Marine Power Generation Apparatus with DC Bus Decoupling
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Solution Overview
Problem
Current marine propulsion systems face inefficiencies due to the need for constant-speed engines, which result in reduced fuel efficiency and increased complexity, along with issues of alternator synchronization and wasted reactive power.
Innovation Solution
Implementing a power generation apparatus with variable speed engines, alternators, rectifiers, inverters, and energy storage devices that decouple alternators from synchronization, allowing for independent control of engine speeds and voltage regulation, and utilizing a DC bus to manage power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant-speed engines are used to drive alternators, then alternators can be synchronized to feed a common AC bus, but fuel efficiency deteriorates and system complexity increases
Solution Approach 1:
A DC bus is introduced as an intermediary between alternators and AC loads. Alternators rectify their AC output to DC and feed it to the DC bus, which then supplies DC to inverters that convert back to AC for the loads. This DC intermediary decouples the alternators from direct AC synchronization requirements, allowing independent speed control while maintaining power delivery reliability.
Solution Approach 2:
The system changes the operating parameters of alternators from fixed frequency and voltage (required for direct AC parallel operation) to variable frequency and voltage (when rectified to DC). This parameter flexibility allows engines to operate at optimal fuel-efficient speeds while the power electronics maintain stable DC bus voltage and subsequently stable AC output for loads.
2Reliability
If constant-speed engines are used to drive alternators, then alternators can be synchronized, but device complexity increases
Solution Approach 1:
The DC bus acts as a simplifying intermediary that eliminates the need for complex synchronization mechanisms, phase matching circuits, and frequency regulation systems required in direct AC parallel operation. Each alternator independently rectifies to DC without needing to coordinate with other alternators, significantly reducing control complexity.
3Power
If parallel-connected alternators are used, then power capacity increases, but reactive power causes energy wastage and voltage instability
Solution Approach 1:
The DC bus intermediary eliminates reactive power circulation between parallel alternators. When alternators connect to a common AC bus, reactive power flows between them to maintain voltage, causing losses. When rectified to DC first, the energy is unidirectional and real-only, eliminating reactive power wastage while maintaining the ability to supply high real power to loads through inverters.
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 configuration enhances fuel efficiency, reduces system complexity, and minimizes energy wastage by enabling flexible control of engine speeds and power distribution, while maintaining stable voltage and frequency for electrical loads.
Implementation Method 1
an alternator that is drivable by an engine for producing a first AC electric current
Implementation Method 2
a rectifier in electrical communication with the alternator for producing a DC electric current
Implementation Method 3
an inverter in electrical communication with the rectifier for producing a second AC electric current. The second AC electric current has an acceptable frequency and/or voltage
Data Source
AI summary
An apparatus including an alternator that is drivable by an engine for producing a first AC electric current, a rectifier in electrical communication with the alternator for producing a DC electric current, an inverter in electrical communication with the rectifier for producing a second AC electric current where the second AC electric current having an acceptable frequency and/or voltage, and the inverter in electrical communication with one or more electric loads responsive to the second AC electric current, and an energy storage device that is able to electrically couple to the alternator, rectifier, and/or inverter.