Interesting safety issue on an EV charging point (MyEnergi Zappi) - Page 1
Forum section: electronics / general

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 26, 2020, 10:34:53 pm
content: Discussed here -https://www.speakev.com/threads/myenergi-identified-a-serious-safety-issue-with-the-latest-version-of-the-kia-e-niro-2020-model.152058/I thought it might be interesting to talk about it here for more technical depth, as well as highlighting a case where it's hard to point blame where two different things are involved.It has been found that a particular combination of 3-phase charger (EVSE) and car - Hyundai Kona and Kia E-Niro 2020 models with a 3-phase onboard charger (OBC) has a rather nasty problem that can potentially damage the EVSE, the supply to it and/or the car's onboard chargerThe issues are as follows :1) The car can charge single-phase 7kW (32A) or 3-phase 11kW ( 16A). The car's on-board charger has three 16A charger stages, and uses two in parallel for single-phase charging - this is a fairly common architecture.When the charge cable is plugged in, the charger figures out if the supply is single or 3-phase, and if single, connects L1 to L2 with a relay, to power the 2 stages. It just connects the 2 pins together, without any sort of changeover, on the assumption that L2 is not connected to anything on a single-phase charger2) The EVSE has the ability to adjust charge level ( by telling the car how much to draw via the CP line), to accommodate solar and load-balancing situations.In addition to adjusting the charge current, it can switch between 1-phase and 3-phase mode, so charging can continue down to 6A 1-phase when the available power is reduced, e.g. for solar.Here's the problem - when switching between 1-phase and 3-phase, the EVSE tells the car's OBC to disconnect by setting the CP line to 0V ( or open, don't know which), and assumes that the car will behave in the same way as if the charge cable had been unplugged and replugged.Unfortunately the Hyundai/Kia OBC doesn't treat this the same as an unplug, remembers the previous 1/3 phase setting, so when the EVSE turns on the 3-phase supply, L1 and L2 are still joined via the OBC's relay and BANG! Best-case it's only tripped the breaker supplying the EVSE, but chances are it's also damaged the contacts in the EVSE's contactor (apparently the latter has been reported), maybe also the relay in the OBC.As far as I can tell, the applicable standards make no mention of switching between 1- and 3-phase modes, but don't prohibit it.However who is actually to blame here :1) The EVSE for assuming it's OK to switch from 1 to 3 phase without unplugging, and that all cars will treat a CP reset as equivalent to unplugging2) The OBC for not checking for 1/3 phase supply on a CP reset, only at plug-in3) The OBC for not isolating L2 when switching to single-phase modeIMO, 1 and 3 at least. The OBC really should isolate L2, and the EVSE shouldn't assume that a car expects a mode-change without unplugging.As physical damage and safety are impacted here, it would be interesting to see what the outcome would be if there was a legal claim for compensation for damage caused..

author: ejeffrey
author_rank: Super Contributor
timestamp: July 27, 2020, 03:24:32 am
content: 3 seems the most clearly wrong, and what most directly leads to the safety issue. Backfeeding power on an input pin for a different phase is just not OK. If you have a three phase power input you have to assume that any of the three live lines can be energized at any time. It might be wrong for charge point to assume the car is going to gracefully switch from one to three phases but it shouldn't cause a a short circuit.

author: uer166
author_rank: Super Contributor
timestamp: July 27, 2020, 06:24:54 am
content: As someone designing EVSEs, this seems 100% the car's fault, a 3-phase EVSE usually has no concept of "single phase" or "3-phase", it simply supplies all 3 phases unconditionally to the on-board charger, with which the car can do whatever it wants. This is an overlook on both the standards' agency and Hyundai.I would like to know, what exactly can a 3-phase EVSE do in this situation.Edit: after actually re-reading the article, it seems like a much more of a grey area than my initial knee-jerk reaction. The EVSE itself seems to be able to switch between a 3-phase supply and a 1-phase supply dynamically? I've never seen such EVSEs before in the wild, I guess it makes sense in some rare circumstances. In any case the EVSE will probably get damaged beyond easy repair due to a single such event. But fundamentally, like ejeffrey said, backfeeding an output through an input is a major no-no for a grid supply, hopefully Hyundai addresses this properly.

author: richard.cs
author_rank: Super Contributor
timestamp: July 27, 2020, 04:58:29 pm
content: Quote from: mikeselectricstuff on July 26, 2020, 10:34:53 pmThe Renault Zoe does something similar, it has an internal contactor between N and L3 that it closes for single phase charging and opens for 3 phase (default is open). I am unsure what logic it uses to control it, and how confused it might get if you for example had a missing L1 and L2 but had L3 and N present. Likewise if the source decided to switch single to 3 phase part way through charging.

