Three-phase four-wire high-frequency uninterrupted power supply (UPS) and method for reducing neutral-ground voltage by using same

Abstract

The invention discloses a three-phase four-wire high-frequency uninterrupted power supply (UPS) and a method for reducing neutral-ground voltage by using the same. The three-phase four-wire high-frequency UPS comprises a bus control circuit, wherein the bus control circuit comprises a double-ring adjusting module, a voltage feedforward module and a pulse-width modulation (PWM) output module; the voltage feedforward module comprises a feedforward calculation unit, a feedforward correction unit and a superposition unit; the feedforward calculation unit is used for calculating the voltage feedforward value according to bus voltage and network voltage; the feedforward correction unit is used for correcting the voltage feedforward value; the corrected voltage feedforward value is used for weakening wave transmitted by the PWM output module when the network voltage is near zero; the superposition unit is used for superposing the corrected voltage feedforward value and the output value of the double-ring adjusting value and outputting the superposed value to the PWM output module. By implementation of the technical scheme of the invention, the sine degree of inductive current is changed well, so that the harmonic wave of the inductive current is effectively reduced, the triple harmonic current is reduced, zero-line current is reduced, and the neutral-ground voltage can be reduced.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to a three-phase four-wire high-frequency UPS and a method for reducing neutral-ground voltage. Background technique [0002] In the high-frequency UPS (uninterrupted power supply, uninterrupted power supply) of the three-phase four-wire system, its neutral line is directly connected to the neutral line of the power distribution system in the computer room, such as figure 1 As shown, if there is no isolation transformer, the high-frequency UPS must have zero-ground voltage. If the neutral-ground voltage of the high-frequency UPS does not meet the requirements of the maximum neutral-ground voltage limit of the equipment it powers, it will cause safety hazards, and the engineers of the equipment manufacturer using the high-frequency UPS will refuse to power on and start up. If the zero-ground voltage of the high-frequency UPS still does not meet the requirements after the wiring is opti...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a three-phase four-wire high-frequency UPS and its method for reducing the neutral-ground voltage in view of the defects of the prior art that the neutral-ground voltage may be too high to meet the user's requirements. The method can reduce the neutral-ground voltage, so as to meet the requirements of the maximum neutral-ground voltage limit for the equipment powered by the high-frequency UPS

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