Doesn't regen make AC power? How can my car handle 60 kilowatts of juice?

SuperCoug · Mar 14, 2013

My 60 kWh Model S is equipped with a single 10,000 watt AC on board charger which (as I understand it) converts AC power from the plug and to DC power to store in the battery.

The Model S has an AC motor so doesn't it produce AC electricity during regen braking? If so, how can my car possibly handle 60,000 watts of AC power during full regen? If it can handle that much AC power from regen why can't it handle that much shore power?

I'm sorry if this is a dumb question or has been explicitly address elsewhere.

Stoneymonster · Mar 14, 2013

I'm guessing it goes through the main inverter between the motor and the battery somehow. Can inverters be reversible?

strider · Mar 14, 2013

Yes, the same way it takes DC from the batteries and converts it into AC for the motor, just in reverse. In the earliest Roadsters they actually used this to charge the car but it had some problems so they went to a dedicated charging circuit.

FredTMC · Mar 14, 2013

SuperCoug said:
My 60 kWh Model S is equipped with a single 10,000 watt AC on board charger which (as I understand it) converts AC power from the plug and to DC power to store in the battery.

The Model S has an AC motor so doesn't it produce AC electricity during regen braking? If so, how can my car possibly handle 60,000 watts of AC power during full regen? If it can handle that much AC power from regen why can't it handle that much shore power?

I'm sorry if this is a dumb question or has been explicitly address elsewhere.

omg, I thought about this exact design issue today! Classic. Yep I bet the inverter is utilized.

Johan · Mar 14, 2013

strider said:
Yes, the same way it takes DC from the batteries and converts it into AC for the motor, just in reverse. In the earliest Roadsters they actually used this to charge the car but it had some problems so they went to a dedicated charging circuit.

The Renault Zoe is said to be doing this - using the drive inverter for plugged in charging, which gives it a cheap 43kW 3-phase charger called "Chameleon charger". There have been many disussions as to why Tesla went the route of s separate AC charging system but that's also how most (all) other EV's except the Zoe does it.

Al Sherman · Mar 15, 2013

So, inverters ARE reversible? I did not know this. We used to call AC to DC a TR (transformer rectifier). If it only did AC to DC would it still be an inverter?

strider · Mar 15, 2013

Al Sherman said:
So, inverters ARE reversible? I did not know this. We used to call AC to DC a TR (transformer rectifier). If it only did AC to DC would it still be an inverter?

A EE boffin/nerd would have to chime in on what it's called. I agree that historically DC->AC is an inverter and AC->DC is a rectifier but Tesla's (and every other EV that I know of) has an "inverter" and it can work in both directions. There's a little bit of detail here:
Power inverter - Wikipedia, the free encyclopedia

gavine · Nov 30, 2015

FredTMC said:
omg, I thought about this exact design issue today! Classic. Yep I bet the inverter is utilized.

And 2 years later, I though of this question and found this thread via search. Glad I'm not the only geek who though about this.

Kalud · Nov 30, 2015

The on-board charger(s) are not used in this process. They are 100% idle while driving.

The inverter is used both ways to re-gen power.

Cosmacelf · Nov 30, 2015

Does anyone know/remember what the problem was with the roadster combo inverter/charger to charge the car? Why did they switch to a dedicated charger for the Model S?

qwk · Nov 30, 2015

Cosmacelf said:
Does anyone know/remember what the problem was with the roadster combo inverter/charger to charge the car? Why did they switch to a dedicated charger for the Model S?

Royalty fees to AC Propulsion.

SabrToothSqrl · Nov 30, 2015

When you invert an inverter, do you just get a verter?

NielsHP · Nov 30, 2015

And those who actually do that, are they invertebrate ?

(https://en.wikipedia.org/wiki/Invertebrate)

jerry33 · Nov 30, 2015

NielsHP said:
And those who actually do that, are they invertebrate ?

No, they're reverberate.

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Doesn't regen make AC power? How can my car handle 60 kilowatts of juice?

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