| 摘要 |
PROBLEM TO BE SOLVED: To properly select whether or not step-up operation in a converter for variably controlling a DC link voltage is required, in a control system in which a plurality of inverters for driving a plurality of AC motors commonly uses the DC link voltage.SOLUTION: A step-up converter 15 is operated either in a non-step-up mode setting a step-up ratio of a DC voltage VL corresponding to the output voltage of a DC power supply B to a DC voltage VH of a power line 7 as 1 or a non-step-up mode setting the step-up ratio as 1 or higher. Inverters 20 and 30 convert a common DC voltage VH to an AC voltage and output it to MG1 and MG2 respectively. When at least either one of a MG1 modulation degree and a MG2 modulation degree which are the modulation degrees of a DC/AC voltage conversion in each of the inverters 20 and 30 is higher than a step-up threshold value, a step-up mode is selected, and on the other hand, when both of the MG1 modulation degree and the MG2 modulation degree are lower than a non-step-up threshold value, the non-step-up mode is selected. |
