Motor drive apparatus and motor drive control method

A motor drive apparatus comprising:

• a rotational position estimation device configured to estimate a rotational position of a rotor by detecting a phase voltage generated in a stator coil of a brushless DC motor;
• a drive control device configured to perform a drive control process of the motor in a first control mode, which is based on the estimated rotational position;
• and
• an overvoltage detection device configured to detect that overvoltage is applied to a power source line,
• wherein the drive control device performs the control process in a second control mode so as to perform a forced commutation of the motor when overvoltage is detected by the overvoltage detection device when the motor is stopped.

A method for a motor drive control, the method comprising:

• detecting a phase voltage generated in a stator coil of a brushless DC motor;
• estimating a rotational position of a rotor based on the detected phase voltage;
• performing a drive control process of the motor in a first control mode, which is based on the estimated rotational position;
• detecting that overvoltage is applied to a power source line when the motor is driven;
• detecting a rotational frequency of the motor when it is detected that the overvoltage is applied to the power source line;
• and
• changing the drive control process to a second control mode so as to perform a forced commutation of the motor based on the detected rotational frequency when it is detected that the overvoltage is applied.

A method for a motor drive control, comprising:

• detecting a phase voltage generated in a stator coil of a brushless DC motor;
• estimating a rotational position of a rotor based on the detected phase voltage;
• performing a drive control process of the motor in a first control mode, which is based on the estimated rotational position;
• and
• changing the drive control process to a second control mode so as to perform a forced commutation of the motor when detecting that an overvoltage is applied to a power source line when the motor is stopped.