Fuses for the automotive industry according to AEC-Q200

Fossil fuels are only available until they are exhausted and when they are burned, they release harmful gases. The role of the electric car is certain to be in our future. But even here, there are challenges ahead, especially when it comes to fuse protection of the battery.

In recent  decades, cars have increased  in numbers as well as dimensions.  They  have become more comfortable, more  powerful, safer and therefore heavier as  well, with mid-range cars already weighing 1.5 tons. It goes without saying that  a significant amount of energy will be  required to adequately power an electric  car of this class in the future.

Thousands of battery cells

This is achieved by interconnecting small  battery cells - size 4 VDC/3200 mAh per  cell - in parallel and in a row. 100 cells in  a row are needed to attain an operating  voltage of approximately 400 VDC. The  endurance, range and performance of  the overall package are then achieved by  connecting many of these 400 V strings in parallel.In very powerful electric vehicles,  several thousand cells are quickly  assembled in this way

Battery Balancing

Bearing in mind that thousands of such  battery cells are fitted in an electric  vehicle, the charging process is of great  importance. The cells must ultimately be  charged within the shortest amount of time  possible. The solution for this tricky task  is referred to as "Battery Balancing". This  describes an electronic circuit -  usually  part of a battery management system -  which ensures a steady even electrical  charge of numerous battery cells within  a battery pack, that are similar in their  construction but  with  slightly differing  manufacturing tolerances.

And this is how it works: The cells that  absorb energy very quickly are slowed  down a little. The weakest link in the chain  sets the pace during the charging process. Each cell needs to be handled  individually. This is the only way to use the  maximum capacitance of a battery pack  and to counteract any aging/weakening of  individual cells

Protect against a short circuit: Cell by  cell

Of course each individual cell in the  battery    pack    must    be    protected  against overcurrents. This takes several  thousand fuses per  battery pack,  depending   on   each   individual  one.  There is no tolerance for errors here. So  what demands are placed on this kind  of fuse? Complete reliability is key. Such  protection must work for at least 15 years  without any hitches. Fuses must perform  their function just as well in the coldest  of winters as in the sweltering heat.  Shock, vibration? Daily grind. Switching  on, switching off, accelerating - cyclical  strength is indispensable. The demands  made on these fuses are enormous.

AEC-Q200

Behind the acronym AEC (Automotive  Electronics Council) there     is a US-  based organization that focuses on the  standardization of the qualification of  electronic components in the automotive  supply industry.

The standard Q200, which was introduced  in the middle of the 1990s, describes the  requirements for passive components,  while standard Q100 and its spinoffs  concentrate on the active components.  These AEC standards are recognized  worldwide and are accepted by all the  leading manufacturers in the automotive  industry.

What about fuses in the context of AEC-Q200?

Specific tests and a set of specifically  defined requirements for for fuses used  in cars were not relevant throughout  automotive development history. However,  this has completely changed with the  introduction of electronic control units and  electric drives. Fuses will also be included  as a topic in the next update of the Q200  standard.

SCHURTER focused on  the  high reliability  requirements of the aerospace industry,  which were developed in cooperation with  ESA. This, together with the specifications  for other passive components according to  AEC-Q200, was also taken into account.  Test procedures were developed for fuses,  which meet the Q200 set of requirements,  by working in close cooperation with key  global players in the automotive industry.  Fuses manufactured in this way may  bear the unrestricted and internationally  recognized Q200 "seal of approval".

Competent contact

SCHURTER now  supplies  a  complete  range of  fuses for  the  automotive  industry in accordance with AEC-Q200,  supporting a wide variety of applications  (battery management, air conditioning,  close- coupled electronics for diesel  and petrol engines, and much more).  SCHURTER's close networking with  international automotive organizations  and the industry itself makes us highly  competent to address all issues relating  to the protection of electronics  in the  manufacturing of vehicles.