Midpoint common-mode injection single-phase inverter power decoupling control system and method

Abstract

The invention belongs to the technical field of single-phase inverters, and discloses a midpoint common-mode injection single-phase inverter power decoupling control system and a midpoint common-modeinjection single-phase inverter power decoupling control method. Two groups of symmetrical capacitors are connected in parallel to the alternating current side and the direct current side of a single-phase inverter power decoupling circuit respectively, and used for buffering double-frequency power, splitting original support capacitors and filter capacitors in the alternating current side and thedirect current side, and connecting midpoints of the two groups of capacitors to form a common-mode loop to provide a loop for the double-frequency power; and a control module comprises a circuit control unit and a secondary ripple control unit and is used for carrying out voltage and current double-loop control and direct current side secondary ripple control. Under the condition of no additional switch, the secondary ripple pulsation of the direct current side of the single-phase inverter can be eliminated only by means of the small-capacitance capacitor, so that the double-frequency poweris compensated, and the purpose of removing the electrolytic capacitor is achieved.

Description

technical field [0001] The invention belongs to the technical field of single-phase inverter control, and in particular relates to a power decoupling control system and a control method of a midpoint common-mode injection type single-phase inverter. Background technique [0002] At present, single-phase inverters are widely used in renewable fields such as energy storage systems, distributed power generation systems, and photovoltaic power generation. Single-phase inverters have inherent double-frequency fluctuations that degrade system performance. For example, problems affecting MPPT tracking in photovoltaic systems, overheating of fuel cell systems, flickering of LED lighting applications, etc. [0003] Nowadays, many power decoupling technologies are used in single-phase inverters, which are mainly divided into active decoupling and passive decoupling. Passive decoupling technology mainly connects a large electrolytic capacitor in parallel on the DC side to buffer the d...

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Problems solved by technology

A power decoupling method with a high-frequency transformer has also been proposed. In the document "A novel parallel active filter for current pulsation smoothing onsingle stage grid-connected AC-PV modules", a bidirectional buck / boost converter is proposed, although it can suppress the secondary ripple purpose, but the additional introduction of low-frequency transformers makes the system loss larger

There is also a solution to construct a decoupling circuit by multiplexing with the original H-bridge circuit switch, and an additional switch tube is required to increase the system cost.

[0004] The above-mentioned solutions can effectively suppress the secondary ripple on the DC side, but they all require additional switching tubes, which increase the cost and loss of the entire system. In addition, after some solutions are decoupled, there are still low-frequency ripples on the DC side, which is not completely decoupled. , while some decoupling schemes do not make effective use of decoupling capacitors

[0005] Through the above analysis, the existing problems and defects of the prior art are as follows: switching devices are generally added through the active decoupling method, which makes the cost higher, the circuit structure is complicated, the algorithm is more complex, and it is difficult to adjust

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