CN108232344B - A battery low temperature heating system and method coupled with a non-dissipative equalization system - Google Patents

Abstract

The invention discloses a low-temperature battery heating system and method coupled with a non-dissipative equalization system, comprising an energy storage element, an auxiliary battery, an auxiliary battery heating device and a battery heating device; the energy storage element is connected with the battery and is used for heating The power is transferred from the high-charge battery to the low-charge battery until the battery is balanced, and the auxiliary battery heating device is connected to the energy storage element for receiving the power from the energy storage element to heat the auxiliary battery, and the battery heating device Connected to the auxiliary battery, used to receive power from the auxiliary battery to heat the battery. The invention couples the non-dissipative balanced energy storage element with the low-temperature heating heat source of the battery, improves the energy utilization rate of the non-dissipative balanced, and simultaneously solves the problems of low-temperature charging of the battery and cold start of the electric vehicle.

Description

A battery low temperature heating system and method coupled with a non-dissipative equalization system

technical field

The invention relates to an electric vehicle battery management system, in particular to a battery low-temperature heating system and method coupled with a non-dissipative equalization system.

Background technique

The power battery is the key to the electric vehicle power system, which can provide electricity for the entire new energy system. Due to the advantages of high single-cell voltage, high specific energy, low self-discharge rate, and long cycle life, lithium-ion batteries have become the main force of electric vehicle power batteries at home and abroad. The characteristics of lithium-ion batteries are easily affected by the ambient temperature, the discharge capacity is reduced in a low temperature environment, and the driving range of the car is reduced. Low temperature charging will not only reduce battery life and effective capacity, but also cause permanent damage to the battery. Therefore, in order to ensure the safety and life of the battery, the battery temperature needs to be increased in a low temperature environment. At present, there are two main methods of low-temperature heating of batteries at home and abroad: internal heating and external heating. The internal heating technology is immature and cannot guarantee the safety of the battery, which is still under further research. There are various external heating methods and a high safety factor, but the choice of heat source has always been a hot and difficult research topic in the field of electric vehicles.

In order to meet the requirements of the power and driving range of electric vehicles, each electric vehicle is equipped with a battery pack composed of multiple batteries in series and parallel. When multiple batteries are used at the same time, there will be battery inhomogeneity, resulting in a single battery reaching the discharge cut-off voltage first during discharge, and a single battery reaching the charging cut-off voltage first during charging. At this time, the battery cannot continue to be charged and discharged, otherwise the battery pack will be damaged due to over-discharge or over-charge of some batteries. Therefore, the battery pack needs to be equipped with a balancing system. According to the circuit topology, equalization is divided into dissipative equalization and non-dissipative equalization. Dissipative equalization converts energy into dissipation. In order to avoid excessive heat in the equalization resistance, the equalization efficiency is generally small and the equalization time is long. The non-dissipative balance uses energy storage elements to achieve energy transfer. Although the structure is more complex, it can reuse energy and reduce resource waste.

SUMMARY OF THE INVENTION

In order to solve the deficiencies of the prior art, the present invention provides a low-temperature battery heating system and method coupled with a non-dissipative equalization system. By adding an auxiliary battery, it is specially used for heating the battery pack, and by selecting a battery with a wide temperature range A non-dissipative equalizing energy storage element for both equalization and auxiliary battery heating. At normal temperature, the system does not use auxiliary batteries, and the energy storage element is only used for energy transfer between batteries, that is, the battery with high capacity is discharged to the energy storage element, and the energy storage element will charge the obtained power to the battery with low power, while in the In a low temperature environment, the energy storage element uses the obtained power to heat the auxiliary battery. After the auxiliary battery is heated to a suitable temperature, it is discharged to heat the battery to solve the problem of low temperature charging and cold start of the battery.

In order to achieve the above object, technical scheme of the present invention is as follows:

A low-temperature battery heating system coupled with a non-dissipative equalization system, comprising an energy storage element, an auxiliary battery, an auxiliary battery heating device and a battery heating device; the energy storage element is connected with the battery and is used to transfer electricity from a high-charge battery Transfer to a low-charge battery until the battery is balanced, and the auxiliary battery heating device is connected to the energy storage element for receiving electricity from the energy storage element to heat the auxiliary battery, the battery heating device is connected to the auxiliary battery, and is used for heating. It is used to receive power from the auxiliary battery to heat the battery.

