Good day to all!

I am planning on designing an Electric Vehicle architecture from scratch. My main DC bus voltage is 400V. However, I have got different voltages in my system. I have got a 600/400V buck converter to supply my air conditioning compressor and I have got a Motor Inverter that outputs 3 phase AC supply.

To make myself clear, I am attaching an image of my High Voltage Junction Box.

With this architecture, I have a confusion about monitoring the insulation resistance of my High Voltage Bus. I am currently planning to keep an Insulation Monitoring Device (IMD) from Bender (Isometer IR155-3203).

I would like to know whether I need separate IMDs for my 400V supply to the Air conditioning as well as the 3 phase AC supply to my Motor. Do I need to be concerned about multiple voltages in the same system? If not, what can I do detect a break in the insulation at any point in my HV bus? I hope my question makes sense, if it doesnt please let me know.

PS: The image is just for representation. Please let me know if you need more details