When the sealing and cutting machine is started, the current of the motor will be 5-6 times higher than the rated value, which not only affects the service life of the motor but also consumes more electricity. When designing the system, there will be some margin in the selection of motors. The speed of the motor is fixed, but in actual use, it is sometimes necessary to operate at a lower or higher speed. Therefore, it is very necessary to carry out frequency conversion transformation.