ICE load vs. IGN: pulse & glide to maximize MPG

Hi. I am interested in analyzing the "happy mode" of the Prius, discussed under point 7 here. In short, happy mode is when the "ICE can drive directly the wheels", without energy loss between MG1 and MG2. That of course happens iff there is close to zero energy flow between MG1 and MG2.

To see, when that "happy mode" kicks in, and if it exists at all, it would be nice to have the current (A) values measured at MG1, MG2, and battery when driving at different speeds.

Questions:
1. Is there a way to measure the breaking power of MG1 at different speeds? (happy mode probably happens at zero breaking power).
2. Is there a way to measure the current (A) to/from MG1, MG2 and the Hybrid Accu at different speeds?
3. Does somebody happen to have measurement data at different speeds?
Different speeds: let say 30, 45, 60, 75 mph.

Thanks in advance!

 

Hi Mrn. You can use Torque app on an Android device with the custom PIDs.

The goal is to adjust the accelerator pedal so that MG1 and MG2 power is near zero.

 

No, at highway speed (65 mph), for MG1 and MG2 power to be near zero, gas engine has to be around 2,800 rpm. From what I have seen, IGN 14 is possible around 1,280 rpm.

 

That's interesting. If you put the ICE RPM at 2800 rpm and the speed at 65 MPG you get MG1 operating pretty much as a stalled motor.
See Toyota Prius - Power Split Device

The thing about "happy" mode is that it minimizes the circulating energy loss between MG1 and MG2 but it tends to correspond to a fixed "gear ratio" so it doesn't necessarily optimize the ICE efficiency. I've read that sometimes it's necessary to waste circulating power on MG1 and MG2 (eg so called "heretical mode" with MG1 motoring and MG2 generating) to optimize the overall efficiency including that of the ICE.

 

Right, for constant speed. However, the "happy" mode is useful to accelerate at highway speed and the glide with an arrow from the battery (stealth).

For constant speed, Prius will be in heretical mode almost all the time at highway speed. The exception is steep hill or acceleration.

 

You just have to show us that screen shot to make those of us with our little 4 inch phone screen jealous now don't you

 

I recorded this as a starter. I have a second video with IGN Timing Advance at higher speed. Will upload it tomorrow.

 

Ok, here is the second part at higher speed. I meant to do high speed but the traffic prevented me, only reaching 65 mph momentarily.

I think only a hardcore HSD would understand what the heck I am talking about. Yea, I do need a better setup because it is not safe to do this while driving.

BTW, I forgot to add engine load. IGN Timing, MPH, MG1 and MG2 plus others.

 

@usbseawolf, thanks a lot for the videos!

Theoretically the following should hold:
MG1 [HP] +MG2 [HP] - losses* = power to/from the ACCU [HP] + losses*.

However the above equation does not seem to be completely valid:
please see below extractions of time, MG1, MG2 and ACCU values..

Analysis of the 2nd video: (values: MG1..MG2 ..BATT)

0m49sec: +1.6, -3.9, 0.0 => sum of losses: 2.3HP
1m07sec: -2.1, +0.6, 0.0 => sum of losses: 1.5HP
3m45sec: 0.0, +10.6, 11.4 => sum of losses: 0.8HP
5m42sec: +7.1, -9.1, 0.0 => sum of losses: 2.0HP
8m20sec: 0.0, -10.7, -6.7 => => sum of losses: 4.0HP

I see 3 possible reasons for the above:
1) the values shown by Torque have some level drift,
2) the values diplayed by Torque do not correspond to one single moment, ie. the MG1 value is not measured at the same instance as MG2, only displayed at the same time.
3) there is a 1-2HP loss between MG1, MG2 and the Accumulator.

* If it turns out that neither 1 nor 2 is the case, then it would be interesting to analyze where that 1-2 HP disappears.

Questions:
1) is there a way to check the validity of the values shown by Torque?
2) @usbseawolf, could you please make some graphs of MG1, MG2 powers and that loss, as a function of speed, and as a function of the power from/to the battery?
3) Is it possible that MG1 feeds MG2 through the battery, and therefore the loss is introduced by the 650V->200V and 200V->650V transformations?
4) Is there a single pair of cable between the inverter and the battery, or two pairs?

UPDATE:
Analysis of the 1st video:
battery charging mode:
0-60sec, ICE 1300rpm, 1 to 2 HP loss between MG1 and BATT

Car standing, ICE off:
3m00s and 5m10s: BATT shows 0.6HP. Why?

EV-mode:
3m20sec - 3m:30: MG2 shows only 1HP when moving the car ?!?
Is it possible?

deceleration:
5m:00s MG1: 0.0, MG2: -30.5HP, BATT: -26 HP => total loss of 4HP acc to Torque

 

...
I have found this:
"One issue with the MG torque readings is that the resolution is too coarse. So a small non-zero torque value would show up as zero. For example when I glide the torque readings almost always show zero even though there are some HV currents flowing."
Source here.

 

MG1 and MG2 horsepowers are from the HV ECU. It is derived from the RPM and Torque they produce. It is not from the current x voltage it consumed. It could be consuming electricity and making maximum torque but at 0 RPM, the gauge will report 0 hp. Something to keep in mind. The electric motor/generator and inverter losses are also in there.

I think MG1 power goes to the power control unit then to MG2. It won't go to the HV battery unless there is a surplus or the battery needs to be charged.

I don't have the entire HV battery pack voltage, just the current. So I added up the voltage from all 14 battery blocks. Perhaps it created some rounding issue? Perhaps, it is consumed by the 12v accessories and charging the 12v lead acid battery.

At that moment, I may have released the accelerator a little bit. Despite the torque you feel from the electric motor at very low speed, it is pulling only a few hp from the battery - very deceiving! Seeing the realtime data really opened my eyes and put a different perspective on power, torque and speed.

 

Thanks a lot for the feedback!