| 摘要 |
PROBLEM TO BE SOLVED: To restrain the operating frequency of a reference waveform generation circuit for an inverter and also shorten its settling time when the synchronization of inverter output with a utility power supply is controlled.SOLUTION: An uninterruptible power supply device comprises: a step width calculation unit 23 which calculates a step width D on the basis of a cycle Tc and a phase difference &thetas; of a utility power supply; a waveform pointer generation unit 24 which generates a waveform pointer P incremented by one step width D at a time; and a sinusoidal wave recording unit 25 which records therein a waveform pattern consisting of many pieces of discrete data. In every certain read cycle ts, discrete data specified by the waveform pointer P is read out from the sinusoidal wave recording unit 25. Therefore, the frequency of a reference waveform can be varied without changing the read cycle ts, and a digital process for generating an inverter control reference waveform can be operated at a low frequency. |
