Author Topic: EV Fast Chargers  (Read 4012 times)

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Offline chuckthevkhamTopic starter

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EV Fast Chargers
« on: June 19, 2021, 07:43:55 am »
Hullo I'm a new starter on this forum so please be kind if I make a boo boo .

As an industrial sparkie I find it hard to believe that fast chargers of 200kW or more are possible given the size of the cable and the plug/socket from the charger station to the car .

I believe fast chargers supply DC so at 300 odd volts it's over 600A . How can the two pins in the plug/socket handle this ?
Then to install multiple chargers at the one site we may be looking at over 1mW which will require a hell of a lot of infrastructure upgrading so how can this be economically feasible ?
 

Offline sleemanj

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Re: EV Fast Chargers
« Reply #1 on: June 19, 2021, 08:42:54 am »
It's not at 300v but 500v to 1000v.

There are plugs & cables rated to 500A, and there are liquid cooled solutions to keep the cables thinner.
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Offline mikeselectricstuff

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Re: EV Fast Chargers
« Reply #2 on: June 19, 2021, 09:06:40 am »
Higher powered units go up to 1000V, currently only the Porsche  Taycan and Hyundai Ioiniq 5 support nominally 800v charging.
Obviously the "350kW" label will be at max V/I which will rarely happen in practice, and many will also be limited by the available grid supply.
Higher powered chargers all have liquid cooled cables, as well as temperature monitoring in the connectors.

Here are some specs on DC charging cable/connector assemblies
https://www.phoenixcontact.com/online/portal/gb?1dmy&urile=wcm:path:/gben/web/main/products/subcategory_pages/DC_charging_cables_for_fast_charging_stations_P-29-03-01/528f4283-28d9-4efc-ae2f-ffc8b0307be2
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Offline mikeselectricstuff

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Re: EV Fast Chargers
« Reply #3 on: June 19, 2021, 09:15:15 am »
More info on a high-end assembly :
https://www.phoenixcontact.com/online/portal/gb/?uri=pxc-oc-itemdetail:pid=1085642&library=gben&pcck=P-29-03-01-01&tab=1&selectedCategory=ALL

500A, 1000V
5x 25mm2 cores ( presumably 2+2 power plus 1 earth )
NTC sensors on each contact and wire inside
Cable weight 1.7kg/m
Connector and cable are cooled. Required cooler capacity 600-1000W for 3-6m cable length, 2 litres/minute


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Offline mikeselectricstuff

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Re: EV Fast Chargers
« Reply #4 on: June 19, 2021, 09:18:29 am »
As regards grid loading, it's standard practice for multiple chargers to load-balance between them according to demand.  I believe in some cases they also dynamically control maximum total output based on communicating with the grid in real time.

Another thing is that above 50kW, the charger itself isn't inside the physical box you see, but in a nearby (large) cabinet
here's a video showing the insides and backend of a charging station in Norway
« Last Edit: June 19, 2021, 09:23:07 am by mikeselectricstuff »
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Online HighVoltage

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Re: EV Fast Chargers
« Reply #5 on: June 19, 2021, 09:24:11 am »
I just took a connector apart and was amazed about the high quality.

All parts were silver plated, some even heavy silver plating on all connector parts.
I put 100A DC through one of these connectors and had a difficult time to measure a voltage drop.
It is impressive how these cables and connectors have evolved in a short time.

 
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Offline chuckthevkhamTopic starter

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Re: EV Fast Chargers
« Reply #6 on: June 21, 2021, 12:09:13 pm »
Thanks for the reply however the Tesla batt is about 350V . Yes some others are 800V so there’ll be about half the current . Even water cooled a 600A load is huge . I’m an industrial sparkie so I’ve got some insight into what’s needed for this amount of current .
 

Offline sandalcandal

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Re: EV Fast Chargers
« Reply #7 on: June 21, 2021, 01:26:43 pm »
The open air ventilated nature of the charging cable with liquid cooling and very limited time under load along with temperature sensing and active power limiting means conductors can be a sized smaller than typical industrial installations which tend to be coded for enclosed runs going 24/7 with head room for overloading.

