Electricity is the backbone of modern life, and our daily life and industrial production cannot be separated from electricity supply. However, enjoying convenient power at the same time, we also face the potential harm brought by the abnormal voltage rise. At this point, the BMS overvoltage protection has become a powerful patron saint of the power system, it can protect the safety of the equipment, systems, and personnel.
What is Overvoltage Protection?
Overvoltage protection is an extremely important feature of voltage, designed to prevent the power supply from feeding too much voltage to more sensitive devices. If the voltage at the power supply output terminals exceeds the OVP setting, the power supply outputs are turned off, thus protecting the devices from being damaged by excessive voltage. Once the power supply is turned on, OVP is always active and you cannot turn it off. If you do not want to activate it, you can set it to the voltage value at which the power supply output is at its maximum value.
There are many causes of overvoltage, including:
- Internal circuit failure: A circuit in the power supply may fail, causing the output voltage to exceed a predetermined value.
- External power influences: External power sources, such as other power sources or batteries connected in parallel with the output, may produce voltages higher than the predetermined value.
- Human error by the operator: The operator may have set the voltage value incorrectly, exceeding the predetermined value, which is the maximum voltage that the measured part can withstand.
What Risks Might Overvoltage Lead to?
Damage to equipment
Overvoltage may cause damage to the internal electronic components of equipment, or even burn them out completely. This includes household appliances such as computers and televisions, as well as industrial equipment and electric vehicles. Damage to equipment not only leads to increased repair or replacement costs but also causes downtime, affecting production and efficiency.
Data loss
Overvoltage can lead to loss or corruption of data in data storage devices such as hard disk drives or solid-state drives. This can result in the loss of personal photos, documents, and important data for individual users, and can cause significant data loss issues for businesses and organizations.
Fire risk
Overvoltage can cause electrical wiring and equipment to become overheated, which increases the risk of fires starting in wires and cables. Electrical equipment can malfunction, such as wires shorting out or components inside the equipment igniting, which poses a threat to the safety of buildings and people.
Battery problems
For charging equipment and electric vehicles, overvoltage can have serious negative effects on batteries. Batteries may overheat, leading to a loss of electrolyte control and even triggering a gas release or explosion. This situation poses a potential risk to the safety of both the user and the environment.
How to Achieve Overvoltage Protection?
After extensive validation, both BMS and battery boards have proven to be effective means for preventing and addressing overvoltage issues. They are critical components used for overvoltage protection, and while their protection principles are fundamentally similar, they differ somewhat in implementation.
BMS overvoltage protection process:
1. Voltage monitoring: The BMS realizes overvoltage protection by monitoring the voltage of each cell individual within the battery pack. These voltage values are checked periodically and are usually scanned in milliseconds. Monitoring voltage is a continuous process to ensure that voltage increases are quickly detected even during the various BMS charging voltage and discharging phases of the battery pack.
2. Comparison and threshold setting: The BMS compares the monitored voltage with a pre-set threshold. If the voltage of any battery cell exceeds the set safety limit, the BMS will consider that a BMS over voltage condition has occurred.
3. Measures: Once overvoltage is detected, the BMS will take measures to prevent further harm. These measures may include:
a. Disconnecting the battery pack from the load to prevent the overvoltage from propagating to other equipment.
b. Reducing the charging current to minimize the rate at which the battery is being charged, thereby reducing the voltage.
c. Alerting the user or the system that an overvoltage event has occurred.
4. Real-time monitoring: The BMS will continue to monitor the battery voltage in real time until the voltage returns to a safe range. Once the voltage returns to normal, the BMS can reconnect the battery pack to the load and gradually increase the charging current to maintain regular battery operation.
Battery Protection Board overvoltage protection process:
The Battery Protection Board is usually integrated into the battery pack and is responsible for monitoring the battery cells and cell over-voltage protection. Its over-voltage protection principle is as follows:
1. Battery cell voltage monitoring: The battery protection board will monitor the voltage of each cell in the battery pack. These voltage values will be compared with the threshold value inside the battery protection board.
