GOTHENBURG, SWEDEN -- Volvo Car Corp. said the Volvo V60 Plug-in Hybrid , due to launch on the market in 2012, has been undergoing a series of in-house safety tests – some of which are designed specifically to evaluate vehicles with an electric powertrain.
"We apply the same high safety standards to all our products but the safety-related challenges may differ depending on the driveline and fuel being used," explained Jan Ivarsson, senior manager of safety strategy and requirements at Volvo Car Corp. “To us, electrification technology is another exciting challenge in our quest to build the safest cars on the market."
Volvo Cars said it is currently conducting wide-ranging analysis of a variety of safety scenarios for cars with electric power. The task involves advanced automatic monitoring of battery status and also encapsulating the battery and protecting it effectively in a collision.
"It is understandable that a lot of questions about electrification safety are related to what will happen in an accident, but it is important to have a holistic approach including all the aspects of day-to-day usage of the car," Ivarsson said. “A holistic, human-centric approach and real-life traffic conditions are always the starting point for our safety work. Based on our massive database with input from actual road incidents and accidents, we know where the focus must lie in everyday traffic conditions. The solutions we have developed for the V60 Plug-in Hybrid take into account the situations that are unique to this type of car.”
The automaker indicated it is using its know-how from actual traffic conditions to carry out detailed testing and verification. This test procedure also includes the general requirements and protocols of the industry's safety institutes.
When analyzing traffic situations from a safety perspective, engineers use a model that illustrates the sequence of events during the whole driving phase. The process is divided into five phases -- from the normal driving situation to after the accident has occurred.
All safety systems in the Volvo V60 will also be available in the plug-in hybrid version. However, electric power also adds new possible safety scenarios to the overall picture and these too must be dealt with.
According to Volvo, the automaker’s safety experts have meticulously analyzed the five accident sequence phases and developed solutions for the battery and for protection of the occupants as necessary.
1. Normal driving: An advanced monitoring system keeps watch and ensures that each cell maintains the correct voltage level and optimal operating temperature by regulating the cooling system. This is of significance to safety as well as for battery capacity. In the event of any deviation, the battery is automatically shut down as a preventive measure.
2. Conflict: The battery pack adds weight that can create new conditions for the vehicle's dynamics and alter the car's behavior -- for instance, in fast avoidance maneuvers. The Volvo V60 braking system is designed to handle the increased mass, and DSTC (Dynamic Stability and Traction Control) helps the driver contain the situation.
3. Avoidance: If a frontal collision is imminent and the driver is acting too late to brake the car, the V60 Plug-in Hybrid can activate automatic systems such as Collision Warning with Full Auto Brake and City Safety to help avoid or reduce the effects of a collision.
4. Collision: In order to reduce the effects of a collision, the safety experts have focused on protecting all electrical components. The rear structure has been modified to ensure a controlled deformation that helps protect the battery pack, which is located under the load floor. Steel beams and other parts of the structure are reinforced. The battery pack is also sturdily encapsulated.
The electrical system in the V60 Plug-in Hybrid is monitored by two systems:
- Crash sensors linked to the battery measure the physical collision forces. At the very moment of collision, they send information about the collision to the car's computer, which automatically shuts off the power supply
- Insulation measurement reacts on deviations in the electrical system. The contactors are opened immediately to brake the power if an earth fault is detected.
If the battery is damaged, resulting in gas leakage, there are special evacuation ducts that lead the gas out under the car. In the event of extreme heat, the occupants are shielded by the battery's encapsulation.
5. After the collision: Volvo works together with emergency rescue services and provides them with detailed instructions on how to safely make sure that the power supply is disconnected before the rescue work begins.
The high voltage in the battery is separated from the car. All high voltage cables are orange to make them easy to identify.
Volvo's safety tests take place in Volvo's crash test facility in several different stages – both virtually in the computer and physically at the automaker’s crash test center.
"The V60 Plug-in Hybrid will go through the same test program as all our new car models. This includes full-scale crash tests with different load cases, such as frontal collision, rear and side collisions to confirm that the battery technology fulfills our stringent safety requirements," Ivarsson said.
The test program includes component tests of the battery pack. The results are used to determine how the collision forces affect the battery -- and how much damage it can withstand before power must be cut in an accident.
"We have decades of experience in how to protect a fuel tank in a collision,” Ivarsson explained. “Now we are building up the same knowledge when it comes to protecting batteries. The tests provide both ourselves and the battery supplier valuable input in the continuous product development.”