Idle stop and go system and method controlling thereof

A method of controlling a vehicle system including an engine operating an alternator, the alternator selectively electrically connected to a capacitor, the method comprising:

• receiving, by a controller, state data of a vehicle;
• determining, by the controller, whether an idle stop condition is satisfied based on the received state data of the vehicle;
• measuring, by the controller, a state of charge of a battery and the capacitor, and comparing the measured SOC values of the battery and the capacitor with first and second predetermined values, respectively;
• determining, by the controller, a brake-recuperation mode when an idle stop condition is satisfied, and the measured SOC value of the capacitor is less than the second predetermined value;
• and
• calculating, by the controller in the brake-recuperation mode, an electric load corresponding to a brake torque to place a position of a crankshaft within a predetermined range, and
• applying, by the controller, the calculated electric load to the engine via the alternator until the position of the crankshaft is within the predetermined range.

A vehicle system for a vehicle having an engine, a starter motor and a battery, the engine having a crankshaft configured to generate power, and the starter motor electrically connected to the battery and configured to start the engine, the vehicle system comprising:

• an alternator operatively connected to the crankshaft of the engine and configured to generate electric power and charge the battery;
• a capacitor electrically connected to the alternator, the battery, and the starter motor, the capacitor configured to store the generated electric power based on a state of charge (SOC) of the battery and capacitor;
• and
• a controller configured to control electric connections between the alternator, the capacitor, the battery, and the starter motor, and to determine an idle stop mode,
• wherein in the idle stop mode, the controller is configured to control a position of the crankshaft by applying a calculated electric load to the alternator such that the crankshaft position is located in a predetermined range.