Motor shaft state detection method, motor control method, motor shaft state detection device, motor control device, vehicle height adjustment device, saddle-type vehicle

A motor shaft state sensing method comprising:

• a rotation determination step of determining, using a detected current waveform of a motor, whether or not to be a non-rotation state in which a rotation speed of the motor is smaller than a predetermined speed;
• a current determination step of determining whether or not to be a supply state in which an absolute value of current supplied to the motor is larger than a predetermined reference value;
• and
• a decision step of deciding that the motor is in a shaft locked state, when it is determined to be the non-rotation state in the rotation determination step and it is determined to be the supply state in the current determination step,
• wherein in the rotation determination step, the rotation speed is perceived using a frequency of a waveform extracted by using the current waveform,
• wherein the motor is a motor provided to a vehicle height adjustment device,
• wherein the current waveform is a current waveform subjected to filtering processing by a low-pass filter and a high-pass filter, and
• wherein in the rotation determination step, it is decided to be the non-rotation state when a number of times of zero cross that the current waveform subjected to the filtering processing passes 0 in a predetermined period, which is a period determined in advance, is smaller than a reference value, and it is decided to be a rotation state when the number of times is equal to or larger than the reference value.