| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power conversion system, capable of improving detection accuracy of a power supply frequency.SOLUTION: A first frequency measurement processing part 16 detects a frequency of an AC power based on a zero-cross point of an AC voltage supplied to an AC power system 8 detected by a zero-cross detection circuit 6, and a second frequency measurement processing part 18 detects the frequency of AC power based on the zero-cross point of the AC voltage detected by an A/D conversion circuit 14. A single operation determination processing part 17 sets a range which determines a single operation state to a threshold value A or more and a threshold value B or less, based on a changing amount of the frequency detected by the first frequency measurement processing part 16. When the changing amount of frequency detected by the first frequency measurement processing part 16 is larger than the threshold value B, the frequency is detected by the second frequency measurement processing part 18. When a difference between the detected frequency and the frequency detected by the first frequency measurement processing part 16 is equal to a threshold value C or less to be set according to a sampling period in an A/D conversion circuit 14, the single operation determination processing part determines the single driving state.SELECTED DRAWING: Figure 1 |
