A Method of Determining Switching Losses of Isolated DC/DC Converters Based on mmc

Abstract

The invention relates to a method for determining loss of an MMC isolation type DC / DC converter switch. The method comprises that parameter fitting for a switch loss characteristic curve of an MMC neutron module power device is carried out; the switch loss energy of a sub module power device at the operation junction temperature is calculated by utilizing an interpolation method; the average switch loss of a single power device is determined; switch loss type distribution of an MMC-DC / AC / DC converter in an AC period is determined; the average switch loss of single-phase upper and lower arms of an input end MMC converter is determined; the switch loss of all power devices of the MMC-DC / AC / DC converter is determined. According to the switch loss equivalent displacement method, an analysis expression for isolation type DC / DC converter switch loss based on a modular multilevel converter is effectively solved, and the MMC-DC / DC converter switch loss value calculation method is disclosed. Quantitative analysis on isolation type MMC-DC / DC converter switch loss is facilitated, and system parameter optimization design programs are conveniently realized and integrated.

Description

technical field [0001] The invention relates to a method for determining switching loss, in particular to a method for determining switching loss of an MMC-based isolated DC / DC converter. Background technique [0002] The shortage of traditional energy and the deteriorating environment have greatly promoted the development and utilization of clean energy such as green renewable energy. However, limited by the consumption capacity of the local power system, most renewable energy has not been effectively utilized, and even the phenomenon of "abandoning wind" and "abandoning light" has occurred. It is urgent to carry out large-scale, high-efficiency, and safe delivery of wind and photovoltaic power Research. The DC grid technology based on conventional DC and flexible DC is one of the effective technical means to solve this situation. One of the main factors hindering the formation of the DC power grid is the lack of high-voltage and large-capacity DC / DC converters, so that D...

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Problems solved by technology

The test detection method is only suitable for low-voltage and low-power occasions, and the physical modeling method is based on a large number of device manufacturing parameters, which is difficult to obtain

At present, the research on the loss of MMC converters adopts mathematical analysis method. According to some device characteristic parameters provided by the manufacturer, the characteristic function of the power device is fitted, and then the loss estimation or online loss calculation based on the average current and effective current of the power device is carried out. The quantitative relationship between MMC switching loss and voltage modulation degree, the number of bridge arm sub-modules, transformer operating frequency and active power transmission power cannot be easily obtained, which is not convenient for quantitative analysis of switching loss and system optimization design

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