OSHW TO247 IGBT watercooled laminated half-bridge

Electric Motors and Controllers
marcos
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Fri Jul 28, 2017 6:53 pm

HighHopes wrote:did u use seeeds to fab the board too? 1oz is good pricing, but 2oz is more than 10x?
You mean the controller board? That was made in http://www.ourpcb.com, they are fast, a bit more expensive though but they can do whatever I come up with, I've been working with them for ages.

I just checked again at seeeds, this half bridge board is now $96 @1Oz and $126 @2Oz for qty=5. Their prices seem to change fast, go figure.

Something I didn't realize is that with the extra copper thickness they derate their minimum track clearance/thickess. The board was laid out at 8mil clearance / 10mil min track width, but at 2Oz seeed only support 10/10. Thats a bummer, I'm not willing to change the layout for that. The last board I sent to ourpcb was 6/8 mils at 2 Oz.

Itead studio also had fairly cheap pcb prototyping, but for this board I might send the job to ourpcb. I don't like the qty=5 to qty=10 jump, I would prefer to just get 6 pcbs, and with ourpcb the boards could jump into our regular pcb shipments, which to me that counts as free fedex shipment.
They also separate the tooling cost from the pcb cost, so if I order now it could be $90 tooling plus $10 per board. If the next guy wants a pcb he only needs to pay the $10 per board.

I'm busy at work now for some days, before sending this gerbers I want to have the copper sheets designed in case something new comes up. I'm also counting on a small 2 layer board to hold a LEM current sensor and a differential opamp so the current signal is fully differential from the sensor. If the distance between the current sensor and this board is not too long it could be a flexible pcb.

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HighHopes
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by HighHopes » Fri Jul 28, 2017 7:02 pm

wait till u see the price of the flexible PCB ;P

marcos
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Fri Jul 28, 2017 8:34 pm

Its around 90usd to make an FPC prototyping batch, I made a few hundred, it ends in 1usd each. Adds a bit to the cool factor and you get differential traces very close to each other on top of a copper plane 0.15mm away. And you can solder smd components and use pth vias. Did I say I hate wiring?
Its only an option, its for sure doable with a 10usd pcb plus wires.

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Sun Aug 06, 2017 8:21 am

Does anyone know a good and fast delta sigma current sensor for ~1000amps?

I've been toying with the idea since day 0.
Pros:
* if the voltage and current signals were delta sigma encoded I could replace 13 opamps by a single fpga in the controller
* Fully digital signal path. Zero noise picked up from the sensor to the microcontroller
* Error detection. Most delta sigmas I've seen implement a way to check if the sensor is not ok. (a stream of 0's means error for example)
* For phase voltage measurement its already here, just change a part# and its delta sigma instead of analog differential. Same footprint and circuit.
* Having an fpga I would remove the discrete logic pwm overlap circuit.

Its a total of 10 ICs plus countless rc filters replaced by a single QFN48 IC.

Cons:
* Its been 5 years since the last time I developed fpga stuff, could take me a while to get this simple hdl done
* Sinc3 filter response time. Right now I have a 4usec response time and I'd like to keep it that way without losing resolution.
* Minor code change to read a DMA-filled register instead of ADC-filled register. fpga would write the microcontroller ram using dma, no cpu involved.
* Apparently no off the shelf current sensors available

So coming back to the original question, are there suitable delta sigma current sensors?
So far the best approach I could find is to build my own using something like this 13usd resistor http://www.isabellenhuette.de/fileadmin ... de/BAS.PDF
plus the same isolation amplifier used in the phase voltage...

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tecnologic
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by tecnologic » Sun Aug 06, 2017 12:02 pm

Hi marcos,

have a look at the AMC1304L05. +-50mV input Range with 80dB SNR. But the shunts needed should be big ones :). Its a pitty LEM has no sensors with sigma delta interface.

On the FPGA need: I use these AMC1304 with an STM32F767 which has the sinc filters on chip, no need for an FPGA. But my currents are in the range of 100 - 300A.

regards

Tec

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by Arlo1 » Sun Aug 06, 2017 12:24 pm

What about a simple hall effect sensor? I use a csla2en sensor it's + - 950 amp AC/DC 3 us response time
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

marcos
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Sun Aug 06, 2017 12:37 pm

have a look at the AMC1304L05. +-50mV input Range
Almost exactly, I was aiming at the AMC1303, thats the one footprint compatible with this layout.
But the shunts needed should be big ones
Big and not easy to order from a common supplier like digikey afaik. LEM uses hall sensors witch are already isolated and already have some hysteresis and lag, so adding a delta modulation on top of that seems like a bad choice.

