Motor control unit and electric power steering apparatus equipped with the same

A vector-control type motor control unit that calculates dq-axes control assist command values, calculates dq-axes current command values from said dq-axes control assist command values, converts said dq-axes current command values into dq-axes voltage command values, converts said dq-axes voltage command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by an inverter of a pulse width modulation (PWM) control, comprising:

• a central processing unit (CPU) which comprises:
• a space vector modulating section to obtain 3-phase voltage command values by performing a space vector modulation to said dq-axes voltage command values;
• an axes current factor phase-correction calculating section to calculate a phase-correction rotational angle by phase-correcting a motor rotational angle using said dq-axes current command values;
• an angle-dead time compensation value functional section to calculate 3-phase dead time reference compensation values based on said phase-correction rotational angle;
• an inverter applying voltage sensitive-gain calculating section to calculate a voltage sensitive gain based on an inverter applying voltage;
• a dead time compensation-value outputting section to output first 3-phase dead time compensation values obtained by multiplying said 3-phase dead time reference compensation values by said voltage sensitive gain;
• and
• a current command value sensitive-gain calculating section to calculate a current command value sensitive gain which makes a compensation amount of said first 3-phase dead time compensation values be variable depending on said control assist command values,
• wherein a dead time compensation of said inverter is performed by calculating second 3-phase dead time compensation values by multiplying said first 3-phase dead time compensation values by said current command value sensitive gain, and adding said second 3-phase dead time compensation values to said 3-phase voltage command values.