EV Charging Power Factors

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FionaZuppa

FionaZuppa

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AZ
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Part Time Electrician (semi retired, old) - EE retired.
anyone have any data on what the PF's look like for the various EV charging stations? i am interested in knowing more about how the proliferation of EV's will impact on power delivery and billing.
 
Level 2 charging stations (J1772) are just (slightly) smart AC switches, so the power factor is determined by the EV.

Level 3 charging stations (Chademo, CCS, Supercharger) do provide DC to the car, so they are presumably power factor corrected. I don't have any data, though.

Cheers, Wayne
 
Either AC or DC charging will require a rectifier input which normally has a power factor of 1 although may produce substantial harmonics. This is what you might want to look into instead of power factor.

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harmonics in what sense, non-linear loads ??
 
170829-1310 EDT

310 BLAZE IT:
Either AC or DC charging will require a rectifier input which normally has a power factor of 1 although may produce substantial harmonics. This is what you might want to look into instead of power factor.
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For the most part that is an incorrect statement. I doubt that you have and EE degree and you certainly have not run experiments on rectifier circuits.

If you have a pure sine wave, then there are no harmonics. As soon as as a periodic waveform deviates from a sine wave, then harmonics are present.

Non-unity power factor can come from a phase shift between sine waves, or from at least one waveform not being a sine wave.

Fundamentally power factor is defined as:

PF = Real Power / Vrms*Irms for a two terminal load.

.
 
gar said:
170829-1310 EDT

310 BLAZE IT:



For the most part that is an incorrect statement. I doubt that you have and EE degree and you certainly have not run experiments on rectifier circuits.

If you have a pure sine wave, then there are no harmonics. As soon as as a periodic waveform deviates from a sine wave, then harmonics are present.

Non-unity power factor can come from a phase shift between sine waves, or from at least one waveform not being a sine wave.

Fundamentally power factor is defined as:

PF = Real Power / Vrms*Irms for a two terminal load.

.
Click to expand...

Nail on head. I've put like this as an attempt at an explanation.
Power factor comes in two flavours. Displacement and distortion.
Displacement is the phase shift between supply voltage and supply current such as you would get with an induction motor. That can be, and often is, corrected using capacitors.
Distortion is, as you say, the supply current deviating from a pure sine wave which is more difficult to correct. Typically, rectifiers produce such distortion.
 
dc-dc power supplies have pretty good impact on power distribution. maybe with stricter PF requirements the PF's will stay .95 or higher?
we might not think of it now, but when ~258 million (gross max) vehicles switch to EV you'll get same, possibly more, power supplies connected to poco.

a few motors on poco with net 0.5PF vs 250 million devices with 0.9PF, run the math, i believe millions at 0.9PF is worse than a few at 0.5PF ??

this is a good read
http://www.mouser.com/pdfdocs/55W_29828_1_Power Measurements on AC-DC.pdf
 
FionaZuppa said:
dc-dc power supplies have pretty good impact on power distribution. maybe with stricter PF requirements the PF's will stay .95 or higher?
we might not think of it now, but when ~258 million (gross max) vehicles switch to EV you'll get same, possibly more, power supplies connected to poco.

a few motors on poco with net 0.5PF vs 250 million devices with 0.9PF, run the math, i believe millions at 0.9PF is worse than a few at 0.5PF ??

this is a good read
http://www.mouser.com/pdfdocs/55W_29828_1_Power Measurements on AC-DC.pdf
Click to expand...
I think you are looking at a thundering herd of buffalo and worrying about the effect their swishing tails will have on the wind. The real impact worth worrying about will be adding 258 million battery chargers to the grid. The distortion PF they present is a minor concern compared to that initial fact. Fortunately, the EV motors are not going to be connected to the grid continuously. Unfortunately, their chargers will collectively be drawing peak power when solar supplements are not going to be contributing. At some point we are going to face peak demand problems for sure.
 
Jraef said:
I think you are looking at a thundering herd of buffalo and worrying about the effect their swishing tails will have on the wind. The real impact worth worrying about will be adding 258 million battery chargers to the grid. The distortion PF they present is a minor concern compared to that initial fact. Fortunately, the EV motors are not going to be connected to the grid continuously. Unfortunately, their chargers will collectively be drawing peak power when solar supplements are not going to be contributing. At some point we are going to face peak demand problems for sure.
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Love your phraseology......the image of the bison.........

You make a good point and one that gives me concerns too. In the UK context for me of course. Here, average domestic electrical energy consumption is around 12kWh/day.
A relatively low power EV has a storage capacity of about 25kWh. And a range of around 100 miles per charge. Average annual mileage is around 12k miles. Or 32 miles a day. So, about three days of stored energy before a 25kWh plus losses recharge is required. Around 10 hours allowing for losses. You could do it overnight but that puts the vehicle out of use for that period. Say, 22:00 to 08:00. Not very convenient. An option would be to beef up the grid. Generation, transmission, and distribution.

EVs are being promoted. But, until we fully address the issues of range, recharge times, and grid infrastructure we are some way off them overtaking the IC engine.
 
Jraef said:
I think you are looking at a thundering herd of buffalo and worrying about the effect their swishing tails will have on the wind. The real impact worth worrying about will be adding 258 million battery chargers to the grid. The distortion PF they present is a minor concern compared to that initial fact. Fortunately, the EV motors are not going to be connected to the grid continuously. Unfortunately, their chargers will collectively be drawing peak power when solar supplements are not going to be contributing. At some point we are going to face peak demand problems for sure.
Click to expand...

San Diego Power Gas & Electric is already getting ready for that. They've applied and been granted permission to redefine the peak period as 1600-2100 hours.
 
