| 摘要 |
PURPOSE:To alleviate the degree of distortion of the output waveform of an inverter by correcting in advance a control signal which is determined from the crossing points of triangular wave that is synchronized with a sinusoidal wave by a delay time, and storing it as a logic pattern. CONSTITUTION:Logic patterns to be stored in ROMs 20, 21 are stored in the ROMs 20, 21 by shifting a switching time point from 0 to 1 by the delay time due to a delay circuit 26 to shift the rising point. The logic patterns thus stored in the ROMs 20, 21 are selected by a speed set signal S6, sequentially read out by a binary counter 23, thereby obtaining the logic patterns for forming unit waveforms of control signals M1 and M2. In case of quantitizing, the number of words corresponding to the delay time is corrected in advance, thereby suppressing the error for the true waveform only for the quantitizing error. |
