Apparatus and method for multi-stage discharging of rechargeable battery system

Abstract

Device (100) for multi-stage discharging of a rechargeable battery system (101) with battery cells (102), semiconductor switches (103), wherein each battery cell (102) has a semiconductor switch (103), a battery management system (104) and a detection means for detecting a damage signal, the battery cell (102) is in electrically conductive connection with the battery management system (104), the detection means is in electrically conductive connection with the battery management system (104), characterized in that the battery management system (104) after detection of a damage signal, operates all semiconductor switches (103) to set the battery cells (102) into a certain state, determines the damaged battery cell, in particular by evaluating the voltage values of the battery cells (102) and the voltage gradient of the battery cells (102), and operates the semiconductor switch (103) of the damaged battery cell to completely discharge the damaged battery cell, wherein the internal current is limited.

Description

Technical Field

[0001] This invention relates to an apparatus and a method for multi-stage discharge of a rechargeable battery system. Background Technology

[0002] In the field of driving electrification, batteries with high voltage levels of several hundred volts (e.g., 400V or 800V) are used. A battery consists of multiple battery cells connected in series and / or parallel. Lithium-based batteries are very common here.

[0003] The downside here is that aging effects or external damage (such as increased pressure or perforation) can cause internal short circuits in the battery. This can lead to a sudden increase in temperature of a single battery cell—a condition known as thermal runaway—which may release harmful gases or create a risk of fire and explosion.

[0004] Thermal runaway is largely determined by the battery's state of charge. Typically, without intervention, the reaction time between a battery short circuit and thermal runaway due to mechanical damage is less than one second.

[0005] To prevent thermal runaway, fast discharge devices, also known as fast discharge devices, are used, in which a switch discharges the battery cells at the highest current. Furthermore, the battery's state of charge can be set to a value below 100%. The installation of a shutdown separator is also known.

[0006] The downside here is that the battery becomes unusable, or for some battery types, the measures taken cannot be implemented quickly enough to prevent thermal runaway. Summary of the Invention

[0007] The purpose of this invention is to overcome these drawbacks.

[0008] An apparatus for multi-stage discharge of a rechargeable battery system includes battery cells, semiconductor switches, a battery management system, and a detection device for detecting damage signals. Each battery cell has a semiconductor switch. The battery cells and the detection device are electrically connected to the battery management system. According to the invention, upon detecting a damage signal, the battery management system manipulates all semiconductor switches to set the battery cell to a specific state. The battery management system identifies the damaged battery cell, in particular, by evaluating the voltage value and voltage gradient of the battery cell. Furthermore, the battery management system manipulates the semiconductor switch of the damaged battery cell to fully discharge the damaged battery cell, wherein internal current is limited.

[0009] The advantage here is that damage signals can be quickly identified and processed without rendering the battery unusable.

[0010] In one configuration, the semiconductor switch is connected or arranged in parallel with the battery cell.

[0011] The advantage here is that damaged battery cells can be discharged quickly.

[0012] In one configuration, the detection device is an inertial navigation system.

[0013] The advantage here is that it can detect impacts to the battery casing or the vehicle.

[0014] In one configuration, the detection device is a pressure sensor, radar sensor, ultrasonic sensor, or infrared sensor.

[0015] The advantage here is that cost-effective sensors can be used.

[0016] In one extended embodiment, the detection device includes a shroud surrounding the housing, within which a rechargeable battery system is disposed, and the shroud is inductively, capacitively, or resistively connected to the battery management system.

[0017] The advantage here is that it can identify damage caused by perforation or deformation of the covering.

[0018] In one configuration, the covering has a stacked layer consisting of a first conductive layer, an insulating layer, and a second conductive layer.

[0019] Advantageous in this regard is the ability to detect damage to the covering material via electrical grounding.

[0020] In one extended scheme, the covering is the vehicle body.

[0021] The advantage here is that, in the event of damage caused by an accident, the increased warning time can be effectively used to regulate the battery.

[0022] In one extended embodiment, the semiconductor switch comprises a thin-film transistor having amorphous silicon or polycrystalline silicon in the channel region.

[0023] Advantageously, semiconductor switches are optimal for these low-voltage applications, offering the highest current density, lowest cost, and highest switching speed.

