Hybrid MMC Submodule With Built-In Galvanic Isolation

Solution Overview

Problem

Traditional modular multilevel converters (MMCs) and hybrid MMCs lack built-in galvanic isolation, requiring external transformers that increase system size, weight, and cost, particularly problematic for motive applications where power density and weight are critical.

Innovation Solution

Incorporating a modular multilevel converter structure with dual active bridge converters and specific semiconductor switches like Si IGBTs, SiC MOSFETs, or GaN MOSFETs, which provide built-in galvanic isolation, reducing the need for external transformers and enhancing power density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the system volume and weight increase significantly

Engineering Contradiction:

Improvegalvanic isolationVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent merges the galvanic isolation function with the existing converter structure by integrating a transformer into the modular multilevel converter architecture. The transformer is combined with submodules that include switching devices and capacitors, creating a unified structure that provides both power conversion and galvanic isolation functions within the same system boundaries, thereby eliminating the need for separate external transformers.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated transformer structure serves multiple functions simultaneously: it provides galvanic isolation, performs power conversion, and enables energy storage through the capacitor elements. This multi-functional design allows a single component to replace what would traditionally require separate dedicated components, reducing overall system weight while maintaining all necessary functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the system power density decreases

Engineering Contradiction:

Improvegalvanic isolationVSAvoidpower density

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent merges the galvanic isolation function with the existing converter structure by integrating a transformer into the modular multilevel converter architecture. The transformer is combined with submodules that include switching devices and capacitors, creating a unified structure that provides both power conversion and galvanic isolation functions within the same system boundaries, thereby eliminating the need for separate external transformers.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a nested structure where the transformer is embedded within the modular multilevel converter framework. The transformer windings are arranged concentrically with capacitive elements, and the entire assembly is integrated into the converter's modular architecture. This nesting allows components to share space efficiently, reducing overall volume while maintaining all functions, thereby preserving power density.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If an external standard stand-alone conventional fundamental frequency transformer is added to provide galvanic isolation, then galvanic isolation is achieved, but the system cost increases

Engineering Contradiction:

Improvegalvanic isolationVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the galvanic isolation function with the existing converter structure by integrating a transformer into the modular multilevel converter architecture. The transformer is combined with submodules that include switching devices and capacitors, creating a unified structure that provides both power conversion and galvanic isolation functions within the same system boundaries, thereby eliminating the need for separate external transformers.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated transformer structure serves multiple functions simultaneously: it provides galvanic isolation, performs power conversion, and enables energy storage through the capacitor elements. This multi-functional design allows a single component to replace what would traditionally require separate dedicated components, reducing overall system weight while maintaining all necessary functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4415237A1Hybrid modular multi-level converter (HMMC) and modular multi-level converter (MMC)

Publication Date: 2024.08.14 GE ENERGY POWER CONVERSION TECHNOLOGY LTD(GB)

Figure 1~2
Figure 3A~3B
Figure 3C~3D

AI summary

Provided are modular multilevel converters and hybrid modular multilevel converters. Each of the modular multilevel converters and hybrid modular multilevel converters include submodules. Each submodule includes a first half bridge converter (210a), a second half bridge converter (211a), and a dual active bridge converter (209) having a first connection (209a), a second connection (209b), a third connection (209c) and a fourth connection (209d). The first half bridge converter (209) is interconnected with the first and second connections (209a, 209b) via a first capacitor (207) and the second half bridge converter (211a) is interconnected with the third and fourth connections (209c, 209d) via a second capacitor (208).