Monitoring battery-cell parameters via CAN

The Emast shaker table by Bertrandt is used in the Volkswagen factory in Chattanooga (US) to test batteries for electric-powered cars.

The multi-axes shaker table for high-voltage batteries enables the simulation of a life cycle. In the Volkswagen facilities, the six table actuators generate 71 171 Newton. The shaker system simulates vibrations equivalent to 14 484 km driving under varying temperature conditions. Operating loads from real-test drives are used as the basis for testing. In this way, the loads experienced by a high-voltage battery in the vehicle are simulated in a realistic way.

The rig at the U.S. Volkswagen facilities provides acceleration shocks from 16 g to 998 kg in a thermal range of -40 °C to +70 °C. The host controller of the vibration simulation system collects the cell parameters via the CAN interface of the battery pack. The system is capable of rapid load cycles, charging at 1 kV (900 kW) at 800 A and discharging at 350 A. On a 5-m² surface, loads of up to 850 kg can be achieved at up to 100 Hz in all six spatial axes. In order to simulate cold winter and hot summer climate conditions, the system can be cooled to -55 °C and heated to +90 °C.

The tested batteries can be continuously loaded with a voltage of up to 1200 kV and a current of ±1 kA at a total power output of 400 kW. The internal temperature control circuit of the high-voltage battery can be continuously adjusted from -40 °C to +150 °C. To detect abnormalities as early as possible, the system can be operated 24 hours at seven days. In the event of mis-function, the cooling and deletion process ensure safe operation and enable a subsequent diagnosis of the battery.

hz