Solutions for active and passive balancing of lithium-ion battery charging -Lithium - Ion Battery Equipment
Solutions for active balancing and passive balancing of lithium-ion battery pack charging. The most important link we need to pay attention to when charging and discharging lithium-ion battery packs is the equalization link. Currently, there are two approaches to address the unbalanced condition of small Li-ion cells in a battery pack: active balancing and passive balancing. The equalization link is to ensure that the input and output of the lithium-ion battery pack are reasonable to each lithium-ion battery, so that it can be used reasonably and effectively without damage.
Lithium-ion battery charge balance method
1. Traditional passive method: In a general lithium-ion battery management system, each battery cell is connected to a load resistor through a switch. This passive circuit discharges individual selected cells. But this method is only suitable for suppressing the voltage rise of the strongest battery cells in charging mode. In order to limit power consumption, such circuits generally only allow discharge at a small current of about 100mA, resulting in a charging balance that can take as long as several hours.(Lithium - Ion Battery Equipment)
2. Active balancing method: There are many kinds of active balancing methods in related materials, all of which require a storage element for transferring energy. If a capacitor is used as the storage element, connecting it to all the battery cells requires a huge array of switches. A more efficient approach is to store energy in a magnetic field. The key component in this circuit is a transformer.
Passive Balancing of Lithium-Ion Batteries
The passive balance of lithium-ion batteries is for the state of charge of lithium-ion batteries. Its premise is that before charging the lithium-ion battery pack, each small battery in the battery pack has a different residual charge, which is determined by the different performance parameters of the battery, due to the performance of each battery Some batteries will be overcharged due to their own "weakness" under the impulse of current, forming overvoltage. Overvoltage is the biggest damage to lithium-ion batteries, it will cause serious damage to the lithium-ion battery pack and even make it impossible to use it again.
The method of passive balancing is: when charging, the current that causes the voltage of the small battery to rise rapidly can be shunted to the bypass resistor. By shunting unwanted charging current to a resistor so that the resistor can dissipate the current, overcharging of the battery can be prevented. This power dissipation function of passive balancing can limit the current shunted from the battery to a certain range, so that all the small batteries are fully charged.
The disadvantage of the passive balancing method is that because power dissipation is used as a means, a part of the balancing current is expressed as heat, which greatly reduces the charging efficiency of the lithium-ion battery pack and increases the cost of manufacturing lithium-ion batteries. In addition, it cannot solve the problem of power imbalance of the lithium-ion battery pack when it is discharged and on hold. Therefore, if you want to achieve the ultimate goal of passive balance-the overall balance of charge and discharge of the lithium-ion battery pack, further measures must be taken, but This will increase the manufacturing cost of lithium-ion battery packs.
The Solution of Active Balancing Method for Lithium-ion Battery Pack Charging
Active balancing abandons the method of passive balancing to consume current, and changes it to the method of transmitting current. The device responsible for charge transfer is a power converter that enables the small cells in a Li-ion battery pack to transfer charge whether they are being charged, discharged, or idle, so that the cells are constantly in dynamic balance.
Due to the extremely high charge transfer efficiency of the active balancing method, higher balancing currents can be supplied, which means that this method is more capable of balancing Li-ion battery packs when charging, discharging and idling.
1. Strong fast charging ability: the active balance function can make the small batteries in the lithium-ion battery pack reach a balance faster, so the safety of fast charging is higher, and it is suitable for a high-rate charging method with a larger current.
2. When idle: Even if each small battery has reached the equilibrium state during charging, due to the different temperature gradients, some small batteries have a higher internal temperature, and some small batteries have a lower internal temperature, which will also make the internal temperature of each small battery The leakage rate is different.
Lithium-ion battery charge balance method
1. Traditional passive method: In a general lithium-ion battery management system, each battery cell is connected to a load resistor through a switch. This passive circuit discharges individual selected cells. But this method is only suitable for suppressing the voltage rise of the strongest battery cells in charging mode. In order to limit power consumption, such circuits generally only allow discharge at a small current of about 100mA, resulting in a charging balance that can take as long as several hours.(Lithium - Ion Battery Equipment)
2. Active balancing method: There are many kinds of active balancing methods in related materials, all of which require a storage element for transferring energy. If a capacitor is used as the storage element, connecting it to all the battery cells requires a huge array of switches. A more efficient approach is to store energy in a magnetic field. The key component in this circuit is a transformer.
Passive Balancing of Lithium-Ion Batteries
The passive balance of lithium-ion batteries is for the state of charge of lithium-ion batteries. Its premise is that before charging the lithium-ion battery pack, each small battery in the battery pack has a different residual charge, which is determined by the different performance parameters of the battery, due to the performance of each battery Some batteries will be overcharged due to their own "weakness" under the impulse of current, forming overvoltage. Overvoltage is the biggest damage to lithium-ion batteries, it will cause serious damage to the lithium-ion battery pack and even make it impossible to use it again.
The method of passive balancing is: when charging, the current that causes the voltage of the small battery to rise rapidly can be shunted to the bypass resistor. By shunting unwanted charging current to a resistor so that the resistor can dissipate the current, overcharging of the battery can be prevented. This power dissipation function of passive balancing can limit the current shunted from the battery to a certain range, so that all the small batteries are fully charged.
The disadvantage of the passive balancing method is that because power dissipation is used as a means, a part of the balancing current is expressed as heat, which greatly reduces the charging efficiency of the lithium-ion battery pack and increases the cost of manufacturing lithium-ion batteries. In addition, it cannot solve the problem of power imbalance of the lithium-ion battery pack when it is discharged and on hold. Therefore, if you want to achieve the ultimate goal of passive balance-the overall balance of charge and discharge of the lithium-ion battery pack, further measures must be taken, but This will increase the manufacturing cost of lithium-ion battery packs.
The Solution of Active Balancing Method for Lithium-ion Battery Pack Charging
Active balancing abandons the method of passive balancing to consume current, and changes it to the method of transmitting current. The device responsible for charge transfer is a power converter that enables the small cells in a Li-ion battery pack to transfer charge whether they are being charged, discharged, or idle, so that the cells are constantly in dynamic balance.
Due to the extremely high charge transfer efficiency of the active balancing method, higher balancing currents can be supplied, which means that this method is more capable of balancing Li-ion battery packs when charging, discharging and idling.
1. Strong fast charging ability: the active balance function can make the small batteries in the lithium-ion battery pack reach a balance faster, so the safety of fast charging is higher, and it is suitable for a high-rate charging method with a larger current.
2. When idle: Even if each small battery has reached the equilibrium state during charging, due to the different temperature gradients, some small batteries have a higher internal temperature, and some small batteries have a lower internal temperature, which will also make the internal temperature of each small battery The leakage rate is different.
