomes approx 9.5:1 or so.
That's how the Atkinson cycle and the VVT-i work!
Ken@Japan
Last edited by ken1784; 10-22-2008 at 06:54 PM.
#3
Re: Old article on 'Prius Classic' - NHW11
Hi Ken,
It as an older article and I didn't read the technical bits closely. Just a couple of observations:
Bob Wilson
It as an older article and I didn't read the technical bits closely. Just a couple of observations:
- maximum system power - the line in the table above "Output at 85km/h" shows "Maximum output in kW(Ps)/vehicle speed km/h" and shows a higher value, "74(101)/120 or higher." This would be 74 kw at speeds above 74 mph (120 km/h).
- Julian comes from a traditional engine background where compression ratio is the same as the expansion ratio. We know better, compression ratio is not the same as expansion ratio, but given his background and 2002, I'm not too surprised he missed that one.
Bob Wilson
#4
Re: Old article on 'Prius Classic' - NHW11
Hi Ken,
Julian corrected the maximum power output to 74 kW. However, he reports the 351 A. came from a Toyota source that was available at the time. I didn't address your other concerns because I'm not really invested in 'hybrid architecture.' As for the Atkinson cycle, I really hadn't taken a close look in this article since I think we're on the same page about compression and expansion ratios.
I have tremendous respect for Julian and the quality of his writing. Unlike some, he is a responsible journalist with serious engineering credentials. His is the only auto journal I could ever recommend. <grins>
Bob Wilson
Julian corrected the maximum power output to 74 kW. However, he reports the 351 A. came from a Toyota source that was available at the time. I didn't address your other concerns because I'm not really invested in 'hybrid architecture.' As for the Atkinson cycle, I really hadn't taken a close look in this article since I think we're on the same page about compression and expansion ratios.
I have tremendous respect for Julian and the quality of his writing. Unlike some, he is a responsible journalist with serious engineering credentials. His is the only auto journal I could ever recommend. <grins>
Bob Wilson
#5
Re: Old article on 'Prius Classic' - NHW11
I see. I stand corrected.
Let's assume the voltage is approx 250V reducing some value from the nominal 273.6V.
The power is 351A X 250V = 88kW
None can supply such huge 88kW.
The max power from battery is approx 20kW.
In other words, the output power at the max torque range is approx 10kW, then we'll see 78kW (88kw - 10kw) heat loss if the 351A was correct.
The motor will be burnt out instantly.
Ken@Japan
However, he reports the 351 A. came from a Toyota source that was available at the time.
The power is 351A X 250V = 88kW
None can supply such huge 88kW.
The max power from battery is approx 20kW.
In other words, the output power at the max torque range is approx 10kW, then we'll see 78kW (88kw - 10kw) heat loss if the 351A was correct.
The motor will be burnt out instantly.
Ken@Japan
#6
Re: Old article on 'Prius Classic' - NHW11
. . .
Let's assume the voltage is approx 250V reducing some value from the nominal 273.6V.
The power is 351A X 250V = 88kW
None can supply such huge 88kW.
The max power from battery is approx 20kW.
In other words, the output power at the max torque range is approx 10kW, then we'll see 78kW (88kw - 10kw) heat loss if the 351A was correct.
The motor will be burnt out instantly.
. . .
Let's assume the voltage is approx 250V reducing some value from the nominal 273.6V.
The power is 351A X 250V = 88kW
None can supply such huge 88kW.
The max power from battery is approx 20kW.
In other words, the output power at the max torque range is approx 10kW, then we'll see 78kW (88kw - 10kw) heat loss if the 351A was correct.
The motor will be burnt out instantly.
. . .
I've got a Fluke, clamp-on, DC meter but it only goes to 100A full scale. Even some of my earliest measurements with home-made, clamp on coils does not show a huge, startup spike:
Some of the initial startup loads:
During the initial startup, the inverter uses pulse-modulation to prevent excessive current flow. You can see that in this trace:
I don't see 351A in my data but IBGTs handling these power levels are available and were considered according to:
. . . One of the largest in existence at the time was the 1,200-volt IGBT that had just been introduced in the Shinkansen (Bullet Train). The group was also able to find a 600-volt device on the market. If the group were to buy the IGBT, the ones that were available would be at the 600-volt 600-ampere level. The group finally had a rough idea of where to begin. . . . (Prius die de wereld, Hideshiitazaki)
I remember one of the earliest Toyota SAE papers about the NHW10 discussing the use of pulse modulation in the initial startup to prevent excessive startup currents. Bob Wilson
ps. Julian pointed out he didn't write that particular article.
Last edited by bwilson4web; 10-24-2008 at 12:01 AM.
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