Rotation angle detecting method, recording medium storing rotation angle detecting program, and rotation angle detecting device

A non-transitory computer-readable recording medium having stored therein a rotation angle detecting program for causing a computer to perform a process comprising:

• measuring a current flowing through a motor;
• and
• obtaining a rotation angle of the motor based on a value of the measured current;
• wherein the obtaining of the rotation angle of the motor includes obtaining the rotation angle in an inertial rotation of the motor based on a rotational angular velocity of the motor immediately before a first time point, a time period from the first time point to a second time point, and a time period from the second time point to a third time point, and
• wherein the first time point is a time point at which driving of the motor is stopped, the second time point is a time point at which a polarity of the value of the measured current is inverted, and the third time point is a time point at which the value of the measured current becomes zero.

A rotation angle detecting device comprising:

• a processor;
• and
• a memory storing program instructions that cause the processor to perform a process comprising:
• measuring a current flowing through a motor;
• and
• obtaining a rotation angle of the motor based on a value of the measured current;
• wherein the obtaining of the rotation angle of the motor includes obtaining the rotation angle in an inertial rotation of the motor based on a rotational angular velocity of the motor immediately before a first time point, a time period from the first time point to a second time point, and a time period from the second time point to a third time point, and
• wherein the first time point is a time point at which driving of the motor is stopped, the second time point is a time point at which a polarity of the value of the measured current is inverted, and the third time point is a time point at which the value of the measured current becomes zero.