Asynchronous machines with flux vector control

The concept of flux vector control, which emerged in the mid-1980s, revolutionized the field of variable speed drives, which were in constant need of performance enhancement. This paved the way for researchers and engineers in various disciplines (automation, electrical engineering, power electronics, industrial computing, microelectronics, instrumentation, etc.) to develop several variants of control algorithms emerging from the concept of flux vector control of asynchronous machines.

The natural independence between flux creation and torque generation is clearly the fundamental intrinsic property of a separately excited DC machine. The aim of vector control of an asynchronous cage machine is to reproduce the quadrature between the current and flux vectors. The complexity of the control lies in the fact that current and flux are strongly coupled variables, and any action on one has repercussions on the other.

We have avoided excessive popularization of the concept of flux orientation, which would have run the risk of obscuring the details, which are of paramount importance to derive maximum static and dynamic performance from the induction machine.

The use of mathematical transformations is inevitably the key to understanding the mechanisms of flux vector control. In our talk, we'll show that matrix calculus, two-axis theory and space vector manipulation provide the essential tools for moving from a real presentation of a three-phase asynchronous machine to the presentation of a fictitious asynchronous machine with orthogonal windings.

To meet increasingly demanding specifications, we need to adopt a global, multidisciplinary approach that takes into account all the correlations directly involved in the control-converter-machine association.

The implementation and industrialization of flow control are covered in article [D 3 564].