A comparative analysis of fuzzy logic and PI speed control in high performance AC drives using experimental approach

One of the frequently discussed applications of artificial intelligence in motion control is the replacement of a standard PI speed controller with a fuzzy logic (FL) speed controller. Regardless of all the work, it appears that a thorough comparison of the drive behaviour under PI and FL speed control, using an experimental rig, is still missing. This paper attempts to fill in this gap, by providing an in-depth comparison of operation of a vector controlled permanent magnet synchronous motor. Speed responses, obtained under PI and FL speed control, are recorded and compared for a variety of operating conditions. The transients studied include response to large step speed command from standstill with nominal inertia and an increased inertia, response to small step speed reference change, response to step load torque application and reversing transient. The transient behaviour is examined for various initial speed settings, so that a thorough comparison is enabled. It is shown that superiority of the FL speed control is much less pronounced than it is often portrayed in literature on the basis of limited comparisons. Indeed, in a number of cases PI speed control provided a superior speed response.