Apparatus and method for driving a permanent magnet synchronous motor for expanding the flux-weakening region

A method for controlling a wide conduction drive flux weakening regions expandable permanent magnet synchronous motor to start the motor at 120 ° conduction drive mode by a closed loop. During the acceleration, when the PWM duty δ exceeds 95% in the 120-degree conduction drive mode, the motor driving mode is switched from the 120-degree conduction drive mode to the 150-degree conduction drive mode. During further acceleration, when the PWM duty δ exceeds 95% at 150 ° conduction drive mode, a motor drive mode from the 150-degree conduction drive mode is switched to the forced drive mode of the open loop. During deceleration, when the zero crossing of the counter electromotive voltage is detected by overlapped successively switches the motor driving mode from the forced drive mode to the 150-degree conduction drive mode. During the further reduction switches the motor driving mode from the 150-degree conduction drive mode to the 120-degree conduction drive mode.