The fight against electromagnetic interference 


We interviewed Emelie Berglund, PhD student in Electronic Systems at Lule√• University of Technology, about Green Transition North's sub-project 2 "Development of active filters for EMC"," which is about reducing electromagnetic interference (EMC) in electric drive systems. Power electronic systems generate interference, and the goal is to develop small, energy-efficient, and integrated filters for electrified transport systems. 


What research questions have you chosen? 
Our research questions aim to find methods to reduce electromagnetic interference generated in electrical drive systems. Active channelling filters are the focus in order to eliminate interference that can lead to electromagnetic emissions, but also to hardware damage. 


Why did you focus on this topic? 
In the past, passive filters have been used to suppress electrical interference. The problem with passive filters is that they take up large areas and can greatly increase the weight of the system. In electric vehicles, for example, weight is a very important aspect because it correlates strongly with the battery capacity, which determines how far you can drive on one charge. To solve this problem and at the same time fulfil the purpose of inhibiting interference, active (cancellation) filters have become a topic of research. 


Can you explain what electromagnetic compatibility (EMC) is and why it is a problem in electric drive systems? 
Electromagnetic compatibility (EMC) describes the electromagnetic nature of an electronic device. An EMC analysis examines, among other things, how the electromagnetic interference of the electronic device affects its own system and other adjacent electronic systems. It also examines how susceptible the device is to external electromagnetic interference, such as a lightning strike. In general, electronic devices with high switching frequencies, such as the drive system of an electric motor, cause electromagnetic emissions that can potentially further interfere not only with its own system but also with other nearby electronic systems. In industry, there is a need to reduce bearing damage, to which bearing currents contribute. Some types of bearing currents are generated by the electric drive system and can be eliminated by active channeling filters. 


What is the difference between passive filters and active filters when it comes to managing EMC? 
As mentioned earlier, when working with low frequencies and high powers, it is better to avoid passive filters as they can be very large. Therefore, active filters are considered as an alternative solution to reduce filter size. The challenges are size and the fact that passive filters can quickly become bulky when working with low frequencies and high power levels. Active filters can help reduce the filter size. 


What results do you hope to achieve? 
By designing and building active channelization filters, we hope to eventually suppress interference to the point where it does not affect the system itself or adjacent systems. 


Can you say something about possible challenges and obstacles? 
The challenge is to design, develop and implement high active channelization filters that are efficient enough to eliminate interference. 


What are the potential benefits for industry and society? 
The more society becomes electrified; the more potential sources of electromagnetic interference will arise. It is important that electronics work within their own system and with other systems, but also that they are not susceptible to interference. For an electrified society to function, the electronics must work. 


Otherwise, what could happen in the worst case? 
There are EMC problems that become a cost issue, such as bearing damage to electric motors caused by bearing currents. But there are also cases where electromagnetic interference has caused major problems, such as a car's ABS system being disrupted by a mobile phone in the car, causing the brakes to stop working. For an electrified society to function and be safe, the electronics must work.