Brief Introduction of Three Common Machine Types of Kelong UPS power Supply

With the vigorous development of market automation and information technology, each industry has more and more stringent demand for power and higher requirements for power protection. As an important equipment to ensure the stability and continuity of power supply, Kehua UPS power supply has been widely applied in various fields. Up to now, there are various types of UPS power supply in the market, among which power frequency machine, high frequency machine, modular machine and backup machine are the four most common types in the UPS power supply market. This paper introduces the basic principles and application characteristics of three types of UPS power supply, and compares the various indicators for the users to choose the type of UPS power supply. Test.

We first define the definition of high frequency machine and power frequency machine. There is no definition of high frequency machine in foreign countries. They define transformer UPS and transformer-less UPS. In China, the frequency of the rectifier is distinguished by the modulation frequency of the rectifier. The modulation frequency of the rectifier is power frequency modulation (50Hz), which is defined as power frequency machine. The rectifier is modulated by high frequency (thousands of Hz), which is defined as high frequency machine.

In addition, UPS can be divided into Rack type UPS, Modular UPS and Tower type UPS. This relatively good understanding, easy to install in the standard server or network cabinet of UPS power supply is generally known as rack UPS power supply, power unit, bypass switching unit using modular structure is called modular UPS power supply, rectifier inverters are designed according to the power requirements of the overall model known as tower type. Usually referred to as high-frequency machine and power-frequency machine tower type, frame UPS only small power (less than 20 KVA) tower type of physical structure adjustment for the installation of the rack, small edition here does not introduce the rack UPS power supply, next article focuses on the rack UPS power supply.

I. Kelong UPS power supply frequency machine

Power frequency UPS is based on transformer output UPS. SCR thyristor devices are used as rectifier components. The modulation frequency of the rectifier is the same as the power grid frequency (50Hz). This type of UPS is called power frequency machine. Power frequency UPS consists of rectifier, inverter, static bypass, maintenance bypass and output transformer. Output transformer is a necessary part of UPS power supply, which plays a boost role. Because the two transformations of UPS rectifier and inverter are step-down links (SCR tube voltage drop), there must be a link for boosting before the output of UPS. This output transformer is used to realize this function.

There are two types of common power frequency machines, 6-pulse power frequency rectifier and 12-pulse power frequency rectifier. The schematic diagram is as follows:

12-pulse rectifier is an additional 6-pulse rectifier and a phase-shifting transformer on the basis of 6-pulse rectifier, which can bring better rectification parameters. Compared with 6-pulse rectifier, 12-pulse rectifier has obvious advantages in input power factor and harmonic current THDi parameters. Its indexes are as follows:


At present, the power frequency machine is gradually shrinking in the market, especially in the data center and communication room, which has been gradually replaced by high frequency machine and modular UPS. Power frequency machine also has its own characteristics. In the industrial field, especially in petrochemical, chemical, high-end manufacturing and other industries, power frequency machine is still the leading role. In the whole UPS industry, the market share of power frequency machine is maintained at more than 30%.

2. Kelong UPS power supply

There are three common types of high-frequency machines. In the late 1990s, a BOOST boost chopper circuit was added at the back end of SCR rectifier to raise DC to the required voltage for UPS output, thus eliminating the output transformer.  It can be simply understood that DC boost replaces AC boost of power frequency UPS transformer before, which not only reduces the cost, but also greatly reduces the volume and weight of UPS. It can be said to be a major technological innovation in UPS industry. This transformerless UPS, although the first half of the rectifier is still SCR device, but the second half of the rectifier contains IGBT high frequency boost chopper circuit, from the domestic definition, it also belongs to high frequency machine. At present, there are fewer and fewer BOOST boost chopper high frequency models, only some small and medium power UPS will continue to be used.

With the continuous development of power electronic power devices and UPS control technology, full IGBT and full IGBT + output isolation transformer models emerge successively, namely IGBT rectifier + IGBT inverter transformer-free model and IGBT rectifier + IGBT inverter transformer model. Its rectifier adopts high frequency adjustment mode, and its modulation frequency is generally thousands of Hz.

According to the UPS model defined by the modulation frequency of the rectifier, the schematic diagrams of the three types of high frequency machines are as follows:


High frequency machine is characterized by no transformer, small size, light weight, high power density, high efficiency, low input harmonic current, so its development prospects are more promising, high frequency is the trend of power electronics development. However, from the application situation, the high frequency machine is still less mature than the high frequency machine in environmental adaptability and impact resistance.

With the increasing demand for green power supply and energy-saving products in the social power supply environment, the technology of high-frequency IGBT rectifier UPS power supply has been greatly developed, and the reliability and stability of IGBT devices have also been greatly developed. Now more and more users have chosen high-frequency machines, especially in the field of data center, finance and communication. Domain high frequency machine is the preferred model for users.

3. Kelong UPS power supply modular model

Modular UPS is to make the power part of high-frequency UPS into one power module separately, and then output each module in parallel. In addition, bypass switching module and control unit are also made into module units, so the whole UPS is a superposition of modules. The biggest characteristic of modular UPS is that the power part can easily realize redundancy function. As long as the power redundancy of UPS on-load is greater than the power of a single module, the power part of UPS can realize "N+1" redundancy, thus improving the reliability of UPS power supply. Modular UPS also has the advantage of high usability. When a module fails, the module is replaced directly. The maintenance time is very short and the maintenance is very convenient. In addition, modular UPS often refers to the mode of "growing while investing". That is, users can purchase fewer power modules in the initial construction, and then purchase power modules for UPS expansion after the increase of user equipment in business growth. The schematic diagram of modular UPS is as follows:


Shortly after the advent of high-frequency machine, Kehua modular UPS came into being. Modular UPS is also a kind of high-frequency machine in theory, but its structure is quite different from ordinary high-frequency tower type. Modular UPS has a high requirement for parallel control technology. The failure rate of modular UPS in the early stage is high, and the cost of module replacement is not low. Therefore, few users choose modular UPS, which is not the mainstream of the market. However, with the maturity of parallel control technology, the reliability of modular UPS is gradually improved, and its characteristics of high efficiency and high availability are gradually recognized by the market. Especially, Kehua brings modular UPS back to the UPS market, which speeds up the rapid development of modular UPS, and its market share rises sharply, especially in IDC information room and finance. In the field of high-frequency tower crane, it has been on the same level as high-frequency tower crane.