Disclosed is a vector flux weakening control method for vector flux weakening for a vehicle permanent magnet synchronous motor, which includes a current closed-loop adjuster, a modulation ratio deviation calculator, a current command angle compensator, a current angle preset processor, a current command angle limiting comparator and a current given vector corrector. The adjusting direction of the present disclosure is always a flux weakening direction, and instability caused by repeated adjustment will not occur; by introducing dq current while performing correction, the pressure against voltage saturation can be shared to both d-axis and q-axis current, so as to avoid excessive output torque deviation caused by excessive adjustment of a single-axis current; the influence of the flux weakening control link on the output torque of the drive system can be minimized as much possible while ensuring the safety of the drive system.

In a control apparatus for an alternating current (AC) motor, a control mode switching determiner compares a modulation rate with a modulation rate threshold, and selects between a synchronous control mode to perform synchronous control in a range where the modulation rate is equal to or greater than a modulation rate threshold and an asynchronous control mode to perform asynchronous control in a range where the modulation rate is less than the modulation rate threshold. The control mode switching determiner uses a different modulation rate threshold in a low rotational speed range and a high rotational speed range such that the modulation rate threshold in the low rotational speed range is greater than the modulation rate threshold in the high rotational speed range. A selector selects between outputting the synchronous pulse signal and outputting the asynchronous pulse signal.

In a control apparatus for an alternating current (AC) motor, a control mode switching determiner compares a modulation rate with a modulation rate threshold, and selects between a synchronous control mode to perform synchronous control in a range where the modulation rate is equal to or greater than a modulation rate threshold and an asynchronous control mode to perform asynchronous control in a range where the modulation rate is less than the modulation rate threshold. The control mode switching determiner uses a different modulation rate threshold in a low rotational speed range and a high rotational speed range such that the modulation rate threshold in the low rotational speed range is greater than the modulation rate threshold in the high rotational speed range. A selector selects between outputting the synchronous pulse signal and outputting the asynchronous pulse signal.

Provides a method for controlling an AC motor, including: receiving a torque command value; generating a command current based on the torque command, and a command voltage by using the generated command current in a current vector controller (CVC) current control mode; switching to a hexagon voltage manipulating controller (HVMC) voltage control mode when the command voltage enters a voltage limit area, and generating a command voltage in the HVMC voltage control mode; and controlling torque of an AC motor by using the command voltage that is generated in the CVC current control mode or the HVMC voltage control mode.

Provides a method for controlling an AC motor, including: receiving a torque command value; generating a command current based on the torque command, and a command voltage by using the generated command current in a current vector controller (CVC) current control mode; switching to a hexagon voltage manipulating controller (HVMC) voltage control mode when the command voltage enters a voltage limit area, and generating a command voltage in the HVMC voltage control mode; and controlling torque of an AC motor by using the command voltage that is generated in the CVC current control mode or the HVMC voltage control mode.

An electric power tool is provided with a permanent magnet synchronous motor, and a controller. The controller is configured to control an operation of the permanent magnet synchronous motor. The controller includes a limiter that limits a current contributing to torque generation by the permanent magnet synchronous motor to a predetermined maximum set value based on a predetermined tightening torque. The controller calculates the maximum set value of the current that contributes to the torque generation by changing one of a rotation speed and an angular speed of the permanent magnet synchronous motor.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

A parameterless and position-sensorless MTPA control of a permanent magnet synchronous motor including: using three rotating reference frames having different observation angles to parse the current vector; using a target current value and a preset current-rotor angle y that is between the current vector and the q.sub.r-axis of the (d.sub.r, q.sub.r) rotor reference frame to obtain the angles between the current vector, the voltage vector, and the rotor position; obtaining the target voltage value and the target voltage angle by using the obtained angles to obtain the target phase voltage values for regulation. The method is simple in controlling the motor, improves the control efficiency and reliability, and improves the control accuracy.

A parameterless and position-sensorless MTPA control of a permanent magnet synchronous motor including: using three rotating reference frames having different observation angles to parse the current vector; using a target current value and a preset current-rotor angle y that is between the current vector and the q.sub.r-axis of the (d.sub.r, q.sub.r) rotor reference frame to obtain the angles between the current vector, the voltage vector, and the rotor position; obtaining the target voltage value and the target voltage angle by using the obtained angles to obtain the target phase voltage values for regulation. The method is simple in controlling the motor, improves the control efficiency and reliability, and improves the control accuracy.