DE102021200902A1 - Electrical system in a motor vehicle and method for heating battery cells of at least one high-voltage battery in an electrical system - Google Patents

Abstract

The invention relates to an electrical system (1) in a motor vehicle, the system (1) having a traction network (2) and an on-board network (3), the traction network (2) having at least one high-voltage battery (5), a pulse-controlled inverter (8) and an electric machine (9), wherein transistors (10) of the pulse-controlled inverter (8) are connected to at least one gate driver component (12), wherein the gate driver component (12) is designed in such a way that at least one gate To generate a driver signal (GTS) for at least one transistor (10) of the pulse-controlled inverter (8), the high-voltage battery (5) and the transistors (10) of the pulse-controlled inverter (8) being thermally coupled, with at least one means for detecting or determining a temperature of battery cells (6) of the high-voltage battery (5) is provided, wherein the gate driver module (12) is designed such that when the temperature of the battery cells (6) is below a threshold value, it switches to a heating mode in which the gate driver signal (GTS) for switching on the transistors (10) has a lower voltage than in normal operation, at least one galvanically isolated DC/DC converter (14) being provided, at the input of which an on-board power supply voltage is supplied and at its at least a driver voltage (TS) for the at least one gate driver module (12) is present at an output, the DC/DC converter (14) being designed with a drive circuit (15) on the input side, the drive circuit (15) being designed in such a way is designed to reduce the output voltage at the DC/DC converter (14) as a function of a signal (S) for the heating operation, and a method for heating battery cells (6) of at least one high-voltage battery (5) in an electrical system (1) in a motor vehicle.

Description

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

Motor vehicles with an electric traction network are known which have a high-voltage battery which in turn has a large number of battery cells. At low temperatures, the power consumption is limited. It is therefore known to preheat the battery cells. This can be done, for example, by means of a separate heating device. Alternatively, it is known to use the heat loss of already existing components in a targeted manner, which are then thermally coupled to the battery cells in order to preheat them in a targeted manner.

From the DE 11 2008 000 360 T5 an electrical system in a motor vehicle is known, the system having a traction network and an on-board network. The traction network also has at least one high-voltage battery, a pulse-controlled inverter and an electric machine, with transistors in the pulse-controlled inverter being connected to at least one gate driver module, with the gate driver module being designed in such a way that at least one gate driver signal is generated for at least to produce a transistor of the pulse-controlled inverter. Furthermore, the transistors of the pulse-controlled inverter are thermally coupled to the high-voltage battery via a shared cooling system. At least one means for detecting or determining a temperature of battery cells of the high-voltage battery is also provided. The gate driver module is designed in such a way that, at a temperature below a threshold value, it switches to a heating mode in which the gate driver signal for switching on the transistors has a lower voltage than in normal mode. In addition, it is disclosed that the gate driver module is designed in such a way that a gate driver signal for blocking the transistors is generated in heating operation, the voltage of which is greater than in normal operation. The power loss in the pulse-controlled inverter is purposefully increased by means of both measures. How this is implemented in the gate driver module is not disclosed.

The invention is based on the technical problem of creating an electrical system in which the implementation of a heating operation by means of an adaptation of the gate driver signal can be implemented in a relatively simple manner from a technical point of view. A further technical problem is the provision of a suitable method for heating battery cells of at least one high-voltage battery in an electrical system in a motor vehicle.

The technical problem is solved by an electrical system with the features of claim 1 and a method with the features of claim 9. Further advantageous refinements of the invention result from the dependent claims.

