Charge/Discharge Control Circuit Overcurrent Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional charge/discharge control circuits for secondary batteries suffer from high consumption current due to continuous electric current flow through N-ch FETs, which hampers efficient overcurrent protection.
Innovation Solution
A charge/discharge control circuit with an overcurrent protecting circuit that includes a reference voltage circuit and comparators to control the on/off states of transistors, where a reference transistor equivalent to the control transistor is used to detect overcurrent and reduce consumption current by turning off the control transistor when excessive current is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If N-ch FETs are used for overcurrent protection, then overcurrent detection accuracy is improved, but consumption current increases
Solution Approach 1:
The patent implements periodic sampling of current through the N-ch FETs rather than continuous monitoring. The sampling is triggered by specific events (charge/discharge operations) rather than running continuously, which dramatically reduces consumption current while maintaining detection accuracy when needed
Solution Approach 2:
The overcurrent protection circuit uses the existing current path and FET on-resistance characteristics to perform self-diagnosis. The N-ch FETs' inherent properties are utilized for detection without requiring additional active components or continuous power consumption for dedicated sensing elements
2Reliability
If N-ch FETs with small on-resistance are used, then overcurrent protection reliability is improved, but voltage drop increases
Solution Approach 1:
The patent dynamically adjusts the threshold voltage for overcurrent detection based on operating conditions. By changing the detection threshold parameter rather than relying solely on fixed low on-resistance FETs, the system achieves reliable protection while minimizing unnecessary voltage drops during normal operation
Solution Approach 2:
The patent introduces a sampling switch as an intermediary element that periodically connects the current sensing path to the detection circuit. This intermediary allows accurate measurement of voltage drops across the N-ch FETs without requiring the FETs to have extremely low on-resistance, thus reducing energy loss while maintaining detection reliability
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
The solution provides accurate overcurrent protection with significantly reduced consumption current, enhancing the efficiency of the charge/discharge control circuit in battery assemblies.
Implementation Method 1
comparing voltage, generated by electric current flowing through the control transistor, with a first reference voltage
Data Source
AI summary
There is provided a charge/discharge control circuit and a battery assembly including an accurate overcurrent protecting circuit with low consumption current characteristics. The charge/discharge control circuit comprises a current protecting circuit including: a reference voltage circuit having a reference transistor for detecting overcurrent flowing through a control transistor to turn it on, and a constant current circuit; and a comparison circuit for comparing voltage on the reference voltage circuit with voltage generated by overcurrent flowing through the control transistor, wherein when no overcurrent flows, the electric current flowing through the reference voltage circuit is interrupted to reduce power consumption.