I have a couple Static inverters I use for testing compressors. I believe t6hat is how your idler is started.. Rotary inverters are the best. Static inverters create a false phase to start the motor then it runs on single phase. With the rotary the third phase is continuous as long as the idler is running..

I know a lot about a lot of things BUT I still have a lot to learn.
Life is what you make of it. So, why not make a working machine to make it easier.