if no other reason.
The only significant DC motor (apart from vehicle starter motors) I have is on my rolling road (treadmill). All the other Larger variable speed drives – other than my cordless tools – are 3 phase induction motors with VFD.
So much more programmable control with those – soft start, speed control (even before pressing the start button), remote pendant control of all operating functions (stop/start/jog/forward or reverse/speed/emergency stop) and with circuit protection trips adjustable for the drive concerned).
Yes, the occasional VFD might fail but, if the experience of the forum is anything to go by, DC drives and their control boards seem to go pop much more often – and more expensively than the VFD route.🙂 Older boards are likely more at risk than more recent designs, mind.
Fractional 3 phase motors do not seem expensive these days. VFDs are obtainable quite cheaply, too. A friend has sourced all his from scrappies, who remove them from scrapped machinery.