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CSM HV DTemp measurement system

High-voltage safe digital temperature measurement system for the development of high-voltage batteries

Patent pending

High-voltage batteries are of central importance for electric vehicles as an energy source. Their temperature behaviour must be studied in detail and temperature models must be verified. The new HV DTemp measurement system enables temperature measurements within high-voltage batteries in a completely new dimension.

Temperature measurement in a high-voltage battery with the CSM HV DTemp measurement system
Temperature measurement in a high-voltage battery with the CSM HV DTemp measurement system

Thermal Characterization of High Voltage Batteries and verification of models

Temperature measurements in the development of high-voltage batteries place special demands on the required number of temperature sensors, their exact positioning and the measurement accuracy. The solutions available to date quickly reach the limits of what is feasible.

The characterisation of HV batteries includes the analysis of the thermal behaviour of the individual battery cells and the entire battery assembly. To verify the temperature behaviour of a high-voltage battery prototype, precise temperature measurements during operation of the HV battery at several points between battery cells are therefore necessary to measure the temperature profile at cell level. Different measurement points between the individual battery cells must also be placed to detect hot and cold spots, which may be caused by the design geometry, mechanical stress or the cooling system.

The exact knowledge of temperature distribution and thermodynamics down to the cell level allows the validation of simulation models and the optimization of battery systems.

The most accurate temperature model of a HV battery is necessary during many production steps of vehicles and charging systems in order to control the corresponding procedures during vehicle operation (calculation of the charging process or the cooling capacity). How precisely the temperature model represents the HV battery is determined by the most accurate verification possible.

Requirements for temperature measurements in high-voltage batteries
  • Synchronous acquisition of up to several hundred measurement points inside and outside the HV battery, also between battery cells
  • Planned, flexible and reproducible arrangement of the measurement points
  • Very thin temperature sensors and sensor cables for placement between the battery cells
  • Minor impact to the structure of the battery housing by the supply lines
  • Low space requirement of the measurement system
  • Interference-free data acquisition and transmission with easy recognition of interference signals and errors
  • Ensuring high-voltage safety to protect measurement system and human operators.
  • Simple application, configuration and operation

The HV DTemp measurement system

The CSM HV DTemp measurement system is designed for the digital and precise measurement of up to 512 temperature measurement points via a single cable connection to the HV DTemp central unit. A HV DTemp measurement system consists of the three components HV DTemp-4 Sensor Modules, HV DTemp-M64 Controller Modules and HV DTemp-P Central Unit.

HV DTemp-P system overview
HV DTemp measurement system overview
HV DTemp-4 Sensor Modules
HV DTemp-4 Sensor Modules with single and group positioning between pouch-cells

HV DTemp-4 Sensor Module

Up to four IC (Integrated Circuit) temperature sensors are connected via digital bus to an HV DTemp-4 Sensor Module. The sensors are arranged individually on a ultra-thin flexible circuit film, or together on one film. The sensor size is in the mm range (W×D×H: 1.5 mm × 1 mm × 0.5 mm). The flexible circuit film design and the sensor position can be determined according to the application and customer-specific requirements. The ultra-thin flexible circuit film itself has a thickness of less than 0.8 mm. The SMD mounting of the temperature sensors on the film ensures exact transmission of the geometric arrangement of the temperature measurement points from the simulation. The ultra-thin flexible circuit film has geometric features that makes it easy to precisely align it with the cell of the HV battery, thus ensuring simple and accurate mounting of the temperature measurement points.

HV DTemp-M64 Controller Module

The HV DTemp-4 Sensor Modules are connected to a HV DTemp-M64 Controller Module. The HV DTemp-M64 Controller Module provides the addressing, power supply of the sensors and transmission of the temperature values to the HV DTemp-P Central Unit. The HV DTemp-M64 Controller Modules are very small (W×D×H: 48 mm × 87 mm × 0,75 mm) and can be installed inside the HV battery housing to save space. They offer connections for up to 16 HV DTemp-4 Sensor Modules, i.e. for up to 64 IC temperature sensors. Up to 8 HV DTemp-M64 Controller Modules can be easily cascaded. Thus 8 Controller Modules with 64 temperature sensors provides a maximum of 512 temperature sensors enabling a very thorough understanding of the battery thermal behavior.

