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June 27, 2016

Dealing with EMC Filtering in Today's Electric and Hybrid Vehicles

Joseph Pulomena
Product Marketing Director, EPCOS, a TDK Group Company

Power Channels: Automotive Electronics, Energy Efficiency

Automobiles have changed significantly over the past 40 years from mechanical systems to computerized systems. As a result there is an increased need for electromagnetic compatibility (EMC) filters in today's electric and hybrid vehicles, also called e-vehicles.
    
The history

40 years ago in the mid-1970s, there were few, if any, computers or electronics in vehicles aside from the car radio. Prior to this time, engines had simple, mechanical designs and circuitry was too large to be practical for automobiles. However, the gas crisis in the late 1970s led automotive manufacturers to include solid state circuitry to control ignition timing, particularly as smaller engines became the norm. About 30 years ago in the 1980s, microchips were used as part of the creation of fuel injection and for other emissions system controls. As the 1990s came, on-board computing became the norm and these systems began to control more and more functions of vehicles. Around this time, most automobiles became too complex for the average car owner to fix.

Since the early 2000s and throughout the past decade, most automotive manufacturers began to include GPS, entertainment systems, advanced climate control and more as standard features. As a result, electronics and the on-board computer have become an essential performance-determining part of the vehicle.

Hybrid and Electrical Vehicles

Today's automotive manufacturers are creating dozens of electric and hybrid vehicles. The difference between yesterday's combustion vehicles with basic electronics and simple on-board computers, and today's fully computerized electric vehicles is an important one: Computers now control every aspect of an electrical vehicle.

Without on-board computing systems the vehicle won't operate. With good on-board computing systems the vehicle's passengers are safe.  They provide not only for the safety, comfort, and convenience of passengers, but they also power the electrical drive systems, high-voltage batteries, inverters, and at least one electric motor.

EMI/EMC filtering

As a result, there are potentially hundreds of things that can go wrong with e-vehicles and their computing systems. Electromagnetic interference (EMI) and the physical damage caused it can cause is one of the biggest. EMC components and filters help maintain the correct operation of the automotive communication networks and all the different equipment in common electromagnetic environments. And, EMC requirements are regulated by international standards such as CISPR 25 or the EU Directive ECE-R10.

Measurement setup according to CISPR 25

As a result, the biggest priority when developing e-vehicles is to ensure that the individual systems, crammed into very restricted spaces, do not cause mutual interference. Because of the unique design of electric vehicles design engineers must use electronic components that are able to withstand vibration, impact, and wide temperature ranges while reducing electromagnetic interference, voltage spikes and ground currents. It is critical for design engineers to ensure that no interference affects systems outside the vehicle. 

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