Friday, February 20, 2015
Most manufacturers have separate product families for "servo drives" and "variable frequency drive" or "inverter". However, if we take one of the many VFDs that support PM motors with sensor and a PM servo drive, the control, is the same up to the speed loop. Both servo and VFD (except for DTC) need an inner vector current control loop, which means torque control, and a speed control regulator. They also need a self-tuning p ...