Jraef said:
I think you are looking at a thundering herd of buffalo and worrying about the effect their swishing tails will have on the wind. The real impact worth worrying about will be adding 258 million battery chargers to the grid. The distortion PF they present is a minor concern compared to that initial fact. Fortunately, the EV motors are not going to be connected to the grid continuously. Unfortunately, their chargers will collectively be drawing peak power when solar supplements are not going to be contributing. At some point we are going to face peak demand problems for sure.
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Peak oil meets peak sunlight? That's not gonna sell near as many tickets as McGregor Maryweather .
 
you beef the grid up how exactly? when oil/gas runs dry you need energy from something to put into EV's at night because ~80% (check the #) of the ~250million are driving during the daytime, and solar is a daytime thing.

lots of chatter of having to store solar during the day and then dump it back to devices later at night. batteries will always have a dwell time for recharging because there's a safety limit on charge rates with lithium batts.

so if batts are to be charged at night where does all that energy come from when oil & gas are long gone? lots of nuke plants can help, but that too is limited.

the best i heard this far is to build potential during sunlight hrs using solar, then use that potential at night. something like pumping water uphill into a dam, they get that hydro power later at night.
 
FionaZuppa said:
you beef the grid up how exactly? when oil/gas runs dry you need energy from something to put into EV's at night because ~80% (check the #) of the ~250million are driving during the daytime, and solar is a daytime thing.

lots of chatter of having to store solar during the day and then dump it back to devices later at night. batteries will always have a dwell time for recharging because there's a safety limit on charge rates with lithium batts.

so if batts are to be charged at night where does all that energy come from when oil & gas are long gone? lots of nuke plants can help, but that too is limited.

the best i heard this far is to build potential during sunlight hrs using solar, then use that potential at night. something like pumping water uphill into a dam, they get that hydro power later at night.
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Yes, the nub of the issue. Fossils are finite. Solar has limited duration over 24 hours. Wind is intermittent. Pumped hydo is a net energy consumer.
So what are we left with?
Dams like Itaipu, Three Gorges. Nuclear?
 
Jraef said:
I think you are looking at a thundering herd of buffalo and worrying about the effect their swishing tails will have on the wind. The real impact worth worrying about will be adding 258 million battery chargers to the grid. The distortion PF they present is a minor concern compared to that initial fact. Fortunately, the EV motors are not going to be connected to the grid continuously. Unfortunately, their chargers will collectively be drawing peak power when solar supplements are not going to be contributing. At some point we are going to face peak demand problems for sure.
Click to expand...
Swappable battery packs?
 
Level 1 will definitely be 0.95-0.995 range and Level 2 most likely as well.

It's harmful to the battery to charge with ripple. It's only tolerated for engine starting battery charging since you don't charge those from AC on a regular basis. High efficiency active PFC rectifier charger is beneficial even for golf courses since reducing ripple reduces wear and tear on battery.

You'll need a DC link capacitor bank the size of a bucket to get clean DC the traditional way from a single phase power or a welder size reactor unless you use active PFC. The circuit size becomes the constraint in charging rate so EV charging will be power factor corrected into 0.99 region. It is ignored for 12v starting battery charging, because, the circuit size of even the 120v 15A outlet is not a constraint to the charging rate.
 
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Electric-Light said:
Level 1 will definitely be 0.95-0.995 range and Level 2 most likely as well.

It's harmful to the battery to charge with ripple. It's only tolerated for engine starting battery charging since you don't charge those from AC on a regular basis.
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Or ever.....
 
mivey said:
Swappable battery packs?
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I personally have felt for a long time that this is the only viable long term solution. I do a lot of facilities work with Tesla and asked some of the guys I know there if this has ever been mentioned around the water cooler, it has. I was thinking that instead of gas stations, there would be battery stations and you pull in, park over a robot, put in your credit card, it swaps out your battery pack and you leave. But they informed me that the problem is that all EV batteries would need to be the same and battery life varies over time, so you might put in a new fresh battery and get one with half the life left on it. It only makes sense for the car owner to have two (or more) batteries and have one charging at home during the day while you use the other. This is actually the concept behind Tesla's Power Wall and their buying Solar City rooftop solar systems. Elon Musk's team is thinking WAY out in front of this entire EV concept, they are not so much in the EV business as they are in the battery business. That Giga Factory outside of Reno, when complete, will be producing more EV batteries than all of today's current world wide production facilities combined. But at the same time, others are scaling up as well. In 5 years high power density battery systems, for homes, businesses or cars, will be all around us.
 
Jraef said:
I personally have felt for a long time that this is the only viable long term solution. I do a lot of facilities work with Tesla and asked some of the guys I know there if this has ever been mentioned around the water cooler, it has. I was thinking that instead of gas stations, there would be battery stations and you pull in, park over a robot, put in your credit card, it swaps out your battery pack and you leave. But they informed me that the problem is that all EV batteries would need to be the same and battery life varies over time, so you might put in a new fresh battery and get one with half the life left on it. It only makes sense for the car owner to have two (or more) batteries and have one charging at home during the day while you use the other. This is actually the concept behind Tesla's Power Wall and their buying Solar City rooftop solar systems. Elon Musk's team is thinking WAY out in front of this entire EV concept, they are not so much in the EV business as they are in the battery business. That Giga Factory outside of Reno, when complete, will be producing more EV batteries than all of today's current world wide production facilities combined. But at the same time, others are scaling up as well. In 5 years high power density battery systems, for homes, businesses or cars, will be all around us.
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And unaffordable. There is only so much cost savings to be had on scale up. It would be cheaper to buy an NG fueled whole house generator and run it when the sun doesn't shine than to get a large enough solar plant with backup batteries to manage the same feat.
 
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