Method for controlling a charging or discharging process of batteries connected in electrical parallel

Abstract

This invention relates to a method, particularly computer-implemented, for controlling an in-vehicle network of a motor vehicle, for charging or discharging a first battery and a second battery, particularly a lithium-ion battery, wherein the charging or discharging of the first and second batteries can be interrupted or activated separately from the other battery. The method comprises the following steps: (i) determining a first state of charge of the first battery; (a-i) comparing the first state of charge with a first reference value during charging of the first and second batteries by an electrical energy source; (a-ii) when the comparison shows that the first state of charge is equal to the first reference value, interrupting the charging of the first battery and continuing the charging of the second battery; or (b-i) comparing the first state of charge with a second reference value during discharging of the first battery; (b-ii) when the comparison shows that the first state of charge is less than the second reference value, interrupting the discharging of the first battery and activating the discharging of the second battery.

Description

Technical Field

[0001] The present invention relates to a method for controlling the charging or discharging process of batteries connected in parallel, particularly a computer-implemented method, a battery device, and a motor vehicle. Background Technology

[0002] In the field of energy storage cells, especially battery cells, particularly lithium-ion battery cells, cylindrical, prismatic, and pouch-shaped battery cells are known. Battery cells for storing electrical energy play a crucial role not only in vehicles with pure electric drive systems but also in vehicles or motor vehicles with hybrid drive systems. However, battery cells are also used in vehicles with internal combustion engines, such as in 12V starter batteries.

[0003] For the vehicle's onboard network, or energy onboard network, which is critical to electrical loads, redundant energy sources are advantageous. For example, in addition to the 12V starter battery commonly found in vehicles, there are supplementary batteries. When multiple batteries, especially lithium-ion batteries, with flat voltage curves are connected in parallel, different loads may occur on each individual battery due to their varying states of charge, internal resistance, and onboard network impedance, potentially leading to uneven aging.

[0004] To counteract the effects of uneven loading on the individual batteries, a power converter is typically connected between them. The disadvantages of this converter include increased manufacturing costs, added vehicle weight, and heat generation in the structural space during converter operation. Summary of the Invention

[0005] The objective of this invention is to improve the charging and discharging of batteries connected in parallel.

[0006] The solution to the task is implemented according to the teachings of the independent claims. Different embodiments and extensions of the invention are the subject of the dependent claims.

[0007] A first aspect of the solution relates to a method, particularly a computer-implemented method, for controlling the charging or discharging process of a first battery and a second battery in an onboard network of a motor vehicle, particularly where the first battery is a lithium-ion battery and the second battery is electrically connected in parallel with the first battery and is also a lithium-ion battery, wherein the charging or discharging of the first and second batteries can be interrupted or activated separately from the other battery, the method comprising the steps of: (i) determining a first state of charge of the first battery; (ai) comparing the first state of charge with a first reference value during charging of the first and second batteries by an electrical energy source, particularly a generator; (a-ii) when the comparison shows that the first state of charge is equal to the first reference value, interrupting the charging of the first battery and continuing the charging of the second battery; or (bi) comparing the first state of charge with a second reference value during the discharging of the first battery; (b-ii) when the comparison shows that the first state of charge is less than the second reference value, interrupting the discharging of the first battery and activating the discharging of the second battery.

[0008] The terms “comprising,” “including,” “containing,” “having,” “having,” “with,” or any other form thereof may be used herein to cover non-exclusive inclusion relationships. Thus, a method or apparatus that includes or has a series of elements is not necessarily limited to those elements, but may contain other elements that are not explicitly stated or that are inherent to such a method or apparatus.

[0009] Furthermore, unless explicitly stated otherwise, "or" refers to an inclusive "or" rather than an exclusive "or". For example, condition A or B is satisfied by one of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); and not only A but also B is true (or exists).

[0010] The concept “one,” as it is used herein, is defined in the sense of “one or more.” The concepts “another” and “an other,” as well as any other forms thereof, can be understood in the sense of “at least one other.”

[0011] The concept of "multiple," as it is used here, can be understood in the sense of "two or more."