[0024] In one extended version, the battery cell contains lithium.

[0025] The advantage here is that it allows for the achievement of high battery cell voltage.

[0026] According to the present invention, a method for multi-stage discharge of a rechargeable battery system includes battery cells and semiconductor switches, wherein each battery cell has a semiconductor switch, a battery management system, and a detection device for detecting damage signals. The method includes detecting damage signals using the detection device and controlling all semiconductor switches using the battery management system to set the battery cell to a specific state. Furthermore, the method includes determining damaged battery cells of the rechargeable battery system by evaluating the voltage values ​​and voltage gradients of the battery cells using the battery management system, and controlling the damaged battery cells to fully discharge them, wherein internal current is limited. In other words, in a first step, all battery cells of the battery system are rapidly transferred to a safe state, particularly a charging state, without damaging or destroying the battery cells, and in a second step, only the damaged battery cells are fully discharged.

[0027] Further advantages are derived from the following description of exemplary embodiments or preferred implementations. Attached Figure Description

[0028] The present invention will now be described with reference to preferred embodiments and accompanying drawings. The drawings show:

[0029] Figure 1 An apparatus for multi-stage discharge of a rechargeable battery system is shown.

[0030] Figure 2 A method for multi-stage discharge of a rechargeable battery system is shown. Detailed Implementation

[0031] Figure 1 A device 100 is shown for multi-stage discharge or regulation of a rechargeable battery system 101 having multiple battery cells 102 and a semiconductor switch 103. The term "battery" includes an electrochemical energy storage device. The device 100 includes a detection device for detecting damage signals, the battery cells 102 and the detection device being electrically connected to the battery management system. The rechargeable battery system 101 is arranged within a housing 107. The battery cells 102 preferably comprise lithium. The semiconductor switch 103 is configured as a thin-film transistor having amorphous or polycrystalline silicon in the channel region. For example, the detection device is configured as an inertial navigation system 105. Alternatively, the detection device has a pressure sensor, radar sensor, ultrasonic sensor, infrared sensor, or a combination of these sensors. Alternatively or additionally, the detection device includes a covering 106 surrounding the housing 107. The covering 106 is connected to the battery management system 104 inductively, capacitively, or resistively. Damage signals indicate, for example, foreign objects. The battery cell 102 is penetrated, the temperature in the battery cell suddenly rises, or the casing 107 is damaged due to impact or force, or the covering is partially or completely damaged.

[0032] In the first embodiment, each battery cell 102 has a semiconductor switch 103. Here, the semiconductor switch 103 is arranged in parallel with the battery cell 102.

[0033] In the second embodiment, the plurality of battery cells 102 connected in parallel have a semiconductor switch 103. Here, the semiconductor switch 103 is connected in parallel with the plurality of battery cells 102. Alternatively, the semiconductor switch 103 may be arranged in parallel with the plurality of battery cells 102 connected in series.

[0034] In the third embodiment, each battery cell 102 has a semiconductor switch 103. Additionally, another semiconductor switch is arranged in series with the battery cell 102, wherein the semiconductor switch 103 is arranged in parallel with the battery cell 102 and the other semiconductor switch. Advantageously, each battery cell 102 can be safely removed by the battery management system 104.

[0035] The device 100 for multi-stage discharge of a rechargeable battery system 104 is used, for example, in electrical equipment (e.g., tools) powered by battery cells connected in series, or in electrically driven vehicles.

