Paul & Sabrina's cheap DIY 144v motor controller

[thingstodo]

Originally Posted by mfox

Hello ,
I'm able to get 4 IGBT-s FF300R12KE3 cheap from scrap yard taken from some industrial device.

From the spec sheet here

https://www.infineon.com/dgdl/Infine...3dd4fda49101e0

Page 4, lower right graph, it looks like thermal losses for this IGBT are 25 - 40 mJ per pulse. There are some losses at the diode as well, but they should be much less.

4 of these at 300 amps each would be 100 - 160 mJ per pulse

This is an IGBT forward and a reverse diode. So it's OK for a DC controller, as you know.

Those are rated as 300A and 1200V . Those will produce too much heat at 1000A peak (or 1200) compared with 3x of CM600DY-12NF ???

From the spec sheet here

http://www.pwrx.com/pwrx/docs/cm600dy_12nf.pdf

Page 4, upper right graph, I read the losses as around 175 mJ per pulse at 300A

So 3 of these at 300A each would be 525 mJ per pulse. The first ones seem better to me, if you are driving them at the same frequency.


But this is a bit deeper into spec sheets than I am normally looking. Perhaps I am not reading something correctly? There should also be a correction graph for temperature in there somewhere, along with some changes based on the voltage used to drive the IGBT and the .. current used to drive the IGBT on and off? I think that's where the capacitance graph comes in, but I'm a bit fuzzy on that part

[jedsmd]

Originally Posted by mfox

Hello ,
I'm able to get 4 IGBT-s FF300R12KE3 cheap from scrap yard taken from some industrial device.
Those are rated as 300A and 1200V . Those will produce too much heat at 1000A peak (or 1200) compared with 3x of CM600DY-12NF ???

Maybe I am over simplifying, but here is my take.

For the 4@ 300 amp IGBTs:
Avg current per device = 1000amps /4 = 250amps
From the first graph in the FF300R12KE3 pdf, voltage drop at 250amps = 1.7volts
So waste heat generated = 4 x 250amps x 1.7volts =1700 watts

For the 3@ 600 amp IGBTs:
Avg current per device = 1000amps /3 = 333amps
From the first graph in the CM600DY-12NF pdf, voltage drop at 330amps = 1.75volts
So waste heat generated = 3 x 333amps x 1.75volts =1750 watts

The 3-600 amp IGBTs are much more robust of course, but the waste heat generated should be similar.

[thingstodo]

Originally Posted by jedsmd

Maybe I am over simplifying, but here is my take.

I like your method better - less complicated!

[mfox]

Tnx friends for detail explenation ,
Shortly, 3x330A Vs 4x250A have approximatley same efficient and produce the same heat.
If is that so , I will try to take them. I need to see first if guy wants to sell it to me.
I was reading in description of Pauls logic board that logic has 6 isolated drivers for running IGBT-s . So if I want it for DC motor , Paul will put me firmware that runs all drivers paralel with same signal for each IGBT?
How works the current limitation? I have read that logic shuts down when pass the limit of setting current. Can I also limit motor RPM ? max rpm of warp 11 should be 4500 . and max warp voltage is 160V , I will have 220V on batteries. I will need to reduce the voltage on motor output...
How the throttle response ? is it smooth for gentle pushing ?

[thingstodo]

Originally Posted by mfox

Tnx friends for detail explenation ,
Shortly, 3x330A Vs 4x250A have approximatley same efficient and produce the same heat.
If is that so , I will try to take them. I need to see first if guy wants to sell it to me.

I'm not certain that we are good enough at reading the spec sheet to be confident. But we think so

I was reading in description of Pauls logic board that logic has 6 isolated drivers for running IGBT-s . So if I want it for DC motor , Paul will put me firmware that runs all drivers paralel with same signal for each IGBT?

I believe he uses 3 IGBT and 3 are only used as 'diodes'. There are 6 IGBT drivers, set up as 3 pairs.

