| 摘要 |
An electric current detection means detects a phase current from an input current based upon information obtained from a duty correction means, which will be described later, and an induced voltage estimating means estimates an induced voltage based upon the phase current and the input voltage. A rotor positional speed detection means estimates the magnetic pole position and speed based upon the estimated induced voltage value. A phase-angle setting means sets a current phase angle of the electric motor based upon the magnetic pole position and a predetermined phase angle. A PWM signal generation means generates a PWM signal based upon the information of the current phase angle, and a duty correction means corrects duty of the signal. A first voltage saturation control means calculates a voltage saturation rate from the inverter input voltage and a voltage instruction value to be applied to the electric motor so that, when the voltage saturation rate is not less than a setting value A, a rotation-speed target value is reduced until the voltage saturation rate has become smaller than the setting value A. When the voltage saturation rate is not less than a setting value B (<A), a second voltage saturation control means gives an instruction for advancing the current phase angle to the phase angle setting means until the voltage saturation rate has become smaller than the setting value B. |
