EV Charging Circuit Protection for Switch Overcurrent Isolation
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Solution Overview
Problem
Existing electrical vehicle charging systems face challenges in protecting electrically controlled switches from damage due to overcurrents, as fuses on the vehicle side are hard to replace and electrically controlled switches can be destroyed if their breaking capacity is exceeded.
Innovation Solution
Incorporating an overcurrent protection device with a breaking current and an electrically controlled switch, where the control device waits for the overcurrent protection device to switch off and then opens the electrically controlled switch after a calculated time, preventing damage from overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electrically controlled switch is used instead of a fuse for overcurrent protection, then the ease of operation and replaceability is improved, but the risk of destroying the switch by exceeding its breaking capacity increases
Solution Approach 1:
The protection function is segmented into two distinct devices: an overcurrent protection device (fuse or circuit breaker) that handles excessive current, and an electrically controlled switch that handles normal switching operations. This segmentation allows each device to be optimized for its specific function, with the switch protected from overcurrent by the dedicated protection device.
Solution Approach 2:
The overcurrent protection device acts as an intermediary between the power source and the electrically controlled switch. It mediates the current flow, blocking excessive current before it reaches the switch, thereby protecting the switch while allowing it to remain electrically controlled and easily replaceable.
2Reliability
If the let through energy of the fuse is chosen very high, then the protection capability is improved, but the damage risk to the electrically controlled switch increases
Solution Approach 1:
The overcurrent protection device is positioned upstream of the electrically controlled switch in the circuit, performing preliminary protection before current reaches the switch. This preliminary action ensures that any overcurrent is interrupted before it can affect the switch, regardless of the fuse's let-through energy characteristics.
Data Source
Figure 1
AI summary
The invention relates to a charging system configured for providing electrical energy to charge a battery (11) of an electrical vehicle (3) with a charging current Ic, comprising an overcurrent protection device (7) characterized by a breaking current lb switching off the overcurrent protection device (7), an electrically controlled switch (8) characterized by switching a maximum switching current lmax, and a control device (7) in electrical connection with at least the electrically controlled switch (8), whereby the electrically controlled switch (8) and the overcurrent protection device (7) are connected in series and arranged in the current path of the charging current lc, and the control device (7) is configured for switching off the electrically controlled switch (8) at a time t > 0 after the charging current lc has exceeded the nominal current IN or after theovercurrent protectiondevice (7) has switched off due to the charging currentIc has exceeded the breaking current lb.