| 主权项 |
1. A method of controlling a motor driven by a three-phase voltage source inverter, the method comprising the steps of:
a) acquiring a rotational speed parameter representing a rotational speed of the motor; b) after step a), selecting one of a first system and a second system as a switching signal generation system based on a result of comparing the rotational speed of the motor represented by the rotational speed parameter with a predetermined reference speed; c) after step a), calculating phase voltage command values for each of three phases of the motor based on a target rotational speed and the rotational speed parameter; d) after steps b) and c), generating switching signals for each of the three phases of the motor by using the selected switching signal generation system based on the phase voltage command values; and e) after step d), outputting the switching signals to the inverter; wherein the first system is a three-phase modulation scheme which calculates duties of the switching signals for each of the three phases of the motor based on voltage values of the phase voltage command values for each of the three phases of the motor and a voltage value of a carrier signal; the second system is a two-phase modulation scheme which, based on the voltage values of the phase voltage command values for each of the three phases and the voltage value of the carrier signal, selects one of the three phases and fixes the duties of the switching signals for the selected phase in an ON state or an OFF state, and calculates the duties of the switching signals for the other two phases; and in step b), the second system is selected when the rotational speed is higher than the reference speed. |
