Joined
·
3,879 Posts
Panic over, tried charging at home, and it seems ok/reset..
In this case it was a granny, but I was stop-starting a lot..It's pretty common to get a BCI on a rapid charger, that can be cleared by a home charge, see my blog: Renault ZOE: Battery Charging Impossible (BCI) - My Renault ZOE electric car
I was once accused of being a nerd.. You could be number two. -)Is it a butterfly?
JJ
This photo ...458.jpg is steady state (30Amp.) charging earth current by measuring the voltage drop acrosss the earth resistor.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?
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 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.
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,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!
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?I am not convinced they are charging any capacitors.
Don't suppose you are anywhere near Cambridge? PM me if so.I need more hands to start charging and catch the action.
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.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?
It's not a flyback converter, as there's no isolation. So it's something more like a simple boost or buck-boost converter.It looks like they are using a flyback system on raw rectified mains via (motor?) inductors,
I am in Wales, boyo, and the sheep are even more uncooperative than my wife.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.
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!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.