By Patrik Kalbermatten, KEMET
Compact nanocrystalline single-phase filters that suppress electromagnetic interference from the power provide engineers with greater design flexibility.
In our increasingly connected world, we are ever more dependent on electronic equipment and devices and the semiconductors contained within.
It is perhaps no surprise, then, to find that demand for components that can manage electromagnetic interference (EMI) – and radio-frequency interference (RMI) in the radio spectrum – is higher than ever before.
Indeed, according to a report by Verified Market Research, the global EMI/RFI filters market is currently valued at around $850 million and is expected to rise to almost $1.1 billion by 2027, growing at a compound annual growth rate of 3.56% over that period. And as the trend towards digitalization and electrification accelerates across industries such as manufacturing and automotive, so the spectrum of application for EMI/RFI filters is likely to become ever-more diverse.
EMI filter design considerations
So, let us look in greater depth at the role of EMI filters, before assessing the performance of some of the latest devices on the market. In general terms, EMI/RFI filters protect from interference occurring on the electrical signals or power lines, which can badly affect the electrical circuit of any device or equipment, impacting performance or eventually potentially leading to complete malfunction. This capability is primarily achieved by blocking out electromagnetic noise in the higher frequency range while allowing the desired lower frequencies to pass.
These components also help manufacturers meet strict electro-mechanical compatibility standards around the world, limiting the amount of noise a device can put back out into the AC grid. This applies to virtually all AC-connected devices from industrial machinery to medical devices and commercial equipment such as ATM cash dispensers to smaller white goods such as coffeemakers. EMI filters are, therefore, ubiquitous in the role and critical to performance.
Historically, one of the most common and effective types of EMI filters has been the common mode choke. Typically, these devices feature conductor windings coupled together via a ferrite core. Common mode toroidal chokes often come with a wide variety of characteristics, being designed with nanocrystalline metal cores that are useful in multiple noise countermeasure fields.
However, technology is moving forward at a rapid pace. More recently, plastic case filters catering to single-phase EMC requirements have come to the fore. Many of these latest-generation devices take advantage of patented refinements to soft nanocrystalline materials, resulting in optimized cores that can deliver some unique performance benefits.
More notably, these nanocrystalline materials offer higher permeability and lower losses than the ferrite variants found in traditional EMI filters. This allows for a compact and high-density design resulting in the highest attenuation capability and smallest volumetric package compared to other EMI filters previously available in the market.
Some nanocrystalline core devices are very small – with some measuring just 75 by 44 by 25 millimeters including the magnetics and capacitors – making them between 20% to 60% smaller than competitive filters using ferrite cores. Yet they are still capable of providing superior attenuation performance. These characteristics prove extremely valuable to design engineers, as they contribute to the ongoing trend towards the miniaturization of electronic devices.
Moreover, ferrite materials with higher magnetic permeability are effective in the lower frequency range, while those with lower magnetic permeability are effective in the higher frequency range. But the latest generation of metal nanocrystal materials is effective throughout a broadband frequency range, in low and high frequencies – therefore providing a highly flexible solution.
EMI filter innovation comes to market
So, what does this kind of research and development activity look like in terms of new product innovation? The latest single-phase filters (figure 1) provide design engineers with excellent noise attenuation in a small and lightweight package. The filters can be rated for up to 250 volts AC at 50 or 60 hertz and are available with current ratings ranging from 6 to 30 amps Often, they come packaged in a housing with screw terminals to provide ease and flexibility when wiring.
The newest devices include multiple class Y capacitor combinations that address different frequencies and support various inverter topologies. These combinations options have class Y capacitors on both the input and the output. The compact devices can operate from minus 25 degrees C to plus 55 degrees C, and they have UL, c-UL, and TUV approvals and are RoHS compliant.
These kinds of performance parameters mean that the latest single-phase filters are finding a broad range of applications across sectors. For example, industrial equipment, where they can be used in general-purpose inverters, factory automation, machine tools, and welders. Meanwhile, in medical equipment, they have been applied in a range of diagnostic equipment and even massage chairs.
GTX Series in action
Here at KEMET, the GTX series provides a solution for suppressing electromagnetic conductive noise on single-phase voltage lines in a compact and lightweight design (Figure 2).
High attenuation performance can be targeted at specific noise frequencies by selecting from 30 product variants according to rated current and desired Y-capacitor pattern (Figure 3).
The GTX-2060-***, for example, is rated at 6 A and can be selected in a variety of Y capacitor configurations. In an application where a 6 A rating is desired, the YXX variant would see peak attenuation at approximately 500 kHz, the Y22 at around 1 MHz, the Y0X at approximately 10 MHz, and so on.
Innovation in EMI/RFI filtering
In conclusion, then, there are high levels of innovation taking place in EMI/RFI filtering. Much of this activity results from concerted research and development efforts in recent years, resulting in new products for suppression of conduction noise on single-phase voltage lines. By employing advanced nanocrystalline core material, these filters achieve excellent attenuation characteristics in a compact plastic case, with the integrated Y capacitor combinations provide flexibility for any application.
Ultimately, this sort of innovation – combined with other products available – provides design engineers with the flexibility they need to ensure that EMI/RFI noise is always under control.
Patrik Kalbermatten is the Senior Manager – Distribution Promotion, Product Management MSABG – Magnetic, Sensor and Actuator, KEMET. Patrick is a graduate of The Graduate Institute of International Studies in Geneva, Switzerland. He has 13 years of experience in the electronics industry working in sales, distribution, marketing, and product management. Since 2013, he has lived in Tokyo, Japan. He enjoys bringing cultures together and finding out what makes something unique, which have been valuable assets in his work at KEMET Electronics.