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Old 10-07-2018, 11:06 PM   #3281 (permalink)
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Originally Posted by BogdanT View Post
Hi everyone,

I've just put in an order for the AC board (along with a DC board as well for a future project). Wondering if anyone has successfully mated any HPEVS motor to the AC board? I'm considering to use the AC35 on an 800Kg city runner
I have not read of one of Paul's AC controller's driving an HPEVS motor, but that doesn't mean it hasn't happened.

An AC35 should be a good match for an 800 kg vehicle. What gearbox are you using? A quick google search gave me a couple of vehicles actually called 'City runner' and a whole bunch that were described as city runners.

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Old 10-08-2018, 02:09 AM   #3282 (permalink)
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I was also just describing it as a city runner ) With the meaning that I won't be doing highway speeds with it.
The car is a Trabant 601. Gearbox and diff ratios below:
Diff: 3,947
1st gear: 4.08
2nd gear: 2.32
3rd gear: 1.52
4th gear: 1.103
Reverse gear: 3.83

Given a max speed of 45mph, the AC-35 might actually be overkill, but I can't seem to find a forklift motor that will fit the tiny bugger (transversal mount and huge wheel wells)
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Old 10-08-2018, 11:45 AM   #3283 (permalink)
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I'd like to push AC35 or AC50 beyond Curtis voltage range with this controller. Would it be possible to parallel IGBTs for 1000 phase amps? Even that 650A amps would do, like Curtis low voltage model is capable. 650A and some 200V to a single motor. Then double motors/controllers for real fun.
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Old 10-08-2018, 05:55 PM   #3284 (permalink)
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Quote:
Originally Posted by mora View Post
I'd like to push AC35 or AC50 beyond Curtis voltage range with this controller. Would it be possible to parallel IGBTs for 1000 phase amps? Even that 650A amps would do, like Curtis low voltage model is capable. 650A and some 200V to a single motor. Then double motors/controllers for real fun.
[without being an expert] Speaking of the AC-35, on the easy&safe side one could use 600V/800A IGBTs to push 650A (with proper cooling) at maybe 156V. Going to extreme, in theory, sharing the load per phase between 2 IGBTs is definitely possible (that's what the DC board does).
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Old 10-08-2018, 07:24 PM   #3285 (permalink)
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Quote:
Originally Posted by mora View Post
I'd like to push AC35 or AC50 beyond Curtis voltage range with this controller. Would it be possible to parallel IGBTs for 1000 phase amps? Even that 650A amps would do, like Curtis low voltage model is capable. 650A and some 200V to a single motor. Then double motors/controllers for real fun.
You can get 1800A 2100V IGBT's if you have the wallet. I have not seen 1800A IGBTs under 600V rated.

I would spend some of that cash on a high-throughput glycol-cooled heat sink so you don't melt anything.

AC35 or AC50 on each wheel would be fun. Finding and sourcing a gearbox that will drop the RPM available to match your desired top speed is likely where you will find difficulty. If you do find a single-speed gearbox that works for you, it may not fit into the space that is available.

I think that's why most conversions use the FWD manual transaxle, or a drive shaft to a standard rear differential ... but that's only a guess.
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Old 10-09-2018, 02:34 PM   #3286 (permalink)
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OMG ... look at what an AC35 in a Trabant has gone to

On my particular application, I have some questions for the experts. I have some IGBT's lying around which I want to use for the P&S AC board running the AC35 at 144V.

1. How much current can I actually push through them for ~10 seconds? Should I aim 75% of the 400A or 800A peak ratings?

2. How fast/slow are they for the EV application?

They are 600V 400A Powerex CM400DY12NF and have these ratings:

Collector Current*** (DC, TC' = 92C) IC 400A
Peak Collector Current ICM 800A
Emitter Current** (TC = 25C) IE 400A
Peak Emitter Current** IEM 800A

Inductive Turn-on Delay Time td(on) — — 300 ns
Load Rise Time tr VCC = 300V, IC = 400A, — — 200 ns
Switch Turn-off Delay Time td(off) VGE1 = VGE2 = 15V, RG = 3.1Ω, — — 450 ns
Time Fall Time tf Inductive Load — — 300 ns

Last edited by BogdanT; 10-09-2018 at 02:53 PM..
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Old 10-09-2018, 04:19 PM   #3287 (permalink)
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Quote:
Originally Posted by BogdanT View Post
On my particular application, I have some questions for the experts. I have some IGBT's lying around which I want to use for the P&S AC board running the AC35 at 144V.

