One of my concerns on 600V design is how to make ADC readings in the 600V area.
I need 3 x Current sensors, 1 x DC Voltage Sensor and 1(2) x Temperature sensors in addition to support for up to 3 resolver sensors as well as an external motor temperature sensor. That sums up to 10 ADC readings coming from or through 600V area. I was investigating ADC to SPI solutions, but specially current readings will happen 25,000 times per second and needs to happen at exact timing. I did find component that do specialized current or ADC readings with isolated ADC output, but those ADC signals will be measured on the far end of a PWM card and needs to be transported to the MCU. The solution I decided to try out is a 2-barrier system. I use an isolated sensor capable of handling xx Voltage ESD andthen a 2nd barier with an Isolated OpAmp on the Controller.board.
I am no expert on this so it will need to test. Calculating cost I am looking at 6.- USD per analogue channel assuming Digikey prices at 10 x. I think the first test is to make a small board testing a single channel to see if this works and what delays and reading quality I get, As for temperatur and accuracy the current sensors will have the same error and drift from temperature so the angle should still be intact + PID + Filter will regulate that regardless.
I will add a MOSFET set on the test so I can load a single channel and verify if my heat calculations work, but I am not that worried as we talk about only 10A on the first board, I did calculate ca 12Watt loss using decent MOSFET’s from Infineon with 105mOhm RDS.