CAN-VIEW (Recovered)

I was the "GP" and it was painless. other than a slight glich with the JBL system not being recognised (long since fixed) the worst part was the drive. And with the factory nav it'll be a really cool addition to the Prius. Just wish I got to use the 2k4 more as I'd like more time to compare the data from the Classic to the G2. Lots looks the same at this point in time with some different as well. The possible additon of the temp at the coolant thermous as well as at the ICE would be interesting and the trottle opening for those with EV would generate some interest as well. I don't have the luxury of the EV do to an accident with the car and possible battey damage and I don't want to compromise any warranty Toyota or the insurance company, who almost crapped their pants when they found out how long the battery warranty was,have assured us is intact. That little bit of liability for them, if they had known about the 8 year battery warranty, they probably would have written off the car. Toyota has said there was no damage and everything is fine, but I will never put in an EV button just incase there ever is an issue. Other date like rpm, HV battery voltage and charge current on regen are similar to the data output to the MiniScanner on the Classic other than the voltage is all different and the current a we bit higher. This is one cool piece of equipement. I'm going to purchase a programmer so I can do the flash without the drive or snail mailing it back to Norm.

 

I'm in for the full version with factory Nav.

Nate

 

Hi guys,

I just installed CAN-view this weekend. The installation was not bad at all. I think the most difficult part was to remove the first piece when you don't know how much force you should use. It took about an hour I think. But it was fun taking apart the dash. I also get to clean the cabin air filter while at it.

Anyways, I was playing with CAN-view screen and driving around to look at the data (under safe condition of course!). I have to say, this thing is so cool! B)

During drive around, CAN-view screen switch back to the energy screen 3 times for no reasons. I can't think of any relevance between the 3 incidences other than twice I was under electric mode (RPM = 0), other is not. By the way, I got version 1. Anybody else experience this?

Another observation is about the HV battery state of charge. When the battery SOC show on energy screen has two bars left, according to CAN-View, it's 40%. The most SOC I've got was 7 bars. And on CAN-view, it shows 66%. According another picture posted by Dr. Evan, that's not the case.


Anybody has any comments on this?

Thanks.

 

Hi ScottY, I display on CAN-view the SOC that appears on the CAN bus as-is, without any filtering or manipulation other than to make it a percentage. Now the Prius MFD presumably takes this same data and filters/manipulates it to come up with the familiar colored bars, so I can't comment on exactly which bar corresponds to what SOC level. Unless someone comes up with a convincing argument, I would tend to believe whats on the raw CAN data bus.

But I'm willing to listen to arguments to the contrary and will always change CAN-view displays if errors are identified.

 

Hi Norm,

Here's another picture I got from Wayne's site, privatenrg.com


With the hysteresis and difference in temperature, I guess the readings are reasonable.

Any comments about CAN-View switching back to energy screen? Any other users experience that? One thing I forgot to mention. After CAN-view screen switch back to energy screen, I'll have to press info button once to get back to CAN-view screen.

Thanks.

 

which radio do you have in your Prius the standard radio or the JBL upgrade. If it's the JBL did you select it in the setup screen? if not it'll problaby switch back on you.

 

Frank,

I have the standard radio and I have the right settings in the setup screen. I had some discussion with Norm and he suggested to inspect the connectors. I'll do that this weekend and see what I can find.

 

just as a try, set it to the JBL and save it, shut the car down and then boot it up and set it to the standard radio and re-save it. See what happens. But it could well be a loose connection and I'd guess on the power supply lead, or on the plugins on the case, but I'd expect it'd be the power supply lead. I had a loose power connection on the early pre-production unit and it would cut out going over rail road tracks and very bump roads.

 

Thanks for the tip Frank. I'll give that a try.

This morning, I changed the update speed from fast to slow (dont' remember the exact wording). Seems like the problem went away on the way to work. I'll see if it happens again on the way back home.

 

I don't quite know where best to post this, so I'll add it here. I've been puzzled for some time about apparent contradictions in power from the Prius battery when it comes to accelerating the car. There's a PC member with an analog ammeter who never sees more than 100Amps. There's Atilla Vass's well documented recordings of nearly 200Amps. There's Oakridge National Labs prius analysis saying the battery has an output of 21kw max. (which at 170 volt under load would be 125 amps) And there's the current, voltage and power readings I get on CAN-view off the CAN-bus. I've never had the chance to go check the basics myself. Until now.

