PROBLEM TO BE SOLVED: To offer a three-phase voltage type PWM inverter device which can detect a current with accuracy in simple and inexpensive constitution even in case the degree of modulation is small or that it is close to the phase of a single fundamental voltage vector.;SOLUTION: This device outputs two fundamental voltage vector components V4 and V5 different by 60°in phase capable of making command voltage vectors, within a first period making one PWM cycle, and outputs two fundamental voltage vector components V1 and V2 which are severally different by 180°in phase from the above fundamental voltage vectors, within a second period making one PWM cycle following the first period. Therefore, even in case that the degree of modulation is small or in a condition that the phase of the output voltage vector becomes a phase approximate to that of a single fundamental voltage vector, it becomes a sufficient length of pulse width, and this can detect a current with accuracy.;COPYRIGHT: (C)2005,JPO&NCIPI
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