Further, the energy storage element and the positive and negative electrodes of the battery are respectively connected through a control switch K, and the control switch K is used to realize the transfer of energy from the battery to the energy storage element and the transfer from the energy storage element to the battery.

Further, the battery and the energy storage element are provided with a voltage monitoring device for monitoring the voltage state of the battery and the energy storage element when the battery is charging the energy storage element.

Further, the auxiliary battery heating device is connected to the energy storage element through a control switch M, and the control switch M is used to transfer energy from the energy storage element to the auxiliary battery heating device.

Further, temperature sensors are provided on the battery and the auxiliary battery.

Further, the battery heating device is connected to the auxiliary battery through a control switch N, and the control switch N is used to transfer energy from the auxiliary battery to the battery heating device.

Further, the energy storage element is an electronic element with a wide temperature range and can be charged and discharged with a large current, including but not limited to a super capacitor.

Further, the battery balancing reference includes but is not limited to the battery state of charge.

A working method of a battery low-temperature heating system based on the above-mentioned coupled non-dissipative equalization system, comprising: under normal temperature, the auxiliary battery does not work, the control switch M and the control switch N are disconnected, and the energy storage element is only used as a battery The inter-energy transfer, that is, the power is transferred from the high-charged battery to the low-charged battery, until the energy of each battery is balanced.

A working method of a battery low-temperature heating system based on the above-mentioned coupled non-dissipative equalization system, comprising: in a low-temperature environment, the control switch M is closed, and the energy storage element transfers the obtained electricity to an auxiliary battery heating device for heating the auxiliary battery. After heating to a suitable temperature, the control switch N is closed, the auxiliary battery is discharged to the battery heating device for battery heating, and the heating process stops until the battery temperature reaches the set temperature.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention provides an efficient non-dissipative battery balancing method. By using energy storage elements to transfer energy from a battery with a higher power to a battery with a lower power, the energy of the single cells of the battery pack can be quickly achieve uniformity.

(2) The present invention provides a system and method for coupling a non-dissipative balanced energy storage element with a low-temperature heating heat source of a battery, which improves the energy utilization rate of the non-dissipative balanced energy and solves the problem of low-temperature battery charging and electric vehicle charging. cold start problem.

(3) The supercapacitor is large in size and low in energy density. Directly using the supercapacitor to heat the entire battery pack will occupy a large volume and the cost will be high. Therefore, the present invention adds an auxiliary battery to the battery, which can be used in a low temperature environment. , The auxiliary battery is used to maintain the working temperature of the battery. Compared with the traditional balancing system and low-temperature battery heating system, the balancing is more efficient, the time is shorter, the energy utilization rate is higher, and the working environment of the battery is more suitable and stable.

Description of drawings

The accompanying drawings that form a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute improper limitations on the present application.

1 is a schematic diagram of a battery heating system coupled to a non-dissipative equalization system according to an embodiment of the present invention;

Fig. 2 is the connection schematic diagram of the voltage monitoring device of the battery and the energy storage element of the present invention;

Fig. 3 is the connection schematic diagram of the auxiliary battery of the present invention and the temperature sensor of the battery;

4 is a schematic diagram of a battery heating system coupled to a non-dissipative equalization system according to another embodiment of the present invention.

Among them: 1. Power battery, 2. Battery heating device, 3. Energy storage element, 4. Auxiliary battery, 5. Auxiliary battery heating device.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. The orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only a relational word determined for the convenience of describing the structural relationship of each component or element of the present invention, and does not specifically refer to any component or element in the present invention, and should not be construed as a reference to the present invention. Invention limitations.

In the present invention, terms such as "fixed connection", "connected", "connected", etc. should be understood in a broad sense, indicating that it can be a fixed connection, an integral connection or a detachable connection; it can be directly connected, or through the middle media are indirectly connected. For the relevant scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to the specific situation, and should not be construed as a limitation of the present invention.

