Device and method for determining a coolant temperature of a cooling circuit

Abstract

Device (100) for determining a coolant temperature of a cooling circuit (300), wherein the cooling circuit (300) is designed for sequential cooling of the power electronics of at least a first and a second electrical power component (510, 520). The device (100) is configured to receive and evaluate a signal that characterises the temperature of the power electronics of the switched-off second component (520) during operation of the first component (510), in order to determine the coolant temperature of the cooling circuit (300), and to receive and evaluate a signal that characterises the temperature of the power electronics of the switched-off first component (510) during operation of the second component (520), in order to determine the coolant temperature of the cooling circuit (300).

Description

[0001] Description

[0002] title

[0003] Device and method for determining a coolant temperature of a cooling circuit

[0004] The invention relates to a device and a method for determining a coolant temperature of a cooling circuit. Furthermore, the invention relates to an electrical system, a drive train with a device, a vehicle with a drive train, a computer program, and a machine-readable storage medium.

[0005] State of the art

[0006] Power electronic devices, preferably in vehicles, such as chargers, DC-DC converters, inverters and / or electrical machines, generate waste heat during operation, which is dissipated from the heat source by means of a coolant in a cooling circuit. The heat sources are preferably power electronic components, preferably power switches. A corresponding implementation is known from the document WO 2017 / 182226 A1. For safe operation of such power electronic devices at their performance limits, the temperature of the coolant must be known. If the coolant temperature exceeds a predeterminable threshold value, sufficient waste heat can no longer be dissipated by the heated coolant. Therefore, the device is switched off or its currently converted power is reduced to such an extent that the coolant temperature drops again and cooling of the power electronic components is again possible.To determine the coolant temperature, temperature sensors are arranged on the cooling circuit or in the coolant. To reduce the installation space required for the temperature sensors, there is a need for solutions for determining the coolant temperature that allow the coolant temperature to be determined without the need for correspondingly arranged temperature sensors in the cooling circuit. Disclosure of the invention.

[0007] A device for determining a coolant temperature of a cooling circuit is provided. The cooling circuit is designed for sequentially cooling the power electronics of at least a first and a second power electronic component. The first component comprises a first sensor device for determining the temperature of the power electronics of the first component. The second component comprises a second sensor device for determining the temperature of the power electronics of the second component. The first component is at least temporarily switched on, and its power electronics generates waste heat. At the same time, the second component is switched off.The device is configured to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched off second component during operation of the first component in order to determine the coolant temperature of the cooling circuit, and to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched off first component during operation of the second component in order to determine the coolant temperature of the cooling circuit.

[0008] The coolant temperature is preferably the temperature of the coolant in the cooling circuit, preferably the average temperature of the coolant in the cooling circuit. The cooling circuit preferably comprises a closed line system through which a cooling medium, cooling fluid or coolant flows, wherein the coolant flows through a heat exchanger and is cooled therein. The coolant then flows past heat sources one after the other, heating up again in the process and being cooled again via the heat exchanger. The heat sources or power-electrical components are preferably individual line-electronic assemblies or devices which, when switched on, preferably during operation, generate waste heat which is dissipated by means of the coolant flowing past. When the power-electrical components are switched off, preferably not in operation, they do not generate any waste heat.The first and second power electronic components can each be arranged in their own housing, or preferably in a common housing, preferably spatially spaced on a common or multiple printed circuit boards. Corresponding power electronic components comprise, for their control, sensor devices for determining the temperature of their power electronic components, preferably power switches, capacitors, chokes, or windings of an electrical machine. Preferably, the sensor devices for determining the temperature of the power electronics of the components are arranged in the immediate vicinity of their power electronics and enable precise determination of the temperature of the power electronics of the component. Preferably, the power electronics are connected to the cooling circuit with excellent thermal conductivity.Consequently, the power electronics quickly assumes the temperature of the coolant when it is not in operation or, preferably, is switched off permanently. To determine the coolant temperature, a signal characterizing the temperature of the switched off power electrical component is received and evaluated by the device or a control device within the device. The signal is preferably received and evaluated by the switched off component or by the sensor device of the switched off component. The greater the distance between the sensor device used to determine the coolant temperature and the actual heat source, the more accurately the actual coolant temperature of the cooling circuit can be determined. The influence of the heat source on the coolant temperature in the area of ​​the sensor device to be considered decreases with increasing distance between the heat source and the sensor device to be considered.Preferably, the coolant temperature is determined during the evaluation of the signal. Preferably, the coolant temperature is determined from the received signal using a calculation model. Preferably, the calculation model taken into account maps the heat transfer from the sensor device to the coolant. Preferably, if the coolant temperature exceeds a predeterminable threshold value and sufficient waste heat is no longer dissipated by the heated coolant, at least one component is switched off or its currently converted power is reduced to such an extent that the coolant temperature drops again and cooling of the power electronic components is enabled again. Alternatively, the volume flow of the coolant is preferably increased or the coolant temperature is lowered by increasing the cooling capacity of the heat exchanger located in the cooling circuit.

