| 摘要 |
PROBLEM TO BE SOLVED: To compensate for the disagreement between input DC currents and reduce a change in DC voltage to the minimum by estimating the input power with calculation including a rate of change in AC output current of a second converter and then controlling the AC current of a first converter according to the value calculated based on the estimated value. SOLUTION: DC terminals of converters 1, 4 which convert AC to DC or vice versa are connected to each other. Between positive terminals and negative terminals of the converters 1, 4, a smoothing capacitor 6 which holds down a change in DC voltage is connected. An estimated value of the power of the converter 4 is calculated by an arithmetic unit 17 based on a current command value it' and an estimated value itΛ of DC input current is also calculated by the arithmetic unit 17. Meanwhile, the power of the converter 1 is linearized against iIΛ and a command value iI2 of an effective value isq is calculated by an arithmetic unit 18. Since the iIΛ is estimated by the arithmetic units 17, 18 based on the it' and the current command value id'2 which allows DC output current ic to be equal to iI is calculated from the iIΛ for controlling AC input current is, a change in DC circuit voltage Vdc is held down. |