author: tom66
author_rank: Super Contributor
timestamp: July 27, 2020, 05:05:54 pm
content: The mistake made with Type2 was that it has no way to indicate 1ph and 3ph. It should have been something like 3x pilot frequency for 3ph, or negative polarity instead of positive.The exact same fault can occur on BMW i3's. The vehicles use 11kW chargers which can be configured as 3 x 16A in 3ph mode (common in Europe) or 1 x 32A in the UK or on a single-phase supply. If the car forgets which state it should be in, which can happen if the car goes to sleep and is woken up by a remote or scheduled charge, it can short the L1 and L2. This is particularly bad because the contactors are after the fuses in the charge module so half the car has to be disassembled to fix this. I stand to be corrected but I believe the REx also uses the 11kW onboard charger as part of its function (the engine generates rough AC which the charger is designed to accept), so this can also disable REx function (on older vehicles)This might also affect Tesla Model 3 as it has the same 3 chargers as one configuration which can do ~48A single phase (IIRC it's limited to 40A due to the connector) or 16A in 3ph, and older Model S/X.

author: coppice
author_rank: Super Contributor
timestamp: July 27, 2020, 05:27:12 pm
content: Quote from: mikeselectricstuff on July 26, 2020, 10:34:53 pmDoes anyone know why its limited to 11kW? The few countries where 3 phase is widely available in homes, like Germany, have a lot of 22kW shower heaters, so its possible to pull a lot more than 11kW.

author: richard.cs
author_rank: Super Contributor
timestamp: July 27, 2020, 05:31:30 pm
content: Quote from: tom66 on July 27, 2020, 05:05:54 pmYes and no. The type 2 standardshouldhave been different, but rather than any fancy signalling it should just have prohibited the car from shorting any phases to each other or to neutral. Manufacturers would then have complied with the standard either with changeover contactors or by using a 4-phase input topology, and all would be well.Generally there are a lot of things that are undefined in the standard and should be defined. This behaviour is one of them, but I would have liked to have seen a stricter definition on which voltage and phase combinations are and are not allowable (disclaimer, I have access to the standard but have only skim-read it). Is a charger connecting L1 and L2 only allowable? How about L2 and L3 only? Or L3 and N? Worse, if I created a charger with L1, L2 and L3 sourced from the same phase will some cars draw 3x32 A and set fire to the neutral with the 96 A return current?Personally I really like the 43 kW AC charging mode (3x 63 A 230/400 V), it's a shame so few cars support it. It has the advantage of being dirt cheap to implement the charger which is good for encouraging infrastructure install. I mean it does offload the power electronics onto the car, but the Zoe approach of reusing the motor driver helps with the cost here, and it's not *that* complex/heavy/expensive when optimised for a particular battery configuration.Quote from: coppice on July 27, 2020, 05:27:12 pmI guess simply because they cheaped-out and used 3x 16A single phase chargers, which is also the only reason it does the switching that causes the shorting problem.

author: tom66
author_rank: Super Contributor
timestamp: July 27, 2020, 06:12:32 pm
content: That's a good point Richard - does it not specify that 1ph is only on L1 and N? And that 3 phases must be 120' separated, with neutral current ~= 0? How do cars handle phase dropouts?Quote from: coppice on July 27, 2020, 05:27:12 pmThere are comparably few people that would benefit from 22kW charging at home (that's a full charge in 3-4 hours with considerable grid load and presumably the rest of the house has to be close to zero load.) And while 22kW chargers do exist in some places, they are usually accompanied by fast DC chargers too. It's one of those things - you can keep putting increasingly bulkier charging equipment on the vehicle but really this should be in a charging station given it is generally only used for long trips. The AC charger is there for domestic use, to keep domestic stations cheap, and for trickle charging at parking lots, at your gran's house, etc.The Porsche Taycan takes this to the extreme. It uses 800V battery setup, so it cannot naturally charge on most 400V CCS stations. To enable charging on those stations an onboard 50kW (with factory option for 150kW) DC-DC converter is used to boost CCS voltage to pack voltage! I wish I was joking but this is the consequence of every manufacturer going their own way. (I wonder why they did not consider contactors to switch the pack into a 400V configuration when charging at a lower input voltage; there must be a good technical reason for this as the cost of a 50kW DC-DC converter is not small.)

author: coppice
author_rank: Super Contributor
timestamp: July 27, 2020, 06:15:12 pm
content: Quote from: tom66 on July 27, 2020, 06:12:32 pmThere are comparably few people that would benefit from any kind of 3 phase charging at home. I'm surprised they offer anything more than 1 phase AC, and high power DC charging. That 3rd charging block is just going to waste.

