Haapala wrote: ↑Tue Sep 05, 2023 3:29 pm
Hi,
Having problem with one LDU inverter. Infact this one is from Mercedes B250e.
Had HV insulation problem. Had water in rotor area, thought that was the cause.
While open no insulation problem in any component, inverter or stator.
I did assemble it but in first test drive insulation problem came back. Car was drivable, but fault codes on dash.
Did measure from motor HV connections that 200kOhm was the resistance to frame on 500V. That was the same that diagnostics showed from OBD.
Did take motor out again and inverter side open. Did take the end piece from inverter that connects 3 "phase cards" together. Also disconnected stator windings from inverter. Did manage to measure 200kOhms on one "phase card", two other was OK.
I took the one third out and measured on table, the same 200kOhms was result. But after 30 min the insulation problem was gone. Again megaOhms.
Let it sit on table for night and in the morning it was 30kOhms. Again later in day megaOhms.
What component could cause this?
Could there be any way to measure what is the cause?
Pretty hard to find inverter parts for Mercedes.
I do have one Tesla S85 LDU, but it had different part number on PCB and also different components on it.