Novel Scalar versus Field Oriented Speed Control of Induction Machine Drives

Scalar stator voltage control of induction machines (IM) is actually along with the more famous slip control an ancient method to control variable speed drives. However, in contrast to slip control it offers the possibility to easily combine both high dynamics at best efficiency. A reasonable control structure and parameter design provided it is even capable to compete with the commonly applied field oriented speed control (FOC) as will be shown in this article. A generic control structure and corresponding parameter design recipes are presented for the scalar stator voltage control facilitating a quick implementation. The obvious drawback of possibly hidden overcurrent events opposes the advantages of a reduced sensor count (no current sensors required) a simpler control algorithm and less parameter sensitivity as compared to FOC. A comparative analysis of the dynamical performance with respect to FOC is provided by an extensive experimental section.