Direct current (DC) side capacitor voltage balancing control circuit for H-bridge cascaded active power filter

Abstract

The invention relates to a direct current (DC) side capacitor voltage balancing control circuit for an H-bridge cascaded active power filter, which comprises a single-phase transformer bank (2), wherein the single-phase transformer bank comprises m single-phase transformers, and primary windings are connected in parallel through a public alternating current (AC) bus (1); n secondary windings of the M single phase transformers are connected with n single-phase half-bridge converters through an inductor and a DC isolation capacitor; the n single phase half-bridge converters are respectively connected with DC voltage supporting capacitor of cascaded power units of an H-bridge cascaded multi-level converter, wherein m and n are natural numbers no less than 2, and m is no more than n. The balancing control circuit can balance DC capacitor voltages in same cascaded power units of the cascaded multi-level converter and DC capacitor voltages of different cascaded power units.

Description

technical field [0001] The invention relates to an H-bridge cascaded active power filter DC side capacitor voltage equalization control circuit. Background technique [0002] With the development of power electronics technology, various nonlinear power electronic devices have been widely used in power systems, industries (especially metallurgy, steel, chemical industry, etc.), transportation, building automation and households, and their device capacity is increasing The large and diversified control methods make the voltage and current waveform distortion in the power grid more and more serious, and the harmonic pollution in the power grid is becoming more and more serious. In order to overcome the shortcomings of passive power filter (PPF), an important trend of harmonic suppression devices is to use active power filter (APF) to meet the harmonic standards IEEE519-1992, GB / T14549-93 "Power Quality Public Grid Harmonics" requirements. Compared with PPF, APF has the follo...

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Problems solved by technology

For APF, its compensation current is a harmonic current, which requires a high switching frequency, a large change in the pulse width of each H-bridge, and requires rapid capacitor voltage balance. The need for harmonic governance

Chinese patent 03142679.4 also performs balance control on the DC side capacitor voltage of the H-bridge cascaded multi-level inverter, and enables active power exchange between the H-bridge cascaded power units through additional external equipment, thereby realizing balanced control of the capacitor voltage , but it uses more power switching devices, which increases system cost and control complexity

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