Galvanic Isolation-Free EV Charger Neutral Current Control
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Solution Overview
Problem
On-board automobile battery chargers without galvanic isolation are sensitive to disturbed electrical power supply networks, leading to potential load cuts and overcurrents, which can result in inefficiencies and system faults, making it challenging to balance charging efficiency and availability across varying network quality.
Innovation Solution
A device and method that determine a corrected neutral current setpoint by measuring the instantaneous frequency of the network voltage, calculating frequency variations, and applying corrections to the neutral current setpoint, while using a regulation map and low-pass filtering to maintain stable charging, even in disturbed conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger safety margin is allowed for currents flowing through the charger to prevent overcurrents and faults, then reliability is improved, but efficiency deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the neutral current setpoint based on real-time detection of network disturbance levels. The system transitions from a static safety margin approach to a dynamic one where the current limit adapts to actual grid conditions, allowing high efficiency during normal operation while maintaining reliability during disturbed networks
Solution Approach 2:
The system changes the operating parameters (neutral current setpoint) based on the detected state of the power supply network. By monitoring network voltage and detecting disturbance levels, the system adjusts the current parameter dynamically, optimizing both efficiency and reliability according to actual operating conditions
2Reliability
If the neutral current setpoint is increased to maintain charging availability on disturbed networks, then charging availability is improved, but efficiency deteriorates
Solution Approach 1:
The system employs feedback control by continuously monitoring the power supply network voltage and detecting disturbance levels. Based on this feedback, the neutral current setpoint is automatically adjusted - increased when disturbances are detected to maintain charging availability, and reduced when the network is stable to optimize efficiency
Data Source
Figure 1~3
AI summary
Device for determining a corrected setting of the neutral current at the output of a rectifier stage of an electrical or hybrid automotive vehicle battery charger without galvanic isolation, the charger being supplied by an electrical supply network, the device comprises a loop phase-locking means (10) able to determine an instantaneous frequency of the network as a function of a measurement of the voltage of the electrical supply network, and a regulating mapping (14) able to determine a setting of neutral current as a function of a setting of battery current. The device comprises a means (11) for calculating the amplitude of the frequency variation of the network as a function of the instantaneous frequency of the network, a correction mapping (12) receiving as input the value of the amplitude of the frequency variation and emitting as output a correction of the neutral current setting, and a summate (15) able to determine a corrected setting of neutral current by adding the correction value for the neutral current setting to the neutral current setting.