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Discussion Starter #1
Current charging.jpg
Current 2kW electic fire.jpg
I am getting the unable to charge mèssage, and no regen. Waiting does not reset it. Any advice? I was doing some tests, just with a clamp on current sensor. I guess I did more on/off charging than it liked. Here iis the data before it broke:

Panic over, tried charging at home, and it seems ok/reset..

Charging impossible.jpg
Ramp up.jpg
 

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Discussion Starter #4 (Edited)
The pure sine wave was 2kW electric fire, for calbration. The others traces were from a 16 Amp. aka, 13 Amp granny. The car was near full charge. I labeled the photos, but the labels are not visible. The earth currents were below the background interference. I will try again at home using a resistor in the earth path. I never intented to go any distance in my Zoe, but not being able to do so makes me want to do so, lots! I wanted to find the earth-check signal but it looks like it might be dc., unless earth and netral are coupled some how in the charger.. The ripple (from the inverter?) is 10kHz..

ps I think I might have got some of the photos/scales mixed up (and deleted) in the panic, as I used both a x1 and x10 probes.
 

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Co-author of CanZE. Q210 nov 2013
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Very nice!

10 kHz is indeed the frequency of the switching power supply.

Just making sure, the 45-ish mA bursts, that is the startup sequence?
 

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Discussion Starter #10
Q
Very nice!

10 kHz is indeed the frequency of the switching power supply.

Just making sure, the 45-ish mA bursts, that is the startup sequence?
This photo ...458.jpg is steady state (30Amp.) charging earth current by measuring the voltage drop acrosss the earth resistor.

Ramp up.jpg is startup of a granny charger by using an Owl meter currrent transformer on the live wire suppling it. It appeared to be 100mV/A @ 50Hz. There is a glitch at the start but I don't think it was repeatable and the scope has 200MHz bw. The current starts at low level (6A?) and then ramps up in small steps.
 

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Very interesting!

It would help with the current traces if you were able to get a voltage trace to go with it - if you haven't a suitable probe, just capacitive coupling (wrap a probe wire around the insulated live) would probably give a useful reference, especially if you calibrate it again with your 2kW heater.

The first current trace looks at least reasonably sinusoidal, with the switching frequency super-imposed as you would expect, though there's a strange 'kink' once per cycle that's not symmetric.

Not sure what the 4th photo (3rd scope shot) is? (edit: OK, you've explained it now).

The last one with the resistor to measure the earth current would explain some things if it is really telling us the truth (I assume you are running the scope battery-powered to avoid ground loops, but even so such measurements are tricky to interpret). A modern electronic RCD will probably integrate all that high-frequency stuff away to nothing (the positive/negative sides cancel), while an older electromechanical one might extract energy from it and be more likely to trip. However, there looks to be quite a significant 50Hz component underneath it - seeming to reach about half a div above/below zero, so about 15mA, though that can't really be accurate as it would be enough to trip many RCDs by itself.

Another interesting experiment, if you have a ferrite ring to hand, would be to build a sense coil like in an RCD and so you can view what the RCD is seeing - take L and N one turn each round the ring, then wind some fine wire a few turns as a sense coil and connect that to the scope.

Finally there's the experiment of increasing that series resistance in the earth until the Zoe starts reporting BCI - which we guess to be somewhere in the region of 150R (assuming you are using a PME earth here so Ze is negligible).
 

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Discussion Starter #12
I'll get my act together after some more look-see. The scope was on battery and floating. I think it can be trusted, but I am rusty using that one. I am tempted to sacrifice the old rcd to see how they are made, and connect the scope somewhere.

I do have the proper probes, but I did not bring the home.

The next job is to look for signs of earth testing by the Zoe, but I need more hands to start charging and catch the action.​
 

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Co-author of CanZE. Q210 nov 2013
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The first current trace looks at least reasonably sinusoidal, with the switching frequency super-imposed as you would expect, though there's a strange 'kink' once per cycle that's not symmetric.
TBH I don't see a lot of assymetry. It seems to match the graph that was made my the network guys at my mate. The kinkyness (heee!!) seems to be a function of the rectifier. Once the capacitors are charged it is hard to get any current flowing close to the zero crossing?

The charging current graph is nice and jives with the noise you hear when starting up. It's a neat "ramp up".

What I don't get is the earth leak graph. I am probably misreading (scale?) but it seems like over 30 mA and that should trip the RCBO? <<== edit: cancel that, arg already answered, high frequency components. I think that roughly jives with the leak current the car itself reports.

I don't have a scope at hand myself but I will at least try to see at what earth resistance value ZOE will tell me to sod it.

Really good stuff @ElectricBeagle Thank you!
 

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Discussion Starter #14
TBH I don't see a lot of assymetry. It seems to match the graph that was made my the network guys at my mate. The kinkyness (heee!!) seems to be a function of the rectifier. Once the capacitors are charged it is hard to get any current flowing close to the zero crossing?

The charging current graph is nice and jives with the noise you hear when starting up. It's a neat "ramp up".

What I don't get is the earth leak graph. I am probably misreading (scale?) but it seems like over 30 mA and that should trip the RCBO? <<== edit: cancel that, arg already answered, high frequency components. I think that roughly jives with the leak current the car itself reports.

I don't have a scope at hand myself but I will at least try to see at what earth resistance value ZOE will tell me to sod it.

Really good stuff @ElectricBeagle Thank you!
I am not convinced they are charging any capacitors. It looks like they are using a flyback system on raw rectified mains via (motor?) inductors,
 

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Co-author of CanZE. Q210 nov 2013
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I am not convinced they are charging any capacitors.
Hmmm, actually, you are right about that, having seen the patent schematics and the pics of the guts. The only capacitors are for filters. But it doesn't change my premise much does it? If the sine is significantly under the battery voltage, there is only so much you can do drawing current?

