Power frequency UPS is not equal to industrial UPS(1)

Industrial frequency machine and high frequency machine have two different technical routes or frameworks,When industrial machines and business machines are used by industry users, the level of reliability and applicability is high.The dominant feature of industrial machines is high EMC immunity (in order to prevent the influence of conduction and radiated electromagnetic interference in the electrical environment on the normal operation of the UPS),High IP protection level (in order to prevent the impact of dust, water splash, harmful gases, etc. on the normal operation of the UPS);Output power frequency isolation transformer (Since the bypass input of the UPS is independent in the industry and requires processing frequency isolation transformers, the output power distribution system is flexible and can regenerate a TN system, IT system, electrical isolation, etc.);The hidden feature is the control algorithm and sampling design of the rectifier and inverter, which are formulated according to the user's electricity environment and load.


First, let's review the origin of the classification of power frequency machines and high frequency machines.In 1956, American J. Moore made thyristor prototypes.In 1957, American R.A. York made a practical thyristor.In the late 1950s, thyristors were used in power electronic devices. Since the 1960s, they have been rapidly promoted, and a series of derived devices have been developed to expand the application fields of power electronic technology.Power electronic circuits With the popularization of thyristor applications, many power electronic circuits have been developed, which can be divided into:①Rectifier circuit that converts AC power into DC power;②Inverter circuit that converts DC power into AC power;③An AC conversion circuit that converts one form of AC power into another form of AC power;④A DC conversion circuit that converts one form of DC energy into another form of DC energy.These circuits all contain thyristors, and each thyristor requires a corresponding trigger.So with these power electronic circuits applied in many fields, many trigger control circuits appeared.Therefore, some experts called the birth of thyristor 1957, the first year of power electronics technology, from which electronic technology disciplines are divided into power electronics technology and information electronics technology.Under this background, the first generation of static power frequency UPS power supply also came into being in 1964. The schematic diagram is shown in Figure 1: 

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4 inverter transformers were designed;The four transformers are divided into two groups, each group contains two transformers;The primary side of the transformer is connected in a triangle, one of the secondary windings is a star, and the other is a zigzag star (Zig-Zag, 30 ° phase shift);Each group of two transformers can eliminate some harmonics to a certain extent;The output voltage of the inverter can be adjusted by adjusting the phase shift between the two sets of transformers.Because the rectifier, inverter, and transformer are all power frequency, they are commonly known as pure power frequency UPS.

Pure power frequency UPS, in terms of inverter output transformer, has experienced the process of reducing the number of transformers from 4 to 2 and from 2 to 1. Schematic diagram as shown in Figure 2 and Figure 3.

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