EMI Suppression Filters (EMC and Noise Suppression)Case: Solving the issues involved with wireless power transfer

What we really need is to be able to see noise that’s invisible! What are the secret strategies that have solved the wireless power transfer issues that people in the industry are talking about?


“Let’s use our own expertise to the full! It’s our decision that wireless power transfer, which everyone is talking about now, will feature in our next mainstay products.”

Company K, a manufacturer of AC adapters, had to wrestle on a daily basis with the competition to reduce the production costs of its AC adapters—a kind of product for which it is hard to create distinctive differences in terms of function.

Let’s use our own expertise to the full! It’s our decision that wireless power transfer, which everyone is talking about now, will feature in our next mainstay products.

Company K was looking for new mainstay products to replace AC adapters, which offer only small profit margins, and was approached by a leading supplier to discuss the possibility of supplying, on an OEM basis, wireless power transfer systems compliant with Qi standards, which are international standards. On the market, the demand for wireless power transfer as a new power-charging method is increasing hand in hand with the rapid spread of tablets and smartphones.

Company K eagerly accepted the challenge and proceeded with development, fully aware both that wireless power transfer systems were experiencing rapid growth and that there were merits inherent to the company being able to use the technology and expertise it had accumulated during its production of AC adapters.

“We decided to go with wireless power transfer as our next mainstay product. But there was a major stumbling block to achieving this that we didn’t see at the time.”

Using the information acquired from IC manufacturers and other sources and its own expertise, the company fabricated some prototypes and started to evaluate them. However, no matter how many evaluations it performed, problems arose, including a deterioration in the reception sensitivity of the sound and data communications and an increase in the radiation noise. The company tried to make improvements, but as a company with no knowledge about suppressing noise generated by wireless power transfer, it could not meet the requirements of the leading supplier on its own.

At a total loss, Company K consulted with the manufacturers of the components used in its project, among others, to find ways of suppressing the noise, but no advice or information was forthcoming, and it was unable to come up with actual noise suppression measures.

Although the company was able to envision the framework of the wireless power transfer main units, it was unable to see how it could deal with the noise problem at all, and the project came to a complete standstill.

Main points of the issues:

  1. Multiple noise problems arose, but the company did not know of any specific means that could be used to suppress the noise.
  2. It consulted with the manufacturers of the components it was using, but did not receive any concrete suggestions for ways to suppress the noise.
How can we solve this problem?