Dual-Battery Charging Circuit With Degradation-Based Mode Switching
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Solution Overview
Problem
In electric circuits with two batteries, an inverter circuit, and a three-phase motor, the degradation of a degraded battery progresses when a high current flows through the battery during charging, leading to inefficient charging and potential battery damage.
Innovation Solution
The electric circuit includes a control circuit that manages a connection switching circuit to execute a degradation determination process, a first charging process, and a second charging process. The control circuit selectively executes step-down charging and direct charging operations based on the output voltage difference between the batteries, and always executes step-down charging when degradation is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high current is used to charge the battery quickly, then charging speed is improved, but battery degradation accelerates
Solution Approach 1:
The patent implements dynamic charging control by switching between two charging modes (first charging process and second charging process) based on real-time battery state assessment. The control circuit dynamically adjusts charging current characteristics - using higher current in the first process when batteries are healthy, and lower current in the second process when degradation is detected - thereby optimizing both charging speed and battery protection throughout the charging cycle
Solution Approach 2:
The patent changes charging parameters (current magnitude and charging process type) based on battery health status. The control circuit monitors battery output voltage differences and switches between different charging current levels - applying higher current for healthy batteries and reduced current for degraded batteries - to balance charging efficiency with degradation suppression
2Reliability
If step-down charging is always used to suppress degradation, then battery life is extended, but charging efficiency decreases
Solution Approach 1:
The patent dynamically selects between step-down charging and direct charging based on real-time battery health assessment. When batteries are healthy (first charging process), direct charging with higher efficiency is used. When degradation is detected (second charging process), step-down charging is activated to protect battery life. This dynamic switching resolves the contradiction by adapting the charging method to current battery conditions
Solution Approach 2:
The patent performs preliminary assessment of battery health status before selecting the charging method. The control circuit evaluates output voltage differences and battery condition in advance, then pre-selects the appropriate charging process (first or second) to avoid degradation during charging. This preliminary assessment enables optimal charging strategy selection before the actual charging begins
3Productivity
If parallel charging of two batteries is implemented, then charging time is reduced, but voltage imbalance and degradation risk increase
Solution Approach 1:
The patent segments the charging control into two independent processes (first charging process and second charging process) that can be selectively applied to different batteries based on their individual health status. The control circuit can charge batteries independently or in parallel by selecting appropriate processes for each battery, thereby managing voltage imbalance while maintaining efficient charging throughput
Solution Approach 2:
The patent applies different charging quality levels to different batteries based on their individual conditions. Healthy batteries receive direct charging with higher current and voltage (first charging process), while degraded or imbalanced batteries receive step-down charging with reduced current (second charging process). This localized quality adjustment resolves voltage imbalance issues while maintaining overall charging efficiency
Data Source
AI summary
An electric circuit mounted on a vehicle includes a first battery, a second battery, a three-phase motor, an inverter circuit, a charging socket, a connection switching circuit, and a control circuit. The control circuit selectively executes the step-down charging operation and the direct charging operation such that, when the deterioration determination process determines that there is no deterioration, the step-down charging operation is executed when the output voltage difference is larger than the reference value and the direct charging operation is executed when the output voltage difference is smaller than the reference value. When it is determined that there is deterioration in the deterioration determination process, the control circuit executes the step-down charging operation regardless of the output voltage difference.