[0009] Advantageously, a simple device is provided that determines the coolant temperature of a cooling circuit. This solution requires no additional components or installation space.

[0010] In another embodiment, the first component is a charger, and the power electronics of the first component comprise power switches. Preferably, the first component is a charger for a vehicle for charging a high-voltage battery that can be connected to the output side. Preferably, the first sensor device for determining the temperature of the power electronics of the first component is arranged in the immediate vicinity of the power switches of the charger and enables precise determination of the temperature of the power switches of the charger. Preferably, the power switches, IGBTs or MOSFETs, are connected to the cooling circuit with excellent thermal conductivity. Consequently, the power switches quickly assume the temperature of the coolant when they are not in operation or, preferably, are permanently switched off.

[0011] Advantageously, an embodiment of a first power electrical component is provided.

[0012] In another embodiment, the second component is a DC-DC converter or an inverter. The power electronics of the second component comprise power switches. Preferably, the second component is a DC-DC converter for converting the high voltage of the high-voltage battery into a low voltage for supplying an on-board electrical system of the vehicle. Preferably, the second sensor device for determining the temperature of the power electronics of the second component is arranged in the immediate vicinity of the power switches of the DC-DC converter and enables precise determination of the temperature of the power switches of the DC-DC converter. Preferably, the power switches, IGBTs or MOSFETs, are connected to the cooling circuit with excellent thermal conductivity. Consequently, the power switches quickly assume the temperature of the coolant when they are not in operation or, preferably permanently, are switched off.Advantageously, an embodiment of a second power electrical component is provided.

[0013] Furthermore, an electrical system is provided which comprises at least a first and a second power electronic component, a common cooling circuit for sequentially cooling the power electronics of the first and second components, and a device for determining a coolant temperature of the cooling circuit. The first component comprises a first sensor device for determining the temperature of the power electronics of the first component, and the second component comprises a second sensor device for determining the temperature of the power electronics of the second component. At least temporarily, the first component is switched on, and its power electronics generates waste heat, while the second component is switched off at the same time, and vice versa.The device is designed to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched off second component during operation of the first component in order to determine the coolant temperature of the cooling circuit, and to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched off first component during operation of the second component in order to determine the coolant temperature of the cooling circuit.

[0014] Advantageously, an electrical system is provided that determines the coolant temperature of a cooling circuit. This solution requires no additional components or installation space.

[0015] The invention further relates to a drivetrain with a device as described above, wherein the drivetrain in particular comprises a high-voltage battery, an inverter, and / or an electric machine. Advantageously, a drivetrain of an electric vehicle is provided with a device that determines the coolant temperature of a cooling circuit. This solution requires no additional components or installation space. The invention further relates to a vehicle with a drivetrain as described above.

[0016] Advantageously, a vehicle is provided with a device that determines the coolant temperature of a cooling circuit. This solution requires no additional components or installation space.

