SPCO MODE The control system must regulate the same speed to both compressors under any operational condition concerning table function where engine’s speed and throttle position are input variable and compressors’ speed is an output variable. The control system requires Downloaded from SAE International by Nan Kai University of Technology, Monday, December 02, 2019the next information: • First stage compressor’s speed (n1), • Second stage compressor’s speed (n2), • Engine speed (n), • Throttle position (g). No pressure sensor is necessary for the basic functioning. In addition, other information like knocking and temperature must be taken into account but these are not distorting the basic regulation principle and are not the subject of this paper. Also the control system must energize the solenoid valve when the functioning is crossing in the right side of the natural crossing line.