[0012] The concept of "configuration" or "setting" is used to satisfy a specific function (and its corresponding variations). As used herein, it can be understood as the corresponding device being in a configuration or adjustment in which the device can perform the function, or the device being at least adjusted, i.e., configured, so that the device can perform the function after the corresponding adjustment. The configuration can be achieved, for example, by corresponding adjustments to process parameters, or by corresponding adjustments to switches or the like for activating or deactivating functionality or adjustment values. In particular, the device can have multiple predetermined configurations or operating modes, such that configuration can be achieved by selecting one of these configurations or operating modes.

[0013] The concept of “substantially equal to” or “substantially the same size”, as used herein, can be understood in particular as two values, especially two batteries, whose states of charge differ from each other by no more than 10%, especially no more than 5%.

[0014] The concept of "battery," as used herein, can be understood, in particular, as a rechargeable battery, especially a rechargeable battery. Such a rechargeable battery can be used, in particular, as a primary battery for storing chemical energy and for releasing electrical energy. Such a battery can have an electrode stack with multiple plate-like elements, including at least two electrodes, namely an anode and a cathode, and a separator that at least partially receives the electrolyte. Preferably, at least one anode, a separator, and a cathode overlap or stack with each other, with the separator at least partially disposed between the anode and the cathode. This sequence of anode, separator, and cathode can be repeated at any frequency within the electrode stack.

[0015] Preferably, each of the plate-shaped elements can be wound into an electrode roll. Before releasing electrical energy, the stored chemical energy is converted into electrical energy. During charging, the electrical energy supplied to the electrode stack is converted into chemical energy and stored. Each electrode can have a current collector, particularly an aluminum current collector for the cathode and a copper current collector for the anode. Thin layers made of a mixture can be applied to both sides of the current collector, the mixture comprising active materials, binders (e.g., PVDF, PTFE, CMS, SBR, LiPAA, PAA, etc.), and conductive additives (carbon black, CNT, carbon fiber, etc.).

[0016] The concept of “charging,” especially “charging of a battery,” as used herein, can be understood in particular as supplying electrical energy to a rechargeable battery, which is converted into chemical energy and stored in the battery, and which can be provided as electrical energy for electrical loads.

[0017] The concept of “discharge,” especially “battery discharge,” as used herein, can be understood as the release or transfer of electrical energy from the battery to an electrical load.

[0018] The concept of "MOSFET" (or metal-oxide-semiconductor field-effect transistor), as used herein, can be understood in particular as a metal-oxide-semiconductor field-effect transistor.

[0019] This can be achieved by following the method of scheme (a) in the first aspect, whereby the charging of the first battery is interrupted when the detected first state of charge equals the first reference value. This is because, in cases where the first and second batteries do not have the same state of charge—for example, the first battery's state of charge may advance further than the second battery's, especially due to different voltage drops—the first battery will reach its maximum state of charge before the second battery. Since the parallel-connected batteries are still not fully charged overall in this situation, the charging process continues. By timely interrupting the charging process of the first battery, i.e., when the reference value for the state of charge is reached, damage to the first battery due to overcharging can be avoided.

[0020] According to the method of scheme (b) in the first aspect, when the state of charge of the first battery is lower than the second reference value, the discharge of the first battery is interrupted and the discharge of the second battery is activated. Therefore, it can be ensured that when the state of charge of the first battery drops below the reference value, the vehicle's on-board network supplied by the first battery should continue to be supplied with electrical energy.

[0021] Furthermore, the current method eliminates the need for a converter between batteries. This avoids the drawbacks associated with an additional converter, such as increased manufacturing costs, added vehicle weight, and heat generation in the structural space during operation.

[0022] The preferred embodiments of the method are described below. They can be combined with each other and with other aspects described herein, unless explicitly excluded or technically impossible.

[0023] In some implementations, according to scheme (a), when the second state of charge of the second battery is identified as a first reference value and it is determined through comparison that the first state of charge is greater than the second state of charge, the charging process of the first battery is interrupted. This allows the second state of charge to equalize with the first state of charge after the interruption.

[0024] In some implementations, according to scheme (a), the interruption of the charging process of the first battery is terminated when the first state of charge and the second state of charge are substantially the same size. This prevents the state of charge of the second battery from becoming greater than that of the first battery, which would again lead to uneven charging of the batteries.