The electrical system has a traction network and an on-board network. The traction network also has at least one high-voltage battery, a pulse-controlled inverter and an electric machine, with transistors in the pulse-controlled inverter being connected to at least one gate driver module, with the gate driver module being designed in such a way that at least one gate driver signal is generated for at least to produce a transistor of the pulse-controlled inverter. Furthermore, the transistors of the pulse-controlled inverter are thermally coupled to the high-voltage battery, with at least one means for detecting or determining a temperature of battery cells of the high-voltage battery being provided, with the gate driver component being designed in such a way that when the temperature of the battery cells is below a threshold value, To switch heating mode, in which the gate driver signal for switching on the transistors has a lower voltage than in normal operation. In this case, a galvanically isolated DC/DC converter is provided, at the input of which there is a vehicle electrical system voltage and at the at least one output of which a driver voltage for the at least one gate driver module is present. The DC/DC converter is designed with a drive circuit on the input side, the drive circuit being designed to reduce the output voltage at the DC/DC converter or driver voltage for the gate driver module depending on a signal for heating operation . This eliminates the need for complex modifications to the gate driver component and simply reduces the driver voltage, so that a lower voltage is automatically used to turn on the transistors. The vehicle electrical system voltage at the input of the DC/DC converter is provided by an vehicle electrical system battery, for example. In one embodiment, the additional heating power is generated only in the phases in which the transistors are switched through. The advantage of this is the very simple technical implementation.

In an alternative embodiment, the gate driver module is designed in such a way that a gate driver signal for blocking the transistors is generated in heating operation, the voltage of which is greater than in normal operation. As a result, the heating power can be increased accordingly, although the gate driver component is correspondingly more heavily modified. A possible implementation would be a correspondingly modulated driver voltage at the output of the DC/DC converter, which then from the gate driver chip to the transistors.

Regardless of the specific embodiment, it should be noted that the heating operation is terminated when the temperature of the battery cells has exceeded the threshold value or a further threshold value, or another termination criterion is met.

In a further embodiment, the DC/DC converter has at least two secondary coils. Thus, several driver voltages can be made available by means of a DC/DC converter. The DC/DC converter preferably has as many secondary coils as there are gate driver components for the pulse-controlled inverter.

In a further embodiment, the gate driver module has at least two outputs which are each connected to a transistor of a half-bridge of the pulse-controlled inverter. In principle, a gate driver component can have as many outputs as there are transistors (typically 6). However, the number of outputs is preferably limited to two, so that in each case one gate driver component is assigned to exactly one half bridge. However, it is also possible for each transistor to be assigned its own gate driver component.

In a further embodiment, at least one microprocessor is provided which is designed in such a way that it generates control signals for at least one gate driver module. In this case, either one microprocessor can control all the gate driver components of the pulse-controlled inverter, or each gate driver component is assigned its own microprocessor, or one microprocessor is assigned to a pair of gate driver components.

In a further embodiment, the at least one microprocessor is designed in such a way that it controls an associated control circuit of the DC/DC converter so that the heating operation is carried out. The advantage is that a temperature, in particular a junction temperature, of the transistors can be transmitted to the microprocessor, so that the microprocessor can possibly interrupt the heating operation if the temperature of the transistors exceeds a critical value.

In a further embodiment, a battery management control unit is provided for the high-voltage battery, which is designed to initiate heating operation depending on a detected or determined temperature of the battery cells, with this being able to take place directly via the microprocessor or the control circuit.

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

With regard to the procedural design of the invention, reference can be made in full to the previous statements.

• 1 ein vereinfachtes Blockschaltbild eines elektrischen Systems in einem Kraftfahrzeug,
• 2 ein Blockschaltbild von DC/DC-Wandler, Mikroprozessor und Gate-Treiber-Baustein,
• 3 eine vereinfachte Darstellung eines DC/DC-Wandlers mit zwei Sekundärspulen und
• 4 eine vereinfachte Darstellung eines DC/DC-Wandlers mit drei Sekundärspulen für drei Gate-Treiber-Bausteine.

The invention is explained in more detail below using preferred exemplary embodiments. The figures show:

• 1 a simplified block diagram of an electrical system in a motor vehicle,
• 2 a block diagram of the DC/DC converter, microprocessor and gate driver module,
• 3 a simplified representation of a DC/DC converter with two secondary coils and
• 4 a simplified representation of a DC/DC converter with three secondary coils for three gate driver devices.

