CN114834318A - Electrical system in a motor vehicle and method for heating a battery cell in an electrical system - Google Patents

Abstract

The invention relates to an electrical system in a motor vehicle, wherein the system has a traction network and a vehicle electrical system, the traction network has a high-voltage battery, a pulse inverter and an electric machine, the high-voltage battery is thermally coupled to a transistor of the pulse inverter, means are provided for detecting the temperature of a battery cell of the high-voltage battery, a grid driver assembly is designed, switching to a warm-up operation when the temperature of the battery cell is below a threshold value, wherein a gate driver signal for switching on the transistor has a lower voltage than in a normal operation, wherein at least one galvanically isolated DC/DC converter is provided, to the input of which a vehicle electrical system voltage is applied and to the output of which a drive voltage for the gate driver component is present, the DC/DC converter being configured on the input side with a control circuit, which is designed to reduce the output voltage across the DC/DC converter in dependence on the signal for the heating operation. The invention also relates to a method for heating a battery cell of at least one high-voltage battery in an electrical system.

Description

Electrical system in a motor vehicle and method of heating battery cells in an electrical system

technical field

The invention relates to an electrical system in a motor vehicle and a method for heating the cells of at least one high-voltage battery in the electrical system in a motor vehicle.

Background technique

Motor vehicles are known which have a traction grid with a high-voltage battery, which in turn has a plurality of battery cells. At low temperatures, power extraction can be limited. It is therefore known to preheat the battery cells. This can be achieved, for example, by means of a separate heating device. Alternatively, it is known to use the heat loss of components already present in a targeted manner, which are then thermally coupled to the battery cells in order to preheat the battery cells in a targeted manner.

An electrical system in a motor vehicle is known from DE 11 2008 000 360 T5, wherein the system has a traction grid and an on-board grid. Furthermore, the traction grid has at least one high-voltage battery, a pulse inverter, and an electric machine, wherein the transistors of the pulse inverter are connected to at least one gate driver assembly, wherein the gate driver assembly is designed to generate power for the pulse inverter. at least one gate driver signal of at least one transistor of the device. Furthermore, the transistors of the pulse inverter are thermally coupled to the high-voltage battery via a common cooling system. Furthermore, at least one device is provided for acquiring or determining the temperature of the cells of the high-voltage battery. The gate driver assembly is designed to switch to heating operation at temperatures below a threshold value, in which the gate driver signal for turning on the transistor has a lower voltage than in normal operation. In addition, it is disclosed that the gate driver assembly is designed such that in heating operation a gate driver signal for switching off the transistor is generated, the voltage of which is higher than in normal operation. By means of these two measures, the power losses in the pulse inverter are increased in a targeted manner. How this is achieved in the gate driver assembly is not disclosed.

SUMMARY OF THE INVENTION

Therefore, the technical problem to be solved by the present invention is to provide an electrical system in which the switching of heating operation can be implemented relatively simply technically by means of adjusting the gate driver signal. A further technical problem to be solved is to provide a suitable method for heating the cells of at least one high-voltage battery in an electrical system in a motor vehicle.

The solution to the above-mentioned technical problem is given by an electrical system with the features according to the invention and a method with the features according to the invention. Further advantageous configurations of the invention are given by the description of the invention.

The electrical system has a traction grid and an on-board grid. Furthermore, the traction grid has at least one high-voltage battery, a pulse inverter, and an electric machine, wherein the transistors of the pulse inverter are connected to at least one gate driver assembly, wherein the gate driver assembly is designed to generate power for the pulse inverter. at least one gate driver signal of at least one transistor of the device. Furthermore, the transistors of the pulse inverter are thermally coupled to the high-voltage battery, wherein at least one device is provided for acquiring or determining the temperature of the battery cells of the high-voltage battery, wherein the gate driver assembly is designed such that in the battery cells In the event of a temperature below the threshold value is switched to heating operation in which the gate driver signal for switching on the transistor has a lower voltage than in normal operation. In this case, a galvanically isolated DC/DC converter is provided, at its input the on-board power supply voltage is applied and at its at least one output a drive voltage for at least one gate driver component is present. In this case, the DC/DC converter is provided with a control circuit on the input side, the control circuit being designed to reduce the output voltage at the DC/DC converter or the drive of the gate driver assembly as a function of the signal for heating operation Voltage. Thereby, complex modifications to the gate driver components can be dispensed with, and the drive voltage is simply reduced, automatically using the lower voltage to turn on the transistor as well. In this case, the on-board electrical system voltage at the input of the DC/DC converter is provided, for example, by the on-board electrical system battery. In one specific embodiment, the additional heating power is generated only in the phases with the transistors that are switched on. The advantage of this is a very simple technical implementation.