[0025] In some embodiments, according to scheme (a), the first reference value is equal to the maximum state of charge of the first battery. Therefore, the first battery can be charged up to its maximum state of charge, which avoids overcharging of the first battery and thus prevents damage to the first battery.

[0026] In some implementations, according to scheme (b), the discharge of the first battery is interrupted when the detected voltage value of the first battery is less than a predetermined threshold. The voltage value can be easily determined, and the reliability of determining the necessity to interrupt the discharge of the first battery can be improved overall because of the possibility that charging will be interrupted due to an excessively low voltage value below the threshold.

[0027] The second aspect of the solution relates to a battery device configured to implement the method of the first aspect.

[0028] Preferred embodiments of the battery device are described below. These embodiments may be combined with each other and with other aspects described herein, unless explicitly excluded or technically impossible.

[0029] In some embodiments, the battery device includes: (i) a first battery, particularly a lithium-ion battery, the first battery including a first separation module configured to correspondingly interrupt and activate the charging and discharging of the first battery; (ii) a second battery, particularly a lithium-ion battery, the second battery including a second separation module configured to correspondingly interrupt and activate the charging and discharging of the second battery; (iii) the first battery and the second battery being connected in parallel with each other; (iv) a detection device configured to detect a first charging state of the first battery and a second charging state of the second battery; and (v) a control device configured to, (ai) in the first battery… During charging of the first and second batteries via an electrical energy source, particularly a generator, a comparison of a first charging state with a first reference value is performed, and (a-ii) when the comparison shows that the first charging state is equal to the first reference value, the charging of the first battery is interrupted when a first separation module is used, and the charging of the second battery is resumed when a second separation module is used; or (bi) during the discharging of the first battery, a comparison of a first charging state with a second reference value is performed, and (b-ii) when the comparison shows that the first charging state is less than the second reference value, the discharging of the first battery is interrupted when a first separation module is used, and the discharging of the second battery is resumed when a second separation module is used.

[0030] In some embodiments, the first separation module has a first charging separation element, particularly a first MOSFET, which is configured to interrupt and activate charging of the first battery. Additionally, the first separation module has a first discharging separation element, particularly a second MOSFET, which is configured to interrupt and activate discharging of the first battery. The first charging separation element and the first discharging separation element allow charging and discharging to be interrupted and activated separately from the second battery.

[0031] In some embodiments, the second separation module has a second charging separation element, particularly a third MOSFET, which is configured to interrupt and activate charging of the second battery. Additionally, the second separation module has a second discharging separation element, particularly a fourth MOSFET, which is configured to interrupt and activate discharging of the second battery. The second charging separation element and the second discharging separation element allow charging and discharging to be interrupted and activated separately from the first battery.

[0032] In some embodiments, the battery device has a first separation module and a second separation module. In these embodiments, optimization can be achieved in the separate charging and discharging of the respective batteries because charging and discharging can be interrupted and reactivated separately for each of the first and second batteries. This can be adapted according to the state of the corresponding other battery and / or also according to the needs of the vehicle network.

[0033] A third aspect of the solution relates to a motor vehicle that includes the battery device according to the second aspect. In particular, the motor vehicle may have an electric drive system, a hybrid drive system, or an internal combustion engine.

[0034] The features and advantages explained by referring to the first aspect of the solution also apply to the other aspects described accordingly.

[0035] Other advantages, features, and application possibilities will become apparent from the following description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0036] The attached image is as follows: Figure 1 A battery device in an in-vehicle network system is schematically shown according to one embodiment; and Figure 2 A flowchart illustrating one implementation of the method is shown schematically.

[0037] In the accompanying drawings, the same reference numerals are always used to denote the same or corresponding elements. Detailed Implementation

[0038] exist Figure 1 The image schematically shows a battery device 100 in an in-vehicle network system 105 according to one embodiment.

[0039] The vehicle network system 105 includes a first vehicle network 160, a second vehicle network 170, an electric power source 150, and a battery device 100. The power source can be a vehicle generator or a high-voltage converter.

