Boost Control with Turbo Speed Sensor and Electric Wastegate
The purpose of this master thesis is to investigate the possibility to refine the
control system of turbochargers in petrol engines by introducing turbo speed
measurement. This thesis also investigates possible control enhancement from
an electric wastegate actuator compared with a traditional pneumatic actuator.
During the thesis work the control problem is divided into 3 sub systems: boost
pressure controller, turbo speed controller, and electric actuator controller. The
design procedure of the controllers follows model-based method in which a sim-
ulation model for engine and a simulation model for electric actuator are used.
The designed controller is then implemented and evaluated in an engine test cell.
The result of the thesis work shows that the electric wastegate actuator is pre-
ferred as it delivers consistent actuation speed and accurate positioning which
favours model-based design that requires exact wastegate position. Although
the purposed controller structure that uses turbo speed measurement cannot yet
achieve faster generation of boost pressure by the end of the thesis work, the use
of turbo speed sensor as controller feedback still shows potential to enhance the
boost controller and ease the controller design, as the turbo speed measurement
can reflect the boost pressure faster and is less sensitive to the disturbances in the
Bohan Liang and Robin Holmbom
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Last updated: 2019-08-05