In an alternative embodiment, the gate driver assembly is designed such that in heating operation a gate driver signal for turning off the transistor is generated, the voltage of the gate driver signal being higher than in normal operation. As a result, the heating power can be increased accordingly, but the gate driver components are modified accordingly more strongly. One possible implementation is a correspondingly modulated drive voltage at the output of the DC/DC converter, which is then conducted from the gate driver assembly to the transistor.

Regardless of the respective embodiment, it should be noted that the heating operation is interrupted when the temperature of the battery cells has exceeded a threshold value or a further threshold value or satisfied further interruption criteria.

In further embodiments, the DC/DC converter has at least two secondary coils. Therefore, a plurality of driving voltages can be provided by means of a DC/DC converter. Preferably, the DC/DC converter has as many secondary coils as there are gate driver modules for the pulse inverter.

In a further embodiment, the gate driver assembly has at least two outputs, which are respectively connected to transistors of the half-bridge of the pulse inverter. In principle, the gate driver module can have as many outputs as there are transistors (usually 6). Preferably, however, the number of outputs is limited to two, so that the gate driver components are each associated with exactly one half-bridge. However, it is also possible that each transistor is associated with its own gate driver component.

In a further embodiment, at least one microprocessor is provided which is designed to generate control signals for the at least one gate driver assembly. Here, the microprocessor may control all gate driver components of the pulse inverter, or each gate driver component may be associated with its own microprocessor, or the microprocessor may be associated with a pair of gate driver components.

In a further embodiment, at least one microprocessor is designed to control the associated control circuit of the DC/DC converter to perform the heating operation. The advantage is that the temperature of the transistor, in particular the junction temperature, can be transmitted to the microprocessor, so that the microprocessor can interrupt the heating operation if necessary when the temperature of the transistor exceeds a critical value.

In a further embodiment, a battery management control device is provided for a high-voltage battery, the battery management control device being designed to initiate a heating operation as a function of the detected or determined temperature of the battery cells, wherein this can be performed by microprocessing controller or control circuit directly.

In a further embodiment, the transistors of the high voltage battery and the pulse inverter are integrated in a common coolant circuit, making thermal coupling very simple.

With regard to the design solution of the method aspect of the present invention, reference may be made to the foregoing embodiments.

Description of drawings

The invention is explained in more detail below on the basis of preferred embodiments. In the attached picture:

Figure 1 shows a simplified block diagram of an electrical system in a motor vehicle,

Figure 2 shows a block diagram of the DC/DC converter, microprocessor and gate driver components,

Figure 3 shows a simplified illustration of a DC/DC converter with two secondary coils, and

Figure 4 shows a simplified illustration of a DC/DC converter with three secondary coils for three gate driver assemblies.

Detailed ways

FIG. 1 shows an electrical system 1 in a motor vehicle in a very simplified manner. The electrical system 1 has a traction grid 2 and an on-board grid 3 with an on-board grid battery 4 . The traction grid 2 has a high-voltage battery 5 with a plurality of battery cells 6 , which are associated with temperature sensors 7 . Furthermore, the traction grid 2 has a pulse inverter 8 and an electric machine 9 . The pulse inverter 8 has a plurality of transistors 10 , which are designed as MOSFETs or IGBTs, for example. Typically, a pulse inverter has six transistors 10, which are connected as a B6 bridge circuit. However, designs with twelve transistors 10 are also known. A temperature sensor 11 and a gate driver assembly 12 are associated with the transistor 10 , wherein the gate driver assembly 12 is connected in data technology to at least one microprocessor 13 . Furthermore, the electrical system 1 has at least one galvanically isolated DC/DC converter 14 , to the input of which the on-board electrical system voltage is applied and at the output of which the grid voltage is present Higher drive voltage TS of driver assembly 12 . Therefore, the DC/DC converter 14 operates as a boost converter. On the input side, the DC/DC converter 14 has a control circuit 15 by means of which the input alternating voltage to the primary coil can be regulated. Furthermore, the electrical system 1 has a battery management control device 16 which, in addition to controlling the high-voltage battery 5 , executes further higher-level control measures and also controls, among other things, the main contactor 17 . Finally, the electrical system 1 has a coolant circuit 18 , shown in dashed lines, via which the transistors 10 of the pulse inverter 8 are thermally coupled to the cells 6 of the high-voltage battery 5 .

