A method and system for optimizing loss distribution in a hybrid modular multilevel converter

By adjusting the output modes of the half-bridge and full-bridge submodules and the capacitor voltage balancing algorithm, the loss distribution of the hybrid modular multilevel converter is optimized, solving the problem of loss imbalance, improving reliability and adaptability, and making it suitable for various operating conditions.

CN116846237BActive Publication Date: 2026-07-17XI AN JIAOTONG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
XI AN JIAOTONG UNIV
Filing Date
2023-06-21
Publication Date
2026-07-17

AI Technical Summary

Technical Problem

The uneven loss distribution between the half-bridge and full-bridge sub-modules in hybrid modular multilevel converters leads to reduced reliability and service life. Existing optimization methods increase total loss or construction costs and have limited applicability.

Method used

By adjusting the output mode allocation of the half-bridge and full-bridge sub-modules, and using an improved capacitor voltage balancing algorithm, the half-bridge sub-modules are given priority in activation and the full-bridge sub-modules are given priority in deactivation. Combined with the PI controller to optimize the loss distribution, the adjustment range of the activation and deactivation of the sub-modules is determined, and the trigger signal of the device is adjusted according to the capacitor voltage sorting and charging/discharging status.

Benefits of technology

Without increasing the total loss of submodules and the construction cost of converters, the loss distribution of half-bridge and full-bridge submodules is optimized to improve reliability and adaptability, making them suitable for various operating conditions, reducing switching losses, and maintaining capacitor voltage balance.

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Abstract

This invention discloses a method and system for optimizing the loss distribution of a hybrid modular multilevel converter. The method calculates the average sub-module-level loss difference between half-bridge and full-bridge sub-modules within a bridge arm; determines the adjustment range for switching sub-modules based on this loss difference; within this adjustment range, the priority of switching half-bridge and full-bridge sub-modules is adjusted, prioritizing the activation of half-bridge sub-modules and the deactivation of full-bridge sub-modules; outside this adjustment range, the switching of each sub-module is determined based on capacitor voltage ranking and capacitor charging / discharging status. An improved capacitor voltage equalization method is used to obtain the trigger signals for each device within the converter, thereby optimizing the sub-module-level loss distribution of the modular multilevel converter. This invention does not increase the total sub-module loss or the converter construction cost, and it enables precise adjustment of the sub-module loss distribution, exhibiting better adaptability to operating conditions and optimization effects.
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