2. Comparison and triggering protection: If the voltage of the battery cells exceeds the preset safety limit, the battery protection board will trigger the protection mechanism.
3. Disconnect cells: In order to prevent overvoltage propagation to other cells, the battery protection board will disconnect the affected cells. This is usually achieved by switching the connectors between the cells.
4. Wait for recovery: The battery protection board will continuously monitor the voltage of the battery cells. Once the voltage has dropped to a safe range, the board will reconnect the cells and allow them to continue to operate normally.
It is important to note that battery protection panels are usually targeted at individual battery packs, whereas BMSs are typically used for larger battery systems, such as electric vehicles or home energy storage systems. Their core principle is to ensure the safe operation of batteries and systems by monitoring voltage and taking action to avoid potential hazards caused by overvoltage.
Overvoltage Protection Solutions by MOKOEnergy
Overcharging can lead to all lithium ions in the positive electrode material migrating into the negative electrode material, causing deformation and collapse of the originally well-structured grid in the positive electrode. During this process, an increasing accumulation of lithium ions in the negative electrode results in the excessive growth of dendritic lithium structures, causing the battery to swell. In severe cases, this can lead to dangerous situations such as fires and explosions.
However, MOKOEnergy‘s BMS and battery protection board effectively address the safety issues that overcharging can cause.
BMS
Our battery management systems introduce voltage and current control at the software and hardware level. For example, our basic hardware for industrial BMS solutions includes:
- Current and voltage transformers.
- Amplifiers and buffers with resistive voltage dividers that increase the amplitude of the output current and voltage, respectively.
- ADCs that convert current and voltage values into digital signals.
- The MCU reads the signals.
Only by realizing high-precision detection and high sensitivity response to voltage and current can the BMS achieve great protection for lithium batteries. Our BMS adopts IC solutions with a high-precision acquisition chip, sensitive circuit detection, and an independently written operation program to achieve voltage accuracy within ±0.025V and short-circuit protection from 250~ 500 us, ensuring efficient battery operation and easily coping with complex application scenarios of high power such as electric vehicles and industrial fields.
Battery Protection Board
Due to the characteristics of the battery materials, which should not be subjected to overcharging, over-discharging, overcurrent, short circuits, and extremely high temperatures during charging and discharging, we have designed and manufactured protective circuit boards for batteries to mitigate these conditions. This helps prevent potential damage to lithium-ion batteries themselves. In particular, with regard to overvoltage protection for battery packs, we adhere to the specific regulations and corresponding testing requirements outlined in national standard GB/T 31241.
We have conducted a variety of tests to ensure the effectiveness of our battery management system overvoltage protection. These tests include scenarios such as normal charging and discharging, battery overcurrent protection during charging, overcurrent during discharging, and operation in high-temperature environments. These tests not only validate that our battery packs’ overvoltage protection functions according to the specifications set by GB/T 31241 but also ensure that the protective actions trigger within a reasonable timeframe and that recovery occurs within an acceptable range.
Our battery protection boards have a wide range of applications and are more suitable for small-scale and simple scenarios such as consumer electronics, two-wheeled electric vehicles, and portable devices than battery management systems, providing a cost-effective and simplified way to manage batteries.
Conclusion
In the realm of electrical systems, BMS overvoltage protection stands as a pivotal measure to ensure the safety of equipment, systems, and personnel. Elevated voltage levels can lead to severe damage and safety hazards, underscoring the critical importance of implementing appropriate overvoltage protection measures. By employing high-quality BMS and battery boards, such as MOKOEnergy’s products, we can confidently rely on electricity without the looming concerns of potential overvoltage issues. These advanced solutions will continue to play a vital role in the realm of electrical power, ensuring the secure and dependable operation of our power systems. If you still find yourself uncertain about the choice of overvoltage protection solutions, please feel free to consult with us.
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