As Mike mentioned, fast charging locations typically have essentially a small substation next to them and the power between multiple "outlets" is shared so you can't get every single spot charging at 250kW at the same time. Again, the 250kW number is a peak which does not occur for the full duration of the ~30min charge.

The need for hefty grid infrastructure connecting to these charging locations is a major cost and limiting factor in installing these high power charging locations everywhere.

Something that hasn't been mentioned yet is some companies attempting to deal with the heavy and "peaky" loading by using battery based buffers. Freewire is a company developing such a system in a highly integrated package, I'm sure there are others too. There's a Charge Fox charging station I've visted next Euroa to that has some ABB and Tritium chargers connected to a nearby PV system setup by ABB (had a chat with some engineers working on it while I was there) but I don't 100% recall if there are any batteries for localised buffering but I think there was some. There's a station just west of Wodonga that has PVs next to it too and probably more I don't know about around the place but again not sure about batteries. There are also other companies making portable charging systems intended for events based on a battery systems. Obviously these systems are limited in the total average power they can pass in a day but the buffering means people can get their charge then run and as long as demand isn't too great then there's time to slowly replenish the buffer between users.
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Offline Alti

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Re: EV Fast Chargers
« Reply #8 on: June 21, 2021, 03:12:19 pm »
The open air ventilated nature of the charging cable with liquid cooling and very limited time under load along with temperature sensing and active power limiting(..)
I am counting safety issues in this part of the sentence.



 

Offline f4eru

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Re: EV Fast Chargers
« Reply #9 on: June 21, 2021, 05:40:00 pm »
I am counting safety issues in this part of the sentence.
I did not get that, can you please explain ?

Offline Alti

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Re: EV Fast Chargers
« Reply #10 on: June 21, 2021, 09:53:17 pm »
I did not get that, can you please explain ?
I meant the concerns OP has w.r.t. the powers these chargers offer. A 250kW 1kV load in industrial environment is nothing to write home about. But the technology behind a 250kW 1kV EV charger every dickhead and his dog are going to use, an appliance that is going to be driven over, pulled, squeezed and kinked, cut, sabotaged, torn apart, jammed, shorted, burnt and twisted, creates several new problems. Mainly safety problems. So when I hear about a liquid cooled, software controlled, 500A charging cable for people, I am starting to count potential safety issues that have to be solved here.
 

Online nctnico

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Re: EV Fast Chargers
« Reply #11 on: June 21, 2021, 10:59:04 pm »
I did not get that, can you please explain ?
I meant the concerns OP has w.r.t. the powers these chargers offer. A 250kW 1kV load in industrial environment is nothing to write home about. But the technology behind a 250kW 1kV EV charger every dickhead and his dog are going to use, an appliance that is going to be driven over, pulled, squeezed and kinked, cut, sabotaged, torn apart, jammed, shorted, burnt and twisted, creates several new problems. Mainly safety problems. So when I hear about a liquid cooled, software controlled, 500A charging cable for people, I am starting to count potential safety issues that have to be solved here.
These have been pretty much solved. For example: any decent EV charger has a DC GFI inside. If the current into the EV differs from the current coming back from the EV by a few tens of mA it will trip and shut the charger down.
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Offline bdunham7

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Re: EV Fast Chargers
« Reply #12 on: June 21, 2021, 11:34:01 pm »
Even water cooled a 600A load is huge . I’m an industrial sparkie so I’ve got some insight into what’s needed for this amount of current .

