Leakage Current Detection Device for Electric Vehicles
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Solution Overview
Problem
Existing electrical protection systems in electric and hybrid vehicles fail to effectively detect leakage currents with DC components, which can lead to unsafe conditions, as conventional differential circuit breakers are often rendered inoperable by the saturation caused by DC components, potentially resulting in electrocution risks for vehicle occupants and individuals nearby.
Innovation Solution
A device embedded in the vehicle is designed to detect leakage currents, including both alternating and direct currents, by generating a magnetic flux and using an integrator-comparator module to measure the current, allowing for the identification of DC components and triggering a degraded charging mode to ensure safety, independent of the external electrical installation's circuit breaker type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional differential circuit breakers are used to protect against leakage currents, then protection against AC leakage currents is provided, but the breakers become inoperable when DC components are present due to magnetic saturation
Solution Approach 1:
The patent extracts the DC component detection function from the conventional AC-only differential circuit breaker by adding a separate DC detection circuit. This separate circuit measures the DC component of leakage current independently, allowing the system to detect both AC and DC leakage currents without the DC component interfering with the AC protection mechanism.
Solution Approach 2:
The patent introduces an intermediary control unit that receives signals from both the conventional differential circuit breaker (for AC leakage detection) and the new DC detection circuit. This intermediary unit processes both signals and controls the tripping mechanism, enabling coordinated protection against both AC and DC leakage currents while preventing false tripping due to DC saturation.
2Reliability
If earth conductor connection is used to protect against leakage currents, then protection is provided when the earth conductor is operational, but the protection fails when the earth conductor is faulty or severed
Solution Approach 1:
The patent implements self-service by having the detection device continuously monitor the integrity of the earth conductor connection and the presence of DC components in leakage current. The system automatically detects faults and triggers appropriate protection actions without requiring external intervention, ensuring continuous safety monitoring regardless of earth conductor status.
3Productivity
If vehicle battery charging is performed using conventional rectifiers, then battery recharging is enabled, but DC component leakage currents are generated that can cause electrocution risks
Solution Approach 1:
The patent applies preliminary action by detecting DC components in leakage current before they reach hazardous levels. The detection device continuously monitors the charging process and triggers protection actions in advance when DC components are detected, preventing electrocution risks before they materialize while allowing normal charging to proceed.
Solution Approach 2:
The patent implements feedback by using the detection device to continuously monitor leakage current during battery charging and providing real-time information to the control system. This feedback loop enables the system to adjust charging parameters or trigger protection actions based on detected DC components, maintaining safe operation throughout the charging process.
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 enables the detection of hazardous DC components in leakage currents, allowing the vehicle to switch to a degraded charging mode, thereby protecting both vehicle occupants and individuals nearby from electrical hazards, regardless of the type of circuit breaker in the domestic electrical installation.
Implementation Method 1
generating a magnetic flux and using an integrator-comparator module to measure the current
Data Source
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AI summary
The invention relates to a device for detecting a leakage current, comprising means (124) for measuring a current from an electrical circuit of a vehicle, in particular a motor vehicle, said detection device being configured to be placed on board said vehicle and being such that the measuring means (124) comprise: a magnetic core (128) configured to be passed through by one or a plurality of conductive elements (127) traversed by the current from the electrical circuit, said conductive element(s) (127) forming a primary winding; a secondary winding (130), wound around the core (128), to generate a magnetic flux from a reference current; and an oscillator (132) for generating the reference current though the secondary winding (130), the reference current being configured to saturate said core (128). According to the invention, the value of the current of the primary winding (127) is obtained from the average value of the current at the secondary winding (130) over a period of oscillation covering a complete core (128) magnetisation and demagnetisation cycle. The invention also relates to various on-board systems using said device.