The synchronous motor variable voltage variable frequency speed regulation system can be divided into other-controlled variable frequency speed regulation and self-controlled variable frequency speed regulation. For other-controlled variable frequency speed regulation, similar to the variable frequency speed regulation of asynchronous motors, it can also be controlled by SVPWM and other control methods according to its mathematical model, and its performance is even better than that of ordinary AC asynchronous motors. The self-controlled variable frequency synchronous motor used to have a variety of names in the development process, such as a commutatorless motor; when a permanent magnet is used and a three-phase sine wave is input, it can be called a sine wave permanent magnet synchronous motor; and if a square wave is input, then It can be called a trapezoidal wave permanent magnet synchronous motor, yes, this is similar to the brushless DC machine (BLDM) mentioned earlier, so the brushless DC motor uses DC input, but uses the frequency conversion technology of the synchronous motor (structure The same as the permanent magnet synchronous motor), the DC brushless motor is used on the Model3.