Related to "hybrid vehicles due"

Description:

Microwave heating is very popular for quick and selective digestion of materials in various industries e.g. Food and feed, Pharmaceutical, Chemistry, Environmental, etc. In these application, the sample is mixed into an acid mixture and heated to high temperature, up to 250 or 300???C. However, spontaneous heating of acid mixture induces exothermic reaction resulting into very rapid change in temperature and pressure.

Therefore, faster and accurate monitoring of temperature and pressure is crucial in minimizing safety risks. Fiber optic sensors for temperature and pressure measurement have been widely successful in microwave assisted digestion applications due their immunity to electro magnetic field within the microwaves.

Related Keyphrases:

acid mixture induces exothermic reaction | digestion applications due | minimizing safety risks | pressure measurement | selective digestion | accurate monitoring | Fiber optic sensors | high temperature | various industries | Pharmaceutical | magnetic field | temperature | Environmental | rapid change | spontaneous

Description:

Temperature management is one of the most important part in the design, development and testing process of electric / hybrid vehicles. The performance and aging of all critical components of electric vehicle highly depend on the temperature distribution and developing hot spots within. Therefore,  faster and accurate temperature measurement is necessary at each stage of EV product development e.g. individual component level testing for identifying performance limits and temperature behavior of individual components, and fully assembled electric vehicles to ensure the overall performance and safety.

Electric / Hybrid vehicle design and architecture differs a lot from the traditional Petrol and Diesel vehicles. The shift from low voltage to high voltage (up to 1000V) connections and operations within the similar vehicle space (or some time lesser space) bring challenges in terms of safety, limited access and electromagnetic noise issues during testing and measurements. Fiber Optic technology based sensors e.g. Fiber Optic Temperature sensors are becoming more and more popular in testing Electric / Hybrid vehicles due to their immunity to electromagnetic field, ruggedness, smaller size, faster response, high accuracy and safety of operation.

Related Keyphrases:

Fiber Optic Temperature sensors | accurate temperature measurement | electromagnetic noise issues | individual component level | temperature distribution | Hybrid vehicle design | Fiber Optic technology | similar vehicle space | individual components | Temperature management | EV product development | Hybrid vehicles due | electric vehicles | electromagnetic field | overall performance

The eMobility sector is going through its transformation phase. With the increasing focus on electric vehicle from the public and private sector, every player in the eMobility industry is working relentlessly on increasing the performance of the electric vehicle with higher efficiency, larger capacity and reduced size. The only objective of all this research and development is to make electric vehicle at par or even better than IC engines at a lower cost.

High Voltage EV Batteries, being the most critical component of the electric vehicle are the ones that are focused most for capacity enhancement, performance optimization and Cost/size reduction. Researchers in the entire value chain of EV Battery, Cell, Module and Pack level are constantly working on fast charging and capacity enhancement projects.

Introduction:

Battery thermal management is one of the most critical aspect in the design and development of EV Batteries for fast charging and capacity enhancement projects. The crucial steps involved in battery thermal management are first identifying the source of the heating, second localizing the weak points in the design and then finally managing thermal issues either with design changes or with better cooling mechanism. This article is mainly focused on Benefits of fiber optic sensor in core temperature monitoring of cylindrical cell.

Why Temperature Monitoring:

Under the fast charging (3C, 4C and more) and discharging (6C, 8C or more) cycles cylindrical cells face tremendous electrochemical and mechanical stress. As a result of these continuous stress, Cells heat up internally and heat gets transmitted to the outer surface in radial and axial directions. It becomes very crucial to understand the stress handling capability of cells under different operating conditions. The EV battery cells must be designed for a wide range of ambient and automotive operating conditions. Identifying thermal issues accurately, during the product development stage and mitigating them effectively is the key for avoiding the huge cost of product recall.  

Benefits of Fiber Optic Temperature Sensors:

Engineers have been using very small thermocouples to measure the thermal profiling of cylindrical cell core. In order to avoid damage to the cell chemical due to the thermocouples, the sensors are coated with a complex and expensive chemical isolation. The isolation process is complex and still not a full proof solution for safe and accurate temperature measurement of cell core. Therefore, Fiber Optic Temperature Sensors are the most suitable alternative to the thermocouples due to the following features of fiber optic sensors: 

  1. Ultra-Small footprint (0.4mm) to fit into Cell Core. This will ensure minimal damage to the mechanical structure of the cylindrical cell.
  2. Safety: Fiber optic sensors are made of silica, Polyimide, Gallium Arsenide (GaAs) crystal and very small Epoxy. Any of the constituents of the complete sensor does not pose any risk to the cell chemical.
  3. Accurate and Noise Free readings – The sensors have an accuracy of ±0.2???C (relative) with 100% repeatability. And this accuracy is not impacted by Strain / Pressure inside Cell.
  4. Wide Measurement Range: The rage of measurement is -269???C to +300???C.
  5. Higher Response Time: The sensors are capable of measuring with 5Hz to 30Hz sampling rate.
  6. Sensors Stability: These sensors are very stable under high electrical, Magnetic and Chemical fields.
  7. Lower cost of installation – The sensors do not need any expensive Isolation / coating. The sensors are also adjustable to fit at different locations inside the cell core.

