Motor drive control device, motor unit, and motor drive control method

A motor drive control method of a motor drive control device, the motor drive control device comprising:

• a control circuit configured to generate a drive control signal being a PWM signal for driving a motor including at least a coil of one phase;
• and
• a driving circuit including a high-side switch and a low-side switch provided corresponding to a coil of each phase of the motor and connected in series with each other, the driving circuit being configured to switch an energization direction of a coil of a corresponding phase by alternately turning on/off the high-side switch and the low-side switch in accordance with the drive control signal, wherein
• the method comprises the control circuit:
• determining a zero-crossing target point of a coil current of a predetermined phase of the motor, based on a position detection signal synchronized with an induced voltage of a coil of the predetermined phase and corresponding to a rotation position of a rotor of the motor;
• estimating for each cycle of the PWM signal, a zero-crossing point of the coil current of the predetermined phase based on interchanging of an order of a timing of a drive voltage of the coil of the predetermined phase reaching a high level and a timing of a switch signal for turning on/off the high-side switch corresponding to the predetermined phase reaching a high level;
• determining necessity of phase adjustment of the coil current, based on a phase difference between the target point determined in the first step and the zero-crossing point estimated in the second step;
• and
• generating the drive control signal, based on a determination result obtained.