This paper proposes a novel method for superheat and capacity control of refrigeration systems. A new low order nonlinear model of the evaporator is developed and used in a backstepping design of a nonlinear controller. The
stability of the proposed method is validated theoretically by Lyapunov analysis and experimental results shows the performance of the system for a wide range of operating points. The method is compared to a conventional
method based on a thermostatic superheat controller.