TABLE OF CONTENTS High-performance motor drives are characterized by the need for smooth rotation down to stall, full control of torque at stall, and fast accelerations and decelerations. In the past, variable speed drives employed predominantly dc motors because of their excellent controllability. However, modern high-performance motor drive systems are usually based on three-phase ac motors, such as the ac induction motor (ACIM) or the permanent magnet synchronous motor (PMSM). These machines have supplanted the dc motor as the machine of choice for variety of applications because of their simple robust construction, low inertia, high power density, high torque density, and good performance at high speeds of rotation.
The vector-control techniques established for controlling these ac motors; and most modern high-performance drives now implement digital closed-loop current control. In such systems, the achievable closed-loop bandwidths are directly related to the rate at which the computationally intensive vector-control algorithms and associated vector rotations can be implemented in real time. Because of this computational burden, many high-performance drives now use digital signal processors (DSPs) to implement the embedded motor-and vector-control schemes. The DSPs are special microprocessors used where real-time manipulation of...
