New open source Isolation monitor?

[joromy]

Have been looking for a isolation monitor for my EV projects, for many years actually.

Most ready build systems are expensive:

https://www.bender.de/en/products/insul ... ir155-3204
http://www.sendyne.com/Products/SIM100% ... nitor.html

Found this reference design from Ti:
http://www.ti.com/tool/TIDA-01513#1

Looks pretty "easy" to build, and the principles are quite simple to.
Make a dummy "leak" to pos, and then to neg. and analyze the measurements.

Anyone interested? A simple microcontroller with CAN could do the job.....

But maybe hardcore EV builders don't care if there is a little tickling in the seat at rainy days?

[tom91]

Looks like most of the circuit is there. I can give it a go in design spark tomorrow, using an 328pb-au (Arduino UNO evolution).
Doing just isolation measurement is a bit simple, will throw in some extra HV checking circuits.

[joromy]

That is great.
But a device like this must have CAN!
Have used the Leonardo from hobbytronics, very useful, for simple CAN projects.
But there may be other "simple" microcontrollers with CAN support?

http://www.hobbytronics.co.uk/arduino/leonardo-canbus

[tom91]

I have made a first draft of the ISO monitor.

It uses an atmega ATMEGA328PB-AU, so it can be programmed in Arduino when loaded with the right bootloader.

The measurement side of things is identical to the TI documents and reference design, only need to derive a 2.5V reference voltage.

There is a can controller and can transceiver onboard so all measurements can be shared on CAN.

If someone would like to review the attached schematic it would be useful.

Also design files on github : https://github.com/tomdebree/SimpISO

[joromy]

Looks great.
Do you have the PCB layout ready tonight, or do I have to wait for tomorrow.

Its a little different use of components, don't you want to use the same design as Ti?

Did you use this document for ref?

[tom91]

I used all their measurement opamps and even the same relay, just driving the relays is different. Plus an off the shelf DCDC is easier to use then their designed power supply.

Will have a look at choosing some connectors.