Novel voltage self-balancing multi-level high-frequency inverter based on switched capacitor principle

Abstract

The invention discloses a novel voltage self-balancing multilevel high-frequency inverter based on a switched capacitor principle. The novel voltage self-balancing multilevel high-frequency inverter comprises an energy storage unit, a switched capacitor circuit and a full-bridge circuit, the energy storage unit comprises n lithium batteries marked as B1,..., Bi,..., Bn-1 and Bn, and the total voltage of the batteries is marked as Vin; the switch capacitor circuit is composed of a switch tube, a diode and a capacitor. Wherein the switching tubes comprise switching tubes Sa1 to Sa1 (n-1), switching tubes Sb1 to Sbn, switching tubes SB1a to SBna, and switching tubes SB1b to SBnb; the diode comprises Dc1 to Dc (n-1); the capacitor comprises C1 to Cn; the full-bridge single circuit comprises switching tubes S1 to S4 and a load. According to the invention, multi-level output is realized, harmonic distortion of output alternating current is reduced, and the efficiency of the inverter is improved; time division multiplexing is performed on the switched capacitor circuit so that voltage equalization between the single batteries can be realized, the energy utilization rate can be enhanced and the system functions can be enriched.

Description

technical field [0001] The invention relates to the field of electric vehicle power supply systems, in particular to a novel voltage self-balancing multi-level high-frequency inverter based on the principle of switched capacitors. Background technique [0002] With the increasingly prominent problems of environmental pollution and energy shortage, it has become a trend for electric vehicles to replace traditional vehicles. As the core of electric vehicles, energy storage systems have always attracted attention from all parties. Many research institutions and enterprises have devoted themselves to research and development of highly reliable Energy storage system with high performance, high power density and high energy density. Among them, lithium batteries have the advantages of high energy density, long cycle life, fast charge and discharge rate, and environmental protection, and have been widely used in energy storage systems of electric vehicles. However, due to differen...

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Literature (E. Babaei, "A Cascade Multilevel Converter Topology With Reduced Number of Switches," in IEEE Transactions on Power Electronics, vol. 23, no. 6, pp.2657-2664, Nov. 2008.) (M. F. Kangarlu and E. Babaei, "A Generalized Cascaded Multilevel Inverter Using Series Connection of Submultilevel Inverters," inIEEE Transactions on Power Electronics, vol. 28, no. 2, pp. 625-636, Feb.2013. (E. Babaei, S. Laali and Z . Bayat, "A Single-Phase Cascaded Multilevel Inverter Based on a New Basic Unit With Reduced Number of Power Switches," in IEEE Transactions on Industrial Electronics, vol. 62, no. 2, pp. 922-929, Feb. 2015.) The inverter increases the number of inverter output levels by increasing the number of input power sources. In the case of more level output, lower harmonic distortion can be achieved without multi-carrier modulation, but the multi-input source The characteristics limit the application range of this type of inverter, especially in the occasions where the number of power sources such as electric vehicles is quite limited, the advantages of this type of inverter will not be realized

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