HV DTemp-M64 Controller-Module
HV DTemp-M64 Controller Module
HV DTemp-P Central Unit
HV DTemp-P Central Unit

HV DTemp-P Central Unit

The HV DTemp-P Central Unit, to which the HV DTemp-M64 Controller Modules are connected via a touch-proof high-voltage connection cable (8 wires, Ø 8 mm), is located outside the HV battery. The HV DTemp-P Central Unit has two galvanically isolated inputs. Thus, temperatures from within two different high-voltage environments can be acquired. The 512 measurement points and HV DTemp-M64 Controller Modules can be divided between the two inputs. The communication of the HV DTemp-P Central Unit with the external measurement computer for the configuration of the measurement system and for data acquisition is done via CAN bus. Each measurement point is assigned its own CAN-ID, documented in a DBC description file. The temperature sensors can thus be clearly assigned and identified. The data transmission on the CAN bus is potential-free in "free running" mode.

The application of the HV DTemp measurement system

The layout of the ultra-thin flexible circuit film with digital temperature sensors can be tailored to the exact requirements of the measurement point arrangement within the high-voltage battery, individual cell modules, and between cells. The IC temperature sensors can also be used individually by connection cables in practically any desired arrangement. This allows very accurate measurements of temperature distribution, temperature paths, temperature profiles or hot spot areas.

For the application, the layout and arrangement of the IC temperature sensors are planned project-specifically in cooperation with CSM when several temperature sensors are to be arranged together on a flexible circuit film. The exact design of the film ensures a good and easy reproducibility of the arrangement from cell to cell.

Due to the low height of the HV DTemp-4 Sensor Modules, they can be pressed directly between the battery cells in the desired arrangement - therefore, including the ultra-thin flexible circuit film in the battery assembly process is possible.

In contrast to analog sensors, possible changes in the measured values due to interference on the measurement cables do not occur because the measured values are immediately and digitally transmitted from the sensor. In the worst case, of extreme interferences, no measured values are transmitted for a short time. As soon as these interferences have subsided, the system automatically resumes proper operation. The maximum measurement range is up to 125°C. The resolution of the measured values is 16-bit.

CSM HV DTemp-Messsystem overview
The CSM HV DTemp measurement system: HV DTemp-P Central Unit, HV DTemp-4 Sensor Modules with single and group positioning on ultra-thin flexible circuit film and HV DTemp-M64 Controller Module (from left to right).

Advantages of the HV DTemp measurement system

Key features

  • Use of IC temperature sensors on digital data bus
    • Miniaturized, highly accurate, robust, very immune to interference
    • Exact positioning and unique identification
    • Sensor arrangement flexibly adaptable to the measurement object
  • Very small space requirement for IC temperature sensors, controller and cables within the battery
    • Temperature measurement in places where it was previously not possible due to lack of space
    • Lowest possible influence on the measured object
  • Scalable up to 512 IC temperature sensors per CAN bus central unit
  • HV-safety up to 1000 V RMS

Advantages over analogue temperature measurement technology according to the current state of the art

  • Excellent suitability also for mobile use due to very little space requirement in the vehicle, as only one compact CAN measurement module is required outside the battery
  • Highly accurate, reproducible positioning of temperature sensors at cell level
  • No falsification of the measured values due to interference on the connecting cables
  • The digital sensor values are queried simultaneously

Advantages of use and benefits

  • Highly accurate temperature characterization of batteries and energy storage devices
  • Accurate verification of temperature models down to cell level
  • Precise localization of hot spot areas down to cell level
  • Simple setup of a measuring battery with up to 512 sensors
  • Simultaneous temperature measurements within two different high voltage areas. (i.e. two batteries or battery and inverter)
  • Only one high-voltage measuring cable out of the environment to the Central Unit outside
  • Customer-specific layout for sensor positioning on the ultra-thin flexible circuit film
  • Free arrangement of individual, digital temperature measurement points via cable
  • Geometric networking of the sensor technology can be easily planned
  • Exact repeatability of sensor positioning
  • Easy identification and allocation of the digital temperature sensors
  • Simple pressing of sensors between cells
  • Integration into a production process
  • Automatic sensor assignment in the measuring system
  • Simple combination with high-voltage and standard measurement technology from the CSM portfolio

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