Common Mode Current Compensation for EV Charging Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for charging electric vehicles from external electrical networks face safety concerns due to leakage currents and the reliance on differential circuit breakers, which can lead to untimely activation and potential harm to users, especially when the earth conductor fails or when users touch electrical components during charging.
Innovation Solution
An electrical device with a measurement system that detects common mode currents and residual currents to compensate and reduce common mode currents, using an electronic component to apply a compensating current, and a control unit to detect failures based on threshold values, ensuring safe energy exchange even if the differential circuit breaker fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an earth conductor is used to connect the chassis to ground, then safety against common mode current is improved, but the system becomes dependent on the differential circuit breaker which may fail or activate untimely
Solution Approach 1:
The patent implements a feedback mechanism by measuring the common mode current with a measurement system and using this information to control a compensation circuit. The control unit continuously monitors the common mode current and adjusts the compensation circuit accordingly, creating a closed-loop system that actively maintains safety without relying on passive earth conductors or circuit breakers.
Solution Approach 2:
The patent introduces a compensation circuit as an intermediary element that actively counteracts common mode current. This compensation circuit, controlled by the measurement system and control unit, serves as a mediator between the earth conductor and the differential circuit breaker, providing an additional layer of protection that reduces dependence on either component alone.
2Reliability
If common mode current compensation is implemented, then unnecessary activation of circuit breakers is prevented, but device complexity increases due to additional measurement and control systems
Solution Approach 1:
The measurement system and control unit serve multiple functions: they measure common mode current, control the compensation circuit, and provide safety monitoring. This multi-functionality reduces the need for separate dedicated components for each function, thereby mitigating the increase in device complexity while achieving reliable prevention of untimely circuit breaker activation.
Solution Approach 2:
The patent merges the measurement system, control unit, and compensation circuit into an integrated safety system. By combining these elements that work together to manage common mode current, the system achieves efficient operation with reduced overall complexity compared to having separate independent systems for each function.
3Reliability
If active common mode current reduction is used, then safety is enhanced independent of earth conductor state, but energy consumption increases due to continuous measurement and compensation
Solution Approach 1:
The compensation circuit is designed to be dynamic rather than static. The control unit continuously adjusts the compensation based on real-time measurements of common mode current, enabling the system to provide safety independent of earth conductor state while minimizing energy consumption by activating compensation only when necessary rather than operating at constant maximum level.
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 reduces common mode currents, enhances safety by detecting faults, and prevents unnecessary activation of circuit breakers, ensuring safe charging of electric vehicles even when the earth conductor is broken or when users touch electrical components.
Implementation Method 1
a first measurement system capable of measuring a common mode current flowing in one of the two parts of the electric line during an exchange of energy between the electric source and the consumer
Implementation Method 2
an electronic component connected on the one hand to said first system for measuring the current of common mode, the component being configured to apply, between the ground line and another terminal of the impedance, an electrical quantity making it possible, when electrical energy is exchanged between the consumer and the source of electrical energy, to reduce the common mode current flowing in the part of the electric line whose current is measured by the first measuring system
Implementation Method 3
a second measuring system able to measure a residual current flowing in at least the part of the electric line whose current is not measured by the first measurement system
Implementation Method 4
a control unit configured to detect a failure of the energy exchange when a value obtained from the current measured by the second measurement system is greater than a threshold value
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to an electrical device (10) for a power security exchange between a power consumer (20) of an electrical circuit of an assembly, in particular of a vehicle, and an power source (30) of an power grid external to said assembly, comprising: an electrical line (100) connecting the power grid to said assembly, said line (100) including electrical conductors in which a first portion (100a), referred to as an power exchange line, is suitable for being connected to said power grid such as to enable a power exchange between the power source (30) of said grid and said power consumer (20); and a second portion (100b), referred to as a ground line, is suitable for implementing an equipotential connection between the electrical mass (22) of the assembly and the ground (32) of the power grid; a first measurement system (101) suitable for measuring a common mode current (i) flowing in one of the two portions (100a, 100b) of the electrical line (100) during a power exchange between the power source (30) and the consumer (20); at least one impedance (120) connected by one of the terminals thereof to the power exchange line (100a) of the electrical line or to an internal potential of the electrical circuit; an electronic component (110) connected to said first measurement system (101) measuring the common mode current, the component (110) being configured to apply, between the ground line (100b) and another terminal of the impedance (120), an electrical quantities which make it possible, when power is exchanged between the consumer (20) and the power source (30), to reduce the common mode current flowing in the portion of the electrical line (100) which has the current that is measured by the first measurement system (101); a second measurement system (102) suitable for measuring a residual current flowing in at least the portion of the electrical line (100) which has the current that is not measured by the first measurement system (101); and a control unit configured to detect a failure of the power exchange when a value obtained from the current measured by the second measurement system (102) is greater than a threshold value.