Motor control device and work machine using the same

A motor control device having a controller that controls a current supplied to a motor in such a manner that a current command value obtained from a torque command value to the motor corresponds to a current detection value regarding the current supplied to the motor via a power inverter, wherein

• the controller estimates torque output by the motor and controls the current supplied to the motor in such a manner that a torque estimate of the motor obtained by the estimation corresponds to the torque command value, and
• the controller includes
• a torque estimation calculator that estimates the torque output by the motor,
• a voltage vector calculator that calculates d-axis and q-axis voltage command values based on d-axis and q-axis current command values, d-axis and q-axis current detection values, a speed estimate, and a setting value of a motor constant,
• a phase error estimation calculator that outputs a phase error estimate that is an estimate of a phase error as a deviation between an estimate of a rotational phase of the motor and a rotational phase value of the motor based on the d-axis and q-axis voltage command values output by the voltage vector calculator, the speed estimate, the d-axis and q-axis current detection values, and the setting value of the motor constant,
• a phase error command calculator that calculates a command value of the phase error from a deviation between the torque estimate obtained by the estimation by the torque estimation calculator and the torque command value, and
• a speed estimation calculator that outputs the speed estimate in such a manner that the phase error estimate output by the phase error estimation calculator corresponds to the command value of the phase error output by the phase error command calculator.

A motor control device having a controller that controls a current supplied to a motor in such a manner that a current command value obtained from a torque command value to the motor corresponds to a current detection value regarding the current supplied to the motor via a power inverter, wherein

• the controller estimates torque output by the motor and controls the current supplied to the motor in such a manner that a torque estimate of the motor obtained by the estimation corresponds to the torque command value, and
• the controller includes
• a torque estimation calculator that estimates the torque output by the motor,
• a voltage vector calculator that calculates d-axis and q-axis voltage command values based on d-axis and q-axis current command values, d-axis and q-axis current detection values, a speed estimate, and a setting value of a motor constant,
• a q-axis inductance correction calculator that calculates a correction value of q-axis inductance from a deviation between the torque estimate obtained by the estimation by the torque estimation calculator and the torque command value,
• a phase error estimation calculator that outputs a phase error estimate that is an estimate of a phase error as a deviation between an estimate of a rotational phase of the motor and a rotational phase value of the motor based on the d-axis and q-axis voltage command values output by the voltage vector calculator, the speed estimate, the d-axis and q-axis current detection values, the setting value of the motor constant, and the correction value of the q-axis inductance, and
• a speed estimation calculator that outputs the speed estimate in such a manner that a command value of the phase error output by the phase error command calculator becomes zero.

A work machine comprising:

• a permanent magnet synchronous electric motor;
• a power inverter that converts a DC voltage to three-phase AC voltages to supply the three-phase AC voltages to the permanent magnet synchronous electric motor and varies output torque of the permanent magnet synchronous electric motor;
• and
• a controller that controls a current supplied to the permanent magnet synchronous electric motor in such a manner that a current command value obtained from a torque command value to the permanent magnet synchronous electric motor corresponds to a current detection value regarding the current supplied to the permanent magnet synchronous electric motor via the power inverter, wherein
• the controller calculates a second torque command value in such a manner that a torque estimate obtained from power information of the power inverter corresponds to a first torque command value given from an upper-level control device, and
• the controller carries out the torque control in accordance with the second torque command value.