Time for MORE POWER! 1400a 1200v IGBT controller build!

Arlo1

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Ok so a much respected member donated some amazing parts on the condition I do another open source build. lol I have no problem with that as I usually get more out of the open source build then if I tried to keep it to my self.

The parts are CM1400DU-24NF They are 1 phase leg saving time/and space in the design.

There is many benefits of this layout. Even though I planned on a multi part layout based on my game changer design these are bad ass and have potential to get me to 1000hp!

Because there is both switches in 1 housing they have a very short and low inductance path from 1 to the other for less voltage spike before the Diode starts to conduct as well less time to recover when turning back on during repetitive switching.

They are rated for 1400a at 96 degC! In my experience with field weakening you can achieve a little more DC current then the max the IGBT is rated for it self. Even 1400 amps at 410v (112s under load) you are at 574000 watts or 769hp. I feel ~1750 amps peak for 5-10 sec or so, is achievable which is 717500 watts. and likely even a little more as these are rated at 96 deg C where as the Fuji parts I am using in the CRX are rated at 80deg C

This will be a new powerstage design. I will need to start over on the driver boards and make sure I push to get to the "NEXT LEVEL"!

I have started a Patreon page and will add a link in time its only because this shit is crazy expensive... I can use help on all levels, from designing tech, parts donations, fabrication, and cost.

Casey Mynott will be hoping to use one of these to run something for the Drag race hi at DSS and I have something planned as well.
The build will all be shared for all to copy but anyone interested remember there will be over $10k in parts alone!

Here is a few pics and one or two comparing to a 800a Fuji IGBT for size comparison.
 

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Thrilled for it Arlin!! You are a massive inspiration!

Creating the future of high performance!
 
Working on Cap Calcs.

From some posts by HH.

Re: Calculating controller power input capacitance

Postby HighHopes » Wed Jan 01, 2014 5:09 pm
hi Njay, in reply to your PM i thought i would post more thorough explanation here for further discussion with forum.

When evaluating components it’s really important to consider the application, design requirements and the technology involved.

Application:
we are not calculating ripple current for a DC/DC converter but a 3-phase VSI inerter. there is a big difference here.. the inverter has bEMF due to motor load which fights the bus voltage and so limits the current ripple at high RPM (a good thing), the frequency on the DC bus is 2xfsw because not one phase leg switching but two, phase shifted.
The input supply is from a battery NOT a rectified AC so there is no reason to ask our DC Link cap to perform filter function, so those calculations can be ignored (i.e. not limiting factor) unless you have an EMI requirement to meet. The failure modes are different, expectations are different.

Design Requirements:
it could be that cost is the #1 design requirement, ahead of functional, ahead of reliability. it could be EMI if you have a specific need to keep this minimized, it could be long life, could be anything. but it helps to have it clear in your mind what your priorities are and in what order because this will help guide discussions especially those that have trade-offs (engineering is all about trade-offs).

Technology:
Electrolytic caps are low cost which makes them attractive for first consideration. It will be interesting to see if, at the end of the evaluation, if they are still considered cheap(er) than other technology. Electrolytics have high ESR/ESL so the limiting factor in the design is how much heat is generated due to ripple current because the capacitor life is cut in half for ever 5degC rise and so the calculation tends towards how many caps in parallel are required to share ripple current rather than how much total uF cap value would be appropriate for desired ripple voltage. This is a significant statement... due to cost requirement, what is being said is that the DC link capacitor uF value cannot be chosen optimally for the application. So straight off we recognize not to have an optimal solution and thus we keep this in mind to look closely at what we must pay for in order to have benefit of low cost electrolytics… there are always trade-offs.

The other dielectric to consider for DC link cap in VSI application is Metalized Polypropelene Film due to its low ESR/ESL and self healing properties which makes is vastly superior. I'll make the argument that it is CHEAPER solution too.

on personal note, i only ever used Polypropelene or other custom made specials for DC link cap in VSI application. i have no experience with electrolytic.
Last edited by HighHopes on Wed Jan 01, 2014 5:10 pm, edited 1 time in total. View post history.
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Re: Calculating controller power input capacitance

Postby HighHopes » Wed Jan 01, 2014 5:11 pm
For electrolytic Caps, ripple current is the deciding factor in establishing DC link capacitance value which depends on battery voltage, phase inductance and duty cycle. The maximum ripple occurs when the bus voltage is lowest allowable (battery near discharged) and duty cycle is 50%. Thus we can eliminate two variable in the equation by setting d = 0.5 (worse case). The phase inductance is also fixed because your motor is pre-selected (how did you get 2.64uH?, that is incredibly low value). Let’s assume phase inductance is accurate, then likely 20kHz switching frequency is too low for such a motor because control bandwidth requirement will be high. To get high control bandwidth probably 100kHz would be more appropriate but good luck keeping the MOSFET power dissipation low.

