Pulse and Glide in EV Mode

As in accelerate electrically in an inefficient range then coast down to an efficient one again? I doubt it.

What you might find is a mileage boost accelerating hard with the ICE then coasting for a while in EV.

 

You don't P&G in an EV: accelerate very gradually and then maintain an efficient speed (LEAF's best is 38mph, I believe) - so DWL rather than P&G. You glide only when you need to lose speed: in the Volt Wayne Gerdes found the N-glide to be very effective, but the PiP might glide nicely.

 

Pulse and Glide works with a gas engine because gas engines are inefficient when lightly loaded. This isn't the case with an electric motor like that found in the Prius. P & G in EV mode will be less efficient than straight EV driving. This is due to the nonlinear nature of aerodynamic drag. The net speed of a car during P & G is the average speed, but because the pulse phase is faster, the total drag comes out higher for P & G.

Tom

 

You could pulse with the gas engine and maintain speed with battery. No need to glide since you have the luxury of extra juice in the PHV pack.

 

Only glide is to be kept, that is, a Neutral state, as ItsNotAboutTheMoney said.
Pulse is useless, since motor efficiency does rely more on speed and current.

 

I think you you might have meant the above. Unless you are talking on just the glide ability of the Volt.

Gerdes did get poorer results when trying to P&G the Volt in electric compared to steady state.

Electric motors do have a point at which they are at an efficiency peak. Their power peak happens at a lower rpm though. So you probably won't hit that efficiency peak during a pulse.

The peak is also relative to the motor's output range. They are still efficient at all rpms, and being in or out of that peak likely wouldn't have much affect on a car's real world efficiency.

 

Gliding to maintain momentum will still be critical. Pulse rates not so much.

On the highway, DWL will rule. In town, one is always needing to glide for timing lights and traffic. You still want to avoid regen conversion losses, hence you are either applying power or gliding for max mileage.

Unlike cars using their gas engines, the rate of pulse will not matter much, and the aero losses being non-linear will take high speed p&g off the table.

 

Should note I suppose that outside the very narrow electric range P&G should still be viable just like in a conventional prius.

 

As folks have said above, in an electric car, or a plug-in hybrid during its electric operation, the most efficient is gentle acceleration, then maintain speed, then coast to a stop. Note, however, that traffic courtesy dictates that you not accelerate slower than the flow of traffic, or coast when it would hold back other cars.

Once you've depleted your grid charge, and the PiP is operating like a regular Prius, P&G should work the same.

Assuming your trip is beyond your EV range, the best strategy is probably to accelerate briskly (but not excessively) using the ICE, and then switch to electric for the steady-speed driving and the slow-down, and then turn the ICE back on again when it's time to accelerate.

Disclaimer: Hard acceleration under electric power is fun. That throw-your-head-back, no-shifting-needed feeling. When range is not an issue it's a thrill. Of course, gentle acceleration and gradual slowing is still more efficient.

 

Yes, although off-topic, P&G in charge sustain is true in the Plug-in-Prius.
But I have to note that after the "very narrow electric range", P&G is not even necessary to smash the competition efficiency numbers.

 

For the next 20 miles (i.e. from 15-35 miles from start), the PiP would be falling far short of the Volt's 94 mpge or the Leaf's 99 mpge.

 

Also it will be willing to travel with one more passenger and with more 5k-10k in the wallet than the Volt adopter.

Oh nevermind, that is off topic, isn't it?

 

:focus:

Re pulse and glide in EV mode. As already pointed out, it's a bad idea, gentle acceleration (and deceleration) rules for maximum efficiency in full EV mode.

The non-linearity of air resistance has already been mentioned, but even more important is the non-linearity of I^2 R losses. These occur in the battery, the inverter, and the motors. They can significantly reduce the electrical efficiency at very high load levels.

 

I always enjoyed even the very low-power EV mode of my Prius. So I agree with the above. Note that, according to a review I read (and I expected this) even in EV mode, the PiP, like its non Pi cousin, will run the ICE if you punch the accelerator. This is actually a good thing on longer drives, given what the PiP is. Under hard acceleration, using the ICE is more efficient. But it's a bad thing on short drives where you'd prefer not to use any gas.

I think we'd have to call the PiP a "mild" plug-in hybrid, since heavy power demand will always run the ICE, regardless of the state of charge of the battery. Its ability to blend gas and electric is a plus, but its insistence on doing so when power is demanded, is a minus.

 

The blended pulse with an electric sustain then glide that Daniel pointed out might actually be the best way to go in terms of pure efficiency.

 

Pulse, meaning hard acelleration to get up to speed, is a bad idea but glide is by no means a bad idea in some circumstances. I have roads where I can glide for more than half a mile while my speed drops about 3mph, then a gentle acelleration back up to 38mph and I am good for another long glide. You just have to use glide more selectively

 

Calling it blended plug-in hybrid is enough for the definition.

"Mild hybrid" was used for some hybrids with lesser use of capabilities of the motor/engine system than a "full hybrid", since they couldn't move without ICE spinning in many occasions.
Making a Civic IMA plug-in-able would change it to "mild plug-in hybrid", wouldn't it?
PiP does use split sources, which makes it a "full plug-in hybrid".

 

Yes it was only in full EV mode (which I think the OP was talking about) where pulse is a bad idea, blended mode is another story. Pulse in EV is less efficient than gentle. I think everyone accepts this, I was just trying to clarify the reasons why (I^2 R non linearity).

Yes, that's essentially just using the terrain to your advantage. Allowing your speed profile to vary slightly so as to make best use of the given terrain is generally going to help with efficiency.