Advantages of frequency conversion speed regulation:

1. The speed regulation efficiency is high, which belongs to the efficient speed regulation mode. This is because after the frequency change, the motor still runs around the synchronous speed, and basically maintains the rated slip. It is only in the frequency conversion device system that there will be current loss, and due to the influence of higher harmonics, the loss of the motor increases, and the efficiency decreases.

2. The speed range is wide, generally up to 20: 1, and has high speed regulation efficiency in the entire speed range. Therefore, frequency conversion speed regulation is suitable for occasions with a wide range of speed regulation and often running under low load.

3. The mechanical characteristics are hard. When there is no automatic control, the speed change rate is less than 5%; when automatic control is used, it can be operated with high precision, and the speed fluctuation rate is controlled at about 0.5% | ~ 1%.

4. In case of failure of the frequency conversion device, it can be withdrawn from operation and replaced with direct power supply from the power grid, and the pump or fan can still continue to run.

5. It can also be used as a starting device, that is, the motor is started to a certain speed through the frequency conversion power supply, and then the frequency conversion power supply is disconnected. The motor can be directly connected to the power frequency power supply to accelerate the pump or fan to full speed. When the frequency conversion power supply is switched to the power frequency power supply, generally 400% to 500% of the inrush current is generated, the grid voltage drops instantaneously, and the motor is subjected to mechanical shock. In order to prevent this phenomenon, a starting reactor can be connected in parallel between the motor and the power frequency power supply, so as to suppress the generation of inrush current when starting. If the prime mover is a synchronous motor, "synchronous switching" is required.

Disadvantages of variable frequency speed regulation

1. From the current point of view, the initial investment of the inverter is too high, which is the main obstacle in the energy saving of the speed regulation of the pump or fan. However, with the development of electronic technology, the cost of products has gradually increased, and its application prospects have become increasingly broad.

2. The high-order harmonics caused by the non-sinusoidal waveform of the current or voltage output by the inverter will have various adverse effects on the motor and power supply. If you use a PWM inverter or a current inverter with multiplexing technology, this problem can be greatly improved.