Dual Fuse Charging System for Electric Vehicle Safety
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Solution Overview
Problem
Existing charging and discharging systems for electric vehicles suffer from inefficiency when both charging and discharging functions are performed by separate devices, leading to potential voltage exposure during breakdown due to short circuits and overcurrents.
Innovation Solution
A charging and discharging system with a vehicle, cable, and device that includes dual fuses and a relay, where the first fuse melts and disconnects earlier than the second fuse during a short circuit, preventing voltage exposure by ensuring electrical disconnection between the vehicle's inlet and electric storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fuse is used in the cable for both charging and discharging modes, then the device complexity is reduced, but the safety reliability deteriorates because the fuse cannot selectively disconnect to prevent voltage exposure during short circuits
Solution Approach 1:
The single fuse is segmented into two separate fuses: a first fuse disposed in the vehicle between the inlet and electric storage device, and a second fuse disposed in the cable between the connector and charging/discharging device. This segmentation allows each fuse to serve a specific protective function, with the first fuse selectively melting to prevent voltage exposure at the inlet during short circuits in discharging mode.
Solution Approach 2:
Different fuses are assigned different rated currents based on their specific protective roles. The first fuse has a rated current smaller than the second fuse, creating local quality differences in their melting characteristics. This ensures the first fuse melts preferentially during short circuits to isolate the electric storage device from the inlet, while the second fuse provides backup protection.
2Adaptability or versatility
If the same cable and fuse configuration is used for both charging and discharging modes, then the adaptability is improved, but the safety deteriorates because the existing fuse cannot prevent voltage exposure when a short circuit occurs during discharging
Solution Approach 1:
The system dynamically adapts to different operational modes (charging and discharging) while maintaining safety through the selective melting characteristic of the first fuse. During discharging mode, if a short circuit occurs, the first fuse is designed to melt preferentially due to its smaller rated current, dynamically isolating the electric storage device from the inlet and preventing voltage exposure, while the same cable configuration serves both charging and discharging functions.
3Reliability
If the first fuse has a smaller rated current than the second fuse, then the reliability of preventing voltage exposure is improved, but the device complexity increases due to requiring two fuses with different specifications
Solution Approach 1:
The key parameter change is the rated current of the fuses. The first fuse is designed with a smaller rated current than the second fuse, creating a deliberate parameter difference that enables selective melting behavior. This parameter change allows the first fuse to melt at lower overcurrent levels, preferentially disconnecting the electric storage device from the inlet during short circuits, while the second fuse with higher rated current provides backup protection and allows the system to maintain adaptability for both charging and discharging modes.
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
Effectively prevents voltage exposure during breakdown by ensuring the inlet and electric storage device are disconnected when a short circuit occurs, enhancing safety and system reliability.
Implementation Method 1
the first fuse is configured to be melted and cut earlier than the second fuse when the power line causes a short circuit in the discharging mode
Data Source
AI summary
A charging and discharging system includes a vehicle, a cable, and a charging and discharging device. The vehicle includes an electric storage device, a first fuse, and an inlet. The cable includes a connector, a second fuse, and a power line. The charging and discharging device is configured to convert AC power supplied from a commercial AC power source into DC power and to supply the DC power to the electric storage device via the cable in a charging mode. The charging and discharging device is configured to convert DC power supplied from the electric storage device via the cable into AC power and to supply the AC power to a load in a discharging mode. The first fuse is configured to be melted and cut earlier than the second fuse when the power line causes a short circuit in the discharging mode.