Implementing HV interlock (Zombieverter)

[J0hannes]

Surprised to NOT find much discussion on the topic here.
At least in Finland, the rules/regulations are such that after vehicle modifications, HV interlock needs to be functional, meaning that HV will not be connected if loop is open.

Not sure if this is just too trivial that this hasn't sprouted a discussion, but I'll be the first then

Anyone implemented HV interlock in their conversion?
Should it be a feature in Zombie or would a passive system be"good enough"

Thinking out loud, why would this not work?
Supply the +12V for contactors through the interlock loop directly or as a relay control signal. If interlock is open, there would be a led lit to indicate interlock loop open. As for zombie, this way you'd have just a precharge fail as contactors won't close...

[Bigpie]

Using it to supply the contactors 12v using a relay on the negative contactor output on zombie is how I'd do it, unless you want to have a specific error in zombie for it. For me Precharge failed would be a sufficient error.

[LRBen]

I've been thinking about this in the last few days.

The downside to running it through one of the contactor control circuit is in the unlikely event of something coming loose when driving(Or even just a loose connection in the interlock circuit) you then cut contactors with current flowing, for some inverters that's not ideal.
Obviously if something is coming loose when we are driving then we don't want to be driving for very long.

Maybe we could run it through one of the inputs pins of zombie, either 12v or to ground depending on the input pin. Then have zombie check for that on the precharge cycle. If it happens during driving, either flag an error, or if you want to be aggressive with it force 0 torque. If we are running out of input pins it could be a seperate system sending canbus to zombie on the status of the interlock circuit.

[johu]

I run interlock only in A2. Super minimal. If you open the lid of the Prius inverter you cut power to the controller and thereby the contactor block as well. So no battery voltage apart from the energy stored in the capacitor.
Touran doesn't have a single HV connector, it's all bolted. So no point to interlock.

Seems to be the point of these systems, cut/disallow HV if any connector is intentionally unplugged.

Wouldn't want to run contactor control through it physically, would make me nervous to loose drive because of corrosion or something. Cutting torque mid drive is not a safety measure but a safety hazard in my opinion. But not closing contactors in the first place while stationary seems a safe thing to do. So a pin that software can react to.