HCH1 Inside the IPU and more power.

[samwichse]

Yep, it jumps right out at you now . There are going to little pics running all over your car soon.

Curious, what format is that file on the fan data?

[retepsnikrep]

You need the free Salea Logic analyser software to view it.

Google is your friend.

[retepsnikrep]

The prototype Data interceptor using the 12F1822 pic works on the bench with an HCH1 IPU IGBT powered up as the data source. The data stream passes straight thru the pic unchanged at present and basically runs a byte behind the data comming from the IGBT.

The baud rate is ~10400 as near as I can figure it, which is a standard rate for serial protocol.

Need to add the data modifying code now.

I'll probably just program in a fixed setting and I'll start with Voltage - 20V so the MCM see's a more reasonable voltage ~170V. I'll have to adjust my voltage tap pot to the same level.
I can tweak it down more later and use the Honda tool to display the Bat V and MPI V so they match better than they do now.

Edit
I think I have the voltage mod code sorted now, I will test it tomorrow it's been a busy day
I can see I will need to change that pot on my fooler matrix for a 100k version to get a bigger range.
With 100k I would be able to pretend voltage was between 100 - 50% of it's true value!

[retepsnikrep]

Just to recap the HCH1 like the G1 detects the system voltage in two places.

1) Via the battery voltage taps, which gives stick pair voltages and a total voltage for the pack.

2) Via the Vpin from the IPU/Igbt Driver board which gives the voltage present at the IGBT power input.

It compares and uses these voltages in the MCM for various functions, including IMA power & current control, main contactor engagement, battery management.

Now we can simulate the battery voltage taps using the very simple 10 x 10k 1% resistor matrix to provide a perfectly balanced input. We can reduce the voltage the system see's with the voltage taps by adding an extra resistor on the + feed to the matrix to give a lower voltage.

We can now also intercept the voltage reported by the Vpin/Igbt data and manipulate that as we wish.

Now the question is should we opt for a fixed lower system voltage or a variable one but with a reduced maximum voltage.

Scenario 1

Add a 20k resistor to the matrix + feed and get battery voltage - x%
Program the Ipu Interceptor to match the % reduction provided by the 20k resistor.
This will give variable current as the voltage rises and falls and operate much as now.

Scenario 2

Feed the resistor matrix from a HV supply provided by a zener diode so it is fixed at say 150V. Program the Ipu Interceptor to fix the Vpin system voltage at 150V. This will give higher current the lower you fix the voltage down to about 125v minimum. However if you fix the voltage below about 140v then IMA start won't work and soc might neg recal all the time and forced charge will be active. So there is a trade off there. I overcame this with the G1 by having a special Voltage boost mode which faked a fixed voltage of around 130V only when maximum assist was being called for, in that situation the car was expecting a lower voltage and ramped up the current accordingly.

The programming of the Ipu interceptor also has to take into account.

1) The MCM uses the fast rise in Ipu voltage when the car is first turned on and the bypass contactor is engaged to charge the filter capacitors and work out when the main contactor can be safetly engaged.

Just a few random thoughts.

[retepsnikrep]

Well interceptor seems to work fine. Voltage is faked at Bat V - 24v which brings it down to around 165v and regen is now operating again Resistor fooler is adjusted to match the IPU interceptor. Lined them up using the Honda Tool to display both voltages.

http://youtu.be/ixz5WtQDU-4

[retepsnikrep]

HCH1 Civic IGBT Power Increase Research Video 3 - YouTube

I don't need it for the project, but for completeness be useful to know which is the temp byte.

Edit

Temp is data byte two in the D2 packet.

Data byte three may also be temp related, but possibly from a heat or ambient temp sensor on the driver board which did not get anywhere near as hot as the base plate I was heating up.

[retepsnikrep]

Tried the simple resistor current hack for +30% Current. gave some IMA errors as expected.

Worked well for assist but gave IMA regen errors above about 45A at low rpm.

Also had problems starting and going into autostop.

Anyway will try the +18.5% version next week.