How works the current limitation? I have read that logic shuts down when pass the limit of setting current.

The current is measured by the Hall Effect sensor and gives a signal from 0 - 5V. That is compared to a reference signal, and the IGBT drivers are turned off if the current goes too high. That is the hard-ware current limit

There is also a software current limit, where you have a setting for the motor current and the software limits the current with the width of the PWM signal. But that is not fast enough to stop damage to the IGBTs if there is a motor short circuit.

Can I also limit motor RPM ? max rpm of warp 11 should be 4500 .

There is a software limit on the AC motor speed. The DC motor controller does not require an encoder. I am not sure - perhaps the newer firmware can limit the max speed. Again, it will not be fast enough to limit the motor speed during a motor fault but is fine for normal driving

and max warp voltage is 160V , I will have 220V on batteries. I will need to reduce the voltage on motor output...

Reducing the voltage and controlling the current is sort of what the PWM output does. If you want to make the bus voltage 160V, so that the motor brushes never see more than that ... then IGBT (or a set of them) will be needed to drop the battery voltage to the controller. But those IGBT(s) will also need to handle full current, so it may be an expensive feature to add.

As I understand the Netgain voltage limit, they are looking to limit how much voltage is across the brushes, not the motor. But I may not understand that part as well as I think I do.

How the throttle response ? is it smooth for gentle pushing ?

The throttle response has a couple of parameters for how long it takes to go from 0 to 100%, minimum throttle, maximum throttle, ramp rate, and gain ... that's all I can remember. I'm going to have to look for some description of how those settings change the throttle response

There are racers using the controller, so it can be very quick. The DC motor response is quite smooth with most controllers. Does anyone else want to chime in on their experience with the DC controller?

[jedsmd]

Does anyone else want to chime in on their experience with the DC controller?

mfox
I use Paul's DC IGBT controller with a hall effect throttle in my truck. It is very smooth, if I want, the truck can creep along with almost imperceptible motion. Makes it very easy to parallel park in a tight space. Actually acceleration is very predictable across the full range.

I asked Paul for a very smooth controller so he may have tweaked my programing different than from the controllers he built for the race crowd.

[mfox]

Tnx for both answers, I'm close to decision to make my own one. . I'm on vacation now and when I come back home I will start to collecting parts.
As I see it wont be problem for normal driving to controll current with pedal, to not to go over current.

[mfox]

I didn't manage to deal with those 300A igbt-s but I found another one .
FUJI 1MBI600U4B-120 , it is 1200V 600A

1MBI600U4B-120 pdf, 1MBI600U4B-120 description, 1MBI600U4B-120 datasheets, 1MBI600U4B-120 view ::: ALLDATASHEET :::
As I can see is the same gate voltage 20V like those before. Will be those good for Paul-s logic board with same setup ??
tnx

[jedsmd]

mfox
You should probably Private Message Paul directly about whether that IGBT is okay. He would be your best source.
Jerald

[MPaulHolmes]

It's always fun to read all these updates when I've been away! Here's my understanding for the losses with the IGBTs. There are switching losses, and conduction losses. The DC controller switches at like 7-12kHz (spread spectrum) so it averages maybe 9.5KHz or something like that. Each time the IGBT turns on and off, that's one of the 9500 per second. So, if the turn-on energy is 50mJ (for example) and the turnoff is 50mJ, then the off/on cycle is 0.1Joule, or 0.1Joule/cycle * 9500cycle/sec = 950 watts. JUST FROM TURNING IT OFF AND ON!!! AAHH!! But notice that their numbers for switching energy are at the absolute worst case. Like 600v and 300amp or whatever. If the current or voltage is less, the switching energy falls dramatically. Sometimes they don't include the full range of switching energy vs current, but sometimes they do.

Then there's the conduction losses, like 1.75v while on. Then if you are at, say, 50% PWM, then it would be current * 1.75v * 0.50 for the waste heat from conduction losses.