Method for operating a voltage equalising apparatus for a high-voltage energy store of an at least partially electrically operated motor vehicle, computer program product, and voltage equalising apparatus

Abstract

The invention relates to a method for operating a voltage equalising apparatus (20) for a high-voltage energy store (12) of an at least partially electrically operated motor vehicle (10), comprising the steps of: providing an electrical dividing apparatus (14) of the voltage equalising apparatus (20) for dividing the high-voltage energy store (12) into at least two sub-stores (16, 18); providing a first DC voltage converter (26) of the voltage equalising apparatus (20) for a first sub-store (16) of the high-voltage energy store (12); providing a second DC voltage converter (28) of the voltage equalising apparatus (20) for a second sub-store (18) of the high-voltage energy store (12); measuring a first sub-voltage of the first sub-store (16) by means of a first measuring device (22) of the voltage equalising apparatus (20); measuring a second sub-voltage of the second sub-store (18) by means of a second measuring device (24) of the voltage equalising apparatus (20); comparing the first sub-voltage with the second sub-voltage by means of an electronic computing device (30) of the voltage equalising apparatus (20); and operating the first DC voltage converter (26) and the second DC voltage converter (28) depending on the comparison by means of the electronic computing device (30). The invention also relates to a computer programme product and to a voltage equalising apparatus (20).

Description

[0001] Method for operating a voltage compensation device for a high-voltage energy storage device of an at least partially electrically operated motor vehicle, computer program product and voltage compensation device

[0002] The invention relates to a method for operating a voltage compensation device for a high-voltage energy storage device of an at least partially electrically operated motor vehicle according to the applicable patent claim 1. Furthermore, the invention relates to a computer program product with program code means and to a voltage compensation device.

[0003] Battery-electric vehicles, for example, can have a so-called 800-volt system. However, there are still a relatively large number of charging stations that can only provide a lower maximum charging voltage. These charging stations cannot then fully charge the corresponding vehicles. For this reason, it is already known from the prior art that, for example, a 400-volt backward-compatible charging function is provided in the vehicle. In this state, the high-voltage energy storage unit is divided into "two" storage halves, which can be charged "in series" at 800-volt charging stations. At charging stations with lower voltages, these are charged in parallel.

[0004] In the case of 400-volt backward-compatible charging, the two storage halves can be connected in parallel without damaging the hardware if the voltage difference between the storage halves is less than a hardware-dependent threshold. Otherwise, uncontrolled equalizing currents can occur between the two partial storage units, which can lead to hardware damage and, for example, the vehicle breaking down.

[0005] DE 102016213 070 B4 relates to a method and a vehicle electrical system comprising an inverter, an electrical energy storage device, an electrical machine, and an alternating current transmission connection, wherein the inverter has a first side and a second side and is configured to transmit power between these sides, wherein on the first side of the inverter, two output terminals of the inverter are connected or connectable to the energy storage device, wherein on the second side of the inverter, at least two phase current terminals of the inverter are connected or connectable to the electrical machine, wherein at least one of the charging inputs of the vehicle electrical system can be switched to an inner motor phase of the electrical machine by a switching device controlled by a controller, and wherein the vehicle electrical system is configured to initially charge the electrical energy storage device with a first voltage,and then charging the electrical energy storage device with a second voltage, wherein the second voltage is greater than the first voltage.

[0006] DE 102013225493 A1 describes an integrated converter and method that combine an on-board charger and a low-voltage DC-DC converter. The integrated converter improves the charging efficiency of a vehicle's battery and delivers high-density power to an electronic device load. The charging efficiency of the high-voltage battery and the power transfer efficiency to the low-voltage converter are improved using the integrated converter. Furthermore, the low-voltage converter receives high-density power because a significantly more stable voltage is input to the low-voltage converter from the integrated converter.

[0007] DE 102016207272 A1 describes a storage system for providing electrical power for driving a vehicle. The storage system comprises a first and a second storage module for storing electrical energy. Furthermore, the storage system comprises a switching unit configured to connect the first storage module and the second storage module in series for a charging process and to connect them in parallel for driving the vehicle. Furthermore, the storage system comprises a control unit configured to initiate one or more measures to reduce a difference between a state of charge of the first storage module and a state of charge of the second storage module in preparation for connecting the first storage module in parallel with the second storage module.

