Control device, control method, motor, and electric oil pump

A control device to control a motor that includes a stator including a coil and a rotor including a permanent magnet, the control device comprising:

• a detector to detect a rotational position of the rotor for each predetermined rotary angle and output a positional signal indicating the detected rotational position;
• a first calculator to receive the positional signal output by the detector and calculate an actual rotation speed of the rotor based on a length of a first range time in which the positional signal is received;
• a second calculator to calculate an estimated rotation speed of the rotor based on a length of a second range of time between a time point at which the first calculator receives the positional signal and an assumed time point at which the first calculator is expected to receive a subsequent positional signal when the first calculator receives the positional signal subsequent to a previous positional signal;
• a comparator to compare the actual rotation speed of the rotor, the estimated rotation speed, and a predetermined rotation speed of the rotor, during a period from when the first calculator receives the positional signal until the first calculator actually receives the subsequent positional signal;
• and
• a controller to calculate a control signal to adjust a voltage to be applied to the coil from the actual rotation speed or the estimated rotation speed and controls the voltage to be applied to the coil based on the calculated control signal;
• wherein
• the controller calculates a control signal to increase the voltage to be applied to the coil based on the estimated rotation speed to increase the voltage to be applied to the coil based on the calculated control signal, in a case where the estimated rotation speed is equal to or lower than the predetermined rotation speed when the estimated rotation speed becomes equal to or lower than the actual rotation speed based on results of the comparison by the comparison portion, and calculates a control signal to decrease the voltage to be applied to the coil based on the estimated rotation speed to decrease the voltage to be applied to the coil based on the calculated control signal, in a case where the estimated rotation speed is higher than the predetermined rotation speed when the estimated rotation speed becomes equal to or lower than the actual rotation speed based on results of the comparison by the comparison portion;
• and
• the controller increases the voltage to be applied to the coil based on a control signal to increase the voltage to be applied to the coil, which is calculated from the actual rotation speed, in a case where the actual rotation speed is equal to or lower than the predetermined rotation speed when the estimated rotation speed becomes higher than the actual rotation speed, and decreases the voltage to be applied to the coil based on a control signal to decrease the voltage to be applied to the coil, which is 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 actual rotation speed.

A method for controlling a motor using a control device to control the motor that includes a stator including a coil and a rotor including a permanent magnet, the method comprising:

• receiving a positional signal that indicates a rotational position of the rotor, which is detected for each predetermined rotary angle of the rotor;
• calculating an actual rotation speed of the rotor based on a length of a first range of time between a time point at which the positional signal is received and a time point at which a previous positional signal prior to the positional signal is received;
• calculating an estimated rotation speed of the rotor based on a length of a second range of time between a time point at which the positional signal is received and an assumed time point at which a subsequent positional signal is expected to be received when the positional signal is received subsequent to a previous positional signal;
• comparing the actual rotation speed, the estimated rotation speed, and a predetermined rotation speed of the rotor, during a period from when the positional signal is received until the subsequent positional signal is received;
• and
• based on results of the comparing, increasing a voltage to be applied to the coil based on a control signal to increase the voltage to be applied to the coil, which is calculated from the estimated rotation speed, when the estimated rotation speed becomes equal to or lower than the predetermined rotation speed, increasing the voltage to be applied to the coil based on a control signal to increase the voltage to be applied to the coil, which is calculated from the actual rotation speed, in a case where the actual rotation speed is equal to or lower than the predetermined rotation speed when the estimated rotation speed becomes higher than the predetermined rotation speed, and decreasing the voltage to be applied to the coil based on a control signal to decrease the voltage to be applied to the coil, which is 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 method for controlling a motor using a control device to control the motor that includes a stator including a coil and a rotor including a permanent magnet, the method comprising:

• receiving a positional signal that indicates a rotational position of the rotor, which is detected for each predetermined rotary angle of the rotor;
• calculating an actual rotation speed of the rotor based on a length of a first range of time between a time point at which the positional signal is received and a time point at which a previous positional signal prior to the positional signal is received;
• calculating an estimated rotation speed of the rotor based on a length of a second time interval a time point at which the positional signal is received and an assumed time point at which a subsequent positional signal is expected to be received when the positional signal is received subsequent to a previous positional signal;
• comparing the actual rotation speed, the estimated rotation speed, and a predetermined rotation speed of the rotor, during a period from when the positional signal is received until the subsequent positional signal is received;
• calculating a control signal to increase the voltage to be applied to the coil based on the estimated rotation speed to increase the voltage to be applied to the coil based on the calculated control signal, in a case where the estimated rotation speed is equal to or lower than the predetermined rotation speed when the estimated rotation speed becomes equal to or lower than the actual rotation speed based on results of the comparison, and calculating a control signal to decrease the voltage to be applied to the coil based on the estimated rotation speed to decrease the voltage to be applied to the coil based on the calculated control signal, in a case where the estimated rotation speed is higher than the predetermined rotation speed when the estimated rotation speed becomes equal to or lower than the actual rotation speed based on results of the comparison by the comparison portion;
• and
• increasing the voltage to be applied to the coil based on a control signal to increase the voltage to be applied to the coil, which is calculated from the actual rotation speed, in a case where the actual rotation speed is equal to or lower than the predetermined rotation speed when the estimated rotation speed becomes higher than the actual rotation speed, and decreasing the voltage to be applied to the coil based on a control signal to decrease the voltage to be applied to the coil, which is 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 actual rotation speed.