1 Introduction
As is well known, high-voltage, high-power fans and pumps utilize variable frequency speed control, which not only facilitates adjustments to operating conditions but also achieves significant energy savings. The direct economic benefits are obvious, while the macroeconomic and social benefits are even greater. It can be predicted that, under the current national policy of vigorously advocating the construction of a conservation-oriented society and achieving harmonious development, the development of new high-voltage, high-power variable frequency speed control technology will become one of the important directions for my country's energy conservation efforts. Statistics show that my country's annual electricity consumption by high-voltage motors is estimated at 360-420 billion kWh, and this figure continues to increase with economic growth.
Background of the Development of 2TS-HVAF1.5 and TS-HVAF1.5R High Voltage Frequency Converters
Currently, there are some solutions for high-voltage variable frequency speed regulation and energy-saving technology both domestically and internationally, but none of them are very ideal. Early foreign products flood the Chinese market. These devices have high requirements for the operating environment, limited service life, complex equipment, poor stability and reliability, and are inconvenient to maintain and transport. They cannot be used safely in environments with high temperature, high humidity, highly corrosive gases, high dust, or explosion-proof conditions.
In fact, high-voltage frequency converters are used in all sectors of industrial production. However, due to the complexity of the application environment, and the various defects mentioned above, traditional high-voltage frequency converters cannot fully meet the needs of users, which limits the promotion and application of high-voltage frequency converters.
Following the successful development of a high-voltage frequency converter based on the "series superposition" principle by Beijing Xianxing New Electromechanical Technology Co., Ltd., Shandong Dianshi Energy Saving Technology Development Co., Ltd., based on the introduction and absorption of foreign technology, has independently developed and successfully manufactured the TS-HVAF1.5 and TS-HVAF1.5R "series superposition" high-voltage frequency converters, achieving a major technological breakthrough in high-voltage frequency converter products and solving major problems existing in traditional high-voltage frequency converters.
Major technological breakthroughs achieved in the 3TS-HVAF1.5 and TS-HVAF1.5R high-voltage frequency converters
3.1 Reduced restrictions on the usage environment
High-voltage, high-power electromechanical equipment draws large currents and experiences significant temperature rises, necessitating excellent ventilation and heat dissipation for its power components. However, ventilation and dust control present a difficult dilemma, making traditional high-voltage frequency converters unsafe for use in environments with high dust, high humidity, high temperatures, and corrosive gases. The TS-HVAF1.5R high-voltage frequency converter utilizes a fully enclosed built-in heat exchanger, eliminating direct air exchange with the external environment and completely overcoming the shortcomings of traditional high-voltage frequency converters, thus greatly expanding their application areas. Because the power unit cabinet of the TS-HVAF1.5 high-voltage frequency converter has a volume of less than 3m³, although a central air conditioning system consisting of six industrial air conditioners is designed for safe operation, the long-term power consumption of the central air conditioning system is only about 2kW.
3.2 Cleaner power output and no pollution to the power grid
The TS-HVAF1.5 series superimposed high-voltage frequency converter uses the pulsating DC superposition principle (maximum frequency 50Hz) to replace the traditional PWM (generally with a fundamental frequency of around 4kHz) technology. The output line voltage waveform and current waveform are both excellent sine waves, which not only greatly reduces output harmonics and pollution to the power grid, but more importantly, greatly extends the service life of the switching devices (IGBT).
3.3 The anti-interference capability is greatly improved.
In the central control system of the TS-HVAF1.5 high-voltage frequency converter, large-scale integrated circuits have replaced the microcontrollers in traditional high-voltage frequency converters, realizing "hardware processing of software problems". This greatly improves the anti-interference capability and eliminates phenomena such as program disorder and system crashes, making the equipment operation safer, more stable and reliable.
3.4 The operation is safer and more reliable.
Due to the simpler and more reliable control program, the TS-HVAF1.5 and TS-HVAF1.5R high-voltage frequency converters can increase the number of splitting and superimposing units compared to traditional high-voltage frequency converters. With the addition of "continuous waveform transformation" technology, even if an individual power unit fails, the output voltage loss is relatively small, and it can still maintain high-power operation, that is, it can continue to operate safely at frequencies of 45Hz and below; while traditional high-voltage frequency converters must significantly reduce the operating power of the controlled motor if even one power unit fails.
3.5 Product factory inspection is more effective
Because the TS-HVAF1.5 high-voltage frequency converter is only about one-third the size of traditional high-voltage frequency converters, it can be transported as a whole unit. This not only greatly shortens the time for on-site installation and commissioning, but also minimizes the production losses caused by installation and commissioning. More importantly, all the inspections of the high-voltage frequency converter at the manufacturing plant are more authentic, reliable and effective.
3.6 This significantly improves the overall reliability of the high-voltage frequency converter.
In the entire structure of the TS-HVAF1.5 high-voltage frequency converter, apart from the incoming and outgoing cables and control circuits, no wires are used, which greatly reduces wiring resistance and possible fault points. The overall layout is simple and clear, which greatly improves the reliability of the high-voltage frequency converter. In addition, the modular design of the whole unit allows users to perform maintenance and repairs on-site.
3.7 A relatively complete system for preventing accidental operation can be set up.
If requested by the user, the TS-HVAF1.5 and TS-HVAF1.5R high-voltage frequency converters can also be equipped with a more comprehensive system to prevent misoperation, thus avoiding the possibility of malfunctions due to operator error.
3.8 Solved the technical challenges of frequency conversion speed regulation retrofitting of synchronous motors in China.
Synchronous motors are equipped with rotor excitation current, and controlling this excitation current is extremely difficult. Currently, only Shandong Dianshi Energy Saving Technology Development Co., Ltd. in China can produce high-voltage frequency converters for synchronous motors. The company can undertake high-voltage frequency converter retrofit projects for synchronous motors when the user meets the following conditions:
(1) The excitation cabinet used by the user is controllable, that is, the excitation current and excitation voltage can be adjusted;
(2) The user permits modification of the excitation cabinet;
(3) The commissioning time at the installation site needs to be extended by 10 to 15 days.
4. Conclusion
The successful development of the TS-HVAF1.5 and TS-HVAF1.5R high-voltage frequency converters can be considered a revolution in the field of high-voltage variable frequency speed control. They greatly improve the reliability, safety, and applicability of high-voltage frequency converters, meet the needs of users to the greatest extent, and enable high-voltage frequency converters to be used in a wider range of fields. They will also play a positive role in promoting the variable frequency speed control transformation of high-voltage, high-power motors.