author: richard.cs
author_rank: Super Contributor
timestamp: July 27, 2020, 06:46:20 pm
content: Quote from: coppice on July 27, 2020, 06:15:12 pm3x 16A = 11 kW is a very common charger in much of Europe, it's the go-to setup for a supermarket or a car park, or in some places a home charger, where in the UK 1x 32A =7 kW is the default. A typical German domestic supply might be 3x 32A.

author: nightfire
author_rank: Frequent Contributor
timestamp: October 11, 2020, 01:47:53 am
content: Just had some dance with the transmission system operators. Wanted to put @work a wallbox with 22kW, so that my boss in his new hybrid company car (and some of our salespeople that also are likely to get some EV in the future) can charge that at the company.Thing is, you have due to regulations here in germany to announce that to the transmission system operators, below 11 kW it is only an announcement, above that they have to acknowledge that the electric capacity they GUARANTEE you for that building is sufficient. In my case, they charged some hard €€€ to raise that, so we can now use 88 kW max. instead of former 66kW...This charge has been declared as compensation for eventual needed building measurements in the streets, to put bigger cables to the street distribution boxes...The other thing is usually the energy counter itseltf. They are mostly rated for 63A (here in germany), but due to regulations it is preferred that measurements are taken via clamps, not direct.There are lots of things to obey and get right....Also, Lots of cars at this time do not have a 22kW-capable charging unit implemented the last time I looked- as in the form of 3x32Amps AC.In household applications this also could very well go above the capacity of some of the wiring in the house or distribution box, which would in the end mean that lots of additional money will have to go into now energy counter, wiring etc.

author: f4eru
author_rank: Super Contributor
timestamp: October 12, 2020, 08:30:31 am
content: You could also have kept the same 66 kW input, and only let a good wallbox with load sharing function let the EV charging function regulate to max out at 66kW total.(EV charging typically happens out of business hours anyway, when the business consumption is low)Of course, you need an addon to measure the total consumption and inform the wallboxGerman regulations are quite crazy, they still try to hinder renewables at the moment(corruption from big energy suppliers), but you can avoid following some of them, especially the "recommendations" that the grid companies make you believe are mandatory....

author: Alti
author_rank: Frequent Contributor
timestamp: October 12, 2020, 07:13:03 pm
content: Quote from: nightfire on October 11, 2020, 01:47:53 am66kW is 95,6A per phase. It is most likely a 100A limit.88kW is 127,5A per phase. It is most likely 125A.The power meters with direct connection are made forup to about 125A. Maybe provider run out of those. With higher currents you need current transformers so a rearrangement in a distribution box might be needed. Or maybe they are anticipating more people would charge EVs in nearest future so the current transformer is the way to go.QuoteI really doubt fast chargers become popular in household applications because you have quite a lot of time to charge EV then. You have to sleep sometimes. An 11kW charger can push in >100kWh during one night.Remember that with energy providers it is the current limit per phase that is actually imposed, not the installed or owned loads really. You can have eight 22kW fast chargers and thirteen kettles with 66kW contract, no problems there. Just control them so that the current draw never exceeds 100A per phase. Well, 125A with the upgrade.Also, the limit is usually imposed with a thermal circuit breaker so it does not work by tripping at 100,01A. As suggested by f4eru you could (read out three currents from power meter and command charger to) top up to 3x100A.

author: nightfire
author_rank: Frequent Contributor
timestamp: October 12, 2020, 08:35:58 pm
content: To clarify: Those 66kW (and later 88 kW) are for a whole house with alltogether 4 floors. The Cabling from the street runs into the cellar to a counter cabinet capable of 10 3phase counters each up to 63 amps. As the wallbox (and some 16A single-phase Schuko Wall outlets) were build about 25 years after that building has been built, it was easier to do something not connected to the rest of that installation. Also cheaper- for infrastructural stuff we were charged about 1000 €, some load distribution mechanism would have cost significantly more and would have to be a pain in some delicate parts to be installed in that building...The EV charging structure was intended to get to a separate counter, to have billing also separate due to some other reasons.

