| 摘要 |
PURPOSE:To remove high frequency components by vector-operating the vector to show the phase of three-phase AC bus side voltage and the vector to show the phase of an inverter to be connected in parallel. CONSTITUTION:In the 1st inverter 21 the output is supplied to the load through a three-phase AC bus bar 4, the voltage of which is detected through a three- phase bus voltage detection circuit 61 and a biaxial signal is obtained by a three-phase to two-phase conversion circuit 62. Another biaxial signal is obtained similarly from a control circuit 51 of the other inverter 22 provided in parallel to the inverter 21. A vector arithmetic circuit 63 operates the phase difference between those biaxial signals from the two sets of three-phase to two-phase conversion circuits 52 and 62. This output is then given to a zero point detection circuit 65 with a saturable magnet core 20 having the secondary winding through a low-pass filter 64, from which a synchronous making signal A is sent out to the inverter 22 when the phase difference between the both biaxial signals are zero. Start the inverter 22 with this signal A, and the output can be connected to the bus bar 4 in parallel with the phase difference at zero. |
