Charging characteristics of lithium-ion battery packs
Because of the inconsistency among the single rechargeable batteries, the inconsistency of the power lithium battery pack is caused. The difference caused by the continuous battery charging cycle system will accelerate the volume attenuation coefficient of some single rechargeable batteries, and the volume of the series-connected lithium battery pack is determined by its minimum volume, so this difference will reduce the service life of the rechargeable battery. The key reasons for this disorder are as follows:
In the whole process of rechargeable battery production, due to the processing technology, the rechargeable batteries manufactured in the same batch are different in terms of volume, internal resistance, etc.;
Lithium batteries have different lifespans for rechargeable batteries. After long-term accumulation, the battery power is different;
In the whole process of rechargeable battery application, the difference of the application natural environment such as temperature and circuit board causes the imbalance of battery power.
Lithium battery rechargeable battery balance battery charging method.
In order to reduce the harm of unbalance to the lithium battery pack, a balanced power supply circuit should be selected when the battery is charged.
Nowadays, there are two ways to carry out balance management methods for lithium batteries, one is energy-consuming and the other is gratitude and feedback. The type of calorie consumption is to show a series loop for a single rechargeable battery, so that a single rechargeable battery with an excessively high operating voltage separates electromagnetic energy to achieve equilibrium. The kind of gratitude feedback refers to the biased kinetic energy between the individual units that is sent to the lithium battery pack or some of the lithium battery packs through the energy converter.
Theoretically speaking, while ignoring the high efficiency of transformation, feedback does not consume kinetic energy and can achieve a stable balance. However, because of the complicated control measures and high manufacturing cost of the feedback design scheme, this charging head uses an energy-consuming design scheme.
Since the internal resistance of alternating current, the working voltage of electric polarization, and the large usable volume are the actual main parameters of rechargeable batteries, most of the SOC of rechargeable batteries has not changed during the whole process of one or several continuous cycles of battery charging, so the lithium battery pack’s Balance is very important, and it is done by adjusting the SOC of each single rechargeable battery. According to scientific research, it has been clarified that the balance target is relatively fixed with SOC as the balance reference target, the balance time is flexibly used, the balance utilization rate is increased, and the balance volume is reduced.
The SOC of the rechargeable battery is used as the control target, and the difference between the SOC and the rechargeable battery is reduced according to the method of charging the battery for a single rechargeable battery. The first is to clarify the overall goal of balancing and set it as the mean concentration polarization state value (SOC) of the lithium battery pack to improve the balance and high efficiency and make full use of the advantages of battery charging balance; in addition, a balance control zone is set (dSOC), carried out the charge and discharge balance for the higher SOC, and carried out the battery charge balance for the reverse.
The key to the balance battery charging technology of the general lithium battery pack is stable separation resistance, short-circuit separation resistance, average battery voltage balance battery charging, power switch capacitor balance battery charging, blood pressure reduction SPWM balance battery charging, inductor balance battery charging, etc. When charging the integrated lithium battery in series, ensure that each battery is charged equally, otherwise the characteristics and service life of the entire set of rechargeable batteries will be endangered during the entire application process.