How to install a Fiber Optic Temperature Sensor in Cylindrical cell Core?

Fiber Optic Temperature sensors can be installed either at the cell formation stage or afterwards. It is simple to fit the sensors during the cell formation stage compared to the fitting sensor on a manufactured cell core. Figure 1 below shows the detailed view of how the Fiber Optic Temperature Sensor installed into Cylindrical Cell Core.

 

  1. Bare Fiber Optic Sensor                                    b) Fiber Optic Sensor with Disposable Tip


                       Figure. 1 Fiber Optic Sensor installed inside the EV Battery Cell

During Cell Formation Stage:

This is a simple approach where Fiber Optic Temperature Sensor can be placed at the core of the cylindrical cell while the assembly process of the cell, before the formation stage. This will require to drill a hole in the cathode cap of the cell. After the formation process, the cathode cap opening must be sealed with silicone sealant, epoxy or Kapton tape.

Into Manufactured Cell:

To install a Fiber Optic Temperature sensor on the readymade Battery cell, requires the use of a drill and glove box. Firstly, it will require to disassemble approximately 8 to 10 cells to find out the internal structure of the cell type. Once the internal structure of the cell is determined a new cell can be placed on the Glove Box for drilling hole. The Glove box is used to prevent the exposure of cell internals to oxygen (O2) and moisture (H2O). A sharp and high precision drill is used to drill a small hole into the cell core. The hole must be as small as possible so that it does not impact the cell electrochemical behavior. Care must be taken while drilling the hole to avoid short circuit and protect the electrode jellyroll.

The easiest option for drilling hole is, open the cathode and drill hole on the plastic protection and insert the fiber optic sensor inside the core. The opening must be sealed with special glue and tape to make it hermetically sealed without damaging the Fiber Optic Temperature Sensor.

Disposable Caps (made of Polyimide material) can also be used to fit into the hole first and then insert the fiber optic temperature sensor, as shown in Figure 1 (b) above.

The fiber optic temperature sensors than can be connected to the monitor for temperature measurement and trending. The monitor has flexibility to record the temperature data, display time-stamped trending and export data to third party systems. The monitor supports industry-standard protocols i.e. High-Speed CANBUS, Modbus, DNP3.0 and comes with drivers for major development environments i.e. Matlab, LabView and python. The below figure 02 shows the sensors and monitor installation.

 Conclusion:

The Fiber Optic Temperature Sensor is the most suitable sensors to use inside the battery cell for Cell Core temperature monitoring. The process of installing the fiber optic temperature sensors is easier than the one used for traditional sensors because fiber optic temperature sensors do not require any isolation. With higher accuracy, repeatability and response of fiber optic temperature sensors, it has become possible to understand better the chemical process inside and identify the real causes of temperature increase. It was found from multiple experiments that the Cell Core temperature is mostly higher than the cell body temperature and the difference is not constant but varies with the charging and discharging rate. The core temperature is maximum during the end of charging and discharging. The difference between the core and cell body temperature could be anywhere from 1???C up to 8???C.

Temperature monitoring of the core cell becomes very critical for fast charging applications. The outcomes of the Cell Core temperature monitoring are being used for battery modelling, Battery Management System and thermal protection of battery cell, module and the entire pack. The accurate Core Cell temperature ensures that thermal safety limits are set correctly to avoid thermal runaway issues.


Description:

The eMobility sector is going through its transformation phase. With the increasing focus on electric vehicle from the public and private sector, every player in the eMobility industry is working relentlessly on increasing the performance of the electric vehicle with higher efficiency, larger capacity and reduced size. The only objective of all this research and development is to make electric vehicle at par or even better than IC engines at a lower cost.

High Voltage EV Batteries, being the most critical component of the electric vehicle are the ones that are focused most for capacity enhancement, performance optimization and Cost/size reduction. Researchers in the entire value chain of EV Battery, Cell, Module and Pack level are constantly working on fast charging and capacity enhancement projects.