[0040] The battery device 100 includes: a primary battery 110, which includes a first discrete module 115 having two MOSFETs 120 and 125; and a secondary battery 130, which includes a second discrete module 135 having two MOSFETs 140 and 145. The primary battery 110 and the secondary battery 130 can be charged by an electrical energy source 150, enabling them to provide electrical energy to loads connected to them, or to associated vehicle networks 160 and 170. Specifically, the primary battery 110 can supply electrical energy to the primary vehicle network 160, and the secondary battery 130 can supply electrical energy to the secondary vehicle network 170. Furthermore, the primary battery 110 and the secondary battery 130 are connected in parallel with each other.

[0041] In the vehicle network system 105, impedances are generated due to the arrangement of the structure and electrical wires, schematically described as Z1, Z3, and Z4. Impedance Z1 is between the electrical energy source 150 and the primary battery 110, impedance Z3 is between the electrical energy source 150 and the primary vehicle network 160, and impedance Z4 is between the electrical energy source 150 and the secondary vehicle network 170. Furthermore, a separation device Z2 is provided between the electrical energy source 150 and the secondary battery 130, thus ensuring the independence of the vehicle network in case of failure.

[0042] The MOSFETs 120 and 125 of the primary battery and the MOSFETs 140 and 145 of the secondary battery are used as disconnecting elements. Therefore, the current supply during the charging process or the current output from the corresponding batteries 110 and 130 to the load can be disconnected or interrupted to prevent damage to the corresponding batteries 110 and 130.

[0043] During the charging process of the primary and secondary batteries, the following situation may occur: the state of charge of the primary battery 110, which is also known as the "state of charge" (SOC), is greater than the state of charge of the secondary battery 130.

[0044] Because these MOSFETs 120, 125, 140, and 145 technically have internal diodes (body diodes), separate MOSFETs 120, 125, 140, and 145 are required to separate the charging and discharging directions. Therefore, both the primary battery 110 and the secondary battery 130 have two MOSFETs 120, 125, 140, and 145 respectively. Here, in the primary battery 110, MOSFET 120 relates to the charging direction, and MOSFET 125 relates to the discharging direction. In the secondary battery 130, MOSFET 140 relates to the charging direction, and MOSFET 145 relates to the discharging direction. Similarly, in each of the batteries 110 and 130, multiple MOSFETs can be connected in parallel to improve current carrying capacity.

[0045] In one operating strategy of the battery device 100, the charging direction of the secondary battery 130 remains separate. In this strategy, regardless of the vehicle network load and impedance of the primary vehicle network 160, the primary battery 110 can be charged to the required state of charge. The state of charge of the first battery 110 and the second battery 130 is detected by the detection device 180 and transmitted to the control device 190 of the battery device 100. At this time, measuring devices (not shown here) can be integrated into the first battery 110 and the second battery 130 respectively to measure or determine electrical characteristic parameters, such as current, voltage, and state of charge. These measured characteristic parameters can then be detected or read by the detection device.

[0046] Discharge is also achieved by the primary battery 110, which, as long as it is operational, can stably maintain the necessary on-board network voltage for the primary on-board network 160. In the event of insufficient on-board network voltage, for example due to increased on-board network load on the primary on-board network 160, or when the available power or energy of the primary battery 110 is too small for the primary on-board network 160, the forward voltage of the diode of the open MOSFET 140 of the secondary battery 130 is reached, and discharge current can flow from the secondary battery 130, thus uninterruptedly supporting the primary on-board network 160.

[0047] In the current embodiment, the primary battery 110 is preferably configured with cycle stability and sufficient capacity to supply the first vehicle network 160. The secondary battery 130 operates with an on-state charging disconnect element, i.e., a MOSFET 140, and thus remains in its current state of charge.

[0048] The on-board network voltage of the primary on-board network 160 is regulated by the control device 190 at this time, so that the primary battery 110 is charged by the electrical energy source 150 and maintained in this charging state, which is also known as a "balance maintenance strategy". In this state, the primary battery 110 can buffer energy (in the charging and discharging directions).

