Battery pack high and low temperature control system

Abstract

A battery pack high and low temperature control system comprises a vehicle control unit, a main battery pack, a main battery pack BMS, an auxiliary battery pack, an auxiliary battery pack BMS and a direct-current equal-voltage / step-down charger. As long as the low-temperature-not-resistant battery cell discharges at a low temperature, the discharge capacity can be reduced in a cliff manner no matter driving a vehicle, heating a battery pack, heating and the like, and the reason is that the battery cell is damaged by discharging at the low temperature instead of increasing the power consumption at the low temperature, which is the main factor of serious battery attenuation. The battery pack high and low temperature control system comprises a main battery pack and an auxiliary battery pack, the main battery pack is a non-low-temperature-resistant battery cell, the auxiliary battery pack is a low-temperature-resistant battery cell, and the two battery packs are controlled by a vehicle control unit to operate independently; in the low-temperature environment, the vehicle control unit controls the auxiliary battery pack to discharge and work and drives the cooling / heating controller to heat the main battery pack, and after the temperature of the main battery pack reaches the temperature suitable for working, discharging of the auxiliary battery pack is cut off, and the situation that the main battery pack attenuates seriously and battery cells are damaged is prevented.

Description

technical field [0001] The invention relates to the technical field of new energy vehicles and energy storage, in particular to a battery pack high and low temperature control system that prevents serious attenuation of the main battery pack and damages the battery cells in a low temperature environment, and eliminates the superimposed temperature increase of the main battery pack in a high temperature environment. Background technique [0002] At present, with the advancement of science and technology and economic development, more and more people are increasingly pursuing free and convenient means of transportation. Cars are one of the most commonly used means of transportation. Although traditional cars are convenient for human travel, the exhaust gas they produce is harmful to human beings. It has brought huge pollution, and more importantly, the raw materials such as gasoline and diesel as the source of power for automobiles are becoming increasingly scarce, so people wa...

AI Technical Summary

Problems solved by technology

[0002] At present, with the advancement of science and technology and economic development, more and more people are increasingly pursuing free and convenient means of transportation. Automobiles are one of the most commonly used means of transportation for people. Although traditional automobiles facilitate human travel, the exhaust gas it produces is harmful It has brought huge pollution, and more importantly, the raw materials such as gasoline and diesel as the source of automobile power are becoming increasingly scarce, so people want to design electric vehicles, such as clean energy vehicles; The advantages of vehicles that drive wheels are: saving fuel energy, reducing waste emissions, high efficiency, and low noise; but its disadvantages are also obvious, that is, most electric vehicle lithium batteries, including lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide , Lithium ternary as the power source. At present, lithium ternary or lithium iron phosphate batteries are the most widely used batteries in electric vehicles. Taking lithium iron phosphate batteries as an example, this kind of battery has high safety and long battery life, but Lithium iron phosphate has a fatal disadvantage:

[0003] 1. Its performance is greatly affected by the ambient temperature. When the ambient temperature is lower than 0°C, the internal resistance of the battery increases rapidly. Lithium iron phosphate lithium-ion batteries use organic electrolytes. When the temperature is below 0°C, the conductivity decreases. The drop is very fast, thereby reducing the battery capacity; in addition, charging at low temperature will cause the solid electrolyte phase interface (SEI) film on the electrode surface to thicken, which will increase the resistance of the SEI film;

[0004] 2. Charging the battery pack in an environment lower than the allowable temperature of the battery pack (such as 0°C) may easily cause lithium precipitation in the battery pack and cause damage to the battery pack. In severe cases, the diaphragm of the battery pack may be pierced, causing the battery The internal short circuit of the battery pack makes the battery pack temperature high and easy to burn out; if the geographical location is relatively cold, the performance of the battery pack will be greatly reduced in the severe cold and low temperature environment, and the service life of the new energy vehicle will also be greatly reduced; in the low temperature environment It is necessary to heat the battery pack in order to increase the working temperature of the battery pack to within the normal working temperature range. This self-heating method will cause serious low-temperature attenuation of the battery pack and damage the battery cells; and how to improve the battery pack in a severe cold and low temperature environment? The temperature of the battery pack to ensure the normal discharge of the battery pack and the normal use of the battery pack has become an urgent problem to be solved

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