| 摘要 |
PURPOSE:To make each phase current into balanced currents, even if a load is in an unbalanced state, by taking in each phase current from an AC power according to the difference between each phase load current mean value and each phase load current. CONSTITUTION:When a load 2 is in an unbalanced state, the current values of AC buses U, V, W on the load side indicates values differing from each other. Then, a mean value is obtained by an average operation circuit 10 and the deviation between said mean value and each phase current is operated by an adder-subtractor circuit 11. Accordingly, when the deviation value is small, a forward power converter 3 is PWM(pulse width modulation)-controlled on the basis of said value and a corresponding current is taken in from an insufficient phase and converted into DC. Also, when the deviation value is large, a reverse power converter 5 is PWM-controlled, the corresponding current value converted into DC previously is converted into AC, and each electric current with a current value corresponding to an overcurrent value is released to the bus of said overcurrent value on the load 2 side via an insulating transformer 6. |
