Speed controller design for induction motor drives using a PDF control and load disturbance observer

Some of the important characteristics required for field-oriented AC drives are a fast run-stop capability and good speed regulation regardless of sudden load change. The properties of a PDF (pseudo derivative feedback) controller are analyzed, and some key features are described compared with the PI (proportional plus integral) controller. In order to get robust speed control performance against variation of load inertia, a load disturbance observer is also applied to the PDF controller, and experimental results are presented. Nominal load inertia is measured by using a digital-signal-processor-based inverter self-tuning function, and parameters needed for the controller can be calculated to get good speed control performance