EMC measurements on batteries
We support you in every aspect of electromagnetic compatibility relating to the battery – from battery development and its EMC qualification and acceptance to final type approval.
In electric vehicles, the traction battery not only supplies energy to the electric drive train, it also provides power to practically all of the electrified systems. However, this key role also makes the battery susceptible to electromagnetic interference, while at the same time it can also emit interference signals itself. Due to the specific properties of batteries, carrying out EMC tests on them can be a major challenge – but not for Mooser.
about
We test batteries of all sizes and look forward to new challenges!
Electromagnetic interference in traction batteries
High-voltage batteries are highly complex systems, and their electromagnetic compatibility has many facets. On the one hand, internal interference emissions can cause interference within the batteries themselves. One example of this is DC/DC converters, which operate using pulse width modulation and can therefore generate interference emissions.
On the other hand, external disturbances can couple into the traction battery and cause irregularities there or be passed on to other components. Such external disturbance might come from the inverter, for example. Its interference signals can radiate through the battery and the HV/LV interface to the low-voltage vehicle electrical system. For this reason, the battery should have a high level of immunity to interference in order to prevent coupled interference from triggering safety shutdowns or generating error memory entries.
Battery measurement - methods of measurement, measuring technology, infrastructure and standards for testing
OEMs wish batteries that are very robust and which have been comprehensively tested. As the preferred EMC partner for OEMs, we at Mooser can not only provide the optimum measuring facilities, but also have the necessary expertise at our disposal. We benefit from the fact that a high-voltage battery essentially has to meet the same legal and OEM-specific EMC requirements as all other automotive components – and EMC is our core competence.
In principle, the requirements and measurement methods that apply to a battery are the same as those for, say, an airbag control unit. Examples include interference immunity tests, coupling with the current injection probe (as defined in ISO 11452-4) or pulses on LV systems. Other well-known testing and measurement standards for traction batteries are documented in CISPR25 as well as in ISO 7637-2 and ISO 7637-3.
What is more, the testing of high-voltage systems also has to comply with additional standards, and these are supplied to the EMC service provider by OEMs in the form of specifications. For example, these may require tests on HV/LV coupling or voltage fluctuations in the high-voltage range. Batteries, however, are a largely constant source of voltage, which means that generating voltage fluctuations is difficult. For that reason, we have specialist testing equipment that can couple pulsed or continuous sinusoidal voltage fluctuations into the battery, as defined in ISO 7637-4, for example.
Another special feature of the traction battery is that it forms an interface between the vehicle and the power grid. Therefore, it is necessary to apply both the ECE standards of the automotive world and the CE standards of the stationary power grid. ECE Regulation R10, which applies to type approvals, requires that standard automotive methods of measurement be performed. Added to these are methods for measuring the charging and discharging process. As an interface to the power grid, the battery also has to meet requirements such as surge, burst orand lightning protection from the power grid affect the battery.
Measurement technology and infrastructure for measurements on traction batteries
A unique feature of modern traction batteries is their dimensions and weight. At Mooser, we have already tested batteries that are 2.4 metres long and 1.5 metres wide and which weigh almost a tonne.
But we have the right infrastructure for this: our measuring chambers have floors with a high load-bearing capacity, doors that are big enough, lifting devices that can handle such heavy weights, and heavy-duty test benches. We also have a storage warehouse that is specially designed for storing traction batteries.
Other special equipment for battery tests includes DC power units for charging and electronic or passive loads for discharging. These loads are defined together with the customer before the tests are performed and are then integrated into the test set-up in the form of high-impedance resistors and capacitors.
With the same flexibility, we can also select the upper and lower limits of the battery state of charge . And what are also very important are extremely high-performance power amplifiers in the low-frequency range, which are used for coupling alternating interference.
Expertise and organizational structure at the highest level
Alongside our comprehensive testing hardware, another equally important aspect of our company is the way in which we maintain and perfect our soft skills for battery tests. Our continuous involvement in national and international standardisation committees helps to reinforce Mooser’s high level of expertise in EMC, which is widely recognised throughout the industry. For example, ISO 7637-4 and the voltage tests defined in it are largely based on Mooser’s work, as are the contents of CISPR 25.
A major benefit for the customer is our special method of handling projects. A fully qualified Mooser engineer is individually assigned to take responsibility for each project. This engineer functions as the fixed contact partner and oversees the project from start to finish. He or she will have many years of professional experience and has been comprehensively trained by us to perform this task. For example, our project and laboratory engineers receive training in high-voltage applications every year, which enables and qualifies them to carry out high-voltage EMC tests.
Mooser is also one of just a few testing service providers who are certified to assess the tested battery before delivery. This evaluation includes a visual check and a list of the most important battery parameters documented in an outbound merchandise log.
Service for all aspects of traction battery measurements
Our engineers have a wealth of experience gained from many hundreds of customer projects, ensuring that they can already show the customer some initial specific steps towards a solution shortly after the problem has been defined. Typical customer requests are EMC measurements according to international standards and/or OEM requirements. Somewhat more specific are inquiries about limit values being exceeded in emission measurements or influences on individual battery parameters, for example. Another possibility is measuring the shielding effectiveness of the battery housing.
