Study of an Electric Drive Control System for Antenna Rotation in a Radar with Account of Non-Linearity of the Magnetic Circuit of a Permanent-Magnet Synchronous Motor

The rotation drive control system in a radar is built on the principle of a closed-loop system with cascaded regulation of the coordinates, wherein the outer loop is the speed circuit, and the inner loops are the current circuits Id and Iq. From the experience of operating existing radars as well as from design analysis of latest-generation radars we can single out a few essential requirements for the antenna rotation drive: smooth acceleration, maintaining constant r.p.m. under various wind loads, possibility of deep regulation of the rotation rate to prevent inadmissible mechanical loads on the antenna structure caused by the great weight and wind resistance of the active phased array. These requirements are met by PMSM-based electric drives with a control system that provides stabilised rotation speed of the radar antenna and the required accuracy of determining the target coordinates. When such a control system is designed, it is assumed that the d - and q -axis flux linkage depends linearly on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$d$</tex>-and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$q$</tex>-axis currents. In practice, however, we observe that the flux linkage depends on the current in a non-linear manner. In this connection, we propose to study the effects of non-linearity of the PMSM magnetic circuit on the rotation drive control system for a radar antenna.