Finbarr Moynihan
Analog Devices

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 demanding servomotor applications because of their simple robust construction, low inertia, high output-power-to-weight ratios, and good performance at high speeds of rotation. This technical paper describes the fundamental principles behind the implementation of high-performance controllers (such as the ADMC401) for three-phase ac motors—combining an integrated DSP controller, with a powerful DSP core, flexible PWM generation, high-resolution A/D conversion, and an embedded encoder interface.