Apparatus and method for preventing an overshoot in the rotation speed of an internal-combustion engine

A method for preventing an overshoot in a rotation speed of an internal-combustion engine, the method using a starter/battery charger that includes 3-phase armature coils, is coupled to a crank shaft of the internal-combustion engine, operates as a starting motor for starting the internal-combustion engine, and also operates as a charging generator for charging a battery after the internal-combustion engine has been started;

• and a controller for performing a driving control for causing the starter/battery charger to generate positive torque and a braking control for causing the starter/battery charger to generate negative torque and thereby controlling the rotation speed of the engine, wherein:
• the starter/battery charger is caused to generate negative torque in the braking control by effecting a 3-phase short-circuiting between phases of the 3-phase armature coils of the starter/battery charger, to thereby prevent the overshoot in the rotation speed of the internal-combustion engine.

A method for preventing an overshoot in a rotation speed of an internal-combustion engine before reaching an idling rotation speed thereof, the method using a starter/battery charger that includes 3-phase armature coils, is coupled to a crank shaft of the internal-combustion engine, operates as a starter for starting the internal-combustion engine, and also operates as a charging generator for charging a battery after the internal-combustion engine has been started;

• and a controller for carrying out a judgment that a self-ignition has been established in the internal-combustion engine prior to the rotation speed reaching an idling rotation speed, switching from a driving control for causing the starter/battery charger to generate a positive torque to a braking control for causing the starter/battery charger to generate a negative torque and thereby controlling the rotation speed of the internal-combustion engine,
• wherein the starter/battery charger is caused to generate the negative torque in the braking control by effecting a 3-phase short-circuiting between phases of the 3-phase armature coils of the starter/battery charger, to thereby prevent the overshoot in the rotation speed of the internal-combustion engine.