Capacitor Unit for EV Battery Aerial Discharge Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing voltage and capacitance in high voltage circuits of assembled batteries in electric vehicles pose a risk of electrocution due to aerial discharge, even when insulation resistance is adequate, as the current flowing during such discharges considers capacitance and inductance components, potentially leading to large impulse currents.
Innovation Solution
A power supply system with a capacitor unit connected to the inter-cell connection points of the assembled battery and an access-preventing unit that covers the battery and power supply paths, ensuring insulation from ground and providing an electric shield to prevent access and reduce noise and current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the voltage and capacitance of the assembled battery are increased to meet vehicle requirements, then the power supply capability is improved, but the risk of electrocution due to aerial discharge increases
Solution Approach 1:
A capacitor unit is introduced as an intermediary component connected between the high voltage circuit and the vehicle body. This capacitor unit acts as a mediator that blocks impulse currents while allowing the high voltage battery to maintain its power supply capability. The capacitor prevents direct coupling between the high voltage circuit and ground, thereby eliminating the harmful aerial discharge path without reducing the battery's voltage or capacitance.
Solution Approach 2:
The invention converts the harmful impulse current path into a beneficial noise filtering mechanism. By connecting the capacitor unit to the vehicle body, the previously harmful discharge path is transformed into a useful function where the capacitor blocks both harmful impulse currents and electromagnetic noise, while the insulation resistance component handles DC leakage current suppression.
2Object-generated harmful factors
If the capacitance of noise reduction capacitors is increased to handle higher currents, then noise suppression is improved, but the risk of aerial discharge current increases
Solution Approach 1:
The noise suppression function is segmented into two distinct components: a capacitor unit for handling high-frequency noise and impulse currents, and an insulation resistance component for DC leakage current suppression. This segmentation allows each component to be optimized for its specific function - the capacitor can be sized appropriately for noise filtering without creating excessive discharge risk, while the insulation resistance handles the DC component separately.
3Reliability
If the high voltage circuit is electrically insulated from the vehicle body, then safety is improved, but noise and impulse currents are not effectively suppressed
Solution Approach 1:
Instead of complete electrical insulation, a capacitor unit is introduced as an intermediary connection between the high voltage circuit and the vehicle body. This capacitor provides a controlled coupling that allows effective suppression of noise and impulse currents while maintaining safety. The capacitor blocks high-frequency signals and impulse currents but allows the circuit to remain referenced to the vehicle body potential.
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 effectively suppresses current flow and noise during aerial discharge, reducing the risk of electrocution by eliminating low-impedance paths and providing an electric shield, thereby protecting workers and maintaining stable battery state.
Implementation Method 1
the current flowing during such discharges considers capacitance and inductance components, potentially leading to large impulse currents
Implementation Method 2
an access-preventing unit that covers the battery and power supply paths, ensuring insulation from ground and providing an electric shield
Data Source
AI summary
A power supply system includes an assembled battery, a positive electrode-side power supply path, a negative electrode-side power supply path, and a capacitor unit. The capacitor unit includes a series connection of a plurality of capacitors having one end connected to the positive electrode power supply path and the other end connected to the negative electrode power supply path. An inter-capacitor connection point located between the capacitors forming the series connection is electrically connected to the inter-cell connection point.