[0008] The object of the present invention is to provide a method, a computer program product and a voltage compensation device by means of which voltages within the high-voltage energy storage device can be reliably compensated.

[0009] This object is achieved by a method, a computer program product, and a voltage compensation device according to the independent patent claims. Advantageous embodiments are specified in the subclaims. One aspect of the invention relates to a method for operating a voltage compensation device for a high-voltage energy storage device of an at least partially electrically operated motor vehicle. An electrical separating device of the voltage compensation device is provided for separating the high-voltage energy storage device into at least two partial storage devices. A first DC-DC converter of the voltage compensation device is provided for a first partial storage device of the high-voltage energy storage device. A second DC-DC converter of the voltage compensation device is provided for the second partial storage device of the high-voltage energy storage device.A first partial voltage of the first partial storage is detected by a first detection device of the voltage compensation device, and a second partial voltage of the second partial storage is detected by a second detection device of the voltage compensation device. The first partial voltage is compared with the second partial voltage by an electronic computing device of the voltage compensation device, and the first DC-DC converter and the second DC-DC converter are operated in accordance with the comparison by the electronic computing device.

[0010] In particular, in order to equalize the voltage delta, or voltage difference, between the two partial storage units, appropriate operating strategies are required to ensure that excessive voltage differences between the two battery halves do not occur. This functionality can also be referred to as pack symmetrization.

[0011] In other words, depending on the voltages within the two storage units, a different operating strategy for the DC-DC converters is implemented. For example, one DC-DC converter may be subjected to a higher load than the other, resulting in greater power consumption by the storage unit assigned to the DC-DC converter. This additional load can then be maintained until the voltages are essentially balanced.

[0012] It goes without saying that, for other voltage levels, the energy storage unit can also be divided into three or four sub-storage units, for example. Each sub-storage unit is then assigned a respective DC-DC converter. Depending on how the individual sub-voltage units relate to one another, a respective operating strategy for the DC-DC converters can be set. According to an advantageous embodiment, electrical energy for a low-voltage vehicle electrical system is provided by the first DC-DC converter or the second DC-DC converter depending on the comparison. In other words, the first DC-DC converter and the second DC-DC converter can provide electrical energy in the high-voltage range, in particular for a low-voltage vehicle electrical system, for example, for a 12-volt vehicle electrical system.In this case, it can then be provided that, depending on the comparison, more electrical energy is provided by one of the two DC-DC converters than by the other of the two DC-DC converters. If, for example, the first partial voltage in the first partial storage device is higher than the second partial voltage in the second partial storage device, it can be provided that electrical energy for the low-voltage vehicle electrical system is provided by the first DC-DC converter. This results in a higher load on the first partial storage device, whereby an adjustment of the partial voltages can be achieved. This can ensure that both partial storage devices have a similar voltage value, in particular during a charging process, for example.

[0013] It is also advantageous if, depending on the comparison, electrical energy is provided by one of the two DC-DC converters to the other of the two DC-DC converters. For example, a corresponding coupling can be provided on the low-voltage side of the two DC-DC converters. If, for example, the first partial voltage is higher than the second partial voltage, electrical energy can be provided by the first DC-DC converter to the second DC-DC converter, so that essentially the second partial storage device can be charged via the first DC-DC converter and thus via the first partial storage device. In particular, charge equalization and voltage equalization can thus be realized. This can also be referred to as a so-called boost function.

[0014] A further advantageous embodiment provides that below a predetermined threshold for a difference between the partial voltages, no differential operation of the two DC-DC converters is performed. In particular, the method can thus only be applied above a predetermined threshold for the difference between the two partial voltages. This prevents excessive loads or cycles, thereby increasing the service life of the high-voltage energy storage device. It is also advantageous if the high-voltage energy storage device is provided with a voltage of substantially 800 volts and / or the first partial voltage and / or the second partial voltage are provided with substantially 400 volts.In other words, the high-voltage energy storage system is designed to operate at 800 volts, and the separation is implemented in such a way that the first storage unit operates at 400 volts, while the second storage unit operates at 400 volts. This makes it possible, for example, to charge at 400-volt charging stations.

