70 mph EV only mode.

ok then i have a special prius.
always know that haha

 

MG2 is rated at 50 kW. I thought the 21 kW is limited by the power the HV battery pack can provide. If the larger NiMH GP pack can provide more than 21 kW, does the OEM BMS allow this? I am guessing no because all the wiring and inverter are not designed to draw more power.

Do you mean over-revving MG1?

 

Under normal conditions, the Prius will draw around 21 KW under maximum load on the motors. They're technically rated at 50 kW yes but that's to protect the motor--they are intentionally over-rated.

Keep in mind that the motor also has to start the ICE so you will see large spikes when the ICE starts. It's over-rated to allow for roughly 21 KW during normal driving and then brief spikes to start the ICE.

The inverter does do a form of current limiting, though again it is also over-rated to protect itself. Theoretically it could be pushed harder than it is but that would certainly void any sort of warranty from Toyota.

There is also the issue of the wiring that goes underneath the Prius to the front. It would need to be upgraded to allow for greater than 21KW of electric power for extended periods of time.

In short, it may be possible to get more than 21KW from the motor, but I wouldn't want to try it on my own car without a backup inverter or two and fire extinguisher =).

Andrew

 

Let's be clear. There are two electric motors. MG1 is responsible to start the ICE and MG2 is the traction motor. MG1 is thought to be rated at 30 kW while MG2 is rated at 50 kW.

The HV battery is rated at 21 kW so the additional 29 kW has to come from the MG1 generator to fully use the 50kW MG2.

Is it your understanding too?

I understand the point you make about the battery being rated at 21kW but in some cases, it can provide addition powerful momentarily.

I was just wondering if the battery pack can provide 50kW, can MG2 use it?

 

In theory, yes it could use it. The inverter does do power limiting while allowing for the occasional boosts (which is where you see the random boosts of power come from) of energy, though it's not clear whether this is limited by current or voltage.

Andrew

 

Hi Andrew,

One of your messsages implies that the Prius MG2 has a 29 KW, or 238 % overrating. This is not the case. As MG2 has to handle power from both the 21 KW battery and MG1 by way of the inverter.

I believe this is what USB... is getting at.

 

FYI,
Following site shows the specification of the Gen2 plug-in prototype Prius from Toyota.
TOYOTA News Releases - Toyota Plug-in Hybrid

It is based on the Gen2 Prius with dual battery pack in parallel.
It uses the same engine(56kW) and MG2(50kW), but it's system power is 100kW comparing 82kW on the standard Prius.
It means the battery power is 44kW on the plug-in and 26kW on the standard.
Also, please note that the max EV speed is 100km/h(62mph).

The Chief Engineer of the plug-in project said there is no modification on the Prius drivetrain, no electric oil pump added to the PSD.

Ken@Japan

 

Hmm that's interesting. I guess they had to upgrade the wiring that goes under the vehicle since it wasn't originally rated for that kind of sustained current draw? It's also interesting that they are still using the 202v nominal pack voltage.

Too bad they aren't already selling these--though I guess if they were, we wouldn't be having so much fun now hmm? =).

Andrew

 

andrew did you not follow the news that this Nimh plugin gen 2 project already stopped ( sofar i know ) and there are already gen 3 prototype's on the road with Litium based packs...
i guess these 2 nimh packs design is not one i think will work that great.
to short range.

 

Yeah, I'm aware of the new gen 3 Prius PHEV prototype. I just found it interesting how they did the gen 2 Prius. I figured they go with Lithium for the long term solution given the greater energy density and higher power output. We'll see what Toyota comes up with I guess.

Andrew

 

well i did the test.

and i did not even use the BMS+

i can easylly pull 100+ amps in full ev without the use of the ice
and also accelerate hard without the ice kicking in ( only when i floor it or want to go even faster )

but in the EU whe have the ev button ( that i needed to push ofcourse ) and that is something diferent from the priussses you have over there...
but even when you connect a switch to have ev mode in the us prius do you still not pull more then the 40 amps your talking about?

 

In EV mode on North American Prius, scanguage has confirmed I can pull in excess of 90A from the battery without causing the ICE to start.

 

i now read the post of andrew again and its al about pulling that kind of amps when on the highway...
i have to test that again ;-)
but i also did see moments where the ice shutoff ( spinning but no fuel ) on the highway and the electric motor was only providing power. i guess at that speeds there must be more then 40 amps of current draw? or not?

 

I had been in the same situation and most of the time, with a full charge of the reserve batteries, sustaining speed of 65MPH, ICE spin, MFD showing 99, keeping with traffic, all electric mode......

 

and what amps do you draw at that moment?

 

That makes much more sense--yes I was referring to highway driving (51+ MPH). With BMS+ or any similar system we have seen a maximum of about 40 amp sustained current draw at highway speeds. You will see pockets of "EV" behavior on the highway if you pull your foot off the pedal and very very gently reapply it (under 20% throttle). Again, you'll probably only see about 40 amps current draw before the ICE turns back on (or should I say, the vehicle starts burning fuel again). 40 amps is not enough to actually accelerate the vehicle in at highway speeds--in fact, its barely enough to sustain your speed depending on how windy it is.

The hybrid energy manager allows for full EV acceleration without any fuel being burned at highway speeds (so full 110 amps without burning fuel at up to 70 MPH) or a blended mode where you first use all 21 KW from the motor and then burn only as much fuel as is necessary to cover the additional energy to propel the vehicle. These modes apply to any vehicle speed (with the noted max of 70 MPH in EV).

Also just because the MFD shows 99.9 MPG does not mean you aren't burning fuel. If the engine is idling at highway speeds you can expect to see high mileage. For example, if the engine is idling and burning around 0.5 gallons per hour while the vehicle is going 65 miles per hour--which can happen even with a stock Prius if you are coasting or going downhill--that's roughly 130 instantaneous MPG which will of course show up as 99.9 MPG on the MFD even though you are burning fuel. A much more definitive test would be to take the average MPG over a larger period of time--or several miles--to see if you are actually burning fuel. Alternatively, if you have access to a scangauge or similar tool you should be able to tell how much fuel is being burned at any given time.

Andrew

 

Border line of and under -60 Amps
EDIT:
and on "linuxpenguin" comment=" 40 amps is not enough to actually accelerate the vehicle in at highway speeds--in fact, its barely enough to sustain your speed depending on how windy it is."..... that's the reason of my -60Amps line mark for speed sustaining with a very light foot

 

hi andrew,

so with your system there is a continus current draw of up to 110 amps.
but when i read this post http://priuschat.com/forums/prius-p...-electric-vehicle-only-mode-9.html#post965372 ( post 88 )
you comment that with the prototype prius the hv line's need to be upgraden because it can not systain high currents at highway speeds.
do you upgrade them in your system replacing the oem battery pack?

 

The wiring needs to be upgraded only if the amperage draw is increased beyond what the Prius normally sees (around 110 normal with small bursts of up to 140 while starting the ICE ~ 21 KW). The Toyota PHEV Prius must draw a great deal more (since they pull 48kw from the battery with the same pack voltage as the normal Prius) and so they probably had to upgrade their wiring. The Plugin Conversions system does not draw more than 21 kw on a constant basis so the wiring does not need to be upgraded.

Andrew

 

i did not read the toyota technical comments at this moment of writing this
so i am not sure but is the 48kw with the gen2 plugin not the max and not a constant current draw figure?