Abstract: A motor control device includes: a motor; an inverter; and a control device. The control device includes: a detection device detecting a rotational position and a revolution speed of the motor; a positioning control device for a rotor; a deceleration device for the motor; and a determination device for the revolution speed of the motor. When the revolution speed is higher than or equal to the first predetermined revolution speed, the motor control device starts controlling the motor to rotate at the target speed, according to the rotational position, without executing the positioning control. When the revolution speed is lower than the first predetermined revolution speed and higher than or equal to the second predetermined revolution speed, the deceleration device decelerates the motor. When the revolution speed is lower than the second predetermined revolution speed, the positioning control device starts executing the positioning control.

Abstract: A motor control device includes: a motor; an inverter; and a control device. The control device includes: a detection device that detects a rotational position and a revolution speed of the motor; a positioning control device for a rotor; a deceleration device for the motor; and a determination device for the revolution speed of the motor. When the revolution speed is higher than or equal to the first predetermined revolution speed, the motor control device starts controlling the motor to rotate at the target speed, according to the rotational position detected by the detection device, without executing the positioning control. When the revolution speed is lower than the first predetermined revolution speed and higher than or equal to the second predetermined revolution speed, the deceleration device decelerates the motor. When the revolution speed is lower than the second predetermined revolution speed, the positioning control device starts executing the positioning control.

Abstract: In a system for driving an inverter, a superimposing element superimposes, on an output voltage of the inverter. The high-frequency voltage signal is correlated with a measured high-frequency component value of a current flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value. A dead-time compensating element shifts a start edge and an end edge of an on duration for each of first and second switching elements of the inverter by a preset same time to compensate for an error due to dead time. A current manipulating element manipulates a current flowing in the rotary machine to maintain an accuracy of calculation of the rotational angle.

Abstract: In a system, a superimposing element sets a command value vector of a high-frequency voltage signal and superimposes the high-frequency voltage signal with the command value vector on an output voltage of an inverter. The high-frequency voltage signal has a frequency higher than an electrical angular frequency of a rotary machine. The command value vector is correlated with a measured high-frequency component value of a current signal flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value of the current signal flowing in the rotary machine. A reducing element controls at least one of the inverter and a direct voltage power supply to reduce a difference due to the dead time between the command value vector and a vector of a high-frequency voltage signal to be actually superimposed on the output voltage of the inverter.

Abstract: In a system for driving an inverter, a superimposing element superimposes, on an output voltage of the inverter. The high-frequency voltage signal is correlated with a measured high-frequency component value of a current flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value. A dead-time compensating element shifts a start edge and an end edge of an on duration for each of first and second switching elements of the inverter by a preset same time to compensate for an error due to dead time. A current manipulating element manipulates a current flowing in the rotary machine to maintain an accuracy of calculation of the rotational angle.

Abstract: In a system, a superimposing element sets a command value vector of a high-frequency voltage signal and superimposes the high-frequency voltage signal with the command value vector on an output voltage of an inverter. The high-frequency voltage signal has a frequency higher than an electrical angular frequency of a rotary machine. The command value vector is correlated with a measured high-frequency component value of a current signal flowing in the rotary machine. A calculating element calculates a rotational angle of the rotary machine based on the measured high-frequency component value of the current signal flowing in the rotary machine. A reducing element controls at least one of the inverter and a direct voltage power supply to reduce a difference due to the dead time between the command value vector and a vector of a high-frequency voltage signal to be actually superimposed on the output voltage of the inverter.