author: Alti
author_rank: Frequent Contributor
timestamp: October 13, 2020, 10:55:16 am
content: Quote from: nightfire on October 12, 2020, 08:35:58 pmThanks for the information, this is a very interesting discussion.@mikeselectricstuff: sorry for hijacking topic.The point is that if someone wants to own an EV and chargers, in majority of cases, including yours, upgrade of infrastructure, cabling, counters, fuses, tariffs is not the only solution. Since you have chosen to increase the power assigned, I must assume this is a rational decision and the alternative paths have been either unknown or discouraging to you (you, an employee). This is not a critique, I am sure there are many more solutions to this problem we are not aware of (tax incentives, charging at neighboring company, paying employees to invest in chargers and charging at their homes, installing generator etc). Out of all options your company decided to choose an upgrade from 100A to 125A.Correct me if I am wrong but I suspect this "brute force path" can only lead to serious and expensive "earthworks" around the country.This is because your boss is not the only one that wants EV. Niether him or You are unique (no offence) and I have to come up to the conclusion that most DE employees faced with same assingnments (from their bosses), being at similar circumstances, would have chosen the same brute force path.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 13, 2020, 11:13:06 am
content: Disconnection of L2 would have added a few bucks of cost of a simple 16A capable relay contact (either as a separate relay, or as an extra contact on the existing relay/contactor)If I had to design such a thing, I definitely wouldn't assume it's acceptable to short phases to each other, unless the standard explicitly and clearly said doing so is normal. An EVSE, after all, is just a fancy power socket.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 13, 2020, 12:52:33 pm
content: Perhaps they should have defined the single phase source to have L1 tied to L2 and L3 tied to N? If nothing else, it would spread out the current over 2 pins in single phase mode.

author: richard.cs
author_rank: Super Contributor
timestamp: October 13, 2020, 01:10:04 pm
content: Quote from: NiHaoMike on October 13, 2020, 12:52:33 pmUsing the four pins as two parallel pairs is a supported mode for DC on a type 2 charging connector. I am not sure anyone uses it in the real world though? Maybe Tesla, don't they use type 2 connectors for DC? The pins are rated for 60-80 A anyway depending how many are conducting.https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Type2_Socket_de.svg/454px-Type2_Socket_de.svg.png

author: nightfire
author_rank: Frequent Contributor
timestamp: October 13, 2020, 06:20:10 pm
content: Quote from: Alti on October 13, 2020, 10:55:16 amIn that case, the cabling into the building is sufficiently strong, I checked myself with some engineer from the power distribution company. The thing is, that the street distribution box (and the transformers for that area...) have to be sized for the assumption that at one day some folks can and will SIMULTANEOUSLY use all that power- so they give the users a guaranteed value of power that they are allowed to use and equally guarantee that they might set up another transformer or so if needed...And for those costs they charged us a calculatory fee.Energy transmission usually is calculated by so called "Gleichzeitigkeitsfaktoren" - thats an assumption how much you can overbook some power lines because you know that usually not every consumer of energy will be used at the same time. Like in a house, you have maybe 50 Amps 3-phase going in, and you have 12 power circuits to the living room, kitchen, sleeping room, childrens room, cellar etc., and on top some warm water heater with 3x32Amps. Altogether 12/3*16Amps=64 A and 32 from the boiler per phase=96- on a 50A input. But because not every circuit is fully loaded at a given time, usually it will hold- I think for households that factor is whether 0.3 or even lower due to german electrical standardization. But in case of EV, this factor is a solid 1 for some hours of time. So capacities have to be re-calculated a bit. I also do not think that our office will use those other 66 kW, even when several colleagues will have to wash their hands verrry thoroughly with hot water- but thats the law/regulations here.(in German: Baukostenzuschuss)

author: f4eru
author_rank: Super Contributor
timestamp: October 13, 2020, 10:06:44 pm
content: Your assumptiomns are wrong, the load factor is not one at all because never will all EVs take full power AND all other loads be on at the same time for a complete area.An average car in Germany travels 40 km/day, that is a measly 30 min of charging at 11 kW, so when you average out more than 5 consumers, you get really really really low usage factor.30 min of charging at 11 kW is not even good enough to get the EV charge box supply cable detectably warm to the touch. That cannot overwhelm any old electrical installation. it's less daily consumption than a typical european (electric) water boiler.

author: nightfire
author_rank: Frequent Contributor
timestamp: October 13, 2020, 10:44:40 pm
content: Quote from: f4eru on October 13, 2020, 10:06:44 pmWell, _I_ also know which load will be imposted on my side of the electricity counter... Unfortunately the energy provider HAS to calculate with a load factor of 1- if he does not, he will at some time hit some spot where there is football championchip, every german is at home in front of the TV and all cars are charging like crazy- therefore potentialy overloading the STREET cabling to the 400V transformer responsible for providing electricity for a couple of streets- or worse, the uplink of this transformer and his colleagues to a 110kV-line to the power plants...

