0curtisjb1988 4 weeks ago ReplyUpvoteAs a millwright I have never heard of 3 phase DC motors. There are technically universal motors that are interchangeable but I have only seen them as high as 220V single phase AC or bi directional DC. But since AC motors is easier to slow down and speed up by playing with the FQ where DC motors use a combo of resistors, capacitors, and transistors with a potentiometer to play with speed. VFD controllers do technically use a PWM of DC power to simulate an sine wave but since the final control is based on the FQ of the power and only AC fluctuates they are considered AC 3 phase. Which is why contactors are always AC rated at the voltages but DC controlled on it's auxilary NO and NC terminals because DC just flows one way while if AC will cause the NO and NC terminals to shut on and off rapidly and need additional parts to avoid that.