MEDIA RELEASE
Cable Design for Hybrid Electric/Fuel Cell Vehicles as it relates to OEM and Harness Maker
Requirements
The innovative hybrid/electric vehicle designs present specific challenges to high voltage
cables and system components that only partially relate to existing solutions:
Voltage
Basic difference to conventional cables is that constructions need to be designed for operating
voltages up to 600volts for automobiles while commercial vehicles and busses use voltages that
can go up to values as high as 1000V.
By contrast, currently used cable for cars activated by a combustion engine are designed for the
use up to 60V.
High voltages lead to a reduction of the power loss (Ploss = I*R) of the system due to the use of
lower currents while keeping the resulting power (P = U*I) constant.
Transmission of high currents
As the cables connect battery, power electronics box and electric motor high currents need to be
transmitted by the high voltage cables. Depending on the power capacity of system components
currents can reach values of 250 through 450Amps.
A transmission of currents at these high levels cannot be found on conventionally activated
vehicles.
Temperature requirements
The transmission of high currents results in high power dissipation and heating of the
components. As a consequence HV-cables have to be designed to withstand high temperatures. A
trend towards increasing temperature requirements can be seen especially in European (150°C
maximum operating temperature up to 180 °C). While the Asia market is focusing on 120 °C – 150
°C.
By contrast, current vehicles commonly use cables rated up to 105°C which is sufficient as long as
the cables are not used underhood or other areas that require resistance towards higher
temperatures.
If routed unfavorably through the hybrid vehicles – such as along the exhaust pipe to connect
battery in the back with motor in the front – an even higher temperature resistance for the HVcables might be specified by the OEMs.
LEONI Kabel GmbH
Stieberstraße 5 · Germany · 91154 Roth · Telefon +49(0)9171-804 2438 Telefax +49 (0)9171-804 2232 · helmut.kalb@leoni.com ·
LEONI Bordnetzsysteme GmbH
Flugplatzstraße 74 · Germany · 97318 Kitzingen · Telefon +49(0)9321-304 448 Telefax +49 (0)9321-304 232 · michael.frommberger@leoni.com ·
http://www.leoni-electromobility.com
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Service Life requirements
Cables for the automotive industry are normally designed for the use for 3000 hours at the
specified temperature class. This value is commonly used for long-term ageing tests in wellrecognized cable standards such as ISO 6722 and its multi-core equivalent ISO 14572. In the area of
HV-applications customer specific requirements can exceed 3000 hours and even reach values of
up to 12,000 accumulated operating hours at the specified temperature
Shielding effectiveness
Shielding of HV-cables is not necessary due to transmission properties as with coaxial cables but to
prevent or reduce radiation from cables, resulting from high switching frequencies in the system,
into surrounding components.
Unlike with gasoline activated vehicles a 3-phase alternating current becomes necessary to control
the electric motor of the HV-vehicle. The sinusoidal voltages are created by energy equivalent
square-pulse signals with different frequencies. The pulses can have steep edges at high
frequencies which lead to harmonic waves that emit energy into the surrounding areas. Solely by
using appropriate shielding methods EMI problems can be resolved.
In some cases the requirements for shielding effectiveness make the combination of different
shielding types essential.
Flexibility of HV-cables
In many cases the development of hybrid vehicles faces the challenge to incorporate additional
electric components in existing series platforms with the available packaging space designed for
standard gasoline engines and its components only.
Even without considering cabling, space constraints can be expected due to the additional
components. In addition, cables and connectors have to be routable through and mountable into
the available space.
Tight bending radii are very often the consequence that can hardly be achieved with standard
cables due to high bending forces inherent with the designs of these cables. To overcome this
issue high flexibility of the HV-cables is crucial. Only with flexible or highly flexible designs the
routing through the vehicle can be realized.
Flex endurance
Is it possible to overcome the space challenges due to the development of separate vehicle
platforms other challenges might need to be solved depending on the vehicle concept?
For instance, if electric motors are located closely to the moving parts of the vehicles, then due to
the continuous motion of the HV-cable it has to be designed to withstand a high amount of
bending cycles to ensure good flex endurance.
LEONI Kabel GmbH
Stieberstraße 5 · Germany · 91154 Roth · Telefon +49(0)9171-804 2438 Telefax +49 (0)9171-804 2232 · helmut.kalb@leoni.com ·
LEONI Bordnetzsysteme GmbH
Flugplatzstraße 74 · Germany · 97318 Kitzingen · Telefon +49(0)9321-304 448 Telefax +49 (0)9321-304 232 · michael.frommberger@leoni.com ·
http://www.leoni-electromobility.com
MEDIA RELEASE
Marking and Identification
Due to the increased risk because of the use of voltages at elevated levels various specifications
define that HV-cables need to be visually distinguishable from regular automotive cables by
specifying an orange insulation color – for example according RAL 2003. Depending on the cable
manufacturer the awareness of high voltages can be supported by special markings and/or
printings, such as “CAUTION! HIGH VOLTAGE 600V DC”.
Status quo Standardization
The challenges and requirements for HV-cables for hybrid and electric vehicle applications
mentioned above made it necessary to create new cable standards. Based on the common 60V
cable specifications standards are modified to comply with the needs for 600V cables, as it can be
seen with ISO6722.
Currently standardization for voltages bigger than 600V is subject of OEM’s as well as 1 Tier’s,
working groups and subcommittees.
About the LEONI group
The LEONI Group, which is market-listed in the German MDAX index, employs about
56,000 people in 34 countries and, with 87 subsidiaries, generated consolidated sales
of € 2.96 billion in 2010.
Contact person for journalists
LEONI Kabel GmbH
LEONI Bordnetz-Systeme GmbH
Dr. Helmut Kalb
Dr. Michael Frommberger
Stieberstraße 5
91154 Roth, Germany
Phone: +49 9171-804-2409
E-mail: helmut.kalb@leoni.com
Flugplatzstraße 74
97318 Kitzingen, Germany
Phone: +49 9321 304 6127
E-Mail: michael.frommberger@leoni.com
http://www.leoni-electromobility.com
LEONI Kabel GmbH
Stieberstraße 5 · Germany · 91154 Roth · Telefon +49(0)9171-804 2438 Telefax +49 (0)9171-804 2232 · helmut.kalb@leoni.com ·
LEONI Bordnetzsysteme GmbH
Flugplatzstraße 74 · Germany · 97318 Kitzingen · Telefon +49(0)9321-304 448 Telefax +49 (0)9321-304 232 · michael.frommberger@leoni.com ·
http://www.leoni-electromobility.com