无刷直流电动机需要多种电压电平来控制转速：0V 使电动机停转，5V 使电动机以最大转速运转，而在0V和5V之间的电压则使电动机以较低的转速运转-The needs of a wide range of brushless DC motor voltage level to control the rotational speed: 0V stop the motor switch, 5V maximum speed of the motor running, and in between 0V