Provide knowledge of UPS uninterruptible power supply, understand the classification of UPS uninterruptible power supply and UPS electrica Circuit, etc.
A circuit form of a three-phase four-wire inverter is shown in Figure 1. This is a four-wire output inverter that uses the midpoint of the DC input supply voltage as the neutral point. For a balanced linear load, the neutral current is equal to zero; but for unbalanced and nonlinear loads, there is a zero-sequence…
The three-phase three-wire inverter circuit using the output filter is shown in Figure 1. When the SPWM control method is adopted, the Fourier series expansion of 3 symmetric switching functions (interface signals) is Using SPWM control, when n=3,5,7,11,13, An=0 can be set, then the inverter output line voltage is In the formula, Ud is the…
The three-phase half-bridge SPWM inverter is the most widely used inverter in three-phase UPS. Regardless of whether it is a power frequency UPS or a high frequency UPS, whether it is a UPS with an isolation transformer or a UPS without an isolation transformer, this inverter is used as the output of the UPS. 1….
The three-level SPWM wave can be obtained by the two-level SPWM wave through the phase-shifting and superposition method, as shown in Figure 1. There are two phase-shifting and superposition methods: one is to first shift the phase of the sinusoidal modulation wave by 360°/2=180°, as shown in Figure 1(b), and then compare it with the…
The main circuit and working waveform of the single-phase three-level SPWM inverter are shown in Figure 1. The figure (a) is the main circuit, and the figure (b) is the working waveform. In figure (b), the sine wave is the modulating wave, and the unipolar triangle wave is the carrier. Compare the sine wave with…
Single-phase two-level SPWM inverter refers to an SPWM inverter whose modulation wave is sine wave, carrier wave is bipolar triangle wave, and output voltage is two-level waveform. It is the most basic of all SPWM inverters. Constituent unit, can be used as a bridge arm of a three-phase SPWM inverter. For SPWM inverters, special attention…
The so-called inverter refers to the reverse converter of a rectifier (also known as a smooth converter). The so-called IGBT three-phase SPWM inverter refers to a power electronic converter that uses the semiconductor power switching device IGBT as a switch and adopts the SPWM control method to convert DC power into a three-phase AC power…
This site uniformly uses SPWM control technology for introduction for two reasons: one is to facilitate the comparison of different schemes; the other is because it is the most basic control technology. Other control technologies are derived from SPWM control technology. With the development of control theory and functional technology, various microcontrollers with excellent performance…
Switching devices for UPS should be selected based on the following factors: switching frequency, switching capacity, switching voltage and current, etc. The switching frequency should be considered first. Figure 1 shows the capacity range and operating frequency of various switching devices. When making a specific selection, you should first determine the switching frequency of the…
Insulated Gate Bipolar Transistor (IGBT) is a composite power switching device that combines power MOSFET and bipolar power transistor. It not only has the advantages of fast switching speed of MOSFET, high input impedance, low driving power and simple driving circuit, but also the advantages of large capacity and high blocking voltage of high-power bipolar…