Method for diagnosis of a temperature control means of a battery pack

Abstract

A method for diagnosis of a temperature control means (30) of a battery pack (10) that comprises a plurality of battery cells (20) and a plurality of temperature sensors for measuring temperatures of the individual battery cells (20), the battery cells (20) being arranged side by side in the battery pack (10), in a longitudinal direction (12) of the battery pack (10), and mechanically connected to each another, and the battery cells (20) being arranged on the temperature control means (30) and mechanically and thermally connected to it. A battery management system, and/or a battery pack (10) may be configured to execute the method. A vehicle may be fitted with a battery pack that carries out the method.

Claims

1. A method for diagnosis of a temperature control means (30) of a battery pack (10) that comprises a plurality of battery cells (20) and a plurality of temperature sensors for measuring temperatures of the individual battery cells (20), the battery cells (20) being arranged side by side in the battery pack (10), in a longitudinal direction (12) of the battery pack (10), and connected to each other, the battery cells (20) being arranged on the temperature control means (30) and connected to the temperature control means (30), wherein the connection includes a thermal connection, the method comprising the following steps: determining a reference temperature distribution of the battery pack (10) in the longitudinal direction (12) of the battery pack (10); measuring the temperatures of the individual battery cells (20) during operation of the battery pack (10) when the temperature control means (30) is switched on, and forming an actual temperature distribution of the battery pack (10), in the longitudinal direction (12) of the battery pack (10), on the basis of the measured temperatures of the individual battery cells (20); comparing the actual temperature distribution with the reference temperature distribution and forming a profile of a difference between the actual and the reference temperature distribution; and identifying an ineffective temperature control state of the temperature control means (30) based on the difference between the actual and the reference temperature distribution exceeding a predefined threshold value.

2. The method according to claim 1, further comprising: identifying one or more battery cells (20) that are temperature-controlled in an ineffective manner by the temperature control means (30), on the basis of the profile of the difference between the actual and the reference temperature distribution.

3. The method according to claim 1, wherein the reference temperature distribution is set by setting a temperature control performance of the temperature control means (30) and/or through design of a structure of the temperature control means (30).

4. The method according to claim 1, wherein the battery cells (20) are mechanically and thermally connected to the temperature control means (30) in a materially bonded manner.

5. The method according to claim 1, wherein the battery cells (20) are each monitored by specifically one temperature sensor.

6. The method according to claim 1, wherein the temperature control means (30) has a channel-type structure for conveying a temperature control medium.

7. The method according to claim 1, wherein the temperature control means (30) is realized as a Peltier element.

8. A battery management system for diagnosis of a temperature control means (30), the batter management system comprising: a battery pack (10) having a plurality of battery cells (20) and a plurality of temperature sensors for measuring temperatures of the individual battery cells (20), the battery cells (20) being arranged side by side in the battery pack (10), in a longitudinal direction (12) of the battery pack (10), and connected to each other, the battery cells (20) being arranged on the temperature control means (30) and connected to the temperature control means (30), wherein the connection includes a thermal connection, the battery management system including an electronic controller programmed to determine a reference temperature distribution of the battery pack (10) in the longitudinal direction (12) of the battery pack (10); measure the temperatures of the individual battery cells (20) during operation of the battery pack (10) when the temperature control means (30) is switched on, and forming an actual temperature distribution of the battery pack (10), in the longitudinal direction (12) of the battery pack (10), on the basis of the measured temperatures of the individual battery cells (20); compare the actual temperature distribution with the reference temperature distribution and forming a profile of a difference between the actual and the reference temperature distribution; and identify an ineffective temperature control state of the temperature control means (30) based on the difference between the actual and the reference temperature distribution exceeding a predefined threshold value.

9. A battery pack (10) for diagnosis of a temperature control means (30), comprising: a plurality of battery cells (20), the battery cells (20) being arranged side by side in the battery pack (10), in a longitudinal direction (12) of the battery pack (10), and connected to each other, a plurality of temperature sensors for measuring temperatures of the individual battery cells (20), the temperature control means (30 connected to the battery cells (20) arranged on the temperature control means (30), wherein the connection includes a thermal connection, and a battery management system that includes an electronic controller, the battery pack (10) configured to determine, with the electronic controller, a reference temperature distribution of the battery pack (10) in the longitudinal direction (12) of the battery pack (10); measure, with the electronic controller, the temperatures of the individual battery cells (20) during operation of the battery pack (10) when the temperature control means (30) is switched on, and forming an actual temperature distribution of the battery pack (10), in the longitudinal direction (12) of the battery pack (10), on the basis of the measured temperatures of the individual battery cells (20); compare, with the electronic controller, the actual temperature distribution with the reference temperature distribution and forming a profile of a difference between the actual and the reference temperature distribution; and identify, with the electronic controller, an ineffective temperature control state of the temperature control means (30) based on the difference between the actual and the reference temperature distribution exceeding a predefined threshold value.

10. A vehicle, which comprises at least one battery pack (10) according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are explained in greater detail on the basis of the drawings and the following description.

(2) FIG. 1 shows a flow diagram of the method according to the invention, and

(3) FIG. 2 shows a schematic diagram of a battery pack.

DETAILED DESCRIPTION

(4) In the following description of the embodiments of the invention, elements that are the same or similar are denoted by the same references, and in individual cases description of these elements is not repeated. The subject-matter of the invention is represented only schematically in the figures.