Battery voltage also fixed due to design requirement so.. we just go ahead and calculate ripple current delta_I:

Ripple Current:
delta_I = d*(1-d)*Vbus/(f*L)
delta_I = 0.5*(1-0.5)*72V/(100kHz*2.64uH)
delta_I = 69App or 49Arms

So how many parallel electrolytic capacitors are needed? Let’s say we arbitrarily chose Panasonic TS-ED series because the advertising for this cap makes us think it is useful for inverter application. So, assuming 60degC ambient max, looks like we would need about 5 x 560uF caps (digikey price of 5*$2.75 = $13.75). That’s ~2.5mF .. wow.. that’s a lot. Now, the next person could argue, just use ONE 560uF to achieve desired voltage ripple could be used; hooks it up turns it ON and it works so says “see you wasted money buying five”. But what is the temperature rise of the capacitor when it is presented with 49Arms and what is the life expectancy?

With 2.5mF of electrolytic capacitor there is no need to calculate the voltage ripple, for sure it is acceptable. But anyway, we will check

Voltage Ripple:
I=C*dV/dt
We know current expected from cap is the ripple current previously calculated 49Arms.
Have to integrate both sides to get delta_V (at 50% duty), some math magic and:
delta_V = Vbattery/(32*L*C*f^2)

delta_V = 72/(32*2.64uH*2.5mF*100k^2) <-- Note that Vbattery should have been the fully charged pack value
delta_V = 0.03Vpp or about 0.05%.

Wow.. really exceeded any reasonable requirement for bus voltage ripple.

Still at cost of $13.75, seems attractive. But such large DC link capacitance comes with other draw backs that need solutions which cost money (inrush, cap bleed for safety, replacement every 5 years and all of these things are sized for the 2.5mF cap!).

* added note to use fully charged pack value when assessing voltage ripple
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Re: Calculating controller power input capacitance

Postby HighHopes » Wed Jan 01, 2014 5:14 pm
For polypropylene film capacitors (proper choice dielectric for VSI application) the situation is different because ripple current rating tends to be at least 10x that of electrolytic. So we skip ahead to determine the voltage ripple allowable first and then second check current ripple (heating). Seems we are just swapping around order of events but don’t miss how important this is. It means we can select DC link capacitor based on energy balance rather than heating limits which is optimal method.

We assume an allowable voltage ripple, for VSI application tends to be 3 to 5%; I always used 5% unless told otherwise.

Voltage Ripple:
delta_V = Vbattery/(32*L*C*f^2)  rearrange, solve for C
C=Vbattery/(32*L*delta_V*f^2)  delta_V = 5%*72 = 3.6V
C=72/(32*2.64uH*3.6*100k^2) <-- Note that Vbattery should have been the fully charged pack value
C = 24uF.

For part number Panasonic EZPE series 50uF, cost is $15. Current ripple rating on this part is 16Arms at 10kHz. Assuming this cap has at least same multiplying factor as electrolytic for ambient temp of 60C (multiplier 2.2) and switching frequency of 100kHz (multiplier 1.5) then 16Arms * 1.5*2.2 = 52.8Arms > 49Arms. Good!

Ya… quite a bit smaller than 2.5mF! So you save money on packaging, time to install. Also the same inrush limiter, safety discharge is sized now for much smaller cap. And replacement ever 20years..

Oh, and did I mention that because of the much lower self inductance, and tighter overall bus-bar packaging, the voltage spikes will be less which is always desirable.

so.. which solution is cheaper?
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Re: Calculating controller power input capacitance

Postby HighHopes » Wed Jan 01, 2014 5:14 pm
Other factors:
So the above considers capacitor dielectric & capacity to suit application and argument made that polypropylene is not an expensive solution. Now we must consider some other application specific factors that may (or may not) influence your decision on cap size.

Load dynamics:
If you have high acceleration then the cap may be asked to supply some of that current for first instant.

Regenerative breaking:
Depends on how fast your battery can take the energy, if the regenerative energy comes faster then the cap will take it raising the voltage. May need big cap to handle this, or, electronics to dissipate excess energy, or reduce ability to regenerate (slower deceleration).

BLDC/Induction:
BLDC motors have magnets so no need to ask inverter to supply magnetic field (medium through which torque is transferred to rotor). But, for induction motor this current (Id) comes from inverter since the machine has no magnets. It is not possible for the battery to supply reactive energy so it all comes from the cap meaning the capacity has to be about 15% higher.