Here's what it looks like under the rear seat of your Prius when you remove the cover from the high voltage cables and clamp a Fluke hall-effect meter round one of the orange high voltage cables.
[attachmentid=1392] I've taken the analog output before the Fluke's digital part has a chance to filter it and taken it over to a modifed CAN-view, using the new serial dump fucntion I've added. That way I can dump to my laptop both the Fluke meter reading and all the CAN-bus readings simultaneously. I only had time for a quick drive so with the cold weather, my maximum charge and discharge had only crept up to 85Amps.

Here is a representative 30 second sample of what I recorded.[attachmentid=1393]
What it shows is that the actual battery current as reported by the Fluke varies quite dramatically more than what the CAN-bus reports. I know its a bit cluttered, but you can see where I'm braking (fuel flow=zero and regenerative braking current rises to just on the steady green charge limit) Also when I'm accelerating you can see the fuel flow rise and the battery discharge into the motor increase, down to, and past, the lower discharge current limit.

Now its more obvious what's happening. The current flow is not steady, its a series of oscillating pulses. So in this 30 second piece I can see 130 amps peak discharge, but thats only for 1/2 a second, followed by a swing the other way.

So I would say the battery ECU issues the two charge and discharge limits based on what it feels is good for the battery at that moment and the inverter ECU tries to comply, but only when averaged over a few seconds. My guess looking at the 1st braking episode is it takes ~3 seconds to average out.

Therefore it is quite possible to see peak currents of nearly 200 amps. (I do have a recording of a short burst of those) But still comply with an average limit of, in this case, just 85amps. So in effect all parties observed current correctly, the analog meter simply didn't respond to these wild swings and averaged out somewhere in-between. And the others who saw 196 amps, did see that, which at a loaded down 170 volts corresponds to 33kW or 44HP, which is way more than Toyota claim. But this is like the good-old days when stereo amp makers published peak music power rather than the RMS power that they all grudgingly agreed to. 44HP for only 1/2 a second isn't real horsepower: it won't suddenly give you an under 8 second 0-60.

I will do a longer drive to get it warmer and up to my normal 125 amp limit and repeat this, but it does mean I will modify what I display on CAN-view. I think it makes more sense now rather to allow any readings under the charge/discharge limits to be displayed as-is, but anything approaching (or over) these limits should be treated to display a more realistic average figure. What this means is that if you are used to seeing a certain current when you brake, the next download will show a significant (but still real) increase. I could of course display these transient high currents, but they are really meaningless.

Sorry for this post length!

 

It would be good to keep in mind that the motor load is NOT a DC load, and the regen does not generate DC. The motor is a 3 phase PWM AC motor. So the battery is feeding the inverter which converts to 3 phase AC to feed the motor. It's not even a sine wave AC (more like a square wave with varying on time, not 50/50), so an RMS ammeter will give different results vs a peak reading ammeter. The reading from the CAN bus (Batt ECU) may not even be averaged, it might just be an instantaneous sample of the hall effect sensor, depends on the software in the Batt ECU.

The best way to really see what's happening with be with a dual trace oscope so you can see current (probe the hall effect sensor) and voltage (probe the batt) waveforms at the same time.

 

The currents here are dc going in and out of the hv battery.

 

But the current out of the hv battery doesn't have to be a smooth current, the load is not resistive, it's a 3 phase AC motor (on the other side of the HV DC-AC inverter). So it would be a pulsating current that matches the pulse widths on the output of the HV inverter, the current will vary thru the cycle of the AC voltage on the output of the inverter. AC motors are inductive not resistive loads. The frequency of the AC varies with the speed of the motor and is controlled by the HV ECU.

Taking a closer look at the schematic to the HV DC-AC inverter (see below) we can see that there is an LC filter at the input to the Boost Converter which will smooth out the pulses but it's still possible that there is some ripple in the current coming from the battery. That's my point - you can get different current measurements depending on whether you're meter reads the current peaks, the average current (and depending on the averaging period) or whether it reads the instantaneous current.

Note: the A/C Inverter in the bottom left of this diagram is for the Air Conditioner compressor which runs on HV AC. The compressor has its own separate inverter.