One fundamental approach is to carry out an examination of the entire EMC layout to determine, for example, whether measures to suppress interference have perhaps been applied incorrectly or have not been applied at all. If there is uncertainty about antenna interference or if decoupling values are found to be poor, we can first measure all the relevant EMC parameters before suggesting and, if necessary, implementing measures to optimise the set-up on that basis. These might include changing the design of the traction battery layout or the wiring, or simply using different screws, for example, which can have a significant effect on minimising disturbances.
Another source of risk is the lack of shielding attenuation. In this case, measuring the attenuation values of the battery housing, which is usually a two-part component, may provide some initial insights. Have suitable materials been used for the base tray and the cover? Are sufficient screw connections provided? Are the contacts ideal? Once these questions have been answered, Mooser will be able to suggest the optimum solution.
Mooser will be able to suggest the optimum solution. For batteries, this service includes, for example, carrying out measurements of the relevant parameters, applying optimisation measures and handling the entire approval procedure in cooperation with the German Federal Motor Transport Authority.
Frequently asked Questions
High-voltage batteries are highly complex systems, and their electromagnetic compatibility has many facets. On the one hand, internal interference emissions can cause interference within the batteries themselves. One example of this is DC/DC converters, which operate using pulse width modulation and can therefore generate interference emissions
On the other hand, external disturbances can couple into the traction battery and cause irregularities there, or they can be passed on to other components. Such external disturbance might come from the inverter, for example. Its interference signals can radiate through the battery and the HV/LV interface to the low-voltage vehicle electrical system. For this reason, the battery should have a high level of immunity to interference in order to prevent coupled interference from triggering safety shutdowns or generating error memory entries.
Another special feature of the traction battery is that it forms an interface between the vehicle and the power grid. Therefore, it is necessary to apply both the ECE standards of the automotive world and the CE standards of the stationary power grid. ECE Regulation R10, which applies to type approvals, requires that standard automotive methods of measurement be performed. Added to these are methods for measuring the charging and discharging process. As an interface to the power grid, the battery also has to meet requirements such as surge, burst and lightning protection.
A high-voltage battery essentially has to meet the same legal and OEM-specific EMC requirements as all other automotive components. Therefore, in principle, the requirements and measurement methods that apply to a battery are the same as those for, say, an airbag control unit. Examples include interference immunity tests, coupling with the current injection probe (as defined in ISO 11452-4) or pulses on LV systems. Other well-known testing and measurement standards for traction batteries are documented in CISPR25 as well as in ISO 7637-2 and ISO 7637-3.
What is more, the testing of high-voltage systems also has to comply with additional standards, and these are supplied to the EMC service provider by OEMs in the form of specifications. For example, these may require tests on HV/LV coupling or voltage fluctuations in the high-voltage range. Batteries, however, are a largely constant source of voltage, which means that generating voltage fluctuations is difficult. For that reason, we have specialist testing equipment that can couple pulsed or continuous sinusoidal voltage fluctuations into the battery, as defined in ISO 7637-4, for example.
When it comes to measuring traction batteries, it is essential first of all to ensure that the parameters of the testing facilities are correct: measuring chambers with floors that have a high load-bearing capacity, doors that are big enough, lifting devices that can handle such heavy weights, and heavy-duty test benches. We also have a storage warehouse that is specially designed for storing traction batteries. After all, some batteries can be more than 2 metres long and 1.5 metres wide and can weigh up to a tonne.
Mooser has the optimum measuring facilities for carrying out battery tests, such as its eCHAMBER®, absorber chambers and shielded chambers, as well as measuring stations for battery electronics. Other special equipment includes DC power units for charging and electronic or passive loads for discharging. These loads are defined together with the customer before the tests are performed and are then integrated into the test set-up in the form of high-impedance resistors and capacitors. With the same flexibility, Mooser can select the upper and lower limits of the battery state of charge. . And what are also very important are extremely high-performance power amplifiers in the low-frequency range, which are used for coupling alternating interference.
One fundamental approach is to carry out an examination of the entire EMC layout to determine, for example, whether measures to suppress interference have perhaps been applied incorrectly or have not been applied at all. If there is uncertainty about antenna interference or if decoupling values are found to be poor, Mooser can first measure all the relevant EMC parameters before suggesting and, if necessary, implementing measures to optimise the set-up on this basis. These might include changing the design of the traction battery layout or the wiring, or simply using different screws, for example, which can have a significant effect on minimising disturbances. Another source of risk is the lack of shielding attenuation. In this case, measuring the attenuation values of the battery housing, which is usually a two-part component, may provide some initial insights. Have suitable materials been used for the base tray and the cover? Are sufficient screw connections provided? Are the contacts ideal? Once these questions have been answered, Mooser will be able to suggest the optimum solution.
Mooser engineers have a wealth of experience gained from many hundreds of customer projects, ensuring that they can already show the customer some initial specific steps towards a solution shortly after the problem has been defined. Typical customer requests are EMC measurements according to international standards and/or OEM requirements. Other requests are for support in battery development. Individual aspects include, for example, compliance with EMC limit values, interference suppression solutions, optimum cable routing or component design.
In addition to these development-related services, Mooser also carries out type approvals on the component or system level on behalf of its customers. For batteries, this service includes, for example, carrying out measurements of the relevant parameters, applying optimisation measures and handling the entire approval procedure in cooperation with the German Federal Motor Transport Authority.
Other services relate to the qualification or approval of batteries on behalf of customers.
