| 摘要 |
A self-commutated invertor is driven at the fundamental frequency, this frequency being variable and it being possible to use it, for example, to control the rotation speed of a motor. In this case, the harmonic content at specific phase angles ( alpha 1, alpha 2, alpha 3, alpha 4) can be reduced by means of additional commutations, but a minimum time interval ( tau t), which corresponds to an interval angle ( DELTA alpha ) which is proportional to the fundamental (f1) must in this case be maintained between successive commutations. The object is to create a control method which is suitable for suppressing harmonics over wide fundamental ranges. The solution provides an automatic changeover in the number of additional commutations (M = 1, 2, 3 ...) as a function of at least one limiting value of the control fundamental (f1) in the opposite sense to the change in said fundamental. <IMAGE> |
