Method for balancing loss of SiC MOS MMC sub-module devices

Abstract

The invention discloses a method for balancing the loss of SiC MOS MMC sub-module devices. According to the method, the working modes of sub-modules are divided into a synchronous rectification mode and a non-synchronous rectification mode, and based on the bidirectional conduction characteristic of a channel of a SiC MOSFET, the two working modes can be switched in a self-adaptive manner in the whole working period by continuously adjusting a current threshold value, so that the proportion of the two working modes in the whole working period is adjusted, and the loss minimization of MMC sub-module devices is realized; starting from the perspective of device control, the quality of electric energy output by a converter is not changed, the characteristic that a SiC MOSFET channel can conduct current in two directions is utilized, and the loss balance of sub-module devices is achieved under the condition that the output waveform of the MMC is not changed, so that the top layer control ofan MMC system is not affected; and the method does not need to add an additional power device, is suitable for the most basic half-bridge sub-module topology, is not limited by the topology, can realize loss balance in a full power factor range from -pi / 2 to pi / 2, and is rich in application scenarios.

Description

technical field [0001] The invention belongs to the field of voltage converters, and more specifically relates to a method for equalizing the loss of SiC MOS MMC sub-module devices. Background technique [0002] Modular Multilevel Converter (MMC) has broad application prospects in DC transmission, motor drive, and renewable energy integration due to its good modularity, flexible scalability, and good waveform quality. . In order to adapt to the operation requirements of complex application scenarios and environments, the efficiency, cost, and environmental adaptability requirements of MMC are gradually increased. At present, Si-based devices are generally used as switching devices in MMC sub-modules. However, traditional Si-based devices belong to the first generation of devices, which have high losses and are difficult to operate in a high temperature environment above 125°C. It is difficult to further improve the transmission efficiency and need to sacrifice a lot of volu...

AI Technical Summary

Problems solved by technology

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method for equalizing the loss of the SiC MOS MMC sub-module device, which is used to solve the problem that the existing method will affect the output power quality of the MMC after loss equalization due to the change of the modulation strategy of the system technical issues

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