Multi-DC-Link Bidirectional Inverter for Flexible Ship Power Conversion
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Solution Overview
Problem
Conventional power systems for electric propulsion ships face inefficiencies when output power varies with operating speed, and require separate power converters for DC-AC conversion and multiple voltage levels, especially for large ships with high power consumption.
Innovation Solution
A bidirectional DC/AC power conversion system with multiple DC links, including a main DC link and auxiliary DC links, utilizing semiconductor-based switching elements and phase terminals for power exchange, allowing for flexible connection of various DC voltage sources to AC outputs without additional converters or transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed frequency/voltage power system is applied to electric propulsion ships, then the system structure is simple, but the efficiency decreases when output power varies with operating speed
Solution Approach 1:
The patent implements a variable-speed engine power generation system with DC-AC conversion capability, allowing the power system to dynamically adjust output frequency and voltage according to operating speed requirements, thereby maintaining high efficiency across varying power demands while providing flexible speed control for electric propulsion
2Adaptability or versatility
If separate power converters are used for DC-AC conversion and multiple voltage levels, then power conversion flexibility is improved, but device complexity and the number of components increase
Solution Approach 1:
The patent designs a unified power conversion system that integrates multiple functions including DC-AC conversion, multiple voltage level generation, and power distribution for both propulsion and hotel loads. This multi-functional converter reduces the number of separate power converters needed while maintaining the flexibility to handle various power conversion requirements
Solution Approach 2:
The patent combines multiple power conversion functions into a single integrated system that can simultaneously provide DC-AC conversion, generate multiple voltage levels, and serve both propulsion motors and hotel loads, thereby reducing component count and system complexity while maintaining versatility
3Power
If large-scale power conversion is implemented for large ships, then power delivery capability is improved, but the requirement for additional separate power converters increases
Solution Approach 1:
The patent divides the large-scale power conversion system into modular converter units that can be configured in series or parallel to achieve the required power level. This modular approach allows scalable power delivery capability while avoiding the need for additional separate full-scale power converters, as modules can be combined to meet different power requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient power conversion and exchange between multiple DC and AC sources, reducing the need for separate converters and transformers, and minimizing supply interruptions by allowing power sharing between DC links.
Implementation Method 1
each cell includes a semiconductor-based switching element
Data Source
AI summary
Embodiments of the present application relate to a bidirectional DC/AC power conversion system having multiple DC links, which comprises: a main DC link; at least one auxiliary DC link including at least one of a first auxiliary DC link having a positive terminal connected to a positive terminal of the main DC link and a second auxiliary DC link having a negative terminal connected to a negative terminal of the main DC link; and a plurality of cells connected in series to form one or more legs.