Modular UPS power supplypower frequency UPS power supplyhigh-frequency UPS power supply comparison

Since the development of UPS uninterruptible power supply, there are various models in the market, among which power frequency, high-frequency, and modular models are the three most common models in the UPS market. This article introduces the basic principles and application characteristics of these three models, compares various indicators, and provides users with reference for selection.
Before discussing high-frequency machines, let's first clarify the definitions of high-frequency machines and industrial frequency machines. There is no concept of a high-frequency machine or a power frequency machine abroad. They define transformer type and transformer less type UPS, namely Transformer UPS and Transformer less UPS. In China, the modulation frequency of rectifiers is used to distinguish them. The modulation frequency of rectifiers is defined as a power frequency machine (50Hz) modulation, while the rectifier is defined as a high-frequency machine (over a thousand Hz) modulation.
In addition, if UPS is distinguished from its external structure, it can be divided into Rack type UPS, Modular UPS, and Tower type UPS models. This is relatively easy to understand, and the UPS that is easy to install in a standard server or network cabinet structure is called a rack type UPS. The power unit and bypass switching unit using a modular structure are called modular UPS, and the rectifier and inverter are all designed according to the specified power, and the overall machine model is called a tower type UPS. The commonly used high-frequency and power frequency machines refer to tower type UPS, while rack type UPS only adjusts the physical structure of low power (less than 20KVA) tower type UPS to fit rack installation. This article does not compare and analyze rack type UPS.
1. Power frequency machine
Power frequency UPS refers to a UPS based on transformer output, which uses SCR thyristor devices as rectifier components. The modulation working frequency of the rectifier is consistent with the grid frequency (50Hz), and this type of machine is called a power frequency machine. The power frequency UPS consists of a rectifier, inverter, static bypass, maintenance bypass, and output transformer. The output transformer is an essential component of UPS and plays a boosting role. Because the two transformations of UPS rectification and inverter are both step-down stages (SCR tube voltage drop), there must be a stage for boosting before the UPS output, and this output transformer is used to achieve this function.
There are two common types of power frequency machines, 6-pulse power frequency rectifier and 12-pulse power frequency rectifier.
The 12 pulse rectification power frequency machine is equipped with an additional 6 pulse rectifier and a phase-shifting transformer on top of the 6 pulses, which can bring better rectification parameter indicators. Compared with the 6 pulse rectification, the 12 pulse rectification has obvious advantages in input power factor and harmonic current THDi parameter indicators.
At present, industrial frequency machines are gradually shrinking in the market, especially in data centers and communication rooms, which have been gradually replaced by high-frequency machines and modular UPS. Power frequency machines also have their own characteristics. In the industrial field, especially in industries such as petroleum and petrochemical, chemical, and high-end manufacturing, power frequency machines still play a leading role. In the entire UPS industry, the market share of power frequency machines remains above 30%.
2. High-frequency machine
There are three common types of high-frequency machines in the 90