[0015] A further advantageous embodiment provides that the method is carried out during a discharging process and / or during a charging process of the high-voltage energy storage device. For example, the method can be carried out as a discharging process, so that the voltage level of the two partial storage devices remains essentially at the same level permanently. Furthermore, the voltage level can also be adjusted during the charging process. For example, each partial storage device can be charged with 400 volts, and then, should corresponding partial voltage differences arise, one partial storage device with a higher voltage can additionally charge the other partial storage device with a lower energy voltage. Thus, voltage equalization can also be carried out during the charging process.

[0016] Furthermore, it has proven advantageous how the respective partial voltages of the partial storage units are substantially equalized using the method. In particular, they are at least equalized or balanced such that the voltage difference is below a predetermined threshold. This prevents unwanted equalizing currents between the two partial storage units or the battery cells of the partial storage units.

[0017] The presented method is, in particular, a computer-implemented method. Therefore, a further aspect of the invention relates to a computer program product with program code means that cause an electronic computing device, when the program code means are processed by the electronic computing device, to perform a method according to the preceding aspect.

[0018] A further aspect of the invention therefore also relates to a computer-readable storage medium comprising the computer program product according to the preceding aspect. The invention also relates to a voltage compensation device for a high-voltage energy storage device of an at least partially electrically operated motor vehicle, comprising at least one electrical isolating device, a first detection device, a second detection device, a first DC-DC converter, a second DC-DC converter, and an electronic computing device, wherein the voltage compensation device is designed to carry out a method according to the preceding aspect. In particular, the method is carried out by means of the voltage compensation device.

[0019] Furthermore, the invention also relates to a high-voltage energy storage device with a voltage compensation device according to the preceding aspect. The high-voltage energy storage device is provided in particular with, for example, 800 volts.

[0020] Furthermore, the invention also relates to an at least partially electrically powered motor vehicle with a high-voltage energy storage device according to the preceding aspect. The motor vehicle can also be fully electric.

[0021] Advantageous embodiments of the method are to be regarded as advantageous embodiments of the voltage balancing device, the high-voltage energy storage device, and the at least partially electrically powered motor vehicle. The voltage balancing device, the high-voltage energy storage device, and the at least partially electrically powered motor vehicle have specific features for this purpose in order to be able to carry out corresponding method steps.

[0022] A computing unit / electronic computing device can be understood, in particular, as a data processing device that contains a processing circuit. The computing unit can therefore, in particular, process data to perform computing operations. This may also include operations for performing indexed access to a data structure, for example, a look-up table (LUT).

[0023] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more single-chip systems (SoCs). The computing unit may also contain one or more processors, for example one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual network of computers or other of the aforementioned units.

[0024] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0025] A memory unit can be a volatile data memory, for example a dynamic random access memory (DRAM) or a static random access memory (SRAM), or a non-volatile data memory, for example a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory or flash EEPROM, a ferroelectric random access memory (FRAM), a magnetoresistive random access memory,MRAM (magnetoresistive random access memory) or phase-change random access memory (PCRAM).

[0026] A battery according to the invention comprises at least one and in particular a plurality of electrically conductively interconnected battery cells, wherein such a battery cell preferably provides a voltage in the range of 3.5 to 4.0 volts. Such a battery cell can be designed, for example, as a prismatic cell, a pouch cell, or a round cell. The battery is preferably configured as a so-called high-voltage battery, which is designed to provide an electrical voltage in the range of more than 60 volts, in particular in the range of several hundred volts. Such a high-voltage battery can be arranged in a motor vehicle, where it can supply an electrical consumer, in particular a drive motor, with electrical energy.