If, in particular before the start of the drive, it is detected by the temperature sensor 7 that the temperature of the battery cells 6 falls below a threshold value (eg 5° C.), a heating operation is started, in which the transistor 10 specifically generates more heat losses , so as to thereby heat the coolant in the coolant circuit 18 so as to thereby heat the battery cells 6 . The determination of whether heating operation is required is preferably made by the battery management control device 16 . The battery management control device 16 then transmits corresponding control commands to the microprocessor 13 . The microprocessor 13 then generates control commands for the control circuit 15, which then changes the input AC voltage to be generated by the on-board grid voltage so that the AC voltage induced in the secondary coil is lower and thus appears at the output after smoothing. The drive voltage TS on the terminal is lower than in normal operation. As a result, the gate driver assembly 12 controls the transistor 10 less than in normal operation, thereby increasing the on-resistance of the transistor in ON operation. As a result, more power is lost in the transistor 10 , thereby heating the battery cells 6 . Here, it is monitored by the temperature sensor 11 that the transistor 10 does not overheat. The temperature sensors forward their data to the microprocessor 13, which can then react to this. The reaction may be an interruption of the heating operation or simply an adjustment of the drive voltage TS, thereby reducing the power losses occurring in the transistor 10 . If the temperature of the battery cells 6 exceeds a threshold value or another threshold value, the battery management control device 16 may interrupt the heating operation.

In addition, it can also be provided that, in the off operation of the transistor 10 , an increased power loss occurs in the heating operation, in that the gate driver assembly 12 applies a higher voltage to the transistor 10 than in normal operation, thereby increasing the power consumption. leakage current. However, this increases the circuit technology overhead. Therefore, it is preferable to increase the heat loss by lowering the drive voltage TS only in ON operation.

FIG. 2 shows a DC/DC converter 14 , at its input the on-board electrical system voltage is applied and at its output a higher drive voltage TS occurs. The on-board grid voltage is, for example, 12V, and the drive voltage TS is 15V to 20V. The gate driver assembly 12 is controlled by a microprocessor 13 which predetermines which pulse pattern the gate driver assembly should utilize to control the associated (not shown) transistor. The gate driver assembly 12 generates the gate driver signal GTS thereon. Here, in the simplest case, the gate driver assembly 12 switches on the drive voltage TS (for switching on operation of the transistors) or switches it off (for switching off operation of the transistors).

The DC/DC converter 14 with a primary coil 19 and two secondary coils 20 is shown in a greatly simplified manner in FIG. 3 , so that the DC/DC converter 14 can be used to generate components for two gate drivers 14 drive voltage TS.

Finally, the DC/DC converter 14 is shown in a very simplified manner in FIG. 4 with a primary coil 19 and three secondary coils 20 in order to supply the three gate driver assemblies 12 with a drive voltage TS. Here, each gate driver assembly has two outputs A in order to respectively control the two transistors of the half-bridge circuit of the pulse inverter 8 .

