Ship DC Power Bus with Bidirectional Converters
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Solution Overview
Problem
Existing electrical energy supply systems for ships, particularly river cruise ships and yachts, are complex, costly, and inefficient due to the need for three-phase current distribution systems and lack of redundancy, making them economically and operationally suboptimal.
Innovation Solution
The system employs asynchronous generators connected via a DC voltage intermediate circuit with bidirectional converters and power capacitors, allowing for automatic adjustment of generator output based on energy demand, eliminating the need for costly control cabinets and enabling galvanic isolation, thus optimizing diesel engine usage and providing a flexible and redundant power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-phase distribution system with control cabinets and switchgear is used, then reliable power distribution is achieved, but device complexity and space requirements increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex control cabinets and switchgear from the ship's electrical system by implementing a DC power bus architecture where generators and consumers connect directly through converters. This removal of intermediate control equipment simplifies the system while maintaining reliability through the inherent stability of the DC bus and converter-based control.
Solution Approach 2:
The patent introduces converters as intermediary devices between generators and the DC power bus, replacing the need for complex control cabinets. These converters act as intelligent mediators that handle all control functions, power conversion, and protection tasks, thereby eliminating the need for traditional switchgear and control equipment while maintaining system reliability.
2Reliability
If diesel generator sets are operated continuously to meet peak demand, then power supply reliability is maintained, but fuel consumption increases
Solution Approach 1:
The patent implements dynamic operation of diesel generator sets by enabling rapid switching between multiple generators connected to the DC power bus. The system dynamically adjusts which generators are operating based on real-time power demand, allowing generators to be started or stopped as needed while maintaining continuous power supply. This dynamic capability optimizes fuel consumption by operating only the necessary number of generators at any given time.
Solution Approach 2:
The system employs feedback control through the DC power bus voltage and converter control systems to automatically manage generator operation. When power demand changes, the control system detects voltage variations and automatically starts or stops appropriate generators to maintain optimal operation, thereby reducing fuel consumption while ensuring continuous reliable power supply.
3Ease of manufacture
If asynchronous generators are used without excitation capability, then generator construction is simplified, but start-up and operation become problematic
Solution Approach 1:
The patent introduces bidirectional converters as intermediary devices between asynchronous generators and the DC power bus. These converters provide the necessary excitation current to the asynchronous generators during start-up and operation, enabling them to function properly without requiring complex internal excitation systems. The converters act as external excitation sources, simplifying generator construction while ensuring ease of operation.
Solution Approach 2:
The bidirectional converters serve multiple functions: they provide excitation current to asynchronous generators, enable bidirectional power flow, and manage power distribution. This multi-functionality allows the use of simple asynchronous generators without compromising operational capability, as the converters compensate for the generators' lack of inherent excitation capability.
4Ease of operation
If voltage changes during operation are not utilized as control variables, then system operation is simpler, but generator output cannot be automatically optimized
Solution Approach 1:
The patent implements feedback control by utilizing voltage changes on the DC power bus as control variables for adjusting generator output. The control system continuously monitors bus voltage and automatically adjusts generator power output in response to voltage variations, thereby optimizing energy efficiency and matching generation to load demand without requiring complex manual control.
Solution Approach 2:
The system achieves self-service operation where voltage changes automatically trigger appropriate generator output adjustments without external intervention. The control system uses the voltage signal itself as the control input, creating a self-regulating mechanism that optimizes energy efficiency while maintaining simple operation through automatic response to system conditions.
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
This design results in a cost-effective, space-efficient, and reliable energy supply that automatically adjusts to energy requirements, reducing fuel consumption and enhancing operational reliability while eliminating the need for complex control systems, thereby achieving unprecedented economic efficiency and flexibility in ship energy management.
Implementation Method 1
the bidirectionally operating converters have at least one capacitor, with the stored energy of which the associated asynchronous generator is excited at start-up
Implementation Method 2
converters are provided for supplying the consumers with AC voltage
Data Source
Figure 1
Figure 2
AI summary
Ship with electric drives, wherein electrical energy for electric motors of the electric drives and an on-board network is preferably generated by asynchronous generators driven by diesel engines, and wherein at least one E-energy bus with self-commutated converters is arranged between the electric drives and the generators, to which electrical energy is supplied and removed, wherein the E-energy bus supplies the entire ship (20) with electrical energy and that the voltage changes occurring during operation in the DC voltage energy bus (3) serve as control variables for the generators.