| 摘要 |
PROBLEM TO BE SOLVED: To improve the availability of a DC power source with a simple means which does not require phase information by outputting a prescribed line voltage by causing the command voltage value of the phase having the largest absolute value among the instantaneous command voltage values of the phases to correspond to the polarity of the output values and controlling the conduction of a switching element. SOLUTION: A maximum value outputting function 1 and a minimum value detecting means 2 respectively output the maximum value and minimum value of command signals 10Ua, 10Va, and 10Wa in each phase. The maximum and minimum values are inputted to a multiplying function 7 through a maximum absolute value detecting function 3, an adding function 4, an absolute value detecting function 5, and a polarity detecting function 6 and the function 7 outputs the signal having the largest value among the command signals of the phases to the (+)-input terminal of a first subtracting function 8. The output of the function 6 is inputted to the (-)-input terminal of the function 8 and second subtracting functions 9W-9V respectively output command signals 10Ub, 10Vb, and 10Wb by performing subtraction. In addition, the voltage command values of the other two phases are adjusted so that the deviations between the command values and the command values of the phase having the largest absolute value can become equal to each other. |