List of reference signs

1 Electrical system

2 Traction grid

3 On-board power grid

4 On-board grid battery

5 High voltage battery

6 battery cells

7 Temperature sensor

8-pulse inverter

9 Motor

10 transistors

11 Temperature sensor

12 Gate Driver Components

13 Microprocessor

14 DC/DC Converters

15 Control circuit

16 Battery management control device

17 Main contactor

18 Coolant circuit

19 Primary coil

20 Secondary coil

S control signal

GTS gate drive signal

TS drive voltage

A output

Claims (9)

1. An electrical system (1) in a motor vehicle, wherein the system (1) has a traction grid (2) and an on-board grid (3), wherein the traction grid (2) has at least one high-voltage battery ( 5), a pulse inverter (8) and a motor (9), wherein a transistor (10) of the pulse inverter (8) is connected to at least one gate driver assembly (12), wherein the gate The driver assembly (12) is designed to generate at least one gate driver signal (GTS) for at least one transistor (10) of the pulse inverter (8), wherein the high voltage battery (5) is connected to the The transistors (10) of the pulse inverter (8) are thermally coupled, wherein at least one device for acquiring or determining the temperature of the battery cells (6) of the high-voltage battery (5) is provided, wherein the gate The driver assembly (12) is designed to switch to a heating operation when the temperature of the battery cells (6) falls below a threshold value, in which heating operation the gate driver for switching on the transistor (10) signal (GTS) has a lower voltage than in normal operation, It is characterized in that, At least one galvanically isolated DC/DC converter (14) is provided, the onboard power supply voltage is applied to the input of the DC/DC converter and at least one output of the DC/DC converter is present for all The drive voltage (TS) of the at least one gate driver assembly (12), wherein the DC/DC converter (14) is configured on the input side with a control circuit (15), wherein the control circuit (15) It is designed to reduce the output voltage at the DC/DC converter (14) as a function of the signal (S) for heating operation. 2 . The electrical system according to claim 1 , wherein the gate driver assembly ( 12 ) is designed such that a gate driver signal ( GTS), the gate driver signal has a higher voltage than in normal operation. 3. The electrical system according to claim 1 or 2, characterized in that the DC/DC converter (14) has at least two secondary coils (20). 4. The electrical system according to any of the preceding claims, characterized in that the gate driver assembly (12) has at least two outputs (A), the at least two outputs (A) being respectively It is connected to the transistor (10) of the half-bridge of the pulse inverter (8). 5 . The electrical system according to claim 1 , wherein at least one microprocessor ( 13 ) is provided, which is designed to generate the components for the at least one gate driver. 6 . (12) control signal. 6. An electrical system according to claim 5, characterized in that the microprocessor (13) is designed to control the associated control circuit (15) of the DC/DC converter (14), thereby The heating operation is performed. 7 . The electrical system according to claim 1 , wherein a battery management control device ( 16 ) is provided for the high-voltage battery ( 5 ), the battery management control device being designed according to the The acquired or determined temperature of the battery cells (6) initiates the heating operation. 8. The electrical system according to any one of the preceding claims, characterized in that the transistors (10) of the high-voltage battery (5) and the pulse inverter (8) are integrated in a common coolant circuit ( 18) in. 9. A method for heating battery cells (6) of at least one high-voltage battery (5) in an electrical system (1) in a motor vehicle, wherein the system (1) has a traction grid (2) and On-board grid (3), wherein the traction grid (2) has at least one high-voltage battery (5), a pulse inverter (8) and an electric machine (9), wherein the transistor (10) of the pulse inverter (8) ) is connected to at least one gate driver assembly (12), wherein the gate driver assembly (12) generates at least one gate driver signal for at least one transistor (10) of the pulse inverter (8) (GTS), wherein the high-voltage battery ( 5 ) is thermally coupled to the transistor ( 10 ), wherein the temperature of the cells ( 6 ) of the high-voltage battery ( 5 ) is detected or determined by means of at least one device to collect or determine the temperature of the battery cells, wherein the gate driver assembly (12) switches to heating operation when the temperature of the battery cells (6) is below a threshold value, in which the heating operation , the gate driver signal (GTS) for turning on the transistor (10) has a lower voltage than in normal operation, It is characterized in that, A drive voltage (TS) for the at least one gate driver assembly (12) is generated by means of at least one galvanically isolated DC/DC converter (14), wherein at the input of the DC/DC converter (14) The on-board power supply voltage is applied to the terminals, wherein the DC/DC converter (14) has a control circuit (15) on the input side, wherein the control circuit (15) reduces the voltage as a function of the signal (S) for heating operation The output voltage on the DC/DC converter (14).

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