[0017] Furthermore, the invention relates to a method for operating a device as presented above, comprising the steps:

[0018] During operation of the first component, receiving a signal that characterizes the temperature of the power electronics of the switched-off second power electronics; evaluating the received signal, and during operation of the second component, receiving a signal that characterizes the temperature of the power electronics of the switched-off first power electronics;

[0019] Evaluating (820) the received signal.

[0020] Advantageously, by receiving and evaluating the signal, a method is provided that determines the coolant temperature of a cooling circuit. This solution requires no additional components or installation space.

[0021] Furthermore, the invention relates to a computer program comprising instructions which, when the program is executed by the device, cause the device to carry out the described method.

[0022] Furthermore, the invention relates to a machine-readable storage medium comprising instructions which, when executed by the device, cause it to carry out the described method.

[0023] It is understood that the features, properties, and advantages of the device apply correspondingly to the electrical system and method, or the drivetrain and the vehicle, and vice versa. Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

[0024] Short description of the drawing

[0025] In the following, the invention will be explained in more detail with reference to some figures, which show:

[0026] Figure 1 shows a schematically illustrated vehicle with a drive train with a device,

[0027] Figure 2 shows a schematic flow diagram for a method for operating the device.

[0028] Embodiments of the invention

[0029] Figure 1 shows a schematically illustrated vehicle 700 with a drive train 600 with a device 100 and an exemplary electrical system 500. The vehicle 700 is illustrated here only as an example with four wheels, although the invention can be used equally in any vehicle with any number of wheels on land, on water, and in the air. The drive train 600 illustrated as an example comprises at least the device 100. Furthermore, the drive train preferably comprises a first and second power-electrical component 510, 520 with a cooling circuit 300 or an electrical system 500, a battery 470, an inverter 472, and / or an electrical machine 474. The device 100 is configured to determine a coolant temperature of the coolant in the cooling circuit 300.The cooling circuit 300 is designed for the sequential cooling of the power electronics of at least the first and second power-electrical components 510, 520. For clarity, only a portion of the cooling circuit 300 is shown in Figure 1. The cooling circuit is preferably a closed system in which the coolant flows and circulates in one direction. The first component 510 comprises a first sensor device 512 for determining the temperature of the power electronics of the first component 510. By way of example, the first component 510 is shown as a charging device, preferably with an input terminal 514 for connecting a single-phase or multi-phase AC voltage source for charging the battery or high-voltage battery 470 that can be connected on the output side. The battery is preferably charged using the AC voltage source when the vehicle is stationary.The second component 520 comprises a second sensor device 522 for determining the temperature of the power electronics of the second component 520. By way of example, the second component 520 is shown as a DC-DC converter, preferably with a low-voltage connection 524, to which the on-board electrical system and a low-voltage battery of a vehicle are preferably connected. By means of the DC-DC converter, the on-board electrical system is preferably supplied with energy from the high-voltage network or the high-voltage battery, wherein the high-voltage input voltage is converted into the low voltage of the on-board electrical system. The low-voltage network is preferably supplied by means of the DC-DC converter while the vehicle is moving. Consequently, the first component 510 is preferably switched on and the second component 520 is switched off while the vehicle is stationary, and the first component 510 is switched off and the second component 520 is switched on while the vehicle is moving.At least temporarily, the first component 510 is thus switched on and its power electronics generate waste heat, while the second component 520 is switched off, and vice versa. The device 100 is configured to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched-off second component 520 during operation of the first component 510 in order to determine the coolant temperature of the cooling circuit 300. Furthermore, the device 100 is configured to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched-off first component 510 during operation of the second component 520 in order to determine the coolant temperature of the cooling circuit 300. Preferably, the device 100 receives the signal via a wired connection directly from one of the components or via a bus system; wireless transmission of the signal is also possible.The signal is preferably the signal from the sensor device; a further processed signal characterizing the temperature of the power electronics of the switched-off power electronics is also possible. The coolant temperature is preferably determined during the evaluation of the signal. The evaluation of the signal preferably comprises the direct further use of the signal or comprises an evaluation that may include filtering, an offset shift, the application of a calculation model, or further signal processing steps. The electrical system 500 comprises at least the first and second power electronic components 510, 520, the common cooling circuit 300, preferably a common cooling circuit section, for sequentially cooling the power electronics of the first and second components 510, 520, and the device 100 for determining the coolant temperature of the cooling circuit 300.By way of example, the electrical system 500 is shown as a combination of a charger and a DC-DC converter, preferably within a housing.

