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How do I find the best connector for applications in the electric car?

  Rutronik

Fully electric vehicles require a number of different connections: Individual Lithium-ion-modules are connected together to form a battery storage system. In addition, various drive systems, converters, auxiliary modules, and charging and monitoring systems have to be combined and connected to work correctly.

The corresponding vehicle connector for this purpose not only has to meet automotive requirements such as contact position assurance (CPA) / terminal position assurance (TPA) or secondary locking, but also those relating to electrical safety features. These include finger safety or the ability to shut the system down before a dangerous state is allowed to develop – for instance, by means of a high-voltage interlock loop (HVIL).

 

Achieving the balance between safety and costs

However, every safety feature requires more or better materials – and this means higher material and development costs. In order to find the ideal balance between safety and price, developers should ask themselves the following questions:

  • Precisely how much power must the cable in question carry?
  • What kind of locking system the connector need to have?
  • Is it a must to be able to work on a module during servicing?
  • How important is it to prevent the mixing up of several modules?

 

The answers to these questions will determine the princing of a connector.

 

Nonetheless, selecting the right connector is not easy, because every place of operation and every application on an electric vehicle demands different things – sometimes it involves a particularly small installation space and low weight, while other times it’s about maximum power and high resistance. Consequently, the portfolios featuring modified connectors that offer good value for money are constantly growing in size. Since no standards have yet been established, the range of products available is becoming increasingly confusing. Here are some recommendations:

 

Several connector versions for electric vehicles

Amphenol has a particularly interesting product range for electric vehicles. Most vehicle connectors are based on RADSOK™ technology, which guarantees contact coverage of up to 65 percent of the contact surface area. For many other features, Amphenol supplies several versions so that the right solution is available for every application:

  • The electromagnetic shielding covers only one single contact, only the entire connector, or both.
  • The Ingress Protection rating extends up to IP6K9K when connected. There are also connector models featuring an additional interlock, secondary locking, keying and color variations.
  • The number of poles can also be selected to suit the application: The Powerlok™ series features single-pole products through to four-pole products, in metal and plastic and in various coding configurations and colors.
  • Contact diameters ranging from 2.8mm to 14mm tolerate currents of up to 650A that may arise directly in a distribution box, in the motor control unit, and on the drive systems. The distribution box can be made electrically safe for currents of up to 630A with the aid of the MSD (Manual Service Disconnect) series.

 

Rugged connector system

The Imperium™ High Voltage / High Current (HVHC) connector system from Molex can withstand more heavy shocks and vibrations than any other available product. The connectors are currently available in diameters measuring 8.00mm and 11.00mm. New configurations are in development – they will demonstrate how Imperium connectors can be repackaged to meet customer-specific requirements.

 

No standard connector

A hot topic in the area of electric cars is the typical connector, although there is as yet no typical design! Most commonly used in Europe is the Mennekes plug, or type 2 plug (IEC 62196-2 and IEC 62196-3). The model that is the very epitome of the electric car – the Tesla – is also charged using a Mennekes plug. This is available as the HVCO series from Amphenol, for example.

 

In Asia, where most of the world’s electric cars can be found, the CHAdeMO standard is primarily used. This is already designed for bidirectional charging. The manufacturer JAE supplies corresponding models in the form of the KW01 and KW02 series. They offer a high degree of reliability with a rust-resistant contact as well as a flame-retardant and weather-resistant resin element and cable. The KW02 series is compatible with V2H (vehicle-to-home), which allows the battery in the electric car to be simultaneously used as an energy storage system to supply power back to the home. Both series are available as complete cable assemblies.