Power Storage Apparatus Duty Ratio Control for Overvoltage Prevention
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Solution Overview
Problem
Power storage devices in vehicles are at risk of overvoltage due to the lack of charge control functionality in inexpensive alternators or chargers, which may not acquire information about the power storage devices, leading to potential overcharge or overdischarge states.
Innovation Solution
A power storage apparatus with a switch, voltage detecting unit, and control unit that adjusts the duty ratio of the switch to prevent or delay voltages from reaching the upper limit voltage during charging, allowing independent control of charge current and voltage balancing across multiple power storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inexpensive alternator or charger without charge control function is used, then device cost is reduced, but power storage devices may reach upper limit voltage causing overcharge risk
Solution Approach 1:
The patent introduces a duty ratio control unit as an intermediary component between the alternator and power storage devices. This control unit monitors voltages of individual power storage devices and adjusts the duty ratio of the switch accordingly, acting as a mediator that prevents overcharge without requiring the alternator itself to have sophisticated control functionality, thus maintaining low device cost while ensuring reliability
Solution Approach 2:
The patent implements a feedback mechanism where the duty ratio control unit continuously monitors the voltages of power storage devices and adjusts the switch duty ratio based on the detected voltage levels. This closed-loop feedback system ensures that power storage devices do not exceed upper limit voltage, providing reliable overcharge prevention while using a simple alternator design
2Productivity
If charge current is not adjusted, then charging speed is maintained, but power storage devices may reach upper limit voltage
Solution Approach 1:
The patent applies dynamic control by adjusting the duty ratio of the switch based on real-time voltage monitoring. The duty ratio is dynamically modified during charging to prevent any power storage device from reaching upper limit voltage, while maintaining high charging speed when voltage levels are safe. This dynamic adjustment resolves the contradiction between charging speed and overvoltage prevention
3Reliability
If a switch with duty ratio control is added, then overvoltage is prevented, but device complexity increases
Solution Approach 1:
The patent segments the control function by providing individual voltage detection and duty ratio control for each power storage device. This segmentation allows precise control of charge current to each device based on its specific voltage level, preventing overvoltage effectively. The segmented approach manages complexity by organizing control functions into modular, device-specific units rather than a monolithic complex system
Data Source
AI summary
A power storage apparatus includes a plurality of power storage devices, a switch provided on a current-carrying path to the plurality of power storage devices, a voltage detecting unit that detects respective voltages of the power storage devices, and a control unit. The control unit switches a duty ratio of the switch so as to prevent or delay the voltages of the power storage devices from reaching an upper limit voltage during the charge.