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DOE OSTI2022

Decentralized Interleaving of Cascaded H-Bridge Multi-Level Converters

This document proposes a simple method to decentralize the interleaving for cascaded H bridge (CHB) converters. In the proposed approach, a single signal sent from the Central controller (CC) to Local Controllers (LC) contains information about the desired pulse width and is synchronized with respect to other LC. While centralized controllers need individual signals for each of the CHB modules, the proposed method requires a single signal per phase which decreases the number of PWM channels needed. A detailed explanation of the proposed method is presented. Experimental results are presented that show the interleaving of two CHB modules for an example DC to AC application.

Montes, Oscar Andres↗
DOE OSTI2020

A Novel Voltage Balancing Control With dv/dt Reduction for 10-kV SiC MOSFET-Based Medium Voltage Modular Multilevel Converter

Using high voltage (HV) silicon carbide (SiC) power semiconductors in a modular multilevel converter (MMC) is promising because it results in fewer submodules and lower switching loss compared to conventional Si based solutions. The nearest level pulsewidth modulation (NL-PWM) is commonly used in the MMC for medium voltage applications. However, with the NL-PWM and existing voltage balancing control, there are many submodules that switch their modes in a control cycle, resulting in a high dv/dt during the deadtime of the power semiconductor, which could be multiple times of the dv/dt of the single device. This poses great challenges on the noise immunity and insulation design in the MMC using HV SiC devices, which have very fast switching speed. A novel voltage balancing control, which ensures only two submodules switch their modes in a control cycle, is proposed in this article, limiting the maximum dv/dt to the dv/dt of a single power semiconductor and also maintaining the voltage balance performance. Furthermore, the proposed voltage balancing control is experimentally validated in a 10-kV SiC mosfet based MMC with four submodules per arm.

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