Provide knowledge of UPS uninterruptible power supply, understand the classification of UPS uninterruptible power supply and UPS electrica Circuit, etc.
In the power frequency UPS, the commonly used SCR polyphase phase-controlled rectifier is a 12-phase two-phase superimposed rectifier, and the 18-phase three-phase superimposed rectifier and the 24-phase four-phase superimposed rectifier may be used. Their characteristic values are compared in Table 1. It can be seen from this table that when the UPS is working at…
Most of the SCR polyphase phase-controlled rectifiers used in three-phase high-power power frequency UPS use 12-phase rectifiers or 12-phase rectification + 11th harmonic passive filters, which have become a typical power frequency UPS circuit mode, which can Meet the requirements of the national standard GB/T 7260.3 for the harmonic content of the mains input current….
The variable amplitude 12-phase two-superimposed rectifier is the most widely used in UPS. When the harmonic injection technology is adopted, its application will be wider. For this reason, we will briefly introduce the influence of the input transformer on the harmonic current. Provide time reference. There are two ways to connect the main circuit of…
This time, we introduce a 12-phase diode rectifier technology that uses transformers to inject harmonics, which can make 12-phase diode rectifiers become 24-phase diode rectifiers to improve the input power factor of mains power. The harmonic injection circuit is composed of an injection transformer and a single-phase rectifier bridge. The circuit utilizes the characteristic that…
In order to further improve the mains input power factor of the SCR polyphase phase-controlled power frequency rectifier, reduce the waveform distortion rate THDi of the mains input current to less than 10%, and make the mains input current and the mains input voltage in the same phase, there is a A simple and effective…
There are two ways to shift the phase of the mains input polyphase rectifier transformer to obtain the polyphase output: one is to use the star and delta connection (Y/△ or △/Y) between the primary and secondary to shift the phase by 30°; One is to use the series connection (zigzag connection) between the secondary…
Definition of SCR polyphase phase controlled power frequency rectifier The so-called SCR polyphase phase controlled power frequency rectifier refers to the use of polyphase rectifier transformer to convert the three-phase power supply of mains power input into an even multiple polyphase power supply of 6-phase, 12-phase, 18-phase and 24, and then connect the corresponding even…
The cascade superposition of independent DC power supply is realized by using the unidirectional conductivity of superposition diode. Its principle circuit includes (a) the main circuit and (b) the control circuit. (a) In, E1 ~ en are n independent DC power supplies, S1 ~ Sn are superposition control switches, VD1 ~ vdn are superposition diodes,…
There are two types of existing SPWM multilevel inverters: one is a clamped multilevel inverter (including diode clamping, capacitor clamping and hybrid clamping multilevel inverters), which are typically The control method is the carrier triangular wave stacked SPWM control method; the other is the H-bridge cascaded multi-level inverter, and its typical control method is the…
For large-capacity three-phase UPS, a high-power three-phase SPWM inverter needs to be selected. Due to the substantial improvement of the power level, new requirements are put forward for the structure of the three-phase SPWM inverter. Using a single-phase full-bridge inverter (2H bridge) as a bridge arm of a three-phase SPWM inverter is one of the…