| 摘要 |
PURPOSE: To perform PWM control by software alone by properly outputting a short voltage containing a neutral point voltage at least for one phase and a zero vector when a command voltage vector is short and also outputting by adding a long voltage vector which outputs only positive and negative potentials of each phase in a high-frequency and high-voltage region. CONSTITUTION: Vector-indicated voltage command V* is obtained by converting three-phase voltage command values LL*, Vv * and Vw *. Present position of the voltage command vector V* is judged and, when the vector V* is located inside a small triangle as shown in (a), half-voltage vectors V01, V02 and zero vector are properly output within control period, and the resultant vectors are made equal to a voltage command vector V*. Also, when V* becomes larger, a full-voltage vector V1, an intermediate voltage vector V12 and a zero vector are properly output within the control period, and the resultant vector is made equal to the voltage command vector V*. |
