High-voltage Safety Concept

Table of Contents
High-voltage System Overview
Wiring and Connector Concept
High-voltage System Components
Thermal Management
High-voltage Safety Concept
Driving Mode Selection

Safety Measures
The high-voltage safety concept was modified for the Volkswagen ID.4. Some of these are carryover from the previous high-voltage concept.

Safety measure overview:
• Color coding of the high-voltage wiring and connectors
• Safety markings on all high-voltage components
• Accidental contact protection
• Emergency cut-out connections: Maintenance connector for high-voltage system Fuse on the A-pillar with a small “flag”
• Pilot line
• Insulation resistance monitoring
• Electrical isolation between high-voltage system and body (terminal 31)
• Active discharging
• Passive discharging
• Crash shutdown
• Monitoring of the high-voltage relays
• Short-circuit test
• Short-circuit shutdown
• Detection of open circuits in high-voltage wires

Marking

Color coding of the wiring and connectors
All high-voltage connectors and wiring are orange to make identification easier.

 

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Safety markings on all high-voltage components

All high-voltage components are marked with warning stickers.
There is an additional high-voltage warning on the lock carrier in the engine compartment with a yellow background.
These warning stickers are relevant for the vehicle safety inspection.

 
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Accidental Contact Protection

All high-voltage connectors are equipped with improved accidental contact protection (IPXXB+, touch-proof). A smaller test finger is used.

High-voltage potentials inside of the components are sealed off by a cover with coded screws and cannot be opened during service work.

Accidental contact protection has also been used inside the high-voltage battery.

The Electromagnetic Compatibility (EMC) filters are adapted to the individual requirements of the different high-voltage components.
They can be made of capacitors, restrictors or more complex circuitry.

 
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Shielding of the high-voltage wires is not required.
The EMC measures are implemented in the high-voltage components by the EMC filter.


Emergency Cut-out Connections

The emergency cut-out connections are the TW Maintenance Connector for High-Voltage System in the left side of the engine compartment,
and the SC28 Fuse 28 (on Fuse Panel C) on the left A-pillar.

The TW Maintenance Connector for High-Voltage System
disconnects terminal 30 A and pilot line.

 
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The fuse SC28 has a small “flag” on it. When removed, terminal 30 A is disconnected.
The small “flag” is attached to allow quick removal without tools.
The small “flag” can be replaced separately and the fuse is commercially available.

 
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Terminal 30 A (previously terminal 30 C) in the VW ID.4 supplies both the voltage for the high-voltage relay in AX2 High-Voltage Battery 1
and the supply voltage for the A19 Voltage Converter.
There is also a Bowden cable located in the trunk to release the charge plug if there is a problem.


Pilot Line and Insulation Resistance Monitoring

Pilot Line
The pilot line is now only routed to the TW Maintenance Connector.
It was removed from other areas because all high-voltage connectors have improved accidental contact protection.
It is monitored by the J840 Battery Regulation Control Module.

 
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A19 – Voltage Converter
AX2 – High-Voltage Battery 1
B298 – Positive Connection 2 (30) (in Main Wiring Harness)
J840 – Battery Regulation Control Module
SC28 – Fuse 28 (on Fuse Panel C)
TW – High-Voltage System Maintenance Connector
T32j – 32-pin Connector, Onboard Supply Connection, on AX2 High-Voltage Battery 1


Insulation Resistance Monitoring

The insulation monitoring checks the electrical isolation of the high-voltage potentials to the chassis.
When the value falls below a threshold of 510 kOhm, a yellow warning lamp illuminates on the instrument cluster.
A red lamp appears when the value falls below 90 kOhm. DC charging is either deactivated or prevented.

The insulation resistance monitoring is initiated by the J623 Engine Control Module and performed by the J840.
Among other things, it is part of highvoltage system activation, which is monitored by the high-voltage coordinator.
Its function and circuitry is similar to the insulation resistance monitoring in the e-Golf.


Active and Passive Discharging

Active Discharging
If there is an emergency shutdown of the high-voltage system, such as if a crash or the TW Maintenance Connector is removed, the high-voltage system is discharged within five seconds.
Active discharging is performed in the JX1 Electric Drive Power and Control Electronics.

Passive Discharging
High-voltage components have capacitors in their circuitry.
Passive discharge guarantees that the voltage falls to < 60 V within two minutes of disconnecting the components from the high-voltage battery.


Crash Shutdown

Following an accident that may damage components in the high-voltage system, the high-voltage system is shut down and actively discharged.

Because a number of high-voltage components in the Volkswagen ID.4 are installed very close to the outer body shell, severe and minor accidents are treated the same.
This means that in case of an accident, the high-voltage potential is immediately disconnected (by pyrotechnic means). This can be repaired in the workshop.

The pyrotechnic disconnection is performed by the S415 Fuse for High-Voltage Battery Interruption in the switching unit for SX7 High-Voltage Battery Control Module, Negative Terminal.

 
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Monitoring of the High-Voltage Relays and Short-Circuit Test

Monitoring of the High-Voltage Relays
• Each high-voltage relay has a voltage tap before and after the relay
• If an unintended condition is identified to be affecting one of the high-voltage relays, the high-voltage system is deactivated until the defect is eliminated
• A lamp is illuminated in the instrument cluster

Short-circuit Test
• When C25 Intermediate Circuit Capacitor 1 is being pre-charged, a current measurement is performed

Short-circuit Shutdown
• If a short circuit occurs during pre-charging, it is isolated and the high-voltage system is not activated
• If a short circuit is detected when the high-voltage system is already activated, the high-voltage system is turned off
• A lamp is illuminated in the instrument cluster