It's not the same situation or rules.  Consider a '20 amp circuit'.  To an electrician (in the US), that means a 12 AWG wire and a maximum continuous load of 16 amps.  In another context, that might mean an 18 AWG wire--less than 1/4 the cross section--and a continuous load of 20 amps, with no issues.  For a 500 amp DC charger cable, that likely just  means a 2/0 fine-stranded cable (67mm2 ) or something in that ballpark. 
« Last Edit: June 25, 2021, 01:25:13 pm by bdunham7 »
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Offline sandalcandal

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Re: EV Fast Chargers
« Reply #13 on: June 21, 2021, 11:38:14 pm »
I did not get that, can you please explain ?
I meant the concerns OP has w.r.t. the powers these chargers offer. A 250kW 1kV load in industrial environment is nothing to write home about. But the technology behind a 250kW 1kV EV charger every dickhead and his dog are going to use, an appliance that is going to be driven over, pulled, squeezed and kinked, cut, sabotaged, torn apart, jammed, shorted, burnt and twisted, creates several new problems. Mainly safety problems. So when I hear about a liquid cooled, software controlled, 500A charging cable for people, I am starting to count potential safety issues that have to be solved here.
If you really feel like getting into the weeds on EV charging safety then you can look up some standards. The UL versions are free to view. Here's some to start (not all of them):
UL 2594 Standard for [AC] Electric Vehicle Supply Equipment
UL 2202 Standard for [DC (<600V)] Electric Vehicle Supply Equipment
UL 2231-1 Standard for Safety for Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: General Requirements
UL 2231-2 Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: Particular Requirements for Protection Devices for Use in Charging Systems
For IEC:
IEC 61851 Electric vehicle conductive charging system and it's numerous parts. Good for "a rated output voltage up to 1 000 V AC or up to 1 500 V DC"
IEC 62196 Plugs, socket-outlets, vehicle connectors and vehicle inlets - Conductive charging of electric vehicles also multiple parts. - 690 V a.c. 50 Hz to 60 Hz, at a rated current not exceeding 250 A;- 1 500 V d.c. at a rated current not exceeding 400 A.
Also see TC 23 / SC 23 Plugs, Socket-outlets and Couplers for industrial and similar applications, and for Electric Vehicles and TC 69 Electrical power/energy transfer systems for electrically propelled road vehicles and industrial trucks
Edit: IEC TS 63379 ED1 Plugs, socket-outlets, vehicle connectors and vehicle inlets – conductive charging of electric vehicles - Vehicle connector, vehicle inlet and cable assembly for Megawatt DC charging. WIP looks like it could be interesting, no public access yet though.
« Last Edit: June 21, 2021, 11:45:31 pm by sandalcandal »
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Offline mikeselectricstuff

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Re: EV Fast Chargers
« Reply #14 on: June 22, 2021, 09:55:29 am »
These have been pretty much solved. For example: any decent EV charger has a DC GFI inside. If the current into the EV differs from the current coming back from the EV by a few tens of mA it will trip and shut the charger down.
They also do low-power isolation checks before turning the HV on
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Offline f4eru

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Re: EV Fast Chargers
« Reply #15 on: June 25, 2021, 12:26:32 pm »
some EVs (all ?) do impedance measurement between HV and 12+chassis circuits constantly. Probably switched off when charging.

Offline uer166

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Re: EV Fast Chargers
« Reply #16 on: June 25, 2021, 06:03:58 pm »
some EVs (all ?) do impedance measurement between HV and 12+chassis circuits constantly. Probably switched off when charging.

All, and during charge the DCFC does that instead of vehicle. You can touch HV- or HV+ and nothing will happen, and the isomon will shut the charge session down.
 

Offline Gregg

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Re: EV Fast Chargers
« Reply #17 on: June 27, 2021, 05:05:26 pm »
For comparison of high amperage cables, water cooled TIG torches use surprisingly small cross section fine strand cables that are immersed in the return cooling water from the torch.  Think of it as a bare copper fine strand cable inside a hose.   Of course the water used needs to be properly treated to reduce corrosion of the copper.  The suitable amperage capacity of the conductor depends on the material and resistance; keeping it cool allows for much higher amperage ratings.  For instance, the electrical code shows much higher capacity for conductors in free air vs multiple conductors in conduit.