As described in the background art, in the prior art, there is a dissipative equalization that converts energy into dissipation. In order to avoid the problems that the equalization resistance heat is too high, the equalization efficiency is small, and the equalization time is long, in order to solve the above technical problems, this The application provides a low-temperature battery heating system and method coupled with a non-dissipative equalization system, so as to solve the problems of low-temperature charging and cold-starting of the battery. Compared with the traditional equalization system and the battery low temperature heating system, the invention has more efficient equalization, shorter time, higher energy utilization rate, and more suitable and stable working environment of the battery.

As shown in FIG. 1, a low-temperature battery heating system coupled with a non-dissipative equalization system includes an energy storage element 3, an auxiliary battery 4, an auxiliary battery heating device 5 and a battery heating device 2; the energy storage element 3 and the battery 1 is connected to transfer the power from the high-charge battery to the low-charge battery until the battery charge is balanced, and the auxiliary battery heating device 5 is connected to the energy storage element 3 for receiving the power from the energy storage element 3. The auxiliary battery 4 is heated, and the battery heating device 5 is connected to the auxiliary battery 4 and used to receive the electric power from the auxiliary battery 4 to heat the battery 1 .

The energy storage element 3 is connected to the positive and negative electrodes of the battery 1 through a control switch K, which is used to transfer energy from the battery 1 to the energy storage element 3 and from the energy storage element 3 to the battery 1 .

The control switch K includes K1+, K1-, K2+, K2-... Kn+, Kn-.

As shown in FIG. 2 , the battery 1 and the energy storage element 3 are provided with a voltage monitoring device for monitoring the voltage state of the battery 1 and the energy storage element 3 when the battery 1 charges the energy storage element 3 .

The auxiliary battery heating device 5 is connected to the energy storage element 3 through a control switch M, and the control switch M is used to transfer energy from the energy storage element 3 to the auxiliary battery heating device 5 .

As shown in FIG. 3 , the battery 1 and the auxiliary battery 4 are provided with temperature sensors.

The temperature inside the battery is not uniform and there is a temperature difference. The arrangement positions of the temperature sensors are the highest temperature area and the lowest temperature area in the battery, that is, the temperature limit area of the battery. Simulation and testing are carried out according to the shape and structure of the battery to obtain the highest and lowest temperature regions. As shown in FIG. 3 , 31 , 32 , 33 , 34 , and 35 are temperature extreme regions in a certain structure battery, so the temperature sensors are arranged in corresponding positions.

The battery heating device 2 is connected to the auxiliary battery 4 through a control switch N, and the control switch N is used to transfer energy from the auxiliary battery 4 to the battery heating device 2 .

The energy storage element 3 is an electronic element with a wide temperature range and can be charged and discharged with a large current, including but not limited to a super capacitor.

The battery 1 balancing reference includes, but is not limited to, the battery state of charge.

A working method of a battery low-temperature heating system based on the above-mentioned coupled non-dissipative equalization system, comprising: under normal temperature, the auxiliary battery 4 does not work, the control switch M and the control switch N are disconnected, and the energy storage element 3 only uses It is used for energy transfer between batteries, that is, the power is transferred from a high-charge battery to a low-charge battery until the energy of each battery is balanced.

In a specific implementation, in order to fully discharge the battery as much as possible, the battery is balanced based on the SOC (State of Charge, battery state of charge) of the battery. When charging, the battery with high SOC is charged to the energy storage element. At the same time, as shown in Figure 2, the battery voltage and the voltage of the energy storage element are monitored. When the battery SOC reaches the set requirement or the energy storage element reaches the full condition, it is cut off. circuit. Turn on the energy storage element and the battery with low SOC, so that the energy storage element is charged to the battery, until the discharge of the energy storage element ends, and the circuit is cut off.