[0027] Further features of the invention emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0028] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawings. They show:

[0029] Fig. 1 is a schematic side view of an embodiment of a

[0030] Motor vehicle with an embodiment of a high-voltage energy storage device with an embodiment of a voltage compensation device;

[0031] Fig. 2 is a schematic block diagram according to an embodiment of the

[0032] procedure; and

[0033] Fig. 3 shows a further schematic block diagram according to a

[0034] Embodiment of the method.

[0035] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0036] Fig. 1 shows a schematic side view of an embodiment of a motor vehicle 10. The motor vehicle 10 is, in particular, at least partially electrically operated or fully electrically operated. For this purpose, the motor vehicle 10 has a high-voltage energy storage device 12. The high-voltage energy storage device 12 can, for example, be operated at 800 volts. In order to be able to realize backward compatibility of the high-voltage energy storage device 12 for charging with a voltage of 400 volts, for example, the high-voltage storage device 12 is provided with a separating device 14, which is, in particular, essentially a switching device that electrically separates a first partial storage device 16 from a second partial storage device 18. In particular, corresponding switching elements can be provided for this purpose, which can essentially connect the first partial storage device 16 and the second partial storage device 18 in parallel or in series, depending on the set circuit.In a series circuit, in particular, 800 volts can be provided, while in a parallel circuit, 400 volts can be provided each.

[0037] To prevent any impairment of the hardware used when partial storage units 16, 18 are connected in parallel, it is necessary to keep voltage differences within the two partial storage units 16, 18 low. In particular, this prevents uncontrolled equalizing currents between the two partial storage units 16, 18.

[0038] In order to keep the corresponding voltage delta small, appropriate operating strategies are necessary to ensure that there are no excessive voltage differences between the two partial storage units 16, 18.

[0039] For this purpose, a voltage compensation device 20 is provided. The voltage compensation device 20 comprises, in particular, at least the electrical isolating device 14, a first detection device 22, a second detection device 24, a first DC-DC converter 26, a second DC-DC converter 28, and an electronic computing device 30.

[0040] The first detection device 22 and the second detection device 24 are designed in particular to detect the respective partial voltages.

[0041] Fig. 1 further shows that, for example, the high-voltage energy storage device 12 can provide electrical energy for an electric drive device 32. Furthermore, the motor vehicle 10 can have a low-voltage electrical system 34.

[0042] In particular, it is thus provided that a first partial voltage of the first partial storage 16 is detected by the first detection device 22 and a second partial voltage of the second partial storage 18 is detected by the second detection device 24. The first partial voltage is compared with the second partial voltage by the electronic computing device 30. Depending on the comparison, the first DC-DC converter 26 and the second DC-DC converter 28 are operated by the electronic computing device 30.

[0043] In particular, the electronic computing device 30 can, for example, transmit corresponding control signals to the first DC-DC converter 26 and the second DC-DC converter 28.

[0044] Fig. 2 shows a schematic block diagram according to an embodiment of the voltage compensation device 20. Fig. 2 shows in particular that electrical energy 36 for the low-voltage network 34 is provided depending on the comparison from the first DC-DC converter 26 or the second DC-DC converter 28. In particular, Fig. 2 shows in the present case that, depending on the comparison, more electrical energy 36 is provided by one of the two DC-DC converters 26, 28 than by the other of the two DC-DC converters 26, 28. Fig. 2 shows in particular that, for example, in the present exemplary embodiment, more electrical energy 36 is provided by the first DC-DC converter 26 than by the second DC-DC converter 28. This is represented in particular in the present case by the size of the corresponding arrows.In other words, the larger arrow represents a higher value of electrical energy 36 than the smaller arrow.

[0045] Fig. 3 shows a further schematic embodiment of the voltage compensation device 20. In the following exemplary embodiment, it is shown in particular that, depending on the comparison, electrical energy 36 is provided from one of the two DC-DC converters 26, 28 for the other of the two DC-DC converters 26, 28. It is shown in particular that the partial voltage in the first partial storage device 16 is greater than in the second partial storage device 18. Electrical energy 36 is therefore provided by the first DC-DC converter 26 both for the low-voltage on-board network 34 and a corresponding electrical energy 36 for the second DC-DC converter 28. The second DC-DC converter 28 can in turn use the provided electrical energy 36, for example, to charge the second partial storage device 18 accordingly, until in particular a predetermined compensation voltage value of the two partial storage devices is reached.In particular, it is provided that the respective partial voltages of the partial storage devices 16, 18 are substantially equalized by means of the method.

