Oct 09, 2020
Inverter maintenance technology
Use variable frequency power supply|stabilizer to adjust speed, one is to adjust the speed according to requirements, and the other is to save energy. It is mainly based on the following factors:
1) The variable frequency speed regulation system has low loss and high working efficiency.
2) The motor always keeps running at a low slip rate to reduce rotor loss.
3) It can realize soft start and brake functions, and reduce the impact of starting current.
When using variable frequency power supply for speed regulation, it is necessary to consider various aspects such as process requirements, saving benefits, and investment recovery period. If only considering process requirements and economic benefits, it is more advantageous to use variable frequency speed regulation in the following situations:
According to the process requirements, the production line or single equipment needs to adjust the motor speed according to the procedure or according to the requirements. Such as: packaging machine transmission system, according to different types of products, the transmission speed of the system needs to be changed, and the use of frequency conversion speed control can make the speed control system simple in structure, accurate in control, and easy to realize program control.
Use frequency conversion speed control instead of mechanical speed change. For example, machine tools can not only save complicated gearboxes, but also improve accuracy and meet program control requirements.
Using variable frequency speed regulation instead of using gates or baffles to adjust flow is suitable for fans, pumps, compressors, etc. For example: the boiler water pump, blower, and induced draft fan are controlled by frequency conversion, which not only eliminates the need for servo amplifiers, electric operators, electric actuators, and water supply valves (or wind deflectors), but also makes the entire boiler boiler control system Fast dynamic response, high control accuracy and stability.
After the 1970s, the development of large-scale integrated circuits and computer control technology, as well as the application of modern control theory, made the AC electric drive system gradually have a wide range of speed regulation, a high speed range, and a high speed stability accuracy. , Fast dynamic response and good technical performance such as reversible operation in four quadrants, which can be comparable to DC electric drive in terms of speed regulation performance. In AC speed regulation technology, frequency conversion speed regulation has absolute advantages, and its speed regulation performance and reliability are continuously improved, and the price is constantly reduced. In particular, frequency conversion speed regulation has obvious power saving effects and is easy to realize process automation. Favor.
1. Excellent characteristics of AC frequency conversion speed regulation
1) Good smoothness and high efficiency during speed regulation. At low speed, the characteristic static closing rate is higher and the relative stability is good.
2) The speed adjustment range is large and the accuracy is high.
3) The starting current is low, no impact on the system and the grid, and the power saving effect is obvious.
4) The variable frequency power supply is small in size, easy to install, debug and maintain.
5) Easy to realize process automation.
6) There must be a dedicated variable frequency power supply|stabilizer, which is currently expensive.
7) During constant torque speed regulation, the overload capacity of the low-speed motor is greatly reduced.
2. Comparison with other speed control methods
There are three kinds of speed regulation methods for AC motors: pole-changing speed regulation, variable slip speed regulation and frequency conversion speed regulation. Among them, frequency conversion speed regulation is the most advantageous. Here is only a comparison between the AC variable frequency speed control system and the DC speed control system.
There is a power saving potential that can be tapped in the AC drive itself. In the AC speed control system, a certain margin is often left when the motor is selected, and the motor does not always run under the maximum load; if the variable frequency power supply speed control technology is used, the motor speed can be controlled by controlling the motor speed when the load is light. To achieve the purpose of power saving. Fans, pumps, compressors, etc. are widely used in industry, and their electricity consumption accounts for about 50% of industrial electricity consumption; if variable frequency power supply speed control technology is adopted, its efficiency can be greatly improved, and electricity consumption can be reduced by 10%.