Speed-sensorless state feedback control of induction machines with LC filter

TL;DR

This paper introduces a sensorless control method for induction machines with LC filters, using a speed-adaptive observer and state feedback to ensure fast, stable, and easy-to-tune performance across various operating conditions.

Contribution

It presents a novel sensorless control scheme combining a speed-adaptive observer with LQR-based gain scheduling for induction machines with LC filters.

Findings

Effective speed and state estimation with only filter current measurements.

Stable and accurate control across different loads and speeds.

Easy tuning process suitable for industrial applications.

Abstract

A speed-sensorless state feedback controller for induction machines (IMs) with LC filter is proposed. The estimation of speed and remaining states is based on a speed-adaptive observer, requiring only the measurement of the filter input currents. The motor currents are controlled by a state-feedback controller with proportional and integral control action to achieve fast and asymptotic set point tracking. Observer \emph{and} controller gains are calculated offline using linear quadratic regulator (LQR) theory and updated online (gain-scheduling), in order to guarantee stability and improve control performance in the whole operation range. The proposed control scheme is validated by simulation and experimental results including several zero-crossings of the mechanical speed. It is shown that the overall control system performs well under various load- and speed conditions; while its tuning remains easy making it attractive also for industrial application.