1. How much current can I actually push through them for ~10 seconds? Should I aim 75% of the 400A or 800A peak ratings?

2. How fast/slow are they for the EV application?

They are 600V 400A Powerex CM400DY12NF and have these ratings:

Collector Current*** (DC, TC' = 92C) IC 400A
Peak Collector Current ICM 800A
Emitter Current** (TC = 25C) IE 400A
Peak Emitter Current** IEM 800A

Inductive Turn-on Delay Time td(on) 300 ns
Load Rise Time tr VCC = 300V, IC = 400A, 200 ns
Switch Turn-off Delay Time td(off) VGE1 = VGE2 = 15V, RG = 3.1Ω, 450 ns
Time Fall Time tf Inductive Load 300 ns
I certainly don't qualify as an expert.

For question 1

From experience, anything around double the voltage works. IE your 600V IGBTs could drive up to 300V peak to peak. 144V pack is fine.

As for the current, I'm not a heat flow guy. I understand that heat flows from high temp to low temp, and that there is resistance to the flow of heat like there is to the flow of electricity. As for the equations, and the integrals ... sorry! Not my area. I would start with 50% max (ie 400A) and do an acceleration test for 5 seconds, or whatever you can reliably and repeatably do. The difference in temperature is what you are looking for.

If the temp rises from say 20C to 70C then you are done. The temperature inside the IGBT is higher than what you can measure at the heat sink. How much higher depends on that math I talked about earlier.

The heat can't get out of the IGBT very fast compared to how fast you can generate it. But it's tough to put a load on an AC motor in the 100's of amps for very long without a dynamometer. I used a DC motor coupled to an AC motor, and ran the DC motor as the 'motor' and the AC motor as the regenerative brake. If the AC and DC controllers are connected to the same battery pack, you only 'discharge' the difference between motoring and braking ... which is what the IGBT's are putting out for heat. You can do some rough calculations with that and figure out how much heat you are dumping.

For the heating up of the IGBT ... I think this is what was posted the last time someone asked ... but of course I can't find that!
- you have a turn-on time, where the transistor is sort of like a resistor. It has to do with time constants, capacitance, and drive current.
- you have a turn-off time, where the transistor is sort of like a resistor It has to do with time constants, capacitance, and drive current.
- you have a pulse width time, where the transistor is a resistor .. RGon I think?

The turn on and turn off times are multiplied by your switching frequency, or carrier frequency.

The RGon is multiplied by the duty cycle of ON and the switching frequency

That whole mess is divided by 6, since you have 3 IGBTs switching high side and 3 IGBTs switching low side.

I think Paul's board has a max output of 90% duty cycle ... but I can't find any doc to support that number.

For question 2 - yes, they are a bit slow. A lower carrier frequency will help reduce your switching power loss. I think Paul uses a random number between 3KHz and 8KHz to make a white noise 'Shh' instead of a hum. We have industrial controllers running at 0.5 Khz and the motors work fine ... but they are a bit noisier.
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Old 10-10-2018, 10:10 AM   #3288 (permalink)
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I thought the spec stated you can run 400a @ rated V for a 92 degree temp rise.
First line collector current.

My swag rule of thumb, 15 seconds tops. My experience is voltage didn't seem to make much thermal difference, or I cant measure it using basic homebrew equipment.
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Old 10-10-2018, 02:13 PM   #3289 (permalink)
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I thought the spec stated you can run 400a @ rated V for a 92 degree temp rise.
First line collector current.
I think that is for the raw IGBT, and depends on how well the heat sink takes away the heat ... Maybe not?

Quote:
My swag rule of thumb, 15 seconds tops. My experience is voltage didn't seem to make much thermal difference, or I cant measure it using basic homebrew equipment.
The voltage does not appear to affect heat. But reflected waves and switching transients do appear to ... amplify? .. the voltage. If you keep your bus voltage to half or less, the IGBTs appear to survive
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Old 10-10-2018, 02:52 PM   #3290 (permalink)
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From my interwebs crash-course in IGBT I think Piotrsko is correct. More specifically the peak values are pulse values (measured in couple of ms). Of course there are a ton of variables that influence the time measure (temp, pulse duration, voltage).

Given that the plan is to run 150V, this will have an influence, but not to the extent that 600V 400A rated IGBTs can be usable in that range of current.

I am hoping to draw 500+ batt amps so looks like I need to source some higher rated ones. Maybe use these for a prototype.

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