Charging Circuit DC Power Disconnection Detection
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Solution Overview
Problem
Existing charging circuits fail to accurately and efficiently detect the disconnection of a DC power source, leading to power wastage and potential erroneous determinations, especially when the DC power source has a small current capacity.
Innovation Solution
A charging circuit with a DC power detecting unit that compares input current and voltage with multiple threshold values, allowing for accurate detection of DC power source disconnection by distinguishing between voltage drops due to current capacity and disconnection, and incorporating a low-voltage detection circuit to set a lower threshold voltage than the fully charged battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single threshold voltage is used for detecting DC power source disconnection, then the detection is simple, but it leads to erroneous determinations when the DC power source has small current capacity
Solution Approach 1:
The single threshold voltage detection is segmented into multiple threshold voltages (first threshold voltage and second threshold voltage). The detection circuit now compares the voltage at the DC input terminal against these multiple thresholds in sequence, allowing differentiation between voltage drops due to small current capacity versus actual disconnection events.
Solution Approach 2:
The detection mechanism dynamically adjusts its behavior based on voltage comparisons. When voltage drops below the first threshold, the system enters a waiting period before confirming disconnection at the second threshold, creating a dynamic, adaptive detection process rather than a static single-threshold approach.
2Measurement precision
If the detection threshold is set low to avoid false positives, then disconnection detection becomes more accurate, but detection time increases due to waiting periods
Solution Approach 1:
The detection process uses periodic action through predetermined waiting periods. When voltage drops below the first threshold voltage, the system waits for a predetermined time before checking against the second threshold. This periodic waiting mechanism reduces false positives while maintaining reasonable detection speed.
Solution Approach 2:
The system performs preliminary detection by first comparing against the first threshold voltage before final confirmation at the second threshold. This preliminary action filters out transient voltage drops and prepares the system for accurate disconnection detection, balancing speed and accuracy.
3Stability of the object's composition
If the charging circuit continues operation after DC power source disconnection, then power supply stability is maintained, but power wastage occurs
Solution Approach 1:
The charging controller implements feedback by continuously monitoring the voltage at the DC input terminal and adjusting charging operations accordingly. When disconnection is detected through the multiple-threshold comparison system, the controller provides feedback to stop charging, eliminating power wastage while maintaining stability during normal operation.
Solution Approach 2:
The charging circuit performs self-service by automatically detecting disconnection and adjusting its operation without external intervention. The system monitors its own power source status and autonomously decides when to continue or stop charging, optimizing both stability and energy efficiency.
Data Source
AI summary
Charging circuit includes: DC input terminal; battery terminal; system terminal; first transistor; second transistor; gate controller for controlling turning on/off of first transistor; charging controller for controlling gate voltage of second transistor to control charging of secondary battery; overcurrent protection circuit for comparing an input current flowing in DC input terminal and first transistor with threshold current having multiple steps of values, and vary gate voltage such that on-resistance is increased when input current reaches threshold current; low-voltage detection circuit for comparing voltage at DC input terminal with predetermined threshold voltage, and decrease threshold current of overcurrent protection circuit by one step when voltage of DC input terminal is below predetermined threshold voltage; and DC power detecting unit for determining, when threshold current is at minimum value and voltage of DC input terminal is below threshold voltage, that DC power source is not connected to charging circuit.