Stiff bus during fault detection:
If your gate drive or phase current sensor has some sort of fault current shut-down, then the cap must supply the fault current for as long as it takes for system to detect fault and tell MOSFET to open. 10uS? The bus voltage is not allowed to drop more than 20% during this time or else fault shut down may not work properly.

Source impedance:
If your battery and/or cable has high source impedance then the voltage will drop as you accelerate. The cap has to take up this droop so is sized higher in proportion to source impedance and acceleration rate.

Filtering/EMI:
Generally not an issue when sourced from battery.
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ts not magic anymore if i have to derive the equations. that i need to check my lab notes to find the papers this equation came from.

Ripple Current:
1. delta_I = d*(1-d)*Vbatteri/(f*L)
how is this ?
start with common inductor equation: V = L*di/dt & integrate both sides & rearrange to get:
2. delta_I = VL*delta_t/L : VL = votlage across motor phase inductor
more discussion,
VL is when the upper mosfet turns ON it puts Vbattery across the phase inductor. but because its a motor with PWM it already had a voltage fighting the applied voltage, the motor's bEMF. so then VL = Vbattery - VbEMF. but what is bEMF voltage? it would be tempting to get crazy with the cheese wiz with more equations but we are only making a rough dimension of the capacitor so i think it is good enough to take an approximation. when the mosfet is OFF the voltage does not suddenly drop to zero, it is roughly maintained due to motor continue to spin and the voltage is roughly what the applied was so we can use bEMF = d*Vbattery. so VL = Vbattery - d*Vbattery. I should put a side note here that we could make a worse case assessment and say that the bEMF (d*Vbattery) is worse case equal to zero, i.e. when the motor is at stand still. but maybe that is a bit excessive if we think that the period of time that this occurs is small in comparison to period of time when motor is running. but perhaps not for EV application.. start/stop..start/stop.. hmm... anyway, for now i will leave it as bEMF = d*Vbattery and just accept that the capacitor is stressed when motor is starting up.

3. delta_I = (Vbattery - d*Vbattery) * delta_t/L : delta_t = mosfet ON time = d*PWM_time = d*1/PWM_frequency = d/f
4. delta_I = (Vbattery - d*Vbattery) * d/f * 1/L
5. delta_I = Vbattery*(1-d)*d/(f*L) : here you have to plot the formula of (1-d)*d to learn that peak is at d = 0.5
6. delta_I = (1-0.5)*0.5*Vbattery/(f*L)
7. delta_I = 0.25*Vbattery/(f*L)

Using 470v as a full battery and 100uH as motor phase-phase inductance with 15khz pwm
I come up with needing only 54.7a RMS current from the caps and I think it was 27uF capacitance.
NOTE: I will run these numbers again tonight.

Also as we push any motor to its limit in drag racing where you want a motor at saturation or close to it we will have very little inductance left.
So its likely we will run 15-20khz pwm so we can run high e-rpm and as close to 50% efficiency as we can push it for the optimal drag setup.
Obviously run the lowest PWM we can but as much as we need......

It would not surprise me if working inductance ends up being 10uh or something.... From my experience with 800 peak phase amps I had to set the motor inductance value in the controller to 60uH when it measures ~190-210uH with low current flowing though it.

My plan is to build a cap array using these caps. http://www.vishay.com/docs/28164/mkp1848dcl.pdf
MKP1848620704P4
 
Thumbs very up man

Ping me if you want the shunt sensor, isabellenhuete agreed to send me samples if I put their logo somewhere.
My gate driver complies with IEC61800 for working voltages of 1000Vrms and basic isolation, and its beefy power supply should be able to feed those Qg. If you are still planning to use kicad that design could be useful.

I guess you're getting a model s rear motor for this? Can't think of any other 1400 amp motor out there :) Well, maybe a train if you're into that.
 
Yup math at 15khz 470v and 100uH works out to only needing 27uF
And 78.3 a P-P or 55.35a RMS.

But when I work the math for 5 khz ans 25 uH and see what that works out to.
I need 940a P-P or 664.58a RMS
And Needing about 1000uF
I would say 5khz is unrealistic and 25uH will be about saturation so Its likely if I build for 5khz and 25uH I will be very safe. But thinking about surviving a short of something it will be a good thing.
 
marcos said:
Thumbs very up man

Ping me if you want the shunt sensor, isabellenhuete agreed to send me samples if I put their logo somewhere.
My gate driver complies with IEC61800 for working voltages of 1000Vrms and basic isolation, and its beefy power supply should be able to feed those Qg. If you are still planning to use kicad that design could be useful.