In the 1 an electrical system 1 in a motor vehicle is shown in a greatly simplified manner. The electrical system 1 has a traction network 2 and an on-board network 3 with an on-board network battery 4 . The traction network 2 has a high-voltage battery 5 with a large number of battery cells 6 with which temperature sensors 7 are assigned. The traction network 2 also has a pulse-controlled inverter 8 and an electric machine 9 . The pulse-controlled inverter 8 has a multiplicity of transistors 10 which are in the form of MOSFETs or IGBTs, for example. The pulse-controlled inverter typically has six transistors 10 which are connected as a B6 bridge circuit. However, designs with twelve transistors 10 are also known. The transistors 10 are assigned temperature sensors 11 and gate driver components 12, with the gate driver components 12 being connected to at least one microprocessor 13 in terms of data technology. Furthermore, the electrical system 1 has at least one galvanically isolated DC/DC converter 14 , at the input of which there is a vehicle electrical system voltage and at the output of which a higher driver voltage TS for the gate driver modules 12 is present. The DC/DC converter 14 thus works as a step-up converter. On the input side, the DC/DC converter 14 has a control circuit 15, by means of which the input AC voltage for a primary coil can be adjusted. Furthermore, the electrical system 1 has a battery management control unit 16, which in addition to controlling the high-voltage battery 5 further performs higher-level control measures and controls, among other things, the main contactor 17. Finally, the electrical system 1 has a coolant circuit 18 which is indicated by dashed lines, the transistors 10 of the pulse-controlled inverter 8 being thermally coupled to the battery cells 6 of the high-voltage battery 5 via this coolant circuit 18 .

If, especially before the start of the journey, the temperature sensors 7 detect that the temperature of the battery cells 6 is below a threshold value (e.g. 5°C), heating operation is initiated in which the transistors 10 generate more heat loss in a targeted manner in order to use the coolant in the coolant -Circuit 18 to heat so as to heat the battery cells 6. The battery management control unit 16 then transmits a corresponding control command to the microprocessor 13. The microprocessor 13 then generates a control command for the control circuit 15, which then the input AC voltage to be generated from the vehicle electrical system voltage changes in such a way that the AC voltage induced in the secondary coil is lower, so that the driver voltage TS present at the output after smoothing is lower than in normal operation. As a result, the gate driver components 12 turn on the transistors 10 less than in normal operation, so that the volume resistance of the transistors increases in forward operation. As a result, more power loss is generated in the transistors 10, so that the battery cells 6 are heated. The temperature sensors 11 monitor that the transistors 10 do not overheat. These forward their data to the microprocessor 13, which can then react to it. The reaction can be a termination of the heating operation or just an adjustment of the driver voltage TS, so that the power loss generated in the transistors 10 is reduced. If the temperature of the battery cells 6 exceeds the threshold value or another threshold value, the battery management control device 16 can interrupt the heating operation.

In addition, provision can also be made for increased power loss to be generated in the heating mode when the transistors 10 are in the blocking mode, in that the gate driver components 12 apply a higher voltage to the transistors 10 than in normal mode, so that the leakage currents are increased. However, this increases the circuit complexity. Therefore, increased heat loss is preferably only generated in forward operation by reducing the driver voltage TS.

In the 2 the DC/DC converter 14 is shown, at the input of which the vehicle electrical system voltage is present and at the output of which the higher driver voltage TS is present. The vehicle electrical system voltage is 12 V, for example, and the driver voltage TS is 15 V to 20 V. The gate driver module 12 is controlled by the microprocessor 13, which specifies the pulse pattern with which the gate driver module controls the associated (not shown) transistor target. The gate driver module 12 then generates a gate driver signal GTS. In the simplest case, the gate driver module 12 switches the driver voltage TS through (on-state operation for the transistors) or blocks it (off-state operation for the transistors).

In the 3 a DC/DC converter 14 with a primary coil 19 and two secondary coils 20 is shown in a highly simplified manner, so that the driver voltages TS for two gate driver components 14 can be generated with a DC/DC converter 14 .

In the 4 Finally, a highly simplified DC/DC converter 14 is shown, which has a primary coil 19 and three secondary coils 20 in order to supply three gate driver components 12 with a driver voltage TS. In this case, each gate driver component has two outputs A in order to drive the two transistors of a half-bridge circuit of the pulse-controlled inverter 8 in each case.

