Decoding BMS technology and exploring three keys to improve the cruising range of electric vehicles

When it comes to the cruising range of pure electric vehicles, people generally think of the energy density of the power battery. Of course, the energy density of the power battery is indeed the main factor affecting the cruising range of the electric vehicle, but the performance of the power battery management system (BMS) also directly affects the cruising range of the electric vehicle.

Decoding BMS technology and exploring three keys to improve the cruising range of electric vehicles


The BMS system usually includes a detection module and an operation control module, wherein the core part of the operation module is application software. Applications for development environments using Simulink are generally divided into two parts: battery state estimation algorithms and fault diagnosis and protection. Battery state estimates include SOC (state of charge), SOP (power state), SOH (health state), and equalization and thermal management. Among them, SOC estimation, SOH estimation and equalization technology are closely related to cruising range.

The higher the SOC estimation accuracy, the farther the cruising range is.

In general, SOC refers to how much power is left in the battery. The SOC is the most important parameter in the BMS and involves all other operations of the BMS, so the accuracy and robustness of the SOC (also called error correction capability) is extremely important. Without an accurate SOC, the BMS will not work properly, the battery will be constantly protected, and the battery life will be shortened.

For batteries of the same capacity, the higher the accuracy of the SOC, the more power the power battery can release under safe operating conditions, and the cruising range will be greatly improved. Therefore, the high-precision SOC estimation can effectively improve the cruising range of the electric vehicle, and the required battery cost will be reduced under the same cruising range.

The higher the SOH estimation accuracy, the slower the power battery decays.

The estimation of SOH is mainly for changes in battery capacity and power. In general, when the power battery capacity is attenuated by 20% or the output power is attenuated by 25%, the power battery will be eliminated. In the process of power battery capacity attenuation, the cruising range will be gradually reduced. The higher the accuracy of SOH estimation and the stronger the robustness, the more accurate the judgment of the management system on the battery capacity attenuation will be, and the cruising range will reach the maximum value in the safe state, which also means the speed of the cruising range is reduced. The slowdown, while the life of the power battery will also be extended.

Active balancing technology extends mileage

The battery balancing technology can effectively alleviate the consistency problem caused by the difference of the cell core, thereby improving the efficiency of the power battery.

Battery equalization technology is divided into passive equalization and active equalization. Passive equalization precedes active equalization. Because of its simple circuit and low cost, it is still widely used. The principle is that the battery's power and voltage are positively correlated. According to the single string battery voltage data, the high-voltage battery energy is discharged through the resistor to maintain the same state as the low-voltage battery, but there is power loss during the process. The heat in the load increases the load on the heat dissipation of the battery pack.

Because of the limitations of passive equilibrium, the concept of active equilibrium has been proposed and developed. Active balancing is the transfer of energy from a high-energy battery to a low-energy battery, thus maximizing battery capacity, thereby extending the life and cruising range of the power battery. Studies have shown that active balancing can increase the cruising range of electric vehicles by more than 10%.

The author believes that the cruising range as an important indicator of electric vehicles directly affects the promotion of electric vehicles. Therefore, people try to improve the cruising range of the power battery from various aspects. As an indispensable management system for the power battery, BMS ensures that the power battery is operating in a safe state, and also controls the power battery in an optimal working state, thereby effectively improving the cruising range of the power battery. With the continuous advancement of technology, research on the battery life of power batteries will also have new breakthroughs and progress.

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