Uninterrupt power supply system with parallel operation function

Abstract

An uninterruptible power system with the function of parallel operation comprises one or a plurality of uninterruptible power supply units, each of which has different capacity. The uninterruptible power supply unit comprises a direct current/alternating current converter and a control circuit controlling the converter. The control circuit comprises a voltage feedback control circuit and a current feedforward control circuit. The voltage feedback control circuit comprises a voltage stabilizing control circuit for controlling the load voltage amplitude and a waveform control circuit for controlling the load voltage waveform. The current feedforward control circuit detects the output current of the direct current/alternating current converter and separates out the fundamental wave and harmonic wave constituents of the output current, operating the fundamental wave and harmonic wave constituents into a virtual fundamental wave resistance and a virtual harmonic wave resistance to be in series connected at the output ends of the direct current/alternating current converter equivalently. The outputs of the voltage feedback control circuit and the current feedforward control circuit are added to form a modulation signal that is output to a pulse-width modulation circuit so as to obtain a driving signal of the direct current/alternating current converter.

Description

technical field [0001] The present invention relates to an uninterruptible power supply system with parallel operation function, in particular to an uninterruptible power supply system with parallel operation of uninterruptible power supply units with different capacities, which controls each of the uninterruptible power supply units according to the capacity ratio of the uninterruptible power supply units The uninterruptible power supply unit is used to distribute the output current of each uninterruptible power supply unit according to its capacity ratio. Background technique [0002] With the development of science and technology and the continuous increase of electrical equipment, so that the load capacity continues to increase, the demand for large-capacity uninterruptible power supply systems is also increasing. In order to increase the capacity of the UPS system, there are generally two existing expansion methods: one is to only increase the capacity of a single UPS u...

AI Technical Summary

Problems solved by technology

In fact, the control method of the UPS system with parallel operation function is only suitable for parallel connection

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