[0036] Figure 2 A method 200 for multi-stage discharge or regulation of a rechargeable battery system is shown, wherein the battery system has battery cells and semiconductor switches, wherein each battery cell has a semiconductor switch, a battery management system, and a detection device for detecting damage signals. Method 200 begins in step 210, in which a damage signal is detected by means of the detection device. In the following step 220, all semiconductor switches are manipulated by means of the battery management system, thereby setting the battery cell to a specific state. In other words, the battery cell is rapidly and effectively pre-regulated without seriously damaging it. The specific state is, for example, a reduced state of charge or state of charge reaching an interface state within the battery cell. This interface state can be set according to the maximum permissible overload current of the battery cell and the decrease in the state of charge of the battery cell, effectively limiting the short-circuit current and thus limiting self-heating. Here, the permissible overload current is several times the rated current, specifically three times the rated current. Alternatively, a specific state is the safe state of charge for all battery cells, such as 80% of the state of charge. This state of charge is higher than the generally safe state of charge, such as 30%, below which thermal runaway of the battery cell will not occur in the event of mechanical damage. In the next step 230, the damaged battery cell of the battery system is identified by means of the battery management system. This is done, for example, by evaluating the voltage value, such as in the case of an embolization below the minimum permissible battery voltage and voltage gradient of the battery cell, for example, if a larger slope of the voltage curve over time can be achieved compared with the voltage curve in the power grid of the connected appliance. In the next step 240, the semiconductor switch of the damaged battery cell is operated to fully discharge the damaged battery cell, wherein the internal current is limited. The internal current is limited by a threshold value representing the short-term permissible extreme current overload that will not trigger thermal runaway or overload the cell's structure and connection technology. The current must be optimally matched to the cell's chemistry and assembly and connection techniques. Damaged cells are further damaged and transitioned to a safe state through this step.

[0037] In other words, the detection device is used to identify battery damage early, allowing the battery management system to take immediate action without damaging other battery cells. Next, voltage assessment or voltage gradients using sensors within individual or other battery cells can be used to selectively shut down the damaged battery cell via the battery management system.

Claims

1. A device (100) for multi-stage discharge of a rechargeable battery system (101), wherein, The device has • Battery cell (102); • Semiconductor switch (103), wherein each battery cell (102) has a semiconductor switch (103). • Battery management system (104), wherein the battery cell (102) is electrically connected to the battery management system (104); and • Detection device, which is used to detect damage signals, wherein the detection device is electrically connected to the battery management system (104); The battery management system (104) is characterized in that... • Upon detecting the damage signal, all semiconductor switches (103) are manipulated to set the battery cell (102) to a specific state, which is the safe state of all battery cells (102) of the battery system (101); • Damaged battery cells are identified by evaluating the voltage value and voltage gradient of the battery cell (102); and • The semiconductor switch (103) of the damaged battery cell is operated to fully discharge the damaged battery cell, wherein the internal current is limited.

2. The device according to claim 1, characterized in that, The semiconductor switch (103) is connected in parallel with the battery cell (102).

3. The device (100) according to any one of claims 1 or 2, characterized in that, The detection device is an inertial navigation system (105).

4. The device (100) according to any one of claims 1 or 2, characterized in that, The detection device is a pressure sensor, radar sensor, ultrasonic sensor, or infrared sensor.

5. The device (100) according to any one of claims 1 or 2, characterized in that, The detection device includes a cover (106) that surrounds a housing (107), wherein the rechargeable battery system (101) is disposed within the housing (107), and the cover (106) is inductively, capacitively, or resistively connected to the battery management system (104).

6. The device (100) according to claim 5, characterized in that, The covering (106) comprises a stacked layer consisting of a first conductive layer, an insulating layer, and a second conductive layer.

7. The device (100) according to claim 5, characterized in that, The covering (106) includes the vehicle body.

8. The device (100) according to any one of claims 1 or 2, characterized in that, The semiconductor switch (103) includes a thin-film transistor having amorphous silicon or polycrystalline silicon in the channel region.

9. The device (100) according to any one of claims 1 or 2, characterized in that, The battery cell (102) contains lithium.

10. A method (200) for multi-stage discharge of a rechargeable battery system, said battery system having battery cells and semiconductor switches, a battery management system and a detection device for detecting damage signals, wherein, Each battery cell has a semiconductor switch, and the method includes the following steps: • The damage signal is detected by means of the detection device (210); • Upon detecting the damage signal, the battery management system controls (220) all semiconductor switches to set the battery cell to a specific state, which is the safe state of all battery cells (102) of the battery system (101). • Using the battery management system, the damaged battery cells of the rechargeable battery system are determined (230) by evaluating the voltage value or voltage gradient of the battery cells; and • Manipulate (240) the semiconductor switch of the damaged battery cell to fully discharge the damaged battery cell, wherein the internal current is limited.

Images