Process operation near an unstable steady state using nonlinear feedback control

✍ Scribed by D.D. Bruns; J.E. Bailey

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 768 KB
• Volume: 30
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(75)85103-7

✦ Synopsis

Process performance is sometimes best at an unstable steady state. Following a new control philosophy, stable operation near an unstable steady state can be realized using a relay with hysteresis as a feedback controller. Properly designed, this control scheme produces a stable, small amplitude oscillation in the neighborhood of the desired state. Approximate solutions for such oscillations can be obtained by Tsypkin's method or Describing Function analysis. Comparisons of these solutions with exact simulation results for an example reveal that replacing the relay with the describing function is a major source of error in the approximate analysis.