Variable belt tensioner for engine and method for controlling mild hybrid vehicle using variable belt tensioner for engine

A method for controlling a mild hybrid vehicle using a variable belt tensioner for an engine, the method comprising steps of:

• controlling, by a controller, a driver connected to a first damper and a second damper that are included in the variable belt tensioner at a start of the engine including a crankshaft pulley to set a tension of a belt connected to the crankshaft pulley and a starter-generator pulley to a first tension;
• controlling, by the controller, the driver to set a tension of the belt to a second tension that is less than the first tension when an electric power is generated by the starter-generator pulley;
• and
• controlling, by the controller, the driver to set a tension of the belt to a third tension that is less than the second tension when the mild hybrid vehicle is accelerated by the engine,
• wherein the variable belt tensioner further comprises:
• a first pulley that is driven by the first damper and the driver to set a tension of the belt as the first tension, the second tension, or the third tension;
• and
• a second pulley that is driven by the second damper and the driver to set a tension of the belt as the first tension, the second tension, or the third tension.