Reference List

1

electrical system

2

traction network

3

electrical system

4

on-board battery

5

high-voltage battery

6

battery cell

7

temperature sensor

8th

pulse inverter

9

electric machine

10

transistor

11

temperature sensor

12

gate driver device

13

microprocessor

14

DC/DC converter

15

control circuit

16

Battery management control unit

17

main contactor

18

coolant circuit

19

primary coil

20

secondary coil

S

control signal

GTS

gate driver signal

TS

driver voltage

A

Exit

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 112008000360 T5 [0003]

Claims (9)

Electrical system (1) in a motor vehicle, the system (1) having a traction network (2) and an on-board network (3), the traction network (2) having at least one high-voltage battery (5), a pulse-controlled inverter (8) and an electric machine ( 9), wherein transistors (10) of the pulse-controlled inverter (8) are connected to at least one gate driver module (12), the gate driver module (12) being designed in such a way that at least one gate driver signal ( GTS) for at least one transistor (10) of the pulse-controlled inverter (8), the high-voltage battery (5) and the transistors (10) of the pulse-controlled inverter (8) being thermally coupled, with at least one means for detecting or determining a temperature of battery cells (6) the high-voltage battery (5) is provided, wherein the gate driver module (12) is designed such that when the temperature of the battery cells (6) is below a threshold value, it switches to a heating mode in which the gate driver signal (GT S) for switching through the transistors (10) has a lower voltage than in normal operation, characterized in that at least one galvanically isolated DC/DC converter (14) is provided, at the input of which is an on-board power supply voltage and at the at least one output of which is a driver voltage (TS) for the at least one gate driver module (12), the DC/DC converter (14) being designed with a drive circuit (15) on the input side, the drive circuit (15) being designed in such a way that in Depending on a signal (S) for the heating mode to reduce the output voltage at the DC/DC converter (14). Electrical system after claim 1 , characterized in that the gate driver module (12) is designed such that in the heating mode a gate driver signal (GTS) for blocking the transistors (10) is generated, the voltage of which is greater than in normal operation. Electrical system after claim 1 or 2 , characterized in that the DC / DC converter (14) has at least two secondary coils (20). Electrical system according to one of the preceding claims, characterized in that the gate driver module (12) has at least two outputs (A), which are each connected to a transistor (10) of a half-bridge of the pulse-controlled inverter (8). Electrical system according to one of the preceding claims, characterized in that at least one microprocessor (13) is provided which is designed in such a way to generate control signals for at least one gate driver module (12). Electrical system after claim 5 , characterized in that the microprocessor (13) is designed in such a way to control an associated control circuit (15) of the DC/DC converter (14), so that the heating operation is carried out. Electrical system according to one of the preceding claims, characterized in that a battery management control unit (16) is provided for the high-voltage battery (5), which is designed in such a way as to initiate heating operation as a function of a detected or determined temperature of the battery cells (6). . Electrical system according to one of the preceding claims, characterized in that the high-voltage battery (5) and the transistors (10) of the pulse-controlled inverter (8) are integrated in a common coolant circuit (18). Method for heating battery cells (6) of at least one high-voltage battery (5) in an electrical system (1) in a motor vehicle, the system (1) having a traction network (2) and an on-board network (3), the traction network (2) has at least one high-voltage battery (5), a pulse-controlled inverter (8) and an electric machine (9), with transistors (10) of the pulse-controlled inverter (8) being connected to at least one gate driver module (12), with the gate driver Module (12) generates at least one gate driver signal (GTS) for at least one transistor (10) of the pulse-controlled inverter (8), the high-voltage battery (5) and the transistors (10) being thermally coupled, with at least one means for Detection or determination of a temperature of the battery cells (6) of the high-voltage battery (5) whose temperature is detected or determined, the gate driver module (12) at a temperature of the battery cells (6) below a threshold value in a Heizbetri eb is switched, in which the gate driver signal (GTS) for switching through the transistors (10) has a lower voltage than in normal operation, characterized in that by means of at least one galvanically isolated DC/DC converter (14) a driver voltage ( TS) for the at least one gate driver module (12) is generated, with an on-board power supply voltage being present at an input of the DC/DC converter (14), with the DC/DC converter (14) having a control circuit ( 15), wherein the drive circuit (15) reduces the output voltage at the DC/DC converter (14) as a function of a signal (S) for the heating mode.

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