[0030] Figure 2 shows a schematic flowchart for a method 800 for operating device 100. Method 800 begins with step 805. In step 810, a signal is received that characterizes the temperature of the power electronics when the power electronics are switched off. The received signal is evaluated in step 820. The coolant temperature is preferably determined during the signal evaluation. The method ends with step 825.

Claims

Device (100) for determining a coolant temperature of a cooling circuit (300), wherein the cooling circuit (300) is designed for the sequential cooling of the power electronics of at least a first and a second power-electrical component (510, 520), wherein the first component (510) comprises a first sensor device (512) for determining the temperature of the power electronics of the first component (510) and the second component (520) comprises a second sensor device (522) for determining the temperature of the power electronics of the second component (520), wherein at least temporarily the first component (510) is switched on and its power electronics generates waste heat and simultaneously the second component (520) is switched off, and vice versa, characterized in that the device (100) is designed to, during operation of the first component (510), for determining the coolant temperature of the cooling circuit (300), a signal,which characterizes the temperature of the power electronics of the switched-off second component (520), and to receive and evaluate a signal characterizing the temperature of the power electronics of the switched-off first component (510) during operation of the second component (520) to determine the coolant temperature of the cooling circuit (300). The device according to claim 1, wherein the first component (510) is a charger and the power electronics of the first component (510) comprise power switches. The device according to one of the preceding claims, wherein the second component (520) is a DC-DC converter or an inverter (472) and the power electronics of the second component (520) comprise power switches. Electrical system (500) comprising at least a first and a second power electronic component (510, 520), a common cooling circuit (300) for sequentially cooling the power electronics of the first and second components (510, 520), and a device (100) for determining a coolant temperature of the cooling circuit (300), wherein the first component (510) comprises a first sensor device (512) for determining the temperature of the power electronics of the first component (510) and the second component (520) comprises a second sensor device (522) for determining the temperature of the power electronics of the second component (520), wherein at least temporarily the first component (510) is switched on and its power electronics generates waste heat and simultaneously the second component (520) is switched off, and vice versa, characterized in that the device (100) is configured to, during operation of the first component (510),To determine the coolant temperature of the cooling circuit (300), to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched-off second component (520), and during operation of the second component (520), to determine the coolant temperature of the cooling circuit (300), to receive and evaluate a signal that characterizes the temperature of the power electronics of the switched-off first component (510). A drive train (600) with a device (100) according to claims 1 to 3 or an electrical system according to claim 4, wherein the drive train (600) comprises, in particular, a high-voltage battery (470), an inverter (472), and / or an electric machine (474). A vehicle (700) with a drive train (600) according to claim 5. Method (800) for determining a coolant temperature of a cooling circuit (300) with a device (100) according to one of the preceding claims, comprising the steps: during operation of the first component (510), Receiving (810) a signal characterizing the temperature of the power electronics of the switched-off second power electronics; Evaluating (820) the received signal and, during operation of the second component (520), receiving (810) a signal which characterizes the temperature of the power electronics of the switched-off first power electronics; Evaluating (820) the received signal. A computer program comprising instructions which, when executed by a device according to any one of claims 1-6, cause the device to perform the method (800) according to claim 7. A machine-readable storage medium comprising instructions which, when executed by a device according to any one of claims 1-6, cause the device to perform the method (800) according to claim 7.

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