Clamping cascading frequency-multiplication multi-level power converter and control method thereof

Abstract

The invention discloses a clamping cascading frequency-multiplication multi-level power converter and a control method thereof. The converter comprises multiple cascaded inversion modules. Each cascading module comprises a clamping five-level H bridge inversion unit. A high voltage direct current source is connected to the input end of an inverter. A voltage average resistor is used for balancingthe direct current input voltage of each module and carrying out switching control of each module IGBT, so it is achieved that a single module outputs five-level stair waves. Through superposition ofthe waveforms output by the modules, multi-level voltage output is formed. In the control method, by setting different module carrier wave phase position initial values, PWM control signals of the IGBTs are output asynchronously and voltage stair waves output by the modules are serially connected and superposed, so multi-level output voltage is formed. According to the invention, by use of the modularization design, through the modularization cascading, increasing of the number of stairs of the output stair waves is achieved; switching frequency of the IGBTs is reduced; switching loss is reduced; and output harmonic waves are greatly reduced.

Description

technical field [0001] The invention relates to a multi-level power converter based on clamping cascaded frequency multiplication. A single inverter module uses fewer power devices, has less switching loss, and has high power conversion efficiency. The system is multi-modular cascaded, ensuring higher High output power, multi-level AC voltage also makes the output voltage low harmonic content, only contains a small amount of fixed high-order harmonics, more suitable for high-power applications where high-voltage DC to high-voltage AC conversion. Background technique [0002] Large-capacity power electronic inverters play an important role in the conversion of energy and electric energy, and are widely used in various fields of the national economy, especially in large-scale oil and gas transmission, liquefied natural gas and pumped storage frequency conversion equipment. These equipment are characterized by super large Capacity, the equipment capacity can be 20-120MW, and th...

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Problems solved by technology

[0004] For a single inverter module structure, the output voltage of the traditional inverter module is a 2-level ladder wave, and the output voltage frequency is the switching frequency of the IGBT, so that if a high-frequency voltage is to be output, the switching frequency of the IGBT must be greatly increased, not only There are switching losses, and it is easy to cause switching noise

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