There are many ways to start a permanent magnet synchronous motor, including direct start, self-coupling decompression start, Y-Δ decompression start, soft start, inverter start, etc. So what's the difference between them?
1. When the grid capacity and load allow full voltage direct start, full voltage direct start can be considered. The advantages are convenient operation and control, simple maintenance, and high economy. It is mainly used to start small power motors.
2. The automatic transmission starts using the multi-touch of the automatic transmission to reduce the pressure, which can not only meet the needs of different loads but also the starting torque will be larger. It is a decompression starting method and is often used to start high-capacity motors.
3. Y-Δ starts to run normally. The squirrel cage asynchronous motor is wound and connected to the delta stator. If the stator is wound into a star when starting, and then connected to the delta after starting, the starting current can be reduced and the impact on the power grid can be alleviated. This start-up mode is referred to as a star-delta decompression start, or star-delta start (Y-delta start). It is suitable for no-load or light-load starting. Compared to any other decompression starter, it has the simplest structure and is also less expensive. In addition, the star-delta starting mode has another advantage, that is, the permanent magnet synchronous motor can be operated in star-connected mode when the load is light. At this time, the rated torque and load can be matched, thereby improving the efficiency of the motor and saving power consumption.
4. The soft starter adopts the phase-shift voltage regulation principle of the 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.
5. The frequency converter is a 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, and it is mainly used in fields that require high requirements for speed regulation and high-speed control.
Decompression start, a common star-delta start, the disadvantage is that the starting torque is small, only suitable for a no-load or light-load start. The advantage is that it is cheap. Soft start, you can set the start time and the initial torque of the starting equipment, realize a soft start and soft stop, and can limit the starting current, the price is moderate. Frequency conversion start, start smoothly according to the set time and let the equipment run at the set frequency, the price is high.