Inter Switchboard Converter for Marine Propulsion
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Solution Overview
Problem
Existing propulsion systems for watercraft, particularly smaller ones, face challenges with high-capacity and costly DC-based installations that require large converters, making them unsuitable due to volume and cost constraints.
Innovation Solution
A propulsion system controller that utilizes an inter grid converter with two power converters and a battery to provide multiple functions with reduced power converter capacity, allowing for flexible operation modes including zero-emission propulsion and peak shaving, while maximizing redundancy with minimal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC-based installation with high capacity converters is used, then propulsion system functionality is achieved, but converter volume and cost increase significantly
Solution Approach 1:
The power conversion system is segmented into multiple independent power converters (first power converter, second power converter) that can operate in different modes. Instead of using a single high-capacity converter, the system divides the conversion function across multiple smaller converters that can share the load and provide redundancy.
Solution Approach 2:
The power converters are designed to perform multiple functions: they can convert DC to AC for motor propulsion, convert AC to DC for battery charging, and operate in different configurations (single converter mode, dual converter mode, battery-assisted mode). This multi-functionality reduces the need for dedicated high-capacity converters for each function.
2Reliability
If DC-based installation with high capacity converters is used, then propulsion system functionality is achieved, but system cost increases
Solution Approach 1:
The system segments the power conversion functionality into standardizable modules (first power converter, second power converter, battery system) that can be manufactured and procured separately. This modular approach allows for better cost optimization and reduces the need for custom high-capacity converter designs.
Solution Approach 2:
The system changes the operating parameters of the power converters dynamically, switching between different conversion modes (DC-AC, AC-DC, battery charging/discharging) based on operational requirements. This flexibility allows the use of smaller, more cost-effective converters rather than oversized units designed for peak capacity only.
3Device complexity
If single power converter configuration is used, then system simplicity is maintained, but system versatility and redundancy are reduced
Solution Approach 1:
The system employs dynamic configuration where the first and second power converters can be selectively connected or disconnected from the variable voltage switchboard and fixed voltage switchboard. The controller dynamically switches between different operational configurations (single converter mode, dual converter mode, battery-assisted mode) to optimize for different operational requirements while maintaining a relatively simple physical architecture.
4Adaptability or versatility
If battery integration is added, then system versatility and redundancy are improved, but device complexity increases
Solution Approach 1:
The battery system is integrated to serve multiple functions: it can charge during regenerative braking, discharge to assist during peak power demands, provide backup power, and enable zero-emission operation modes. The first and second power converters are designed to handle both motor control and battery charge/discharge functions, eliminating the need for separate dedicated systems for each function.
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
The solution enables efficient and flexible power management, reducing converter capacity needs and allowing for high ship speed operation with reduced component usage, while providing redundancy and cost-effectiveness.
Implementation Method 1
control said first converter to convert DC power from said second power converter and said battery to AC power with a voltage and a frequency corresponding to a speed or power selected for said one or more electric propulsion motors
Implementation Method 2
control said second power converter to convert AC power from said one or more electric generators to DC power with a voltage suitable for said battery
Implementation Method 3
a battery coupled to said first power converter and said second power converter
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A propulsion system comprises two switchboards (1,2), an inter switchboard converter (9), one or more electric propulsion motors (16,17) and one or more electric generators (11-14). The inter switchboard converter comprises two power converters (4,5) and a battery (7). In a first mode, a controller controls a generator to generate electricity at a constant voltage and frequency, controls the second converter to convert AC power from the generator to DC power with a voltage suitable for the battery, and controls the first converter to convert DC power from the second converter and the battery to AC power with a voltage and a frequency corresponding to a speed or power selected for the propulsion motor(s). In a second mode, the controller controls the generator(s) not to generate electricity and controls the first converter to convert DC power from the battery to AC power, which is provided to the propulsion motor(s).