1. When the grid capacity and load allow full voltage direct starting, full voltage direct starting can be considered. The utility model has the advantages of convenient operation and control, simple maintenance and high economy. It is mainly used to start small power motors. From the point of view of energy conservation, these methods are not suitable for the starting modes of five permanent magnet synchronous motors above 11 kw.

2. The starting of automatic transmission adopts the multi touch of automatic transmission to reduce the pressure, which can not only meet the requirements of different loads, but also increase the starting torque. It is a decompression starting method, usually used to start large capacity motors. When the winding faucet is 80%, the initial torque can reach 64% of the direct initial torque. The starting torque can be adjusted by clicking. It is still widely used.

3、Y- Δ Squirrel cage asynchronous motor starts to operate normally and is wound with delta stator. If the stator is wound into a star during startup and connected to a triangle after startup, the startup current and the impact on the power grid can be reduced. This startup mode is called star delta decompression startup or star delta startup (Y- Δ Start). When star delta starts, the starting current is only 1/3 of that of delta direct connection. If the direct starting current is 6-7-7ie, the starting current of the star delta is only 2-2.3 times. That is to say, when the star delta starts, according to the delta connection, the initial torque is also reduced to 1/3 of the original direct start. Suitable for starting without load or with light load. Compared with any other decompression starter, it has the simplest structure and is cheap. In addition, the star delta starting mode has another advantage, that is, when the load is light, the permanent magnet synchronous motor can operate in the star connection mode. At this time, the rated torque and load can be matched to improve motor efficiency and save power consumption.

4. The soft starter adopts the phase shift voltage regulation principle of silicon controlled rectifier to realize the voltage regulation start of the motor. It is mainly used for starting control of permanent magnet synchronous motor, with good starting effect and high cost. In addition, the fluctuation of the power grid will also affect the transmission of thyme, especially when there are multiple thymes in the same power grid. Therefore, the chest failure rate is high, because it involves power electronics technology, so the requirements for maintenance technicians are also high.

5. Frequency converter is the motor control device with the highest technical content, the most complete control functions and the best control effect in the field of modern motor control. It adjusts the speed and torque of the permanent magnet synchronous motor by changing the frequency of the power grid. Due to the power electronic technology and microcomputer technology, the cost is high, and the requirements for maintenance technicians are also high. Therefore, it is mainly used in the fields requiring high-speed regulation and high-speed control. Decompression startup, common star delta startup, has the disadvantage of small startup torque and is only suitable for no-load or light load startup. The advantage is cheap. Soft start: start time and initial torque of starting equipment can be set to realize soft start and soft stop, limit starting current, and the price is moderate. Variable frequency startup, smooth startup according to the set time, and the equipment operates at the set frequency, with high price.