| 摘要 |
PROBLEM TO BE SOLVED: To reduce a switching loss in a voltage-type three-level inverter using an instantaneous space vector control system. SOLUTION: The whole space of a vector is divided into six sections, and the respective sections are divided each into four ranges. A first means 1 finds a section and a range, in which a command vector V exists, on the basis of the magnitude and the angle of rotation of the command vector V given from a vector control device 5. In addition, a third means 3 estimates the power factor angle β of a load on the basis of a load current and on the basis of a line voltage pulse. A fourth means 4 decides the transmission order of a vector, which can reduce a switching loss, on the basis of the power-factor angle β and on the basis of the found section and the found range, it computes the output time of every vector, and it switches every switching element at a voltage-type inverter. Thereby, when the power factor angle of the load is at 30 deg. or lower, a region which is not switched can be placed near the center of the load current, and the switching loss can be reduced. |
