Why do some hybrid cars choose ECVT gearbox?

In fact, it should not be said that some hybrid vehicles use ECVT gearboxes. It should be said that only Toyota hybrid models use ECVT gearbox, because ECVT gearbox is the core technology of Toyota hybrid, and Toyota has technical patents, so only Toyota hybrid models use ECVT gearbox. Many people misunderstand the ECVT gearbox and think that it is a close relative of CVT gearbox. In fact, these two gearboxes are basically two gearboxes with different structures except for their similar names. E of ECVT stands for motor, while CVT indicates that this gearbox can be as smooth as CVT gearbox. ECVT gearbox consists of two motors and a planetary gear mechanism. When the vehicle runs at a low speed with sufficient power, the motor in the gearbox drives the vehicle. If the power is insufficient or needs rapid acceleration, the engine will start to intervene, and then part of the power of the engine is used to drive the vehicle and part of the power is used to drive the generator to charge the battery. The main functions of the ECVT gearbox are: firstly, to drive the vehicle by the motor alone; secondly, to fully adjust and utilize the power of the engine, so as to keep the engine in the optimal speed range, thus achieving the purpose of reducing fuel consumption.