[0046] In particular, it is thus provided that the voltage difference between the corresponding partial storage units 16, 18 is kept correspondingly low. For this purpose, it is possible, for example, for the power consumption in one of the two DC-DC converters 26, 28 to be higher than in the other of the two DC-DC converters 26, 28. Furthermore, as shown in Fig. 3, electrical energy 36 can be integrated, for example, via the 12-volt side from the first DC-DC converter 26 to the second DC-DC converter 28.

[0047] Of course, it is also possible, for example if the second partial voltage of the second partial storage 18 is higher than that in the first partial storage 16, that the method is carried out in reverse, as shown in the figures.

[0048] List of reference symbols

[0049] motor vehicle

[0050] High-voltage energy storage separating device first partial storage second partial storage

[0051] Voltage compensation device first detection device second detection device first DC-DC converter second DC-DC converter electronic computing device drive device low-voltage vehicle electrical system electrical energy

Claims

Patent claims 1. A method for operating a voltage compensation device (20) for a high-voltage energy storage device (12) of an at least partially electrically operated motor vehicle (10), comprising the steps: Providing an electrical separating device (14) of the voltage equalization device (20) for separating the high-voltage energy storage device (12) into at least two partial storage devices (16, 18); Providing a first DC-DC converter (26) of the voltage equalization device (20) for a first partial storage device (16) of the high-voltage energy storage device (12); Providing a second DC-DC converter (28) of the voltage compensation device (20) for a second partial storage device (18) of the high-voltage energy storage device (12); Detecting a first partial voltage of the first partial storage (16) by means of a first detection device (22) of the voltage compensation device (20); Detecting a second partial voltage of the second partial storage (18) by means of a second detection device (24) of the voltage compensation device (20); Comparing the first partial voltage with the second partial voltage by means of an electronic computing device (30) of the voltage compensation device (20); and Operating the first DC-DC converter (26) and the second DC-DC converter (28) in dependence on the comparison by means of the electronic computing device (30).

2. Method according to claim 1, characterized in that electrical energy (36) for a low-voltage electrical system (34) of the motor vehicle (10) is provided by the first DC-DC converter (26) or the second DC-DC converter (28) as a function of the comparison.

3. Method according to claim 1 or 2, characterized in that, depending on the comparison, more electrical energy (36) is provided by one of the two DC-DC converters (26, 28) than by the other of the two DC-DC converters (26, 28).

4. Method according to one of the preceding claims, characterized in that, depending on the comparison, electrical energy (36) is provided from one of the two DC-DC converters (26, 28) for the other of the two DC-DC converters (26, 28).

5. Method according to one of claims 2 to 4, characterized in that below a predetermined threshold value for a difference for the partial voltages, no different operation of the two DC-DC converters (26, 28) is carried out.

6. Method according to one of the preceding claims, characterized in that the high-voltage energy storage device (12) is provided with a voltage of substantially 800V and / or the first partial voltage and / or the second partial voltage is provided with substantially 400V.

7. Method according to one of the preceding claims, characterized in that the method is carried out during a discharging process and / or during a charging process of the high-voltage storage device (12).

8. Method according to one of the preceding claims, characterized in that respective partial voltages of the partial storage devices (16, 18) are substantially equalized by means of the method.

9. Computer program product with program code means which cause an electronic computing device (30) to carry out a method according to one of claims 1 to 8 when the program code means are processed by the electronic computing device (30).

10. Voltage compensation device (20) for a high-voltage energy storage device (12) of an at least partially electrically operated motor vehicle (10), with at least one electrical isolating device (14), a first detection device (22), a second detection device (24), a first DC-DC converter (26), a second DC-DC converter (28) and an electronic computing device (30), wherein the voltage compensation device (20) is designed to carry out a method according to one of claims 1 to 8.

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