Sub Battery State Detection Using Forced Discharge
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Solution Overview
Problem
Existing methods for detecting the state of a sub battery in on-vehicle power supply systems, particularly lead-acid batteries, struggle to accurately measure both the reaction resistance and parts resistance during vehicle travel, making it difficult to assess the battery's condition and prevent potential failures.
Innovation Solution
An on-vehicle power supply system that includes a main battery, a sub battery connected in parallel, a voltage adjuster, and a state detector with first and second calculating units to determine internal resistances based on voltage drop and inrush current, and forced discharging of the sub battery to accurately assess its state, allowing for the determination of both reaction and parts resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the internal resistance is calculated based on voltage drop and inrush current during vehicle travel, then the reaction resistance can be detected, but the parts resistance cannot be detected separately
Solution Approach 1:
The patent segments the internal resistance measurement into two distinct components: reaction resistance (measured during normal vehicle travel using voltage drop and inrush current) and parts resistance (measured during forced discharge). By separating these measurements, the system can detect both components independently and accurately assess the battery's overall state.
Solution Approach 2:
The patent performs forced discharge of the sub battery as a preliminary action to measure parts resistance before normal operation continues. This preliminary measurement allows the system to obtain complete internal resistance information (both reaction and parts resistance) in advance, enabling accurate state assessment without affecting normal vehicle operation.
2Reliability
If the sub battery is used as an emergency power source during normal vehicle travel, then the main battery supplies power, but the sub battery state cannot be accurately monitored
Solution Approach 1:
The patent implements periodic forced discharge of the sub battery during normal vehicle travel to measure its parts resistance. This periodic action occurs independently of the main battery's continuous operation, allowing the system to monitor the sub battery's state regularly without affecting the emergency power supply function. The forced discharge is performed at appropriate intervals to keep the sub battery ready for emergency use.
3Ease of operation
If only the reaction resistance is measured during vehicle travel, then the measurement method is simple, but the battery state assessment is inaccurate
Solution Approach 1:
The patent uses the voltage adjuster, which is already part of the power supply system, to perform forced discharge of the sub battery for measuring parts resistance. This self-service approach utilizes existing system components rather than requiring separate measurement equipment, maintaining ease of operation while achieving accurate measurement of both reaction and parts resistance for comprehensive battery state assessment.
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
Enables accurate detection of the sub battery's state during vehicle travel, preventing potential power source failures by calculating both reaction and parts resistances, ensuring the sub battery remains operational.
Implementation Method 1
a first calculating unit which obtains a first internal resistance that contains a reaction resistance and a parts resistance of the sub battery... the first calculating unit calculates the first internal resistance based on a voltage drop amount and an inrush current of the sub battery when supplying power to a load
Implementation Method 2
a second calculating unit which obtains a second internal resistance that contains a reaction resistance of the sub battery... the second calculating unit calculates the second internal resistance based on a relation between a voltage and a current of the sub battery when forcedly discharging the sub battery
Data Source
AI summary
A vehicle-mounted power supply system according to the present invention is provided with: a main battery; a sub-battery; a voltage regulating unit which regulates the voltage of power supplied from the main battery and the sub-battery; and a state detecting unit which detects the state of the sub-battery. The state detecting unit is provided with: a first calculating unit which calculates a first internal resistance on the basis of a drop in the voltage across the sub-battery and an inrush current when the sub-battery supplies power to a load; a second calculating unit which manipulates the voltage regulating unit immediately following the calculation of the first internal resistance, and subsequently at least one more time, to cause the sub-battery to be forcibly discharged, and calculates a second internal resistance on the basis of a relationship between the voltage across the sub-battery and the current flowing thereinto when forcibly discharged; and a state determining unit which determines the state of the sub-battery on the basis of the first internal resistance and changes in the second internal resistance.