| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide the electric power transformer which can make a current pulse width in a DC side to the width or more with a current detectable to convert electric power by pulse width modulation without generating mutual intervention of switching. <P>SOLUTION: The electric power transformer for variably speed controlling an electric motor comprises a current detection part detecting a current in a DC side of the electric power transformer to detect this detected current and an AC current of three phase part flowing in an electric motor from a gate signal, a motor control part outputting an AC voltage command signal of three phase part based on the detected AC current signal of three phase part and on a speed command signal given from outside, a voltage command correction part correcting the AC voltage command signal of three phase part with a pulse width of the current in the DC side as made in a width or more with a current detectable in a period with an interphase voltage of the AC current signal of three phase part smaller than a prescribed value, and a PWM control part outputting the gate signal by pulse width modulation based on the AC voltage command signal of three phase part corrected in the voltage command correction part. <P>COPYRIGHT: (C)2007,JPO&INPIT |
