Electric motor control apparatus and electric supercharging apparatus using electric motor control apparatus

An electric motor control apparatus controlling an electric motor, comprising:

• a position sensor that detects a position of a magnetic pole of the electric motor;
• a sensor phase generation portion that outputs a first phase generated therein on the basis of a signal from the position sensor;
• a rotation speed computation portion that outputs a rotation speed of the electric motor computed therein on the basis of the signal from the position sensor;
• a phase correction portion that outputs an amount of phase correction generated therein, the amount of phase correction to be used to correct a phase of the signal from the position sensor;
• a phase command generation portion that outputs a phase command generated therein on the basis of the first phase and the amount of phase correction;
• an amplitude command generation portion that outputs an amplitude command generated therein, the amplitude command indicating a magnitude of an energization signal to be outputted to the electric motor;
• and
• an energization portion that generates the energization signal according to an energization stop signal stopping energization of the electric motor, the phase command, and the amplitude command and outputs the energization signal to the electric motor,
• wherein the phase correction portion generates and outputs the energization stop signal and stores the amount of phase correction generated therein according to a comparison between an induced voltage of the electric motor and one of the signal from the position sensor or the first phase, arid outputs the stored amount of phase correction in response to determining that the rotation speed of the electric motor is within a predetermined range and a variation of the rotation speed of the electric motor is within a predetermined range.