The design of electric drive system has gone through the development stages of independent, two-in-one, three-in-one and all-in-one.Independent refers to the independent existence of motors, electronic controls, reducers and other accessories. This model mainly exists in early electric vehicle products. The advantage is that the technology is simple, and the disadvantage is that it takes up a lot of space.The two-in-one solution is to integrate the motor and the reducer, and the three-in-one is to integrate the electronic control, motor and reducer. The three-in-one is currently the mainstream solution of the electric drive system.The integration of more functions in electric drive systems is the general trend. For example, Huawei's upcoming electric drive system DriveONE system integrates MCU (micro-control unit), motor, reducer, DCDC (DC converter), OBC (car charger), PDU (power distribution unit), BCU (battery control unit) seven components, realizing the deep integration of mechanical components and power components.