Battery Pack Relay Voltage Threshold Control for Surge Protection
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Solution Overview
Problem
Existing battery management systems (BMS) fail to prevent damage to charging and discharging switches due to overvoltage without considering the withstanding voltage of the switches, leading to potential damage even when no overcurrent is present.
Innovation Solution
A relay control apparatus that includes a comparator to set a reference voltage corresponding to the withstanding voltage of the relay, controlling its operation state based on comparison voltage, and a variable resistor to adjust this voltage, preventing surges and high voltages from damaging the relay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference voltage is set based on the maximum voltage of the capacitor, then overcurrent protection is achieved, but the charging switch and discharging switch may be damaged by voltage exceeding their withstanding voltage
Solution Approach 1:
The patent changes the reference voltage parameter from being based solely on capacitor maximum voltage to being based on the minimum withstanding voltage of the charging and discharging switches. This parameter change ensures that the reference voltage reflects the actual voltage tolerance limits of the switches, preventing voltage-induced damage while maintaining overcurrent protection functionality.
2Reliability
If the BMS controls the operation state of charging and discharging switches, then battery pack voltage control is achieved, but control is impossible when the BMS is in wake-up state
Solution Approach 1:
The patent implements preliminary action by having the comparator continuously monitor the voltage difference between the reference voltage (based on switch withstanding voltage) and the actual battery pack voltage before the BMS needs to respond. This allows the system to be prepared for overvoltage conditions in advance, enabling faster response when the BMS transitions from wake-up state without requiring complex real-time control during the transition.
3Device complexity
If the relay withstanding voltage is not considered in reference voltage setting, then simple voltage-based control is maintained, but the relay may be damaged by surge voltage
Solution Approach 1:
The patent introduces a comparator as an intermediary component that automatically compares the actual voltage with the reference voltage (set based on relay withstanding voltage) and controls the relay accordingly. This intermediary handles the complex voltage monitoring and comparison tasks, protecting the relay from surge voltage while maintaining relative simplicity in the overall control architecture. The comparator acts as a buffer between the voltage monitoring function and the relay control function.
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
Prevents surges and high voltages from damaging the relay, thereby protecting the battery pack's components by ensuring the relay operates within its withstanding voltage limits, even with degradation or replacement.
Implementation Method 1
a comparator configured to receive a comparison voltage from the main path and output a result signal to the relay based on a difference between a reference voltage and the comparison voltage
Implementation Method 2
a variable resistor configured to be disposed between the voltage source and the comparator, and a control unit configured to adjust the magnitude of the reference voltage applied to the comparator to correspond to the withstanding voltage of the relay by adjusting a resistance of the variable resistor
Data Source
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AI summary
A relay control apparatus according to an embodiment of the present disclosure includes: a relay disposed on a main path between a battery cell and a pack terminal and configured to electrically connect or disconnect the main path according to an operation state; and a comparator configured to receive a comparison voltage from the main path and output a result signal to the relay based on a difference between a reference voltage and the comparison voltage, wherein the relay is configured to receive the result signal and control the operation state to a turn-on state or a turn-off state according to the magnitude of the received result signal.