Multi-level matrix converter suitable for high-power density occasion and clamp capacitor voltage control method thereof

Abstract

The invention discloses a multi-level matrix converter suitable for a high-power density occasion and a clamp capacitor voltage control method thereof. The converter can be suitable for the direct AC-AC conversion occasion with high power density and reliability requirement. The converter topology structure can realize the output of multi-level, and the withstand voltage of the single-device is lower than the traditional two-level topology, the output end harmonic wave can be effectively reduced, and the voltage step is smaller; and the proportion of the clamp circuit voltages at different levels can be 1: 2: 3: ...N-1. Compared with the prior art, all devices in the converter are consistent in stress, maximum withstand voltages born by various bidirectional switches are consistent, the modularity is strong, the device model selection and maintenance are convenient, and the later cost is effectively reduced; furthermore, the capacitor balancing region is increased, the capacitor voltage controllable range is greatly increased, the capacitor can be completely controlled at a low-modulation region (low in voltage utilization efficiency), and the capacitance balancing computation complexity is reduced.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a multilevel matrix converter suitable for high power density occasions and a clamping capacitor voltage control method thereof. Background technique [0002] In order to improve energy utilization efficiency and achieve low-carbon economy, high-voltage, large-capacity, high-reliability power electronic converters are used in new energy power generation, new energy vehicles, high-voltage power systems, all-electric ship drives, electric locomotive traction and Aerospace and other fields are widely used. New energy power generation, electric vehicles, new energy storage devices, and other directions in line with low-carbon economy and sustainable development have gradually become research hotspots. The topology of new power electronic converters with high power density and high reliability and the corresponding modulation , Control strategy is a key technica...

AI Technical Summary

Problems solved by technology

[0004] (1) The converters of the AC-DC-AC topology all contain a large-capacity DC energy storage link, and its huge volume and weight reduce the power density of the converter, causing inconvenience in the installation, maintenance and use of the converter

When a large-capacity electrolytic capacitor is used for the energy storage device, due to the unstable characteristics of the electrolyte, it is easily affected by environmental factors (temperature, humidity), and the high failure rate of the electrolytic capacitor seriously affects the service life of the converter; such as using a film capacitor As an energy storage device, the overall cost of the system will increase significantly

[0005] (2) In industrial applications such as locomotive traction and elevators that require frequent switching between electric and braking processes, some AC-DC-AC topology converters lack energy feedback channels during the braking process. It is necessary to consume energy through braking resistors, resulting in a waste of energy, which is inconsistent with the concept of low-carbon economy; what is more serious is that in special industrial applications such as chemical plants and fuel plants, high-power braking resistors may cause fires. Major safety hazards in the production process

[0006] (3) The rectification side of some AC-DC-AC converter topologies uses a diode full bridge, which not only produces a lot of harmonic pollution to the grid, but also makes it difficult to control the power factor at the input side, increasing the difficulty of reactive power control

Although the series-parallel connection of devices can directly realize high-voltage and high-power conversion, because the consistency of device parameters cannot be guaranteed, it is difficult for multiple series-parallel devices to be turned on or off at the same time, and transient voltage and current sharing of devices will occur. And other problems, when a large number of devices are connected in series or in parallel, the system reliability is difficult to meet the use requirements

In addition, the original electromagnetic interference, voltage change rate, output harmonics, and common-mode voltage of the two-level converter will be greatly amplified in high-voltage applications, which will seriously affect system performance.

At present, many scholars study the transient process of devices connected in series, adding auxiliary active current and voltage equalization circuits, but there is no extensive industrial application

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