 

Quick update: I am probing the hall-effect sensor, which in my Fluke 336 fortunately has a low impedance driver, feeding it into an analog to digital converter in the CANview (there is one, just not normally hooked up) and sampling both current and voltage 5 times a second, then dumping that out the serial port to my laptop at the same rate. You can see from the graph that the hall-effect measured current is responding to these transients much more rapidly than the CAN-bus ones. I also have a Fluke 97 dual trace portable storage scope and it doesn't show anything markedly different from these 5 per second samplings, so I think the 5-per-second ones are reasonnably valid.

I acknowledge if I were measuring 3-phase AC current at the inverter I would see something totally different.

Whether the Prius sensors themselves have in-built analog filtering or whether the ECU that reports these sensor readings has digital filtering seems a moot point.

I'm hoping for a longer (read warmer) drive today to reach my more normal 125amp discharge/105amp charge limits and do another recording. If I have got these backwards, these should show up. The last recording didnt help because both limits were almost the same at 85 and 86 amps.

 

I've just noticed kk6yb responded at the same time i sent my post above, so I was responding prior to reading his new post.

 

Where did you get the neat inverter picture?
Fast response, yes the inverter 3 phase drives result in pulsed current from the battery, but with multiple poles surely at a high multiple of motor rpm, (i.e in the ms region) not the several hundred ms pulses recorded. Those seem more like instability and overshoot. Yes? No? Maybe?

 

Very nice. I like the peak power RMS analogy. That is somthing I can get my teeth into. A little more light in the darkness.

 

I’m away from Winnipeg on business until the first week in January, but would like to comment on this.

First of all, the “reactor†shown in the Prius inverter schematic – provided by kk6yb – is probably used to minimize the current pulses, same as on an industrial motor drive. Actually, the inverter schematic is remarkably similar to VFD (Variable Frequency Drive) industrial 3-phase motor drives.

If you look at the pictures of the disassembled MG1&2, that Oak Ridge National Laboratories took apart, the stator/rotor insulation is also remarkably similar to industrial 3 phase motors that are rated “Inverter Duty.†The motor needs that to reduce the possibility of corona from the rapid frequency/current changes. As a 3-phase motor is almost purely inductive, there are complicated mathematical relationships especially related to interharmonics (3rd, 5th, etc). You need proper instrumentation to analyze this.

You really can’t take a standard hobbyist 2 channel scope and expect to get valid data regarding complex frequency drives or high speed industrial bus traffic (CANBus, Foundation FieldBus, ControlNet, etc).

At the very least, you need to perform Fourier Transform’s to characterize more complex power/frequency relationships. At work we use several $7,500 AEMC power quality analyzers to resolve industrial power issues, especially capacitor bank tuning and motor drive analysis.

As far as interpreting the CANBus “raw†data, a standard PC isn’t capable of interpolating this sort of data. The information you’re retrieving – even “raw†– has been buffered/filtered by processing before you see it. This is the same as an internal PID loop on a heat exchanger in an industrial application, the internal embedded system has to be fast to do the math right. If you send the “raw†data down the bus to a central computer, crunch it, and back to the device, there is too much jitter/delay and the PID loop runs wild.

If you really want to characterize truly “raw†CANBus data (Or Foundation FieldBus, ProfiBus DP, ControlNet, AS-I, etc) – or especially complex motor drive analysis - you need a dedicated scope with good memory depth (At least 1 Mpts) and very fast sample collection. We use the Agilent 6000 at work, the 500 MHz model with 4 channels and 16 Logical channels, yours for only $18,000 USD.

The Agilent 6000 has standard software that will trigger on the CAN frame, either on Low or High signal. It can handle math like integration, differentiation, and Fast Fourier Transforms. It will also trigger on the LIN synch break the start of the frame. If I recall, it will detect at either 250 pS or 500 pS. I’m away from the office and will have to look that up when I get back next month.

Long story short, we have to accept the buffered/filtered data on the CANBus as is. We can get fairly basic measurements with a torroidal probe, but this data isn’t really accurate.

If I can get access to one of the Agilent 6000’s at work, I’m willing to pursue this deeper. Does anybody know if the Prius uses CAN 2.0A or 2.0B? I’m going to assume the Prius structures the CAN message frame same as industrial CAN: Arbitration, Control, Data, CRC, etc.

 

Who are you masked man? I was beginning to get this and now you do this??! Now I have to go back to school and get another degree just to translate this. Now all I need is a Sugar Baby who will send be back to college forever. Could you translate just a bit. I took Physics 101, a bit of math, a lot of chemistry and biology, including almost understanding Physical Chemistry.

 

i think he is saying that all figures are rounded