Method of controlling engine and transmission of hybrid vehicle

A method of controlling an engine and a transmission of a vehicle, the method comprising:

• determining, by a controller, whether the engine is restarted after releasing the vehicle's SSC (Start & Stop coasting) or whether the vehicle is accelerating during NCC (Neutral Coasting control);
• determining, by the controller, an RPM and gear stage of the transmission if it is determined that the engine is restarted after releasing the vehicle's SSC or the vehicle is accelerating during NCC;
• determining, by the controller, a mild hybrid starter and generator (MHSG) target RPM and an MHSG target RPM gradient of the vehicle;
• performing, by the controller, MHSG RPM control of the vehicle to follow the MHSG target RPM and the MHSG target RPM gradient;
• determining, by the controller, whether the MHSG RPM slips compared to the MHSG target RPM;
• and
• performing, by the controller, proportional-integral-derivative (PID) control to follow the MHSG target RPM if the MHSG RPM slips compared to the MHSG target RPM;
• wherein:
• in determining the MHSG target RPM and the MHSG target RPM gradient of the vehicle,
• the controller determines a speed of the vehicle,
• the controller determines the MHSG RPM at the time of switching to an engine reference control calculated by the first map table preset for the speed and the gear stage, and
• the controller determines the MHSG target RPM and the MHSG target RPM gradient calculated by the preset second map table for the MHSG RPM at the time of switching to the current MHSG RPM and the engine reference control.