EV Fast Chargers - Page 1
Forum section: electronics / general

author: chuckthevkham
author_rank: Newbie
timestamp: June 19, 2021, 07:43:55 am
content: 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 ?

author: sleemanj
author_rank: Super Contributor
timestamp: June 19, 2021, 08:42:54 am
content: 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.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 19, 2021, 09:06:40 am
content: 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 assemblieshttps://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

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 19, 2021, 09:15:15 am
content: 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=ALL500A, 1000V5x 25mm2 cores ( presumably 2+2 power plus 1 earth )NTC sensors on each contact and wire insideCable weight 1.7kg/mConnector and cable are cooled. Required cooler capacity 600-1000W for 3-6m cable length, 2 litres/minute

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 19, 2021, 09:18:29 am
content: 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) cabinethere's a video showing the insides and backend of a charging station in Norway

author: HighVoltage
author_rank: Super Contributor
timestamp: June 19, 2021, 09:24:11 am
content: 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.

author: chuckthevkham
author_rank: Newbie
timestamp: June 21, 2021, 12:09:13 pm
content: 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 .

author: sandalcandal
author_rank: Unknown
timestamp: June 21, 2021, 01:26:43 pm
content: 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.Freewireis 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.

author: Alti
author_rank: Frequent Contributor
timestamp: June 21, 2021, 03:12:19 pm
content: Quote from: sandalcandal on June 21, 2021, 01:26:43 pmI am counting safety issues in this part of the sentence.

author: f4eru
author_rank: Super Contributor
timestamp: June 21, 2021, 05:40:00 pm
content: Quote from: Alti on June 21, 2021, 03:12:19 pmI did not get that, can you please explain ?

author: Alti
author_rank: Frequent Contributor
timestamp: June 21, 2021, 09:53:17 pm
content: Quote from: f4eru on June 21, 2021, 05:40:00 pmI 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.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2021, 10:59:04 pm
content: Quote from: Alti on June 21, 2021, 09:53:17 pmThese 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.

author: bdunham7
author_rank: Super Contributor
timestamp: June 21, 2021, 11:34:01 pm
content: Quote from: chuckthevkham on June 21, 2021, 12:09:13 pmIt'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.

author: sandalcandal
author_rank: Unknown
timestamp: June 21, 2021, 11:38:14 pm
content: Quote from: Alti on June 21, 2021, 09:53:17 pmIf 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 2594Standard for  Electric Vehicle Supply EquipmentUL 2202Standard for [DC (<600V)] Electric Vehicle Supply EquipmentUL 2231-1Standard for Safety for Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: General RequirementsUL 2231-2Personnel Protection Systems for Electric Vehicle (EV) Supply Circuits: Particular Requirements for Protection Devices for Use in Charging SystemsFor IEC:IEC 61851 Electric vehicle conductive charging systemand 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 vehiclesalso 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 seeTC 23 / SC 23Plugs, Socket-outlets and Couplers for industrial and similar applications, and for Electric Vehicles andTC 69Electrical power/energy transfer systems for electrically propelled road vehicles and industrial trucksEdit:IEC TS 63379 ED1Plugs, 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.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 22, 2021, 09:55:29 am
content: Quote from: nctnico on June 21, 2021, 10:59:04 pmThey also do low-power isolation checks before turning the HV on

author: f4eru
author_rank: Super Contributor
timestamp: June 25, 2021, 12:26:32 pm
content: some EVs (all ?) do impedance measurement between HV and 12+chassis circuits constantly. Probably switched off when charging.

author: uer166
author_rank: Super Contributor
timestamp: June 25, 2021, 06:03:58 pm
content: Quote from: f4eru on June 25, 2021, 12:26:32 pmAll, 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.

author: Gregg
author_rank: Super Contributor
timestamp: June 27, 2021, 05:05:26 pm
content: 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.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2021, 09:11:33 pm
content: Quote from: Gregg on June 27, 2021, 05:05:26 pmOr use a nonconductive coolant like oil?

author: f4eru
author_rank: Super Contributor
timestamp: June 27, 2021, 09:12:07 pm
content: or you could use non-conductive coolant... like mineral oil.Less effective as a coolant.but less reliability hassle also

author: 2N3055
author_rank: Super Contributor
timestamp: June 27, 2021, 09:59:49 pm
content: Quote from: f4eru on June 27, 2021, 09:12:07 pmAnd flammable....

author: sandalcandal
author_rank: Unknown
timestamp: June 27, 2021, 11:41:51 pm
content: 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=ALLPresumably there is some barrier between the conductors and coolant.

author: 2N3055
author_rank: Super Contributor
timestamp: June 28, 2021, 06:41:13 am
content: Quote from: sandalcandal on June 27, 2021, 11:41:51 pmGlysofor N is there because there is direct contact with metals...

author: sandalcandal
author_rank: Unknown
timestamp: June 28, 2021, 08:30:32 am
content: Quote from: 2N3055 on June 28, 2021, 06:41:13 amYeah, 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 theconductorsotherwise electrolysis would probably be an issue at 1000VDC as mentioned.

author: 2N3055
author_rank: Super Contributor
timestamp: June 28, 2021, 09:37:04 am
content: Quote from: sandalcandal on June 28, 2021, 08:30:32 amYou can have two coolant loops... It all depends on how much cooling performance is needed.

author: sandalcandal
author_rank: Unknown
timestamp: June 28, 2021, 10:38:47 am
content: Quote from: 2N3055 on June 28, 2021, 09:37:04 amQuote from: sandalcandal on June 27, 2021, 11:41:51 pmIt has non isolated loops.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 28, 2021, 11:25:12 am
content: Quote from: 2N3055 on June 28, 2021, 09:37:04 amI suspect the twin return lines may be to do with the cable lay-up, maybe to allow a return line to be next to each DC core. The drawing in the Phoenix PDF shows the two returns joined at the charger end.

author: sandalcandal
author_rank: Unknown
timestamp: June 28, 2021, 11:31:25 am
content: Quote from: mikeselectricstuff on June 28, 2021, 11:25:12 amDiagrams also show three separate coolant tubes entering the cooling system. Unfortunately the public documentation is a bit sparse.