Need to pull the codes now and have a look at what's what.

[retepsnikrep]

Gathered some live data from the IPUA line from the IGBT to the MCM as the error given with the +30% mod was Motor short circuit. (Not hacked current sensor errors) The only comms from the IPU (IGBT) to the MCM is over the IPUA serial line so there must be a flag in there that is being set.

To be fair the error does not appear under hard assist or moderate to heavy regen at > 1000 rpm. Performance is very lively as you would expect

The problem appears when the motor is starting/autostarting from stop or autostoping under car heavy regen/stop command. This is when motor is stopped or turning over at slowest and when back emf is low and current is at it's peak. Probably also when motor is being driven with square wave instead of sine wave pwm IIRC but I haven't looked at the HCH1 drive waveforms yet to confirm this. If it is using a hard square wave pwm at say < 1000 rpm then current will shoot up when the motor is starting/stopping.

Interestingly the G1 insight does not suffer so much from this problem when using higher current perhaps due to the fact it's a lighter engine internals and only 3 cylinders, so the starting torque reqd is less, which means it spins up more easily and doesn't stress the IGBT. Vice versa for autostop which reqs more regen to stop the four cylinder HCH1 and so the current doesn't fall away so quickly as it does in the G1 3 cylinder lightweight engine crank etc. Just a possible explanation.

So the basic problem with +30% current is igbt overcurrent alarm when starting/stopping/low rpm.

Possible solutions.

1) Abuse the IGBT and find the over current flag in the IPUA data and suppress it! I already have an interceptor on that line to monitor/control the detected voltage and igbt temp etc. Fairly easy to do but may not be good for the IGBT longevity. The IPUA data I have captured today should contain the flag as I have forced the error several times stopping/starting and driving around. The fact the error does not appear every time means it's right on the limit, so it is not consistently overcurrent. Probably due to the exact position of the engine crank/pistons etc when it is stopped i.e. right at bottom/middle/top of a compression/ignition stroke so more resistance to initial start/stop torque on start/stop cycle.

2) The commands to start/stop the engine come from the ECM over the MOTA line which has my IMAC&C installed. So I could use that to look for the IMA start/autostop commands from the ecm and then modify the start/autostop assist/regen level commanded and reduce it by say 30% before passing it to the MCM. That may do the trick.

Anyway I'll try adjusting the IMAC&C to start with. I like the extra omph and the nice whine the motor/electronics makes under the higher current so I want to crack the problem.

Dave Hancock (HCH1 IMAC&C owner and ex Honda Mechanic) came over yesterday and we had a good play about with some stuff. It was whilst talking/brainstorming with him that I had the idea about using the IMAC&C to modify the start/stop/low rpm regen commands. It's always useful to have other ideas thrown in.

[retepsnikrep]

Well I found the byte and tried suppressing the IGBT error flag bit in the IPUA data stream and that works.
No IMA codes or system shutdown.

The IPU (IGBT) still shuts itself down (protects itself) momentarily and you now feel the motor stutter for a millisecond then it carries on as normal. I'll see how it goes.

Regen current is the most stressing for the unit and that is running at 70A+
Slowing down with high regen from high rpm/speed does not cause the over current error until the revs fall to around 1000rpm when you feel the igbt cut out briefly. (Switch over from sine to square wave or vice versa?)

I might add a simple led to the dash (Controlled by the IPUA Interceptor) so I can see when the igbt shortcircuit/overcurrent flag is being set. Constantly clearing IMA errors was a PITA. (I don't have to do that now which is nice!)

This testing is with +30% current and 180V * 82A = about 14.7kw

Edit. just back from 40 mile trip and a couple of good hills seems to work well.

Now to transfer this research to my G1 project car and boost the current on that

PS I tweaked up the IPU fan a bit as well for some extra cooling. Saw IGBT 50C max on the trip.

[honda-dave]

Glad to see you got that one sorted Peter, it really did make a big difference to the usable power the car had and the gentle hum of the electronics in the back really makes some sweet sounds!

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