When no electricity is delivered, a voltage difference between the electrodes drives a current in the other direction.
当没有电流流通时，电极之间的电压差驱动电子反方向流动。
2
Note that conventional current flow is used, hence the current in each element is shown in the direction of decreasing voltage.
请注意，由于采用了约定的电流方向，因此每个元件中的电流是沿着电压下降的方向流动。
3
By getting the direction function from the output AC current, the applied time of voltage vectors in one PWM period was chosen, the direction of central current was controlled for DC voltage balance.