author: f4eru
author_rank: Super Contributor
timestamp: October 14, 2020, 05:22:02 am
content: Somehow you move the goal posts from industrial to residential now, OK...let's see your "bad case:"TV : 100W3x LED lamp : 20WFridge for beers : 100WEV : 11kWTotal per home : 11,220 kWThis hypothetical use case of all EV charging at the same time is still not more than a boiler per home, it cannot overload even the local grid, sorry.Your assumptions about EV overloading the local grid are wrong. Make some measurements on a real residential grid, you'll see how it works, and how it adds up, and you'll see the worst case peak load factor being in reality much lower than the 0,3 your grid company uses for calculation. also, local transformers are big massive oil reservoirs, and can be overloaded for 30 min/1hour without consequences, so there's even more headroom here.Furthermore, when all homes in Germany, or any other country will have EVs, we will of course obviously manage those charging EV in a time shift manner, so they will in turn stabilize the grid.Adding this capability to the EV to time shift and manage is trivial if they are connected to the internet, no need to install any other special infrastructure, appart from a TOU capable energy meter. New cars are connected, and can update their firmware OTA.The grid companies will do it to save huge money, even if today they are opposed in germany, it will be really painfully obvious to them in 1-2 years.The users will do it because they will get much cheaper electricity when they switch to hourly or 1/4 hourly market price for electricity, and they will reduce their car "fuel" cost by 50% by updating their car's software.Adding a lot of managed EVsAdding a lot of renewables.The future is that simple.The only thing lacking is a solution for seasonal storage at scale.

author: Alti
author_rank: Frequent Contributor
timestamp: October 14, 2020, 11:03:17 am
content: Quote from: f4eru on October 14, 2020, 05:22:02 amThe "bad case" is the blackout and the penalties that come from there.Each user has fixed current limit assigned, this is constant limit over time. Of course the distribution company can gamble and sell more amps that are physically available in hope not all of the customers charge and take shower at the same time. Now this gambling strategy is a function of correlation of the events. The distribution company knows the loads from the past but I bet they have very little idea about the incoming EV future. They know dates of football games, they know sunrise and sunset, weather forcast, covid?, Persian Gulf situation, I bet they are even aware of solar eclipse. Before they gain confidence in their load estimation, the only thing they can do to be on a safe side is to assume EVs are being charged simultaneously. For me this sounds quite a rational decision in a monopoly, don't you think? Whether this correlation is going to be 1 or less in 20 years, is another story. I'd be really surprised if with "brute force" policy nightfire describes, an EV owner did not start pulling 22kW right after parking the EV. This correlates with highway traffic jams close to 1. Residential/commercial/industrial, does not seem to be much difference, it is the people that use EVs.QuoteIt is not nightfire's assumption, he is just reporting the rules distributor has to follow. That is not possible to measure or estimate load in 20 years right now because some people own IC cars (99%?). We shall see what is going to happen when ICs get extinct.QuoteDid you read what nightfire just wrote? They will not, "brute force" method was chosen. You are assuming nightfire's boss likes burning money so he decided to sponsor local excavations. Sorry, f4eru, this is unreasonable. The "time shift manner" is a myth in nightfire's case and since he is just one out of may alike, I cannot see how this could be different elswhere. Or do you consider nightfire's situation "rare as hen's teeth"?QuoteYou do not know EU it seems. Here the distribution companies do not compete among themselves. It is a natural monopoly, they cannot get bankrupt, they just have to comply to regulatory rules. They will not loose or gain anything. The cost of running the distribution company, sponsored football teams and marble arches is divided between customers and they have no choice but to choke on that and then swallow.

author: f4eru
author_rank: Super Contributor
timestamp: October 14, 2020, 02:11:18 pm
content: Yes, his company got tricked into an unecessary upgrade by the electricity company. Happens often in Germany, I would call this a scam.It will take some time until most people realize you don't need to invest that much into charging EVs at home (or at the workplace, for that matter)

author: tom66
author_rank: Super Contributor
timestamp: October 14, 2020, 08:19:56 pm
content: The UK DNOs have reported that if everyone wants to get EVs, some upgrade of distribution equipment and cabling will be essential. It's not a myth. Most DNOs have a calculated assessment of each customer at ca 2kW. The cabling to the home is capable (usually 100A rated) but the 11kV feed and distribution transformers will almost certainly need upgrading.Right now they require notification if 2 or more 7kW EV chargers are installed in order to ensure there is sufficient capacity available. You are also only allowed 1 EV charger if you have an electric shower or electric central heating installed.Frankly why we are still building homes with just 100A 1ph service in 2020 is baffling, 40A 3ph should be the minimum and ideally 50A 3ph. Would allow for 16A 3ph EV charging @ 11.1kW, plus heatpump at another ~5kW or so.