Introduction:

Battery thermal management is one of the most critical aspect in the design and development of EV Batteries for fast charging and capacity enhancement projects. The crucial steps involved in battery thermal management are first identifying the source of the heating, second localizing the weak points in the design and then finally managing thermal issues either with design changes or with better cooling mechanism. This article is mainly focused on Benefits of fiber optic sensor in core temperature monitoring of cylindrical cell.

Why Temperature Monitoring:

Under the fast charging (3C, 4C and more) and discharging (6C, 8C or more) cycles cylindrical cells face tremendous electrochemical and mechanical stress. As a result of these continuous stress, Cells heat up internally and heat gets transmitted to the outer surface in radial and axial directions. It becomes very crucial to understand the stress handling capability of cells under different operating conditions. The EV battery cells must be designed for a wide range of ambient and automotive operating conditions. Identifying thermal issues accurately, during the product development stage and mitigating them effectively is the key for avoiding the huge cost of product recall.  

Benefits of Fiber Optic Temperature Sensors:

Engineers have been using very small thermocouples to measure the thermal profiling of cylindrical cell core. In order to avoid damage to the cell chemical due to the thermocouples, the sensors are coated with a complex and expensive chemical isolation. The isolation process is complex and still not a full proof solution for safe and accurate temperature measurement of cell core. Therefore, Fiber Optic Temperature Sensors are the most suitable alternative to the thermocouples due to the following features of fiber optic sensors: 

  1. Ultra-Small footprint (0.4mm) to fit into Cell Core. This will ensure minimal damage to the mechanical structure of the cylindrical cell.
  2. Safety: Fiber optic sensors are made of silica, Polyimide, Gallium Arsenide (GaAs) crystal and very small Epoxy. Any of the constituents of the complete sensor does not pose any risk to the cell chemical.
  3. Accurate and Noise Free readings – The sensors have an accuracy of ±0.2???C (relative) with 100% repeatability. And this accuracy is not impacted by Strain / Pressure inside Cell.
  4. Wide Measurement Range: The rage of measurement is -269???C to +300???C.
  5. Higher Response Time: The sensors are capable of measuring with 5Hz to 30Hz sampling rate.
  6. Sensors Stability: These sensors are very stable under high electrical, Magnetic and Chemical fields.
  7. Lower cost of installation – The sensors do not need any expensive Isolation / coating. The sensors are also adjustable to fit at different locations inside the cell core.

How to install a Fiber Optic Temperature Sensor in Cylindrical cell Core?

Fiber Optic Temperature sensors can be installed either at the cell formation stage or afterwards. It is simple to fit the sensors during the cell formation stage compared to the fitting sensor on a manufactured cell core. Figure 1 below shows the detailed view of how the Fiber Optic Temperature Sensor installed into Cylindrical Cell Core.

 

  1. Bare Fiber Optic Sensor                                    b) Fiber Optic Sensor with Disposable Tip


                       Figure. 1 Fiber Optic Sensor installed inside the EV Battery Cell

During Cell Formation Stage:

This is a simple approach where Fiber Optic Temperature Sensor can be placed at the core of the cylindrical cell while the assembly process of the cell, before the formation stage. This will require to drill a hole in the cathode cap of the cell. After the formation process, the cathode cap opening must be sealed with silicone sealant, epoxy or Kapton tape.

Into Manufactured Cell:

To install a Fiber Optic Temperature sensor on the readymade Battery cell, requires the use of a drill and glove box. Firstly, it will require to disassemble approximately 8 to 10 cells to find out the internal structure of the cell type. Once the internal structure of the cell is determined a new cell can be placed on the Glove Box for drilling hole. The Glove box is used to prevent the exposure of cell internals to oxygen (O2) and moisture (H2O). A sharp and high precision drill is used to drill a small hole into the cell core. The hole must be as small as possible so that it does not impact the cell electrochemical behavior. Care must be taken while drilling the hole to avoid short circuit and protect the electrode jellyroll.

The easiest option for drilling hole is, open the cathode and drill hole on the plastic protection and insert the fiber optic sensor inside the core. The opening must be sealed with special glue and tape to make it hermetically sealed without damaging the Fiber Optic Temperature Sensor.

Disposable Caps (made of Polyimide material) can also be used to fit into the hole first and then insert the fiber optic temperature sensor, as shown in Figure 1 (b) above.

The fiber optic temperature sensors than can be connected to the monitor for temperature measurement and trending. The monitor has flexibility to record the temperature data, display time-stamped trending and export data to third party systems. The monitor supports industry-standard protocols i.e. High-Speed CANBUS, Modbus, DNP3.0 and comes with drivers for major development environments i.e. Matlab, LabView and python. The below figure 02 shows the sensors and monitor installation.

