HEV Aux Power Grounding
HEV Aux Power Grounding
(OP)
I am working on a hybrid electric vehicle application. The electrical system will put out some auxiliary power (30kW) to use for various loads. Most of the power will be used when the vehicle is stopped (not during vehicle propulsion) but some will be used on-the-fly.
My question is ... Are there any best practices for grounding the HEV electrical system when the vehicle is parked and the power is being drawn for external use?
My question is ... Are there any best practices for grounding the HEV electrical system when the vehicle is parked and the power is being drawn for external use?
Vince Socci
www.ontargettechnology.com





RE: HEV Aux Power Grounding
I have seen HEV systems where there is a potential divider system to the vehicle body (i.e. high value resistors are connected from each side of the battery to the vehicle body). The purpose of this is to detect when there is an earth fault on either side of the battery, because the voltages across the resistors no longer balance. In the case of a fault there is a contactor in the battery management system which opens to isolate the battery output.
RE: HEV Aux Power Grounding
You are also allowed to use a vehicle that is listed for the purpose as a parallel power production source but you have to have a listed cogeneration transfer switch with a control relay that disconnects from the utility when the utility power fails. Your hookup has to be approved by the utility for safety and power quality reasons.
Previous editions of NEC did not allow this.