For example, suppose the i-th battery is the battery with the highest SOC, and the j-th battery is the battery with the lowest SOC. By turning on the control switches Ki+ and Ki-, the i-th battery is charged to the energy storage element 3, and the battery SOC and the energy storage element are monitored at the same time. When the i-th battery SOC reaches the set requirements, or the energy storage element 3 is fully charged condition, open switches Ki+ and Ki-. Then, the switches Kj+ and Kj- are turned on to make the energy storage element 3 charge the jth battery. When the SOC of the jth battery reaches the set requirement, or the energy storage element 3 reaches the discharge cut-off condition, Kj+ and Kj- are turned off.

Query the remaining batteries with the highest SOC, and charge the energy storage element. The energy storage element then charges the remaining batteries with the lowest SOC. This cycle is repeated until the SOC of the batteries in the battery pack is consistent.

When an energy storage element, such as a supercapacitor, charges the battery, the supercapacitor cannot be fully discharged according to the battery voltage and the discharge characteristics of the supercapacitor.

A working method of a battery low-temperature heating system based on the above-mentioned coupled non-dissipative equalization system, comprising: in a low-temperature environment, the control switch M is closed, and the energy storage element 3 transfers the obtained electricity to the auxiliary battery heating device 5 for auxiliary battery heating. The battery 4 is heated. After heating to a suitable temperature, the control switch N is closed, and the auxiliary battery 4 is discharged to the battery heating device 2 for heating the battery 1. When the temperature of the battery 1 reaches the set temperature, the heating process stops.

In a small and medium-sized battery system, the auxiliary battery can be omitted, and the battery is directly heated by the energy storage element, as shown in FIG. 4 .

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they do not limit the scope of protection of the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, those skilled in the art do not need to pay creative efforts. Various modifications or deformations that can be made are still within the protection scope of the present invention.

Claims (5)

1. A battery low-temperature heating system coupled to a non-dissipative balancing system, characterized in that: comprising an energy storage element, an auxiliary battery, an auxiliary battery heating device and a battery heating device; The power is transferred from the high-charge battery to the low-charge battery until the battery is balanced, and the auxiliary battery heating device is connected to the energy storage element for receiving the power from the energy storage element to heat the auxiliary battery, and the battery heating device Connected to the auxiliary battery, used to receive power from the auxiliary battery to heat the battery; The energy storage element is an electronic element with a wide temperature range and can be charged and discharged with a large current, including a super capacitor. When the battery is charged, the super capacitor is not fully discharged; The battery and the energy storage element are provided with a voltage monitoring device for monitoring the voltage state of the battery and the energy storage element when the battery charges the energy storage element; The auxiliary battery heating device is connected to the energy storage element through a control switch M, and the control switch M is used to transfer energy from the energy storage element to the auxiliary battery heating device; The battery heating device is connected to the auxiliary battery through a control switch N, and the control switch N is used to transfer energy from the auxiliary battery to the battery heating device. 2 . The battery low-temperature heating system coupled to a non-dissipative balancing system according to claim 1 , wherein the energy storage element is connected to the positive and negative electrodes of the battery through a control switch K, and the control switch K is 2 . It is used to realize the transfer of energy from the battery to the energy storage element and from the energy storage element to the battery. 3 . The battery low-temperature heating system coupled with a non-dissipative equalization system according to claim 1 , wherein a temperature sensor is provided on the battery and the auxiliary battery. 4 . 4. A working method of a battery low-temperature heating system based on the coupled non-dissipative equalization system according to any one of claims 1-3, characterized in that, under normal temperature, the auxiliary battery does not work, and the control switch M and the control switch N are disconnected, and the energy storage element is only used for energy transfer between batteries, that is, the power is transferred from the high-charge battery to the low-charge battery, until the energy of each battery is balanced. 5. A working method based on the battery low-temperature heating system of the coupled non-dissipative balancing system according to any one of claims 1-3, characterized in that, in a low-temperature environment, the control switch M is closed, and the energy storage element will The obtained power is transferred to the auxiliary battery heating device for heating the auxiliary battery. After heating to a suitable temperature, the control switch N is closed, and the auxiliary battery is discharged to the battery heating device for battery heating until the battery temperature reaches the set temperature. Process stops.

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