Suppliers of inverter energy feedback devices remind you that with the continuous development of science and technology, people have paid more attention to electrical energy conservation. The weak links of traditional DC drive are gradually showing signs of not meeting the requirements of the times. The commutator restricts the maintenance and use of DC motors. So people began to study the application of AC speed regulation technology, and it wasn't until the 1970s that the rapid development of electronic technology, especially control technology and microelectronics technology, gradually replaced DC speed regulation with AC speed regulation performance. As a result, frequency converters were born.
1. Regarding the frequency converter
The initial function of frequency converters was speed regulation, but with the development of technology, the current application of frequency converters in China mainly focuses on energy conservation, emphasizing the energy-saving role in the electrical field. Our country is short of energy, and due to technological issues, the utilization rate of energy is not high. Especially as a clean energy source, electricity is extremely scarce. In the huge electricity consumption, the energy in energy-saving state only accounts for a small part of the total energy consumption. However, there are a huge number of motors with energy-saving potential in China, and energy-saving applications have broad prospects and are a very necessary trend, which also promotes the development of variable frequency technology to a certain extent.
2. Regarding harmonics
Frequency waves are the biggest problem during the operation of frequency converters. The development of electronic technology has enabled general frequency converters to achieve filtering functions through reasonable software and hardware design. After processing, it can effectively prevent and filter out the vast majority of high-order harmonics, ensuring that electrical products comply with electromagnetic compatibility - EMC. However, some companies' electronic equipment, instruments, etc. are relatively aging, so they are particularly sensitive to certain high-order harmonics and cannot work properly when used with frequency converters. The main reason for this situation is that the nonlinear components of the rectifier and inverter parts of the frequency converter cause changes in the power supply, leading to harmonic interference and affecting the frequency conversion effect. The main solution is to use shielded cables for output, and single ended grounding can effectively prevent interference. Adding filters to the input and output sections can significantly reduce the amplitude of low order harmonics and achieve energy-saving effects by filtering out harmonics. For signal control, especially for analog signals, twisted pair shielded wires are generally used for single ended grounding design, which can effectively prevent external interference. The SPWM control method currently used in frequency converters has a positive effect on regulating harmonic components and controlling distortion factors. Therefore, the anti harmonic interference ability of PWM frequency converters compared to SPWM control frequency converters has a significant gap.
3. Application of frequency converters in industrial production
3.1 Application of frequency converter in industrial machinery and equipment pump loads
The reason why frequency converters can be widely used in industrial machinery and equipment pump loads is because of their powerful speed regulation technology, which uses the frequency of the stator of the motor to change the speed of the motor accordingly, ultimately changing the working conditions of pump loads and making the original equipment more capable of meeting production requirements. If there is a significant change in the load of mechanical equipment and pumps in industrial production, using frequency converter technology to control the output of the frequency converter can enable the pump load to meet the production process conditions, achieve the best energy-saving effect, improve production level, accelerate the process of industrial automation, and prolong the service life of equipment, improve product quality, increase production efficiency, and enable enterprises to obtain higher economic benefits.
3.2 Application of frequency converter in industrial production machinery fan load
Fans are basically used in cooling systems, boiler systems, drying systems, and exhaust systems in industrial production. In the production process, we will control factors such as air volume and temperature that affect production in order to achieve good conditions for production technology and working conditions. In the previous control process, the method often used was to adjust the opening and closing degree of the air outlet and baffle. The disadvantage of using this control method is that regardless of the production process and working conditions, the fan always runs at a constant speed, which cannot accurately meet the conditions of the production process and operating conditions, wastes energy and consumes equipment and materials, reduces production profits, and shortens the service life of the equipment. For example, chemical fiber plants, steel plants, cement plants, etc. all use fans. If we use adjusting the air outlet to change the air volume, the motor will always operate at full load, but the opening of the air damper is only between 50% and 80%, which would be a wasteful behavior. The frequency converter technology is used in the load of the fan, and its stepless speed regulation performance can expand the speed range of the fan, make it more reliable, easy to schedule, and achieve high conditions for production processes and working conditions.
3.3 Application of frequency converters in energy conservation and consumption reduction
In places where the motor load is generally constant, such as textile mills and steel mills, the motor usually operates at a certain power, and the performance of the frequency converter is difficult to replace by other equipment, such as smooth acceleration and deceleration, precise control torque, and good working stability, so it can be well utilized. In such factories, frequency converters not only fail to save energy, but on the contrary, due to their high cost and energy consumption, the entire system becomes more expensive and consumes more energy. On the contrary, in applications such as fans and pumps, the energy-saving and consumption reducing characteristics become very prominent. In these applications, the current load often changes. If several motors are used in parallel, it will definitely increase equipment costs. If the previous speed regulation method is used, it is also not conducive to achieving the goal of production automation. In this case, some manufacturers have produced specialized frequency converters for this application. This type of frequency converter does not have the characteristics of high-precision speed regulation and torque control, so its production cost is also very low.
4. Selection of frequency converter
Due to the development of frequency conversion technology, there are currently numerous brands and data of frequency converters in the market. The main control methods include: flat pressure control method, i.e. U/F=K technology; Vector control method, also known as VECTOR technology; Direct torque control (DTC) technology, etc. Enterprises can choose frequency converters according to their actual situation to meet the control requirements of various equipment, especially in the application of frequency converters in mechanical equipment with variable torque loads, which can achieve better energy-saving effects. In terms of capacity selection for frequency converters, it should be scientifically chosen based on the actual current of the load. You can also choose a frequency converter with built-in PID for configuration control according to actual needs. At present, many frequency converters on the market have bus interfaces, and in the production process, frequency converters act as a node of the network to connect with other communication devices, which can effectively improve efficiency and achieve energy saving, and promote a good trend of higher control accuracy and intelligence. Fieldbus technology is currently an advanced automation technology that integrates computer control technology, communication technology, and automatic control principle technology. Therefore, it can achieve the multifunctional transmission of multiple signal parameters on a pair of wires and provide power for multiple devices, which not only saves electricity but also saves costs.
The energy-saving characteristics of frequency converters have attracted widespread attention from society and have been applied in various fields. The market frequency converter is mainly used for regulating the speed of AC motors, and is currently the most ideal and promising speed control solution in the application field. More importantly, frequency converters have energy-saving effects, and energy conservation is an issue that must be taken seriously in industrial development and energy consumption, and is a necessary guarantee for achieving sustainable development of enterprises. Due to its energy-saving effect and speed control technology, frequency converters have become a popular automation equipment and have therefore been rapidly developed and applied. The future prospects of frequency converters are very promising, and they may be applied in a wider range of fields, playing a greater role in reducing energy consumption and increasing efficiency for enterprises. The application of frequency converters has a very broad development prospect.