Engine control apparatus and engine control method

An engine control apparatus that controls an engine which is restarted using an AC motor, the engine control apparatus comprising:

• an engine rotational direction determining section configured to determine a rotational direction of the engine;
• a restart command determining section configured to determine if a restart command occurred while a rotational speed of the engine is decreasing due to an idle stop command;
• an engine restart prohibiting section configured to selectively prohibit the engine from being restarted by the AC motor in response to the restart command upon determining the engine is rotating backward;
• and
• an excitation section configured to commence to excite a field magnet of the AC motor when the rotational speed of the engine is equal to or below a prescribed rotational speed, the prescribed rotational speed being set such that if the excitation is commenced when the prescribed rotational speed is reached, then the excitation is completed simultaneously with the transition of the engine from backward rotation to forward rotation.