Your formulation is not precise. According to what you said, the actual is to parallel a capacitor to 380v two-phase voltage, then the capacitor is a repeated charge and discharge process, the waveform at both ends of the capacitor is a sine wave, the waveform lag line voltage an Angle, in theory is 90 degrees, the actual less than 90 degrees. One end of the charge is positive, the other end is not negative, for example, at a certain instantaneous moment, both phases are positive, and the two phase amplitude is different, there is a voltage difference at both ends of the capacitor, you can be in the charge and discharge process.