EV Charging Relay Switching for Voltage-Adaptive Booster Bypass
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Solution Overview
Problem
Existing electrically powered vehicles experience efficiency losses during charging due to the activation of boosters, even when the power storage device can be charged without them.
Innovation Solution
An electrically powered vehicle is equipped with a booster, a charging relay, and a controller that selectively routes the external power supply to either the high-voltage side or the low-voltage side of the booster based on the inter-terminal voltage of the power storage device, thereby avoiding unnecessary booster activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the booster is always activated to charge the power storage device, then the power storage device can be charged regardless of voltage conditions, but charging efficiency is reduced due to power loss in the boost operation
Solution Approach 1:
The system dynamically changes the operating parameters by switching between two charging paths based on the voltage relationship between the power storage device and external power supply. When the power storage device voltage is lower than the external supply voltage, it charges directly without boost. When the power storage device voltage is higher, it activates the booster to step up the voltage. This parameter-based switching resolves the contradiction by adapting the charging method to current voltage conditions.
Solution Approach 2:
The charging system transitions from a static configuration (booster always on or always off) to a dynamic configuration where the charging path is selectively switched based on real-time voltage conditions. The switching element enables the system to adapt its structure and operation mode dynamically, achieving both versatility across different voltage scenarios and energy efficiency by avoiding unnecessary boost operations.
2Device complexity
If a fixed reference voltage is used to determine charging mode, then the control logic is simple, but the charging mode may be incorrectly selected when the power storage device voltage differs from the reference voltage
Solution Approach 1:
The system employs feedback by continuously monitoring the actual voltage of the power storage device and comparing it with the external power supply voltage. This real-time feedback mechanism ensures accurate determination of the appropriate charging mode, replacing the unreliable fixed reference voltage approach. The feedback loop maintains reliability while keeping control logic relatively simple through direct voltage comparison.
Solution Approach 2:
Before initiating charging, the system performs a preliminary voltage comparison between the power storage device and external power supply. This preliminary action determines the appropriate charging path in advance, preventing incorrect mode selection and ensuring reliable operation from the start of 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
This configuration suppresses efficiency losses in charging by ensuring that the power storage device is charged without activating the booster when possible, and using the booster only when necessary to achieve efficient charging.
Implementation Method 1
a booster (20). The booster (20) has a high-voltage side connected to the power storage device (10). The booster (20) is configured to boost a voltage of electric power provided to a low-voltage side of the booster (20) and to provide electric power of the boosted voltage to the high-voltage side
Data Source
AI summary
An inter-terminal voltage obtaining unit obtains an inter-terminal voltage of a battery. A comparator compares the inter-terminal voltage with a maximum output voltage of a charger. When relation of VB≤VCmax is satisfied, an AC charging relay is switched such that output electric power from the charger is supplied to a high-voltage side of a buck-boost converter. When relation of VB>VCmax is satisfied, the AC charging relay is switched such that an output voltage of the charger is supplied to a low-voltage side of the buck-boost converter and the buck-boost converter is activated.