A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supplied power to the motor that is a position sensorless synchronous machine, and includes a controller that outputs a control signal to control the inverter. The method includes reducing output torque of the motor to be less than maximum output torque, in a speed range that is lower than a first speed at which the motor rotates. The maximum torque that is output from the motor is the maximum output torque in a case the motor drive apparatus drives the motor.

A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supplied power to the motor that is a position sensorless synchronous machine, and includes a controller that outputs a control signal to control the inverter. The method includes reducing output torque of the motor to be less than maximum output torque, in a speed range that is lower than a first speed at which the motor rotates. The maximum torque that is output from the motor is the maximum output torque in a case the motor drive apparatus drives the motor.

A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supplied power to the motor that is a position sensorless synchronous machine, and includes a controller that outputs a control signal to control the inverter. The method includes reducing output torque of the motor to be less than maximum output torque, in a speed range that is lower than a first speed at which the motor rotates. The maximum torque that is output from the motor is the maximum output torque in a case the motor drive apparatus drives the motor.

A motor drive method is a method of driving a motor by a motor drive apparatus. The motor drive apparatus includes an inverter that regulates supplied power to the motor that is a position sensorless synchronous machine, and includes a controller that outputs a control signal to control the inverter. The method includes reducing output torque of the motor to be less than maximum output torque, in a speed range that is lower than a first speed at which the motor rotates. The maximum torque that is output from the motor is the maximum output torque in a case the motor drive apparatus drives the motor.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor. The controller is configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor within a variable speed range of zero to at least 15,000 rotations-per-minute (RPM), and control the drive signal based on the detected angular position of the rotor to electronically commutate the motor within a torque range of zero to at least 15 newton-meters (N.m.) and a power output of zero to at least 1500 watts.

A controller of a motor control device increases a voltage to be applied to a coil based on a control signal calculated from an estimated rotation speed, when the estimated rotation speed becomes equal to or lower than a predetermined rotation speed, increases the voltage to be applied to the coil based on a control signal calculated from an actual rotation speed, in a case where the actual rotation speed is lower than the predetermined rotation speed when the estimated rotation speed becomes higher than the predetermined rotation speed, and decreases the voltage to be applied to the coil based on a control signal calculated from the actual rotation speed, in a case where the actual rotation speed is higher than the predetermined rotation speed when the estimated rotation speed becomes higher than the predetermined rotation speed.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor. The controller is configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor within a variable speed range of zero to at least 15,000 rotations-per-minute (RPM), and control the drive signal based on the detected angular position of the rotor to electronically commutate the motor within a power output of zero to at least 1500 watts.

A motor control device provided with a control unit which controls the number of rotations of a motor by implementing a first control which enables high-torque and precise control, or a second control enabling more efficient control than the first control with respect to the motor; and a switching determination unit which, if an actual measurement value of the number of rotations of the motor is greater than a prescribed threshold value of the number of rotations, switches the first control to the second control. The switching determination unit further switches the first control to the second control if the actual measurement value of the number of rotations is not more than the threshold value of the number of rotations, and when a prescribed time has passed from a point in time at which the actual measurement value of the number of rotations matched the required number of rotations.

The system determines that a multiphase electric motor is in a low-speed operating range, near stall. The system determines a duty cycle for each phase of the multiphase electric motor. The duty cycle includes a nominal component and a zero-sequence component configured to balance temperature rises of power electronics devices of the motor drive. Power electronics devices can include diodes, IGBTs, or other switches or devices. The system causes each duty cycle to be applied to a corresponding switch of the corresponding phase of the multiphase electric motor to cause current flow in the corresponding phase. The system may determine duty cycles corresponding to a thermal balance between a switch and a diode of a phase and a thermal balance between a pair of like devices of different phases, and then determine which duty cycle is closer to a predetermined value.

The system determines that a multiphase electric motor is in a low-speed operating range, near stall. The system determines a duty cycle for each phase of the multiphase electric motor. The duty cycle includes a nominal component and a zero-sequence component configured to balance temperature rises of power electronics devices of the motor drive. Power electronics devices can include diodes, IGBTs, or other switches or devices. The system causes each duty cycle to be applied to a corresponding switch of the corresponding phase of the multiphase electric motor to cause current flow in the corresponding phase. The system may determine duty cycles corresponding to a thermal balance between a switch and a diode of a phase and a thermal balance between a pair of like devices of different phases, and then determine which duty cycle is closer to a predetermined value.