Introduction to Common UPS Technologies

1. Overview of UPS industry development

Due to the continuous development of IT technology and the users' emphasis on the protection of important information loads, the use of UPS is becoming more and more extensive, penetrating into various industries (such as finance, communications, securities, chemicals, medical care, etc.), and playing the role of power protection god. As a result, a huge UPS user market has emerged in China. Domestic and foreign brand manufacturers are optimistic about this market, and the competition is becoming increasingly fierce. In order to adapt to the market, various manufacturers continue to launch new products.

While launching new products, new technologies adopted by UPS in the market are also emerging in an endless stream. The technologies adopted by different manufacturers are also different, such as: module redundancy technology, synchronous control technology, high-frequency technology, etc. Different technologies and different promotion angles bring great troubles to users in choosing UPS. Now we summarize and introduce some technologies adopted by UPS in the market.

2. Introduction to the technologies currently used by UPS in the market

ØParallel redundancy technology

The development of parallel

From parallel cabinets, parallel modules, parallel boards, parallel boards without parallel boards, wireless parallel to digital control automatic parallel (the parallel UPS adopts current control and equalization, completely independent control), the development process, but the parallel technology of each process still exists in the market. Mainstream manufacturers such as Delta UPS use direct parallel technology without adding parallel boards and parallel modules. Up to 8 units can be paralleled at the same time, realizing large-capacity UPS online economic expansion and redundancy.

Parallel control method

The parallel operation control mode is generally divided into four schemes: centralized control, master-slave control, distributed logic control and independent control without interconnection lines. Delta UPS adopts a digital design based on high-speed microprocessor operation and a unique thermal compensation distributed logic control parallel technology. No additional parallel card or parallel cabinet is required between UPS units. A loop communication cable connection is used to transmit real-time signals to achieve "current sharing" control of parallel operation. For each UPS in the parallel system, all are in a completely "equal" regulation state. And a unique synchronous phase modulation method is adopted. Each UPS can "intelligently" adjust the synchronous tracking of each UPS in the parallel system to the best state (the phase difference between each unit is almost zero) and dynamically adjust the load percentage in real time to achieve high-precision load sharing. When one of the UPS fails in the parallel system, the failed UPS will be quickly and reliably offline from the parallel system, thereby ensuring that the parallel system continues to provide users with high-quality inverter power.

ØSynchronous control technology

Synchronous control technology

It mainly involves the synchronization of mains and bypass, the synchronization of dual power input, and the synchronization of the parallel system to form a dual bus. There are external synchronization control and internal synchronization control for the synchronization of the dual bus system. There are external synchronization modules and external load synchronization controllers specially produced based on this technology on the market. Internal synchronization control technology is mostly used for parallel (N+X) redundancy. Wireless paralleling also uses internal synchronization control technology.

Delta UPS uses synchronous control technology

In the distributed redundant UPS system solution (dual bus redundancy solution), Delta UPS uses internal synchronization control technology, with a built-in synchronization detection circuit and corresponding control software in the main control board to achieve system synchronization and ensure that the STS switches power steadily and reliably.

The implementation schematic is as follows:

Ø Delta conversion technology

Delta conversion UPS is also a type of UPS design technology. Here is a brief introduction to its working principle: 1. When the mains is available, inverters (I) and (II) only adjust and compensate for the difference between the input voltage and the output voltage, and the power supply with high output voltage stability supplies power to the user's load.

2. When the AC power fails, the system switches to battery power supply. When the load current is distorted, the inverter (II) will also adjust and compensate for it.

3. During normal operation, 85% of the power supplied to the load is directly from the mains grid, and less than 15% is provided by the "inverter (I)".

4. The output frequency depends on the input frequency, and it is difficult to improve the jump problem of the input frequency. At present, most UPS on the market adopt double conversion pure online design instead of Delta conversion.

Delta conversion principle block diagram

From the principle block diagram and working principle, the Delta conversion has the following characteristics:

1. High input power factor and low input current harmonics.

2. The inverter only provides 15% energy, has strong overload capacity, and has sufficient inverter margin.

3. The main energy is provided by the city electricity, with high efficiency.

4. Poor resistance to input frequency transients.

ØModular redundancy technology

In traditional high-end UPS products, there has always been a problem that a single UPS is prone to single-point failure. In the past, users' safety measures for this were to adopt the traditional "1+1" or "N+1" parallel redundancy method, which not only increased the cost of procurement, installation and maintenance, but also generally only tolerated one fault. In a modular UPS system, users only need to purchase the corresponding power modules to achieve "N+X" fault redundancy and expansion and upgrade. If any module fails, it can automatically disconnect from the system to ensure the normal operation of the system. The modular design of Delta UPS not only achieves redundancy in modules, but also in the internal auxiliary power supply and PCB board. It truly realizes the independence of each functional module, and damage to any functional module will not interfere with each other. At the same time, it can also achieve 1+1 parallel redundancy, greatly improving the reliability and availability of the system.

