EV Charging Relay Powering via Inlet-Side Voltage Conversion
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Solution Overview
Problem
The charging relay in electric vehicles may fail to switch to the connected state prior to the start of external charging due to insufficient operating voltage from the auxiliary battery, which increases with repeated switching operations and is affected by the state of charge and age of the auxiliary battery.
Innovation Solution
A charging system that includes an inlet-side voltage converter to step down the inlet voltage to an auxiliary voltage, supplying the charging relay with operating power before switching to the connected state, controlled by a controller to ensure sufficient voltage for reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging relay is used repeatedly for switching operations, then the minimum requisite operating voltage increases, but the voltage supplied by the auxiliary battery decreases due to state of charge reduction and aging
Solution Approach 1:
The inlet-side voltage converter is activated before the charging relay switching operation to pre-charge the auxiliary battery or directly supply operating voltage to the charging relay, ensuring sufficient voltage is available when the relay needs to switch, thereby preventing switching failure due to voltage depletion from repeated operations
Solution Approach 2:
The inlet-side voltage converter acts as an intermediary power supply between the inlet and the charging relay, providing the necessary operating voltage to the charging relay without depleting the auxiliary battery, thus ensuring reliable switching operations even after repeated use
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
Prevents the charging relay from failing to switch to the connected state during external charging by providing adequate operating power, ensuring reliable switching and preventing system failures.
Implementation Method 1
an inlet-side voltage converter that steps down a voltage of electric power from the inlet to an auxiliary voltage
Data Source
AI summary
A charging system includes: a main battery storing electric power for a vehicle to travel; an inlet connected to a charging connector; a charging relay that switches a path of electric power from the inlet to the main battery; a converter that steps down a voltage of the electric power from the inlet; and an ECU that controls the charging relay and the converter. The ECU: controls the converter so that the converter starts stepping down the voltage of the electric power from the inlet to the auxiliary voltage after receiving the electric power from the inlet; supplies, before the charging relay switches to the connected state, the charging relay with the electric power from the converter as operating power for switching to the connected state; and controls the charging relay so that the charging relay switches from the disconnected state to the connected state, using the operating power.