Looks like shunt resistor is the only way to go for a digital current measurement. At 50mv 1000A its 50W per phase shunt. Hmmm.
On the FPGA need: I use these AMC1304 with an STM32F767 which has the sinc filters on chip, no need for an FPGA. But my currents are in the range of 100 - 300A.
I hear you there. I almost use that family for a job that needed the delta sigma filter built in. In this case I can't steer the vesc project (the controller I plan to use) to migrate from STM32F4 to STM32F7, but it was a good call, thanks.

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Sun Aug 06, 2017 12:49 pm

Arlo1 wrote:What about a simple hall effect sensor? I use a csla2en sensor it's + - 950 amp AC/DC 3 us response time
Thats similar to what I'm using now, its been working for a couple of months. So far this is only an idea that would lower noise, tolerances, and parts count/cost plus adding fault detection in exchange of more development hours with the fpga code...

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by Arlo1 » Sun Aug 06, 2017 3:15 pm

marcos wrote:
Arlo1 wrote:What about a simple hall effect sensor? I use a csla2en sensor it's + - 950 amp AC/DC 3 us response time
Thats similar to what I'm using now, its been working for a couple of months. So far this is only an idea that would lower noise, tolerances, and parts count/cost plus adding fault detection in exchange of more development hours with the fpga code...
Why don't we start a current sensor thread. I am about to. I need 2000amp current and soon. But I also use a melixis current sensor on the DC input wire to the controller for my gauges. It's hard to get a sheild that has 0 magnetic memory....
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

marcos
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Sun Aug 06, 2017 3:32 pm

Why don't we start a current sensor thread. I am about to.
Go for it and I'll follow.

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by HighHopes » Sun Aug 06, 2017 8:14 pm

i've never used shunt for high power. i don't believe you'll get the SNR necessary, especially at low to mid range amps (at very low, probably have to turn current loop off). anyway, i did look into it a few months ago for a high amp project. i'll post what i found in your other thread which relates to shunt resistors.

combining an FPGA with simple uC makes a lot of sense for motor control project but its not really necessary to get the basic thing working well. i have done this before including a CPLD instead of the discretes for overlap avoidance. but i did this because FPGA counts as hardware, not software, and there are certain advantages to that for certification reason. for one-off build of personal use, dunno if its worth your time to develop. $0.02

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by Arlo1 » Mon Aug 07, 2017 12:14 am

Ok I started a current sensor thread here. https://endless-sphere.com/forums/viewt ... 30&t=89911
My Leaf motor controller build. https://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer

marcos
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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Mon Aug 07, 2017 5:39 am

HighHopes wrote:for one-off build of personal use, dunno if its worth your time to develop.
Maybe I'm trying to get away from one-off build territory :wink:

Having an fpga as supervisor (and digital filter for these digital signals) would make safer to use a very non certified brain. Thats the thing with my controller, its a industrial non automotive mcu running non certified garage tested firmare. Honestly I don't know if a fpga would ease the certification path in this case. If it doesn't I'd lose a big reason to get involved in the fpga design.

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Re: OSHW TO247 IGBT watercooled laminated half-bridge

Post by marcos » Mon Oct 30, 2017 9:24 pm

Reviewing the board this week I noted a couple of things:

1) If a booster circuit with external pnp+npn is used to increase gate drive current, the ISO5852 built-in soft turn-off doesn't work, so I had to add an R+C. (tiduc70a.pdf) This way the turn-off during a desat fault would extend for around 3us. Basically the IC expects some capacitance in the IGBT gate to build the delay but the small pnp bjt has almost no capacitance, so we add those 10nF that resembles an IGBT gate.

Good thing I saw this, it would have detected desat but kill the igbt due to turn off overvoltage.

2) Added igbt active clamping for safe turn-off during fault currents.
Which is not the same thing as a desat fault turn-off. In case there is a very high current and the gate driver is commanded to turn off just *before* a DESAT event, the IGBT would turn off fast as usual, the Vce overvoltage would be high and no soft turn-off would happen (its only triggered by a desaturation event). This new hardwired clamping will make the IGBT avoid overvoltage conditions, usually caused by interrupting a large current flow.
gate driver mods.png
gate driver mods.png (83.7 KiB) Viewed 88 times
Also changed the boost transistors for an AEC-Q101 qualified part.

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