My old charger reported in de order of 93% PF, which I thought was not bad, given the design. Yes, the motor is used as the inductor.
 

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I need more hands to start charging and catch the action.
Don't suppose you are anywhere near Cambridge? PM me if so.

TBH I don't see a lot of assymetry. It seems to match the graph that was made my the network guys at my mate. The kinkyness (heee!!) seems to be a function of the rectifier. Once the capacitors are charged it is hard to get any current flowing close to the zero crossing?
The asymmetry I meant is that the kink seems much greater on the rising edge than the falling edge - but I suppose that could be a measurement artifact.

The trace your mate provided was a different situation as it was running on three phase and our guess there was that the kink was the transition from one phase to the next like a six-diode rectifier (which only draws current from the phases furthest apart).

In single-phase mode, it can't be so crude as a simple rectifier/capacitor arrangement (as used in small devices that don't care about power factor), as that would give current only at the peak voltage, enormous harmonics and terrible power factor.

Assuming the patent accurately describes the configuration, they are limited in three-phase mode by having only in effect a single inductor (or at least a single link from the rectifier to the inductors), they can't simply run three copies of the single phase configuration when in three-phase mode.

So I think we have to analyse single-phase and three-phase operation separately.

It looks like they are using a flyback system on raw rectified mains via (motor?) inductors,
It's not a flyback converter, as there's no isolation. So it's something more like a simple boost or buck-boost converter.

What exactly is the Zoe battery voltage? Possibly the kink could be the transition from boost mode to buck mode, though I don't see why. Maybe the transition from discontinuous to continuous conduction mode in the inductor?

Given that they are achieving something like a sinusoidal current waveform, they must be regulating the duty cycle like a standard PFC stage; since there's no sign of any capacitors big enough to store the energy from a complete 50Hz half-cycle then they must be accepting a sinusoidal charge current into the battery on single phase. On there-phase it will be smoother, so that's probably acceptable - at the lower overall power on single-phase, the output current isn't limited by the battery anyhow, so it doesn't matter that the peak is sqrt(2) higher than the average because it will still be lower than the battery can accept.
 

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Agreed (singe-triple phase), In single phase the rectified voltage goes to 0, where in 3 phase it doesn't.

The battery voltage is 400 volt and indeed unisolated. The 400 volt bus is connected to mains when charging (which is why i.e. a defect in the isolation of the A/C compressor, which runs on the 400 volt bus, leads to no charging.

I think the sinusoidal current curve is indeed programmed by very actively controlling the MOSFETs that are used instead of diodes. It seems to me like a bit of a balancing act between boosting efficiently and trying to keep the PF in check, using PMW; I don't see them using the MOSFETs in anything other than switch mode or heat would immediately get out of hand.
 

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Discussion Starter #18
Don't suppose you are anywhere near Cambridge? PM me if so.



The asymmetry I meant is that the kink seems much greater on the rising edge than the falling edge - but I suppose that could be a measurement artifact.

The trace your mate provided was a different situation as it was running on three phase and our guess there was that the kink was the transition from one phase to the next like a six-diode rectifier (which only draws current from the phases furthest apart).

In single-phase mode, it can't be so crude as a simple rectifier/capacitor arrangement (as used in small devices that don't care about power factor), as that would give current only at the peak voltage, enormous harmonics and terrible power factor.

Assuming the patent accurately describes the configuration, they are limited in three-phase mode by having only in effect a single inductor (or at least a single link from the rectifier to the inductors), they can't simply run three copies of the single phase configuration when in three-phase mode.

So I think we have to analyse single-phase and three-phase operation separately.



It's not a flyback converter, as there's no isolation. So it's something more like a simple boost or buck-boost converter.

What exactly is the Zoe battery voltage? Possibly the kink could be the transition from boost mode to buck mode, though I don't see why. Maybe the transition from discontinuous to continuous conduction mode in the inductor?

Given that they are achieving something like a sinusoidal current waveform, they must be regulating the duty cycle like a standard PFC stage; since there's no sign of any capacitors big enough to store the energy from a complete 50Hz half-cycle then they must be accepting a sinusoidal charge current into the battery on single phase. On there-phase it will be smoother, so that's probably acceptable - at the lower overall power on single-phase, the output current isn't limited by the battery anyhow, so it doesn't matter that the peak is sqrt(2) higher than the average because it will still be lower than the battery can accept.
I am in Wales, boyo, and the sheep are even more uncooperative than my wife.

I am new to this so, although very old, I will avoid too much speculation until I learn some more.

Took my RCD apart and I think I will pass on restoring it. I did not expect them to use a permanent magnet in a balance against rectified residual current electromagnetism. Looked like it should work with audio frequencies fine.
 

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Discussion Starter #20
Hmmm, actually, you are right about that, having seen the patent schematics and the pics of the guts. The only capacitors are for filters. But it doesn't change my premise much does it? If the sine is significantly under the battery voltage, there is only so much you can do drawing current?

My old charger reported in de order of 93% PF, which I thought was not bad, given the design. Yes, the motor is used as the inductor.
With a flyback converter (which apparently this is not) you basically put the supply across the inductor (eg. Via a mosfet switch) until you reach the required current, and then switch off. The voltage reverses and the current is switched to the battery by another diode. This can be at a much higher voltage than the instantaneous rectified supply. If the battery is at a much higher voltage than the supply, the rate of decay of current to the battery is faster than the increase when connected to the supply. It is along time since I dabbled in 'lectric, so I might have had a brain fart, just now!
 
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