Disclosed in the present invention are a pole changing method for an asynchronous electric motor, a derived system, a component, a new energy vehicle, etc. In the present invention, the number of poles of an asynchronous electric motor (comprising an asynchronous variable-frequency electric motor) is changed by means of control software, such that for both a high-rotation-speed low-torque application scenario and a high-torque low-rotation-speed application scenario, the function of a transmission in a system can be replaced (or omitted) by means of changing poles within a certain application range. By means of frequency variation, an asynchronous variable-frequency electric motor can also be adapted to both a high-rotation-speed low-torque application scenario and a high-torque low-rotation-speed application scenario, but the increase in frequency is limited. By means of the present invention, the adaptive range of the asynchronous variable-frequency electric motor is exponentially expanded, without using a transmission, such that the cost is hardly increased, and the apparent power (the product of multiplying the maximum output torque by the maximum output rotation speed) of a system in which the asynchronous variable-frequency electric motor is located is exponentially increased, and thus, the present application can be applied to a device, such as a new energy vehicle that is driven by an asynchronous variable-frequency electric motor. Therefore, dedicated components, such as a variable-frequency power supply and an electric motor, which are applied in the present invention are also generated.