Introducing the conductive emission nightmare.

The title of this chapter may sound familiar if you had a similar experience.

It can be a nightmare to fix a problem like conductive emission if you don't know what the root cause of the problem is. Fortunately for our customer, we had a clear understanding of what the issue was and what steps to take to resolve it.

As a result of our unique approach, we are able to assure our customers with an accuracy of 99%.

It is worth mentioning that we do our pre-compliance EMC testing with only one EMC testing house. This is in order to ensure that a problem is solved if one arises. Having worked with them for many years, there has now been a great deal of trust and professionalism between the two of us.

It is our main objective to make sure that our customers are able to pass the EMC exam!

To ensure that all our tests can be conducted in a controlled environment, we book one or two days at their lab. This will enable us to carry out all of our tests. As a result, it will be possible for the EMC lab in which the test will ultimately be performed to have this possibility. It is our recommendation that our customers use the same EMC twin lab for all their EMC testing. In addition, they should acquire their CE/FCC/UK CA marks from the same lab whenever they conduct the final EMC testing for us.

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Having conductive emission issues is one of the most common issues that can occur on an electric vehicle charger. A large part of the reason is the use of a highly efficient DCDC converter, which at some point returns to neutral or to earth. There are many different issues that can arise as a result.

Due to our experience, however, we know how to "reduce the efficiency" of a DCDC converter and, therefore, reduce emissions. We solved the problem in just a few hours of work.

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As we looked at the return path, we kept an eye out for the maximum value that we could have on the capacitors for Y and X in the return path. Because we didn't want the value of the Y capacitor to exceed 4.7 nF, we also began to investigate the possibility of increasing the impedance of the DCDC converter between the earth and the converter.

We can achieve this within some limits. This is because you, the reader, probably already know that there is one kHz signal whose return is the earth. If any impedance is added on this side, it may solve some issues. However, on the other side, it may degrade the pilot signal just enough that we would have encountered some problems in some cars.

As a result of this, we did a simulation, very similar to the one the author has described in this article. After we convinced ourselves that the solution could have worked, we moved ahead and implemented it. it worked!

The happiness of our customers cannot be expressed in words. After the fix was applied and the final layout change was made, they were able to get the EMC fully tested. As far as we know they are currently selling their product. We wish them all the best in their future endeavours.