| 摘要 |
PURPOSE:To obtain a starting torque corresponding to the capacity of a power converter by separating the capacitor of a filter circuit at starting time, and directly controlling a DC current from a DC power source. CONSTITUTION:A low frequency detector 41 shifts switches 43, 45 when voltage and frequency references are set values or lower to select a current reference circuit 43 and a gate pulse generator 32, to open a switch 46 to separate the capacitor 14 of a filter circuit from the circuit. A current reference circuit 42 inputs the output signal S0 of six times frequency of the frequency reference from an oscillator 31, reduces the DC current to zero only during a period initially determined at a timing of every 60 deg. of the output frequency, and outputs a current reference signal S2 to flow a DC current determined during the remaining period. On the other hand, a gate pulse signal generator 44 inputs the signal S0, and outputs a conduction signal S3, nonconduction signal S3' at a timing of every 120 deg. of the output frequency. |
