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根据正弦交流电图象如何写出数学表达式i=I_msin(wt+φ)是学生普遍感到困难的一个问题,其中最难的是确定初相。下面介绍一种简单法则,以供参考。 法则:交流电的波形图线由负值到正值的过零点中,最靠近坐标原点的过零点,到坐标原点的距离对应的电角度即为初相。最靠近坐标原点的过零点在坐标原点的左边初相为正,反之为负。若图线以完整的正弦图起始于坐标原点,则初相为零。
How to write out the mathematical expression i = I_msin (wt + φ) according to the sinusoidal alternating current image is a problem commonly encountered by students, of which the most difficult is to determine the first phase. Here’s a simple rule, for reference. Rule: AC waveform chart from negative to positive zero crossing, the nearest zero point of the origin of coordinates, the distance to the origin of coordinates corresponding to the electrical phase is the first phase. The zero-crossing point closest to the origin of the coordinates is positive on the left-hand side of the origin of coordinates and negative on the other hand. If the line begins with the complete sine diagram at the origin of the coordinates, the initial phase is zero.