Battery Relay Control via OP AMP Comparator for EV Safety
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Solution Overview
Problem
Existing battery management systems for electric vehicles struggle to properly control high voltage relays during operation problems or overcharging, leading to risks of battery fires or explosions due to reliance on microchip control signals alone.
Innovation Solution
Incorporating an operational amplifier (OP AMP) comparator within or outside the battery management system to generate a dual relay control signal, which compares the battery voltage with a reference voltage and outputs a control signal to ensure safe relay operation, even in high voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microchip control signal is used to control the relay, then the control system is simple, but the reliability is insufficient when the battery has high voltage due to operation problems or overcharging
Solution Approach 1:
An OP AMP comparator is introduced as an intermediary component between the battery voltage source and the relay control circuit. The comparator receives the battery voltage and compares it with a reference voltage, then outputs a control signal to the relay. This intermediary device ensures that the relay is controlled based on actual voltage conditions rather than relying solely on microchip control signals, thereby improving reliability while adding only a single comparator component to the system.
2Object-affected harmful factors
If the BMS controls the relay only with a control signal through a microchip, then the device complexity is low, but the safety is compromised when the BMS has problems or erroneous operations occur
Solution Approach 1:
The OP AMP comparator performs preliminary voltage comparison and control signal generation before the relay is actuated. By continuously monitoring the battery voltage and comparing it with the reference voltage in advance, the system ensures that the relay control signal is generated based on actual voltage conditions. This preliminary action prevents erroneous relay operation even when the microchip control signal is abnormal, thereby improving battery safety with minimal additional complexity.
3Reliability
If a dual relay control signal system is implemented with an OP AMP comparator, then the safety and reliability are improved, but the device complexity increases
Solution Approach 1:
The relay control function is segmented into two independent parts: the microchip control signal path and the OP AMP comparator control signal path. Each path operates independently to control the relay based on different criteria. This segmentation allows the system to improve reliability through redundant control mechanisms while keeping each individual control path simple and manageable, thereby limiting the overall increase in system complexity.
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
This solution effectively controls the relay to prevent overcharging and maintain safety by dualizing the control signal, thereby reducing the risk of battery-related incidents during operation problems or overcharging.
Implementation Method 1
an operational amplifier (OP AMP) comparator disposed inside or outside the battery management system (BMS) in order to output the voltage relay control signal. The OP AMP comparator may compare an input voltage of the high voltage battery with a reference voltage of the battery management system
Data Source
AI summary
A circuit for protecting a battery for an electric vehicle includes a high voltage battery configured to output a DC voltage, an inverter configured to selectively receive the DC voltage from the high voltage battery and invert the DC voltage into an AC voltage when the inverter receives the DC voltage, a relay disposed between the high voltage battery and the inverter and configured to selectively block the DC voltage from the high voltage battery to the inverter, and a battery management system including a microchip configured to output a main relay control signal for controlling the relay. The battery management system is configured to receive the DC voltage from the high voltage battery, and output a voltage relay control signal controlling the relay separately from the control by the microchip.