Contactor Monitoring

5. Contactor monitoring

The battery system contains three contactors, to disconnect HV power supply while terminal 15 off.
The contactors are:
- precharge contactor
- plus contactor
- negative contactor

5.1 Contactor drive circuit monitoring

5.1.1 Contactor drive circuit- open / shortcut ground (P0ADD, P0AD9, P0AE4)

5.1.1.1 Monitoring strategy
This monitoring strategy checks the internal contactor hardware circuit.
A shortcut to ground or a open circuit can not be distinguished.

A malfunction is detected, if the contactor is controlled as open, while the internal hardware driver status is "close".

5.1.1.2 Enable conditions






5.1.1.3 Chart(s) and flowchart(s)






5.1.2 Contactor drive circuit- shortcut battery (P0ADC)

5.1.2.1 Monitoring strategy
This monitoring strategy checks the internal contactor hardware circuit.
This monitoring strategy will check, if the internal hardware driver status is closed, while the contactor is controlled as open.

5.1.2.2 Enable conditions






5.1.2.3 Chart(s) and flowchart(s)






5.2 High sophisticated German sensor check

5.2.1 Monitoring strategy
This monitoring strategy will check during start up if contactors or pack voltage sensors have a malfunction.
The intend of this monitoring strategy is to distinguish a malfunction in pack voltage measurement or at contactors side.
This monitoring strategy contains normally five states, in case of malfunction a sixth state is added, to point out the component with the malfunction.
- State 1: all contactors off
- State 2: control negative contactor to close
- State 3: control precharge contactor to close
- State 4: control positive contactor to close
- State 5: control precharge contactor to open

in case of malfunction
- State 6: control negative contactor to open

5.2.2 Enable conditions






5.2.3 Chart(s) and flowchart(s)






5.3 Contactors remains closed (P0AA1)

5.3.1 Monitoring strategy
This monitoring strategy checks if the contactors are closed while they are commanded open.
The BECM compares contactor pack voltage and battery pack voltage, if the voltages are different a contactor malfunction is detected (see Figure 5-3).






5.3.2 Enable conditions






5.3.3 Chart(s) and flowchart(s)






5.4 contactors are open during contactor are commanded closed (P0AA5, P0AA2)

5.4.1 Monitoring strategy
This monitoring strategy checks, if contactors are open while they are commanded close.
A malfunction is detected if contactor voltage value is zero while contactors should be closed (see Figure 5-4).






5.4.2 Enable conditions






5.4.3 Chart(s) and flowchart(s)