| 摘要 |
PURPOSE:To prevent the occurrence of a DC overvoltage after the inversion of a tidal current by suppressing the value of an output limiter to a low level for a fixed period during and immediately after the inversion of the tidal current. CONSTITUTION:When a tidal current inverting command is issued, a delay circuit 37 switches the value of a limiter from the upper limit to the lower limit by generating appropriate timing and, at the same time, inputs an output to a limiter control circuit 38. Upon receiving the output, the circuit 38 generates such a signal which lowers the value of the limiter for a fixed period and gradually increases the value to the original level thereafter. In addition, a minimum value selection circuit 39 selects the smaller value of the outputs of the circuit 38 and a switch 36 and controls the upper limiter of a constant-voltage control circuit 9. Therefore, the occurrence of a DC overvoltage can be prevented immediately after the tidal current is inverted, since the upper limit of the output of the circuit 9 is controlled by means of the output of the circuit 38 for a fixed period during and immediately after the inversion of the tidal current. |
