Take a three-phase asynchronous motor as an example, when the motor is started directly, the starting current will reach 5 to 7 times the rated current, and the starting torque can reach 1.2 to 1.3 times the rated torque. This is because a large current will cause the motor winding to overheat, and at the same time, a large torque is not good for the motor body and the driven equipment.

However, if the inverter is combined with the motor, the motor starting characteristics will be restricted by the inverter, and the starting torque, starting current and starting time will change. During the starting process, the current upper limit is generally set at 1.2 to 1.5 times the rated current, and the corresponding acceleration torque is smaller than that of direct starting, so the corresponding starting time will be relatively longer. In the process of variable frequency starting, the synchronous speed is actually gradually increased, so the starting will be relatively stable; for the motor directly started by the power frequency, at the moment of starting, it will be obvious that the motor has a large shake, especially for small-sized high-speed motors, some of which have a direct feeling of jumping.

Take a three-phase asynchronous motor as an example, when the motor is started directly, the starting current will reach 5 to 7 times the rated current, and the starting torque can reach 1.2 to 1.3 times the rated torque. This is because a large current will cause the motor winding to overheat, and at the same time, a large torque is not good for the motor body and the driven equipment.

However, if the inverter is combined with the motor, the motor starting characteristics will be restricted by the inverter, and the starting torque, starting current and starting time will change. During the starting process, the current upper limit is generally set at 1.2 to 1.5 times the rated current, and the corresponding acceleration torque is smaller than that of direct starting, so the corresponding starting time will be relatively longer. In the process of variable frequency starting, the synchronous speed is actually gradually increased, so the starting will be relatively stable; for the motor directly started by the power frequency, at the moment of starting, it will be obvious that the motor has a large shake, especially for small-sized high-speed motors, some of which have a direct feeling of jumping.