Therefore, modular UPS has been launched continuously in recent years, which shows users' recognition of modular technology and reflects a market trend.

ØFunctional integration technology

The so-called functional integration means the transition from the traditional single system to a new integrated overall solution, using a system integration approach. For example, an integrated computer room organically combines multiple functions such as air conditioning, input distribution cabinets, ATS cabinets, battery switch cabinets, UPS, batteries, output distribution cabinets, and monitoring to achieve mutual compatibility, making the original overall equipment more coordinated and easier to install (similar to the way of stacking blocks), achieving the effect of the whole being greater than the individual, and obtaining a value-added overall solution. Another example is Delta's indoor/outdoor integrated UPS, which combines UPS, batteries, waterproofing, timers, dry contacts, maintenance bypass switches, access control alarms, etc., effectively increasing the integrity and added value of the UPS, just like a well-decorated house that can be moved in after purchase, reducing the user's choice of various decoration materials.

ØHighly intelligent technology

High intelligence technology is reflected in the networking, remote monitoring and control capabilities, and fault prediction capabilities of UPS. First, you can check whether the UPS is equipped with basic communication interfaces such as RS232, RS485, dry contacts, and SNMP card slots. There are also some USB cards and MODBUS converter cards that are suitable for different occasions. Through the communication interface, UPS fault alarms can be sent to users in the form of text messages, E-mails, and broadcasts. Now the market has begun to try to use mobile phones to understand UPS operating information in real time and control UPS switches. At the same time, future trends can be predicted. UPS monitoring implements a large network, and then the UPS operating status information can be opened to UPS manufacturers. Through the manufacturer's technical strength, data analysis can be carried out to find out in advance the use of UPS that needs maintenance. This greatly improves the ability to prevent problems before they happen, and allows UPS to have a virtuous cycle of use.

Ø 12 Rectification technology

In order to reduce the input current harmonics, you can choose to install a 12-pulse rectifier. It is usually built into the host. Its principle is to generate two sets of voltage sources with a phase difference of 30 degrees through the input voltage transformer and send them to two sets of rectifiers respectively. Its main function is to eliminate the fifth and seventh current harmonics at the input end, so as to achieve the purpose of reducing the total harmonics of the input current. Its input current total harmonic distortion rate can be reduced to below 10~14%. The basic structure of the 12-pulse rectifier is shown in Figure 1

Figure 1

ØHigh frequency green energy-saving technology

The country's encouragement of green products is becoming more and more obvious. The Ministry of Finance and the National Development and Reform Commission have formulated and promulgated the "Opinions on the Implementation of Government Procurement of Energy-Saving Products" in line with the current national policy of vigorously developing energy-saving and environmentally friendly products. According to this "Opinion", when state organs, institutions and groups at all levels use fiscal funds for procurement, they should give priority to purchasing energy-saving products listed in the energy-saving list under the same conditions of technology, service and other indicators.

As a high-tech product, UPS also responded to the country's call and adopted the following technologies:

Input rectifier uses high frequency technology

It can make the input power factor>0.99 and the input current harmonics<3%, reaching the real green power supply standard. At the same time, it can reduce the capacity of cables, fuses, circuit breakers, etc. at the UPS input end, reduce the matching capacity of the generator, and reduce the user's investment cost. There is no need to increase the loss of UPS by adding additional filters .

High overall efficiency

Delta's C series UPS has greatly improved the efficiency of the entire machine to over 94%, and the fan can be adjusted in multiple speeds according to load and temperature. The input current harmonics are small, which reduces cable losses and input circuit breaker capacity, etc., and can better meet customers' power-saving needs from the details.

3. Summary

This article summarizes and introduces the common UPS technologies on the market. It is hoped that this introduction will allow everyone to learn more about the technologies used in UPS and use it as a reference when selecting a UPS. Generally, a certain series of products from each manufacturer will use some of the above technologies. Of course, UPS technology is constantly being innovated. Whether a new technology can replace traditional technology, only technologies that can pass the test of the market are worth promoting. As a leading company in the power electronics industry, Delta has invested heavily in researching the next generation of UPS. Let us look forward to new changes.