 Conclusion:

The Fiber Optic Temperature Sensor is the most suitable sensors to use inside the battery cell for Cell Core temperature monitoring. The process of installing the fiber optic temperature sensors is easier than the one used for traditional sensors because fiber optic temperature sensors do not require any isolation. With higher accuracy, repeatability and response of fiber optic temperature sensors, it has become possible to understand better the chemical process inside and identify the real causes of temperature increase. It was found from multiple experiments that the Cell Core temperature is mostly higher than the cell body temperature and the difference is not constant but varies with the charging and discharging rate. The core temperature is maximum during the end of charging and discharging. The difference between the core and cell body temperature could be anywhere from 1???C up to 8???C.

Temperature monitoring of the core cell becomes very critical for fast charging applications. The outcomes of the Cell Core temperature monitoring are being used for battery modelling, Battery Management System and thermal protection of battery cell, module and the entire pack. The accurate Core Cell temperature ensures that thermal safety limits are set correctly to avoid thermal runaway issues.


Related Keyphrases:

Fiber Optic Temperature Sensors | Cell Core temperature monitoring | accurate Core Cell temperature | cell body temperature | EV Battery CellDuring Cell Formation Stage | 1 Fiber Optic Sensor | Bare Fiber Optic Sensor | cell electrochemical behavior | accurate temperature measurement | Cylindrical cell Core | cell formation stage | readymade Battery cell | fiber optic sensors | cell chemical due | fiber optic sensor inside

Thermocouples are widely used in automotive industry for temperature testing at product design and EOL (End of Line) stages and for permanent monitoring afterwards. However, with the increasing voltage levels in Emobility thermocouples possess many risks in product design and testing stages. Some of them are safety related risk and have potential to be life threatening for employees (research and test engineers).

Thermocouples are based on the principles, that a small voltage (in milli-volts) gets produced when a junction (joint) of two dissimilar metal wires is cooled or heated. The generated voltage signal is measured at the other end of the metal wires and calibrated for the temperature range. During the temperature testing the junction end is put on the test object and voltage is being measured at the other end to estimate the temperature of test object.

Now imagine if the two metal wires are put on the 1000 V Battery or Motor for temperature testing and somehow the test engineers touch the wire by mistake. Even worse how accurate will be the milli-volt signal when it passes through an environment where there is high electric and magnetic field.

Without getting into more technicality let us take a closer look on the common reasons why thermocouples have failed in Emobility testing and should be replaced with intrinsically safe sensors.

1. Safety

safety It is very obvious and common sensical thing to find out the safety risk of using thermocouples in Emobility testing, especially when test engineers have to adjust sensing location such as finding the right hot spot or reach to the measuring points that are not easily accessible (Inverters, Stator Windings, Battery Cooling duct). Thermocouples are subject to creating a short circuit and electrocution risks to the employees.


2. Noise

noiseWith the Emobility going towards 1000V and even higher 2500V (for commercial vehicles), thermocouples are highly susceptible to noise. The milli-volt signal requires lot of isolation under such large voltages and even then, the signal is not clear enough to measure accurate temperature.



3. Larger Size  

larger sizeThermocouples are not suitable for Emobility applications that has very tiny space for putting sensors such as Charging Points, Invertor IGBTs, Battery Inter-cell temperature measurement etc. It has been observed that thermocouples are less responsive and inaccurate (up to 20 to 30 Deg Celsius) if they are not put directly on the charging points. 


4. Non-Linearity Over The Range  

Non-Linearity Over The RangeThough the thermocouples are calibrated for a certain range, they still need complex compensation algorithm to maintain linearity over the range since they are being used at harsh conditions (High electric, chemical and magnetic fields) and different test environments.



5. Longer Response Time  

FLonger Response Time aster and accurate measurement is critical for Emobility during the performance, life cycle and abuse testing. Not only the accuracy, thermocouples are also limited by the response time requirements of Emobility applications such as detection of Thermal Runaway Issues, Charging Point Temperature, Stator Winding Temperature etc.


6. Poor Repeatability 

Poor Repeatability Thermocouples are made of two dissimilar metallic wires and susceptive to material purity which varies from batch to batch and manufacturer to manufacturer. This variation creates calibration issues resulting into non-repeatability of accurate measurements. Further the chemical composition of metal changes with time especially if they are put into chemical environment like Batteries.


