| 摘要 |
PURPOSE:To reduce the number of switching operations of an inverter part by securing the width of the maximum value and the minimum value of a predetermined primary flux linkage in such a way that the locus of a primary flux linkage vector becomes a hexagon and selecting the switching-voltage pattern of the inverter part. CONSTITUTION:In a latch circuit 26 which is installed at a switching-pattern selection circuit 7, the magnetic-flux declination region of a primary flux linkage obtained from a magnetic-flux declination computation device 23 is input as 3-bit data, and the output of a magnetic flux comparator 24 becomes the enable signal of the latch circuit 26. By the enable signal, pieces of input data (D1 to D3) are latched respectively on 3-bit output sides (Q1 to Q3). Consequently, when the magnetic-flux-declination region of the primary flux linkage is changed over, the maximum value of the primary flux linkage is selected to be large, and the width of the minimum value and of the maximum value of the primary flux linkage is selected to be large. Then, the track of the primary flux linkage becomes a hexagon, and the number of switching changeover operations of an inverter 3 can be reduced. |