A charger with high voltage and high amperage may have to use two isolated water cooling systems to avoid electrolysis of the coolant; some hydrogen and oxygen gassing off could lead to major disaster. 
 

Offline NiHaoMike

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Re: EV Fast Chargers
« Reply #18 on: June 27, 2021, 09:11:33 pm »
A charger with high voltage and high amperage may have to use two isolated water cooling systems to avoid electrolysis of the coolant; some hydrogen and oxygen gassing off could lead to major disaster.
Or use a nonconductive coolant like oil?
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Offline f4eru

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Re: EV Fast Chargers
« Reply #19 on: June 27, 2021, 09:12:07 pm »
or you could use non-conductive coolant... like mineral oil.
Less effective as a coolant.
but less reliability hassle also

Offline 2N3055

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Re: EV Fast Chargers
« Reply #20 on: June 27, 2021, 09:59:49 pm »
or you could use non-conductive coolant... like mineral oil.
Less effective as a coolant.
but less reliability hassle also

And flammable....
 

Offline sandalcandal

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Re: EV Fast Chargers
« Reply #21 on: June 27, 2021, 11:41:51 pm »
The cable posted by Mike has 1 supply coolant line and 2 return coolant lines. Also recommends 50-50 water-glycol coolant. Diagrams for cooling system also on product page.

https://www.phoenixcontact.com/online/portal/gb/?uri=pxc-oc-itemdetail:pid=1085642&library=gben&pcck=P-29-03-01-01&tab=1&selectedCategory=ALL

Presumably there is some barrier between the conductors and coolant.
« Last Edit: June 27, 2021, 11:45:44 pm by sandalcandal »
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Offline 2N3055

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Re: EV Fast Chargers
« Reply #22 on: June 28, 2021, 06:41:13 am »
The cable posted by Mike has 1 supply coolant line and 2 return coolant lines. Also recommends 50-50 water-glycol coolant. Diagrams for cooling system also on product page.

https://www.phoenixcontact.com/online/portal/gb/?uri=pxc-oc-itemdetail:pid=1085642&library=gben&pcck=P-29-03-01-01&tab=1&selectedCategory=ALL

Presumably there is some barrier between the conductors and coolant.

Glysofor N is there because there is direct contact with metals...
 

Offline sandalcandal

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Re: EV Fast Chargers
« Reply #23 on: June 28, 2021, 08:30:32 am »
The cable posted by Mike has 1 supply coolant line and 2 return coolant lines. Also recommends 50-50 water-glycol coolant. Diagrams for cooling system also on product page.
[img]
https://www.phoenixcontact.com/online/portal/gb/?uri=pxc-oc-itemdetail:pid=1085642&library=gben&pcck=P-29-03-01-01&tab=1&selectedCategory=ALL

Presumably there is some barrier between the conductors and coolant.
Glysofor N is there because there is direct contact with metals...
Yeah, it's a corrosion inhibiting glycol based coolant, there's probably metal in the loop somewhere e.g. heat exchangers. Doesn't mean there's contact with the conductors otherwise electrolysis would probably be an issue at 1000VDC as mentioned.
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Offline 2N3055

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Re: EV Fast Chargers
« Reply #24 on: June 28, 2021, 09:37:04 am »
The cable posted by Mike has 1 supply coolant line and 2 return coolant lines. Also recommends 50-50 water-glycol coolant. Diagrams for cooling system also on product page.
[img]
https://www.phoenixcontact.com/online/portal/gb/?uri=pxc-oc-itemdetail:pid=1085642&library=gben&pcck=P-29-03-01-01&tab=1&selectedCategory=ALL

Presumably there is some barrier between the conductors and coolant.
Glysofor N is there because there is direct contact with metals...
Yeah, it's a corrosion inhibiting glycol based coolant, there's probably metal in the loop somewhere e.g. heat exchangers. Doesn't mean there's contact with the conductors otherwise electrolysis would probably be an issue at 1000VDC as mentioned.
You can have two coolant loops... It all depends on how much cooling performance is needed.
 


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