Description:

Thermocouples are widely used in automotive industry for temperature testing at product design and EOL (End of Line) stages and for permanent monitoring afterwards. However, with the increasing voltage levels in Emobility thermocouples possess many risks in product design and testing stages. Some of them are safety related risk and have potential to be life threatening for employees (research and test engineers).

Thermocouples are based on the principles, that a small voltage (in milli-volts) gets produced when a junction (joint) of two dissimilar metal wires is cooled or heated. The generated voltage signal is measured at the other end of the metal wires and calibrated for the temperature range. During the temperature testing the junction end is put on the test object and voltage is being measured at the other end to estimate the temperature of test object.

Now imagine if the two metal wires are put on the 1000 V Battery or Motor for temperature testing and somehow the test engineers touch the wire by mistake. Even worse how accurate will be the milli-volt signal when it passes through an environment where there is high electric and magnetic field.

Without getting into more technicality let us take a closer look on the common reasons why thermocouples have failed in Emobility testing and should be replaced with intrinsically safe sensors.

1. Safety

safety It is very obvious and common sensical thing to find out the safety risk of using thermocouples in Emobility testing, especially when test engineers have to adjust sensing location such as finding the right hot spot or reach to the measuring points that are not easily accessible (Inverters, Stator Windings, Battery Cooling duct). Thermocouples are subject to creating a short circuit and electrocution risks to the employees.


2. Noise

noiseWith the Emobility going towards 1000V and even higher 2500V (for commercial vehicles), thermocouples are highly susceptible to noise. The milli-volt signal requires lot of isolation under such large voltages and even then, the signal is not clear enough to measure accurate temperature.



3. Larger Size  

larger sizeThermocouples are not suitable for Emobility applications that has very tiny space for putting sensors such as Charging Points, Invertor IGBTs, Battery Inter-cell temperature measurement etc. It has been observed that thermocouples are less responsive and inaccurate (up to 20 to 30 Deg Celsius) if they are not put directly on the charging points. 


4. Non-Linearity Over The Range  

Non-Linearity Over The RangeThough the thermocouples are calibrated for a certain range, they still need complex compensation algorithm to maintain linearity over the range since they are being used at harsh conditions (High electric, chemical and magnetic fields) and different test environments.



5. Longer Response Time  

FLonger Response Time aster and accurate measurement is critical for Emobility during the performance, life cycle and abuse testing. Not only the accuracy, thermocouples are also limited by the response time requirements of Emobility applications such as detection of Thermal Runaway Issues, Charging Point Temperature, Stator Winding Temperature etc.


6. Poor Repeatability 

Poor Repeatability Thermocouples are made of two dissimilar metallic wires and susceptive to material purity which varies from batch to batch and manufacturer to manufacturer. This variation creates calibration issues resulting into non-repeatability of accurate measurements. Further the chemical composition of metal changes with time especially if they are put into chemical environment like Batteries.


Related Keyphrases:

two dissimilar metal wires | two dissimilar metallic wires | Emobility thermocouples | permanent monitoring afterwards | generated voltage signal | temperature measurement | complex compensation algorithm | Emobility applications | Stator Winding Temperature | Charging Point Temperature | response time requirements | test engineers touch | temperature range | accurate measurements | accurate measurement

Description:

Thermocouples are widely used in automotive industry for temperature testing at product design and EOL (End of Line) stages and for permanent monitoring afterwards. However, with the increasing voltage levels in Emobility thermocouples posses many risks in product design and testing stages. Some of them are safety related risk and have potential to be life threatening for employees (research and test engineers).

Researchers and testing experts in Emobility have seen the following major challenges with using Thermocouples for temperature testing in high voltage applications.

  1. Safety: Thermocouples are subject to creating a short circuit and electrocution risks to the employees.
  2. Noise: With the Emobility going towards 1000V and even higher 2500V (for commercial vehicles), thermocouples are highly susceptible to noise.
  3. Linearity: Though the thermocouples are calibrated for a certain range, they still need complex compensation algorithm to maintain linearity over the range
  4. Response Time: Thermocouples are not fast enough and accurate for thermal profiling of key components of Electric Vehicles such as Charging Points, Battery, Motor Windings and Power Electronics.
  5. Repeatability: Thermocouples are made of two dissimilar metallic wires and susceptive to material purity which varies from batch to batch and manufacturer to manufacturer.

Related Keyphrases:

permanent monitoring afterwards | complex compensation algorithm | two dissimilar metallic wires | Emobility thermocouples | electrocution risks | commercial vehicles | automotive industry | rangeResponse Time | Electric Vehicles | major challenges | product design | material purity | voltage levels | Charging Points | key components