Active LDC Control for Electric Vehicle Battery Overcharging
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Solution Overview
Problem
Electric vehicles experience reduced miles per charge and shortened battery lifespan due to continuous overcharging of low-voltage batteries, leading to unnecessary power consumption and gas generation from excessive charging.
Innovation Solution
An active control system for the Low-voltage DC/DC Converter (LDC) in electric vehicles, managed by a Vehicle Control Unit (VCU), which adjusts charging times and output voltages based on driving information to prevent overcharging and optimize battery charging, using a voltage table to control LDC output voltages and limit overcurrent charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LDC continuously outputs high voltage (14.3V) to charge the low voltage battery, then the battery charging is maintained, but the low voltage battery becomes overcharged leading to reduced lifespan and gas generation
Solution Approach 1:
The LDC output voltage is changed from a fixed constant value to a dynamic variable that adjusts based on charging time. The system implements multiple voltage levels (first voltage level for initial charging, second voltage level for maintenance charging) that are selectively applied based on the charging state, thereby preventing overcharging while maintaining reliable battery charging throughout the vehicle operation cycle.
Solution Approach 2:
The patent changes the voltage parameter of the LDC output from a single fixed value (14.3V) to multiple discrete voltage levels. By switching between a first voltage level during initial charging and a second voltage level during maintenance charging, the system optimizes both charging efficiency and battery lifespan, preventing the harmful effects of continuous high-voltage charging while ensuring adequate battery power supply.
2Reliability
If the LDC operates continuously to charge the low voltage battery, then the battery remains charged, but unnecessary power is consumed reducing miles per charge
Solution Approach 1:
The LDC charging operation is changed from continuous operation to periodic or conditional operation. The system monitors charging time and battery state, activating the LDC only when charging is needed (initial charging phase or when power demand exceeds supply) and deactivating it during maintenance phases, thereby eliminating unnecessary power consumption while ensuring the battery remains adequately charged.
Solution Approach 2:
The LDC operational state is dynamically controlled based on real-time charging conditions. The controller switches the LDC between active and inactive states, and between different voltage levels, according to the charging time and battery requirements, optimizing the balance between maintaining battery charge state and minimizing energy consumption to maximize miles per charge.
3Reliability
If the LDC outputs constant high voltage, then charging is maintained, but gas generation occurs due to overcharging
Solution Approach 1:
The patent implements parameter changes in the LDC output voltage to prevent gas generation. By switching from a constant high voltage (14.3V) to a variable voltage system with multiple levels, the system applies a lower second voltage level during maintenance charging phases, keeping the battery charge state sufficient for operation while preventing the electrolysis of water that causes gas generation and extends battery lifespan.
Solution Approach 2:
The system incorporates feedback control by monitoring charging time and battery state to regulate LDC output. The controller adjusts the LDC voltage based on the charging phase (initial vs. maintenance) and battery requirements, ensuring charging continuity while preventing overcharging conditions that lead to gas generation, thereby resolving the contradiction between reliable charging and harmful gas production.
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 solution increases the number of miles an electric vehicle can travel on a single charge and extends battery lifespan by preventing overcharging and gas generation, while optimizing charging times and currents.
Implementation Method 1
an LDC (Low-voltage DC/DC Converter) disposed between a high voltage battery and a low voltage battery and dropping and boosting the voltage in two directions
Data Source
AI summary
An active control system for a LDC (Low-voltage DC/DC Converter) in a vehicle is disclosed. The LDC is disposed between a high voltage battery and a low voltage battery, rectifies the voltage in two directions and a VCU (Vehicle Control Unit) configured to control the LDC. The VCU is configured to control when a DC active control mode is initiated to obtain the minimum charging time of the low voltage battery.