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Alright then, hi all.

For a Mobility Design Master Thesis Project I want to charge an EV battery through the road while driving.

I just can't get to grips with this. I'm slightly frustrated, don't bash on me if the question is stupid (again). I tried understanding some similar questions, but they seem to tell that I need a ground connection. I didn't find an answer to my questions, or I was to stewpid to filter out what I need to know :D)).

How many contacts do I need? Aren't 2 enough? Does it need to be grounded? Does the ground connection have to be a "proper connection"? Or is a grounding strap enough? Do I even need this ####? Isn't the chassis enough grounding anyway? Cars don't need extra grounding on the ride, do they? So why extra grounding for charging???

How do these guys get along with 2 contacts? (basically what I want to do) Does it have anyting to do with DC? Is it possible with DC? How about AC?

Long story short: Do I need an external ground connection? What would be a "proper" ground connection? Do I need 3 connectors to the road?

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closed as too broad by Bimpelrekkie, Leon Heller, Charles Cowie, Wesley Lee, DerStrom8 Nov 14 '17 at 20:22

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Start by learning what a ground connection does and when it is needed. I could just answer yes/no you need it or not but this is your project/Thesis so you should know. You can't just write: I use this and that because some guy on Stack Exchange EE said I should, now can you? You just have too many basic questions. We're not here to educate you to the level needed for doing your project. \$\endgroup\$ – Bimpelrekkie Nov 14 '17 at 19:40
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    \$\begingroup\$ I'm struggling with the concept of someone getting a master's thesis in EE without being able to answer this question! \$\endgroup\$ – pjc50 Nov 14 '17 at 20:03
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    \$\begingroup\$ I don't feel like we have enough information about your premise to answer this, anyway... Are you talking about a tram system that would allow EV cars to charge while on that road if they have your product, or an EV car that charges by taking energy from the Earth/friction? Are you talking about Ground as a 0 point for your charging, or an emergency Ground (as you'd have in High V such as Electrical work)? \$\endgroup\$ – Ifusaso Nov 14 '17 at 20:08
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    \$\begingroup\$ Damn. That system looks like a recipe for dead pedestrians. Two exposed rails in the road at 750VDC and enough current to accelerate a car to 100kph in just a few hundred meters. \$\endgroup\$ – JRE Nov 14 '17 at 20:10
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    \$\begingroup\$ @JRE.. there is a lot of that kind of technological "advancements" going on these days...... most of them half baked ideas if you ask me. \$\endgroup\$ – Trevor_G Nov 14 '17 at 20:11
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enter image description here

Figure 1. A popular road-supplied vehicle power system. Source: SpeedHunters.com.

How many contacts do I need?

Minimum of two.

Aren't 2 enough?

Could be if you don't need 3-phase electricity.

Does it need to be grounded?

Usually, yes, to prevent the supply voltages floating to very high voltages.

Rather than, for example, having a ground (0 V) rail and a 400 V rail the system could be designed with -200 V and +200 V rail with respect to ground. I don't think that anyone touching either would survive.

Does the ground connection have to be a "proper connection"?

Yes because you will be dealing with high currents.

Or is a grounding strap enough?

Grounding straps are for static discharge. This involves tiny currents at extremely high voltages.

Do I even need this ####?

'####' is a term with which I am unfamiliar.

Isn't the chassis enough grounding anyway? Cars don't need extra grounding on the ride, do they? So why extra grounding for charging???

Because electrical current requires a circuit back to the source and vehicle tyres are insulators.

How do these guys get along with 2 contacts? (basically what I want to do) Does it have anyting to do with DC? Is it possible with DC? How about AC?

Feed and return. This can be AC or DC.


The article you linked to does not address safety. For long lengths of track as shown in the photo high voltages will be required. This has multiple problems:

  • Safety for humans and animals.
  • Insulation from ground.
  • Prevention of leakage current in rain and snow.
  • How to charge (financially) for power usage.
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  • \$\begingroup\$ Thanks, that seems to help :) So, I need 480V, when i use +240V and -240V AC, then I wouldn't need a 0-Ground? (I think I got something wrong again) \$\endgroup\$ – Dmitri Nov 14 '17 at 21:11
  • \$\begingroup\$ AC means alternating current. Alternating current means that the sign of the voltage changes at the supply frequency. Therefore + and - are meaningless. For an AC system this could be referred to as split-phase as the two wires would be in anti-phase. I don't know why you think you need 480 V in particular. \$\endgroup\$ – Transistor Nov 14 '17 at 21:16
  • \$\begingroup\$ 480V I chose because of the battery charging, I think batteries work with those Volts. Tesla Superchargers use this Volts, for a reason maybe? Probably easier because it doesn't need to be transformed (down from 960V), I guess? I don't know, that's why rather left it as it is. \$\endgroup\$ – Dmitri Nov 14 '17 at 21:29
  • \$\begingroup\$ "Feed and return" - do you mean this? \$\endgroup\$ – Dmitri Nov 14 '17 at 21:30
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    \$\begingroup\$ No. Read the theory section. It's not practical. I'm sorry, Dmitri, but you are trying to design a complex system without basic electrical knowledge. This is doomed to failure. You need at least a couple of weeks studying basic circuit theory and DC and AC circuits. \$\endgroup\$ – Transistor Nov 14 '17 at 21:36

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