(5) FIG. 1 shows a flow diagram 100 of the method according to the invention for diagnosis of a temperature control means 30 (see FIG. 2) of a battery pack 10 (see FIG. 2), which a plurality of battery cells 20 (see FIG. 2) and a plurality of temperature sensors for measuring the temperatures of the individual battery cells 20.

(6) In a first step 101, firstly, a reference temperature distribution of the battery pack 10 in a longitudinal direction 12 (see FIG. 2) of the battery pack 10 is determined.

(7) Then, in a second step 102, the temperatures of the individual battery cells 20 during operation of the battery pack 10 are measured, when the temperature control means 30 is switched on. An actual temperature distribution of the battery pack 10 in the longitudinal direction 12 of the battery pack 10 is formed, based on the measured temperatures of the individual battery cells 20.

(8) After that, in a step 103, the actual temperature distribution is compared with the reference temperature distribution. In this case a profile of a difference between the actual and the reference temperature distribution is formed.

(9) Then, in a step 104, an ineffective temperature control state of the temperature control means 30 is identified if the difference between the actual and the reference temperature distribution exceeds a predefined threshold value. Preferably, the predefined threshold value may be set.

(10) After that, in a step 105, there is identification one or more battery cells 20 that are temperature-controlled in an ineffective manner by the temperature control means 30. The battery cells 20 that are temperature-controlled in an ineffective manner by the temperature control means 30 have a higher than expected temperature. These battery cells 20 are identified by the profile of the difference between the actual and the reference temperature distribution.

(11) Preferably, the method according to the invention is executed by means of a battery management system for monitoring and controlling the battery pack 10. It is also conceivable for the method according to the invention to be executed by another control unit such as, for example, a vehicle control device (VCU: vehicle control unit).

(12) Preferably, following the identification of an ineffective temperature control state of the temperature control means 30, and/or following the identification of one or more battery cells 20 that are temperature-controlled in an ineffective manner by the temperature control means 30, a service procedure is initiated in order to investigate or check, for example, whether connection points between the respective battery cells 20 and the temperature control means 30 is defective, or whether the temperature control means 30 is defective.

(13) A battery pack 10 is represented schematically in FIG. 2.

(14) The battery pack 10 in this case comprises a plurality of battery cells 20. FIG. 2 shows nine battery cells 20, namely, as viewed from the right, a first battery cell 21 to a ninth battery cell 29. The battery cells 20, 21 to 29 are in this case arranged side by side in the battery pack 10, in a longitudinal direction 12 of battery pack 10, and are mechanically connected to each other. The battery cells 20, 21 to 29 are arranged on a temperature control means 30, and are mechanically and thermally connected to it by an adhesive layer 40.

(15) The battery cells 20, 21 to 29 in this case may also be mechanically and thermally connected to the temperature control means 30 by welding or soldering.

(16) The battery cells 20, 21 to 29 are each realized as a lithium-ion battery cell and are prismatic.

(17) The temperature control means 30 has a channel-type structure (not represented), which serves to convey a temperature control medium such as, for example, water. The temperature control means 30 in this case has a supply connection 31 for supplying the temperature control medium, and has a discharge connection 32 for discharging the temperature control medium.

(18) It is also conceivable for the temperature control means 30 to be realized as a Peltier element.

(19) For the battery pack 10 represented in FIG. 2, a reference temperature distribution is determined, which has such a distribution pattern that the temperature in the battery pack 10 drops from a central region of the battery pack 10 to respective peripheral regions 14 of the battery pack 10 when the temperature control means 30 is switched on. In the present embodiment, the fifth battery cell 25, which is arranged in a central region of the battery pack 10, has a highest temperature in the battery pack 10.

(20) The battery pack 10 additionally comprises a plurality of temperature sensors (not represented) for measuring the temperatures of the individual battery cells 20, 21 to 29. Preferably, the battery cells 20, 21 to 29 are each monitored by specifically one temperature sensor.

(21) During operation of battery pack 10, the temperatures of the individual battery cells 20, 21 to 29 are measured when the temperature control means 30 is switched on. Based on the measured temperatures of the individual battery cells 20, 21 to 29, an actual temperature distribution of battery pack 10 in the longitudinal direction 12 of battery pack 10 is formed.

(22) A profile of a difference between the actual and the reference temperature distribution is then formed by comparison of the actual the and reference temperature distribution.

(23) It can be seen from FIG. 2 that the adhesive layer 40 has a defect 50 in an region between the third battery cell 23 and the temperature control means 30, which results in an impairment of a thermal connection between the third battery cell 23 and the temperature control means 30. The defect 50 may in this case be caused by ageing of the adhesive layer 40, high temperatures of the battery cells 20, 21 to 29, an accident or a material defect. In this case, less heat is transferred from the third battery cell 23 to the temperature control means 30, or from the temperature control means 30 to the third battery cell 23, and the third battery cell 23 has a higher than expected temperature.

(24) A difference between the measured temperature of the third battery cell 23 and a temperature resulting from the reference temperature distribution of the battery pack 10 is represented by means of the profile of the difference between the actual and the reference temperature distribution.

(25) If the difference between the measured temperature of the third battery cell 23 and a temperature resulting from the reference temperature distribution of the battery pack 10 exceeds a given threshold value, an ineffective temperature control state of temperature control means 30 is identified.

(26) If the battery cells 20, 21 to 29 are each monitored by specifically one temperature sensor, a position at which the thermal connection between the third battery cell 23 and the temperature control means 30 is impaired can be identified.

(27) The invention is not limited to the design exemplary embodiments described here and to the aspects highlighted therein. Rather, within the range indicated by the claims, a large number of variations are possible, which are within the scope of professional practice.