I guess you're getting a model s rear motor for this? Can't think of any other 1400 amp motor out there :) Well, maybe a train if you're into that.
Thanks.

I am not worried about finding the limits of any motor. So many people are so far out to lunch when they talk a true 10sec - 30sec limit of a motor.

But I do accept donations if anyone wants to send me motors... or any EV parts..... ;)
 
Awesome Arlo! Looking forward to this build. Let me know if you need any CNC milling done, I would be happy to contribute to your build.
 
Did some quick tests yesterday and made sure the 3 parts I have all turn on and off and the diodes still conduct.
I first use a lab supply and turn on and off the gate watching the Collector to Emitter with a multi meter on diode check more then. I hooked up 110v DC and a load and flowed about 8 amps thought them to a heat dish to make sure they work on and off. Everything seems good.

I notice the very low voltage drop on the diode and the switch when turned on with the multi meter.

I would suspect this is from the many parts in parallel.
 

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Arlo1 said:
They are rated for 1400a at 96 degC! In my experience with field weakening you can achieve a little more DC current then the max the IGBT is rated for it self. Even 1400 amps at 410v (112s under load) you are at 574000 watts or 769hp. I feel ~1750 amps peak for 5-10 sec or so, is achievable which is 717500 watts. and likely even a little more as these are rated at 96 deg C where as the Fuji parts I am using in the CRX are rated at 80deg C

0.7MW? That's crazy. Can't wait to see that run. Amazing they get that much through those little bonding wires. The batteries might have a hard time keeping up.
 
Ohbse said:
Awesome stuff Arlo, love your work. Get that Patreon page set up - I will happily contribute.


Awesome thanks. I have a page up and running I am just working on editing it.

But I also want to point out I can use help in every way shape or form If someone has endless amounts of money cool send me some I will put it to good use. But if anyone has more parts or time to help out let me know this has all been a group effort this far and I think I can learn a lot more by working as a team on everything I do.

I have a solidworks file I am working on and its all new to me. I am at the point where I need to extrude the base and I am getting faults.

Anyone who wants to help tech me solidworks or any other part of this. It all getting posted online for others to learn from.

As well. I am developing other items like a charger I will try to keep everything open source.

-Arlin
 
Down to help any way I can, whether it be machining or SW or whatever. Shoot me the SW file and I'll see what I can do with it.

-Cole
 
I will see if it lets me attach it here.

:Edit extension sldprt is now allowed :)
I will try to zip it.

here is the data sheet
http://www.pwrx.com/pwrx/docs/cm1400du_24nf.pdf
 

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Most IGBTs need a little more voltage on the gates when compared to MOSFETs

I set the drivers up in my CRX to 16v out of the supplies and after voltage drop I get ~ 14.5v at the gates at the end of the switching cycle before it turns off.
 
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fechter said:
Arlo1 said:
I will see if it lets me attach it here.

:Edit nope extension sldprt not allowed :(

I added that to the allowed extension list. See if it works now.

Awesome thanks
 
I would highly recommend you look at Fusion 360 rather than solidworks. I've found it substantially more intuitive, it's got really solid CAM as well as CAD and it's free for private use. Hell, even if you pay it's a subscription based model for $200 a year, much more reasonable than constantly buying new versions of solidworks. They're taking a lot of market share and it's really actively being developed with a great community for learning.

I've now got a 200 square metre workshop, 4x8' CNC router and gradually picking up more machine tools. Been teaching myself Fusion in a hurry and it's going well so far. Shipping might be a bitch but if you need aluminium/plastic stuff machined I can help. If you've got drawings I can assist with creating the initial model too.
 
Lebowski said:
I looked at Fusion 360 (as I want to get a 3D printer) but all I can seen is $25 a month subscription ? I am thinking about going the FreeCAD route...


At this URL it talks about startups, enthusiasts and hobbyists.

https://www.autodesk.com/products/fusion-360/free-trial
 
Thanks guys. I will look at getting fusion 360 as well.
I think Highhopes was playing with it.

I wanted to learn solid works as I want to do more work in the EE industry and Solidworks is the go to platform at this moment.
 
Finally something in my wheelhouse...Stay far away from Freecad and use Fusion. It IS free for hobbyist and education use. I have a subscription because I use it for all my 3D and multi-axis toolpath work on the CAM side. Coming from SW before Fusion, I don't find it intuitive at all. Most people who have have very little experience with CAD software do find it easier, though.

I've attached the beginnings of a model with the native SW part and a step file. I tried to get Mitsubishi to give me the step file, but they only release solids with NDA's. I could get it, but not share it, ha.

-Cole
 

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