[0049] In the event of insufficient voltage in the primary vehicle network 160—that is, a voltage drop due to excessive load (load dynamics) and the primary battery 110 ultimately providing insufficient usable electrical power or energy for the primary vehicle network 160—current flows through the diode of the MOSFET 140 in the secondary battery 130. This current flow results in power loss at the charge-disconnect element, MOSFET 140, of the secondary battery 130. When this power loss exceeds a predetermined reference value, the charge-disconnect element, MOSFET 140, closes to minimize the power loss. When the discharge current of the secondary battery 130 has decreased, the charge-disconnect element, MOSFET 140, reopens.

[0050] To charge the secondary battery 130, and to ensure the correct state of charge for sufficient buffering capacity (in the discharge direction), two cases can be distinguished: In the first scenario, the secondary battery 130 has a lower state of charge than the primary battery 110. In this state, the charging disconnect element, MOSFET 120, of the primary battery 110 is turned on, and for a short time, e.g., 100 ms, the charging disconnect element, MOSFET 140, of the secondary battery 130 is turned off. With the control device 190 employed, the secondary battery 130 is charged to the target state of charge. Once the states of charge of the primary battery 110 and the secondary battery 130 are balanced, the charging disconnect element, MOSFET 120, of the primary battery 110 is turned off. A short balancing current may also flow between the primary battery 110 and the secondary battery 130. Subsequently, the primary battery 110 and the secondary battery 130 are charged in parallel or simultaneously. Once the secondary battery 130 reaches the target state of charge, the charging disconnect element, MOSFET 140, of the secondary battery is turned on, and the secondary battery 130 is then held in this state.

[0051] In the second scenario, the secondary battery 130 has a higher state of charge than the primary battery 110. In this scenario, the primary battery 110 is charged until the two states of charge are equalized. In this state, the charging disconnect element, MOSFET 140, of the secondary battery 130 is closed, and the secondary battery 130 is charged together until it reaches its rated state of charge. Subsequently, the charging disconnect element, MOSFET 140, is turned on again, and the secondary battery 130 remains in this state.

[0052] exist Figure 2 The flowchart 200 is shown schematically to describe an implementation of a method for controlling the charging or discharging process of a first battery 110 and a second battery 130 of a vehicle's onboard network. The first battery is, in particular, a lithium-ion battery, and the second battery is connected in parallel with the first battery and is also, in particular, a lithium-ion battery. The charging or discharging of the first battery 110 and the second battery 130 can be interrupted or activated separately from the other battery.

[0053] In the first step S210 of the method, the first state of charge of the first battery 110 is determined. To determine this state of charge, for example, the current can be measured across a reference resistor, which is also known as a "shunt," and the current measurement is integrated over time. This can be achieved using a charge counter. Additionally, for this purpose, the voltage of the first battery 110 is measured, and the current capacity is estimated. The determined state of charge can then be transmitted to the control device 190, particularly via the detection device 180, as for... Figure 1 Explanation.

[0054] According to the first scheme (a), in another step S220 of the method, the first charging state is compared with a first reference value during the charging of the first battery 110 and the second battery 130 by a generator, especially a generator of a vehicle or motor vehicle.

[0055] In a further step S230 of the method according to scheme (a), when it is determined by comparison that the first charging state is equal to the first reference value, the charging of the first battery 110 is interrupted and the charging of the second battery 130 continues.

[0056] According to the second scheme (b), in another step S240 of the method, the first state of charge is compared with a second reference value during the discharge of the first battery 110.

[0057] In another step S250 of the method according to scheme (b), if the comparison shows that the first state of charge is less than the second reference value, the discharge of the first battery 110 is interrupted and the discharge of the second battery 130 is activated.

[0058] For steps S220 to S250, control devices 190 may be employed, such as those for... Figure 1 As already explained.

[0059] While at least one exemplary embodiment has been described above, it should be noted that numerous variations thereof exist. It should also be noted that the exemplary embodiments described are merely non-limiting examples and are not intended, and therefore not to limit, the scope, applicability, or configuration of the apparatus and methods described herein. More precisely, the foregoing description is intended to provide guidance to those skilled in the art for implementing at least one exemplary embodiment; it is self-evident that different changes can be made to the operation and arrangement of the elements described in the exemplary embodiments without departing from the subject matter separately defined in the appended claims and its legal equivalents.

