Sliding Mode Anti-windup Strategy for Mass Flow-Rate Regulation of Compressors with Rate-Limited Motors

In this paper, the control of the mass flow-rate for a centrifugal compressor is discussed. The compressor is driven by a rate-limited actuating motor. To avoid integral windup, a sliding mode control (SMC) based anti-windup strategy is proposed. The developed scheme essentially avoids the integral windup of PI controllers by adapting the controller gain such that output of controller is not influenced by the rate limiter. Furthermore, a relay-based optimal tuning methodology for PI controllers in rate-limited systems is presented and discussed. Optimal tuning of the PI controller is done at different operating conditions of the compressor and used to create a gain schedule that provides a more robust control structure compared to standard manually tuned PI controllers.