Test of Battery Junction Box (BJB) in electric vehicles
Module of the Battery Management in electric cars
Battery Junction Box (BJB) is a switching unit for the battery in an electric vehicle. It connects or disconnects the components in the vehicle, which need energy from the battery.
With one or more bus interfaces, this component is networked with the entire vehicle. The BJB is usually a switching box that switches the high-voltage connection on or off. It ensures that the high voltage is only applied to the necessary contacts when the ignition is switched on.
In these vehicles the high voltage can be up to 1000 VDC. The BJB has a safety function: in case of danger it disconnects the high-voltage battery from the electrical system including all electrical components of the vehicle.
For example, in the event of an accident it must be ensured that no high voltage is present in the vehicle in an uncontrolled state in order not to expose rescue workers to any danger.
Competences for BJB from GOEPEL electronic
With an End-of-Line test system (EOL test) for Battery Junction Boxes we bring safety into the electric vehicle.
All necessary functions of the BJB component are checked by the EOL tester. For example, the correct on/off switching of the high voltage switching elements is tested.
The safety shutdown of the high voltage is checked with a simulated crash pulse. With the aid of a corresponding load simulation the current capacity of all high voltage paths is tested.
We create the residual bus simulation of the automotive network environment according to the specifications of the project and implement it in the test. This is the only way to ensure correct communication with the DUT during the test. The BJB is contacted by an automated handling system.
Since the energy storage is powered with high voltage, also the BJB is connected to these voltages. An insulation voltage test is therefore absolutely necessary as a safety test with a correspondingly high test voltage.
This high voltage can be up to 4000 V DC.
With our test systems for the high-voltage test of the Battery Junction Box, we prove the insulation voltage resistance and a required insulation resistance.
With a function test for the Battery Junction Box we check all functions of this component. The test system provides voltages up to 1000 V DC and 50 A in the high-voltage range.
These power supplies simulate a battery. With the simulated battery the on/off switching of the high voltage switching elements as well as their current carrying capacity is checked at the BJB.
The crash shutdown function of the Battery Junction Box serves as a safety function and is used to disconnect the battery from the vehicle's high-voltage network in case of danger. The test of this function is performed with a specially generated crash impulse, the parameters of which can be flexibly adjusted.
One component of the Battery Junction Boxes is the so-called insulation monitor, which must also be tested. Up to 1000 A flow through the BJB during normal operation. In order to check these, the current carrying capacity is realized by measuring the contact resistances. The measurement technology is designed in such a way that contact resistances in the µOhm range are monitored with sufficient accuracy. In addition, the test system performs the residual bus simulation.
We realize hard- and software for the adjustment of high current sensors, which measure currents between -800 A DC and +800 A DC.
These are sensors which record the current consumption from the storage and provide it to other components in the vehicle.
This hardware and software can be integrated into function test systems.