1、频率方面：
1, frequency aspects:
软启动器的输出频率固定为电源频率，频率不可调；变频器是输出频率可调。
The output frequency of the soft starter is fixed as the power frequency and the frequency is not adjustable; the frequency converter is adjustable output frequency.
2、电压方面：
2, voltage aspects:
软启动器通过控制可控硅（或其他电力电子元件）导通角来控制输出电压，其输出电压由0V慢慢升到额定电压；变频器的电压是可调的。
The soft starter controls the output voltage by controlling the turn-on angle of SCR (or other power electronic components), the output voltage rises from 0V to the rated voltage, and the voltage of the converter is adjustable.
3、电机速度方面：
3, motor speed aspects:
软启动器不可调节电机速度；变频器可以调节电机在任何速度运行。
The soft starter can not adjust the motor speed; the frequency converter can adjust the motor running at any speed.
