Motor Drive Control

Most of the generated electrical energy in the world, is used to produce motion in industrial processes, most of which do not require control of the dynamic behavior, and are known as standard motor applications. However, there is a steadily growing share of adjustable speed drives fed and controlled by power converters. Among the reasons are the cost reduction of power electronics, the increase of its realiability and most of all the energy efficiency that variable speed operation provides. The development of control strategies for high-performance AC drives reached maturity over the past three decades. Currently, two technologies largely dominate the industrial market: Field Oriented Control (FOC) and Direct Torque Control (DTC). These strategies were developed in the 70’s and 80’s respectively. Although both strategies have differences in their operating principles an operation, both have the same control objectives: to achieve decoupled control of torque and flux to achieve high dynamic performance speed control. High performance drives have found wide spread acceptance in demanding applictions such as train traction, wind turbines, electric and hybrid electric vehicles, steel rolling mills and flywheel energy storage, to name a few. At powerlab several research lines have led to improvements to motor drive control, particularly in relation to sensorless speed control, PWM based DTC, multilevel-converter-fed drives, and more recently predictive torque and flux control.