Nonlinear exhaust pressure control of an SI engine with VGT using partial model inversion

An important target for car manufacturers when developing new cars is to reduce fuel consumption. One approach to this problem is to use a downsized turbocharged engine. To fully utilize the benefits of the new hardware introduced, good control systems are needed. This paper presents a nonlinear controller for controlling the exhaust pressure in a SI engine equipped with VGT. A mapping from the states, inputs and disturbances to future outputs is formed, and inverting the input-output relation in this mapping gives a control law. An analysis shows that the controller adapts its gain to the input-output sensitivity. The controller is evaluated using both simulations and measurements on a real engine, showing the benefit of using the nonlinear controller over a corresponding linear controller.