Advanced Engine Cooling System Subjected to Ram Air Effect—Nonlinear Adaptive Multiple Input and Multiple Output (NAMIMO) Control

Advanced engine cooling systems typically replace the traditional mechanical cooling actuators with electrical controlled ones to reduce unnecessary power losses. The real time adjustment of the pump, valve, and radiator fans allow the engine temperature to be more accurately regulated. This paper investigates a nonlinear adaptive multi-input and multi-output (NAMIMO) controller to operate the valve and radiator fans to control the engine temperature under different operating conditions. A nonlinear adaptive backstepping (NAB) control strategy and a state flow (SF) control law are introduced for comparison. An experimental laboratory station has been fabricated to evaluate the proposed controllers. The test results show that the NAMIMO controller can regulate the engine temperature to a desired value (|e| <; 0.5 °C at steady state) and compensate for unknown heat loads and ram air effects. In contrast, the NAB control law consumes the least radiator fan power but realized a larger average temperature tracking error (40% greater than NAMIMO controller) and longer response time (34% greater than NAMIMO controller) and shows weakness when the heat load is low. Finally, the SF controller, characterized by greater oscillation and electrical power consumption (18.9% greater than the NAMIMO controller), was easy to realize and maintained the engine temperature within |e| <; 0.5°C. The main technical contribution of the study is a nonlinear control strategy which regulates the engine temperature while compensating for unknown heat loads and ram air effects.