[0060] List of reference numerals

[0061] 100 battery device

[0062] 105 Vehicle Network System

[0063] 110 Primary battery

[0064] 115 First Separation Module

[0065] 120, 125 MOSFET

[0066] 130 Second Separation Module

[0067] 140, 145 MOSFET

[0068] 150 kWh energy source

[0069] 160 Basic In-Vehicle Network

[0070] 170 secondary vehicle network

[0071] 180 Detection Device

[0072] 190 Control device

[0073] Z1 - Z4 Zener diodes

[0074] 200 Flowchart

[0075] S210 Determines First Charging State

[0076] S220 compares the first charging state with the first reference value.

[0077] S230 interrupts charging of the first battery.

[0078] S240 compares the first charging state with the second reference value.

[0079] S250 interrupts charging of the second battery.

Claims

1. A method for controlling a charging or discharging process of a first battery (1 10) and a second battery (130) of an on-board network (160) of a motor vehicle, the second battery being electrically parallel to the first battery, wherein, The charging or discharging of the first battery (110) and the second battery (130) can be interrupted or activated separately from the other battery, and the method includes the following steps: Determine the first charging state of the first battery (110); (a) During the charging of the first battery (110) and the second battery (130) by the electrical energy source (150), the first state of charge is compared with a first reference value; when the comparison shows that the first state of charge is equal to the first reference value, the charging of the first battery (110) is interrupted and the charging of the second battery (130) continues; or (b) During the discharge of the first battery (110), the first state of charge is compared with a second reference value; when the comparison shows that the first state of charge is less than the second reference value, the discharge of the first battery (110) is interrupted and the discharge of the second battery (130) is activated.

2. The method according to claim 1, wherein, According to scheme (a), when the second charging state of the second battery (130) is identified as the first reference value and it is found that the first charging state is greater than the second charging state, the charging process of the first battery (110) is interrupted.

3. The method according to claim 1 or 2, wherein, According to scheme (a), the interruption of the charging process of the first battery (110) is terminated when the first charging state and the second charging state are substantially the same size.

4. The method according to any one of the preceding claims, wherein, According to scheme (a), the first reference value is equal to the maximum state of charge of the first battery (110).

5. The method according to any one of the preceding claims, wherein, According to scheme (b), when the detected voltage value of the first battery (110) is less than a predetermined threshold, the discharge of the first battery (110) is interrupted.

6. A battery device (110) configured to perform the method according to any one of the preceding claims.

7. The battery device (100) according to claim 6, wherein the battery device comprises: A first battery, the first battery including a first separation module (115), the first separation module being configured to interrupt and activate the charging and discharging of the first battery (110) accordingly; The second battery includes a second separation module (135), which is configured to interrupt and activate the charging and discharging of the second battery (130) accordingly. in, The first battery (110) and the second battery (130) are connected in parallel with each other; The detection device (180) is configured to detect the first charging state of the first battery (110) and the second charging state of the second battery (130); Control device (190), the control device is configured to, (a) During the charging of the first battery (110) and the second battery (130) by the electrical energy source (150), a comparison of a first charging state with a first reference value is performed; and when the comparison shows that the first charging state is equal to the first reference value, the charging of the first battery (110) is interrupted when the first separation module (115) is used, and the charging of the second battery (135) is resumed when the second separation module (135) is used. or (b) During the discharge of the first battery (110), a comparison is performed between a first state of charge and a second reference value; and when the comparison shows that the first state of charge is less than the second reference value, the discharge of the first battery (110) is interrupted when the first separation module is used, and the discharge of the second battery is caused when the second separation module is used.

8. The battery device (100) according to claim 7, wherein, The first separation module (115) has: a first charging separation element (120), which is configured to interrupt and activate the charging of the first battery (110); and a first discharging separation element (125), which is configured to interrupt and activate the discharging of the first battery (110).

9. The battery device (100) according to any one of claims 6 to 8, wherein, The second separation module (135) has: a second charging separation element (140), which is configured to interrupt and activate the charging of the second battery (130); and a second discharging separation element (145), which is configured to interrupt and activate the discharging of the second battery (130).

10. A motor vehicle comprising a battery device (100) according to any one of claims 6 to 9.

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