Marine Inverter SOC Estimation Using Integrated Voltage Detection
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Solution Overview
Problem
Existing marine vessel power supply systems face challenges in accurately determining battery state of charge (SOC) without the need for additional sensors and communication modules, and in stabilizing voltage measurements for accurate OCV detection.
Innovation Solution
A marine vessel power supply system that includes an inverter with a voltage detector to detect voltage between the battery and inverter circuit, and a microcomputer to estimate SOC based on detected voltage values, eliminating the need for separate OCV sensors and communication modules, and utilizing current detectors to update SOC estimates in real time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate OCV sensor and communication module are added to detect battery voltage for SOC calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the OCV detection function into the existing inverter by integrating a voltage detector and microcomputer into the inverter circuit. This eliminates the need for separate OCV sensors and communication modules, as the inverter's existing components are utilized to detect battery voltage and communicate SOC information to the engine ECU, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The inverter is designed to perform multiple functions: it not only converts DC to AC power but also detects battery OCV through its integrated voltage detector and microcomputer. This multi-functionality allows the inverter to serve dual purposes (power conversion and voltage detection), eliminating the need for dedicated OCV sensing components and reducing overall system complexity
2Productivity
If voltage detection is performed during battery power supply to the inverter, then real-time monitoring is improved, but measurement precision deteriorates due to voltage fluctuations
Solution Approach 1:
The patent implements preliminary voltage detection before the inverter starts supplying power to the battery. The engine ECU requests SOC information from the inverter before power supply begins, allowing the inverter to measure battery OCV under stable conditions without voltage fluctuations from active power conversion, thereby ensuring measurement precision while still providing timely SOC information
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
Accurately determines battery SOC without additional sensors, stabilizes OCV measurement, and reduces component count, ensuring precise power management while maintaining system stability and efficiency.
Implementation Method 1
a voltage detector to detect the voltage in a wiring between the battery and the inverter circuit
Implementation Method 2
an inverter circuit to convert DC electric power supplied from the battery to AC electric power
Data Source
AI summary
A marine vessel power supply system for a marine vessel including an electric motor to rotate a propeller includes an inverter to supply electric power to the electric motor, a battery to supply electric power to the inverter, and an electronic control unit configured or programmed to control the inverter. The inverter includes an inverter circuit to convert DC electric power supplied from the battery to AC electric power, a voltage detector to detect the voltage in a wiring between the battery and the inverter circuit, and a microcomputer configured or programmed to communicate with the electronic control unit and to control the inverter circuit according to a command supplied from the electronic control unit. The electronic control unit calculates an SOC estimate indicative of an estimated state-of-charge value of the battery based on a value of the voltage detected by the voltage detector and acquired from the microcomputer.