High Voltage Monitoring Systems Description

High Voltage Monitoring Systems Description

The hybrid system monitors several high voltage components for attempted access. Additionally, a minimum amount of resistance (isolation) is maintained at all times between both negative and positive poles of the hybrid battery and the vehicle chassis. The drive motor/generator power inverter module (PIM) microprocessors and the battery energy control module (BECM) monitor the hybrid system for access and loss of isolation detection.

High Voltage Interlock Loop (HVIL)

The HVIL circuit is a wire loop that passes through certain high voltage components. The HVIL circuit is used to determine if access to high voltage components is being attempted. The opening of these high voltage components causes the HVIL circuit to open. The hybrid system may react to the loss of HVIL continuity by opening the high voltage relays (contactors) and discharging the high voltage capacitors. The HVIL signal is generated by the BECM. The HVIL circuit status is monitored by each motor control module (MCM) as well as the hybrid control module (HCM) and the BECM.

High Voltage dc Chassis Isolation

The hybrid system monitors the electrical potential between high voltage and the vehicle chassis. High voltage should always be isolated from the vehicle chassis by a certain amount of resistance to avoid the potential for a life threatening current path. In the event that a high voltage leak path is detected to the vehicle chassis, the hybrid system will set a diagnostic trouble code (DTC) and take the appropriate action. High voltage DC chassis isolation is monitored by both the MCMs and the BECM.