LQG/LTR Controller Design for a Gas Engine

The dynamics of a gas engine vary strongly over its power range with controlled engine speed. The major nonlinearities result from the turbo charger driven by exhaust gas. The recirculation valve adjusts the power of the turbo charger, by leading part of the compressed mixture back to the inlet. The position of the throttle valve affects the mass flow into the engine. Both actuators are used to control the engine speed. In order to optimize the switching between the actuators, LQG control is applied. For linear state feedback control suitable states have to be determined and unmeasured states must be estimated in an acceptable way. This paper shows that LQG control is able to enhance the performance of the engine speed control by using both actuators simultaneously.