As part of building an inverter-generator setup I am looking into 48V alternators.
I realised that cars increasingly have such things built in to provide a "mini-eco" function. They effectively have an entirely separate 48V electrical system comprising a 48V starter/alternator, and a 48V battery. The alternator mode puts energy into the battery during braking, and the battery can use the "motor" mode of the device to both provide the stop/start function and also provide a bit of extra power when accelerating.
So, these are pretty interesting devices and available relatively cheaply on the 'used' market, and I figured I would see if I could use one as the basis of my generator. I bought a "salvaged but servicable" one from a Ford Focus (a 1-litre petrol car) which is a 48V 150A unit - it was cheap enough I reckoned if I broke it while dismantling, I would at least have learned something. I found a slightly strange setup and I'm wondering if people here can shed some light on it. Obviously things will be complicated by the Starter functionality, and it might even be possible to use that, but let's see.
First weird thing is the stator has 5, (yes five) connections. It's densely packed, 80 slots :
You cannot view this attachment.
The five leads come out onto the back and are labelled U, V, W, X, Y. There is no Z like I was expecting (well actually I was hoping for just 3, but you can't have everything). They do not seem to be isolated pairs, and there is about half an ohm between every combination / pair of terminals. Here's the backplate :
You cannot view this attachment.
The wires are led through fat copper tracks to spade-type terminals which are spot-welded onto tags from the electronics package, in the visible groups of 2, 2, 1. This is turns out is so they can be led into the regulator/manager in the right places. The regulator package is large! and heavily potted/sealed so was a devil to get apart. It looks like this :
You cannot view this attachment.
Forgive the fragments of plastic from my ham-fisted and exasperated attempts to open things up. There was a LOT of potting, spot-welding, and sharp-edged connectors and my pain levels got to a point where the red mist descended and the hammer and screwdriver came out. I was reflecting that I didn't really want the control package, just the main body of the device, so I wasn't concerned about re-using it.
You can see five small boards with golden components on them - this is where the five stator leads come in. The prominent gold components are precision resistors, so something is monitoring current very precisely. I can't see the rectifiers but I think they're potted-in up the top of the picture.
The rotor has a small magnet attached to the end, which I suspect is driving a hall-effect sensor in this package so the system knows where the rotor is, rotationally - it needs this for the Motor mode, I think ? Because it has to generate / synthesize a waveform to move the rotor around based on where it is relative to the stator coils. Some controllers do this by sensing the change in inductance as the rotor moves past stator coils, but this appears to use a sensor. I guess that gives it more control.
The control harness comes in at the top-right, it's a six-way connector but only four of them are used, you can just see four little loops of wire coming onto the central processor board.
So it is WAY more complex than I need, but if I could figure out the stator windings I could perhaps use it. The sliprings/rotor connections are very accessible. So I'm posting this (a) because people might like to see inside these things and (b) to ask if anyone knows what the five stator tags signify and whether it's possible to three-phase rectify this.
I might try tearing-down the manager a bit more to try and find the heavyweight rectifiers, and there must be some chunky switches in there (FETs or a relay maybe?) to switch between Motor and Alternator modes.
Thoughts appreciated !
Richard
I realised that cars increasingly have such things built in to provide a "mini-eco" function. They effectively have an entirely separate 48V electrical system comprising a 48V starter/alternator, and a 48V battery. The alternator mode puts energy into the battery during braking, and the battery can use the "motor" mode of the device to both provide the stop/start function and also provide a bit of extra power when accelerating.
So, these are pretty interesting devices and available relatively cheaply on the 'used' market, and I figured I would see if I could use one as the basis of my generator. I bought a "salvaged but servicable" one from a Ford Focus (a 1-litre petrol car) which is a 48V 150A unit - it was cheap enough I reckoned if I broke it while dismantling, I would at least have learned something. I found a slightly strange setup and I'm wondering if people here can shed some light on it. Obviously things will be complicated by the Starter functionality, and it might even be possible to use that, but let's see.
First weird thing is the stator has 5, (yes five) connections. It's densely packed, 80 slots :
You cannot view this attachment.
The five leads come out onto the back and are labelled U, V, W, X, Y. There is no Z like I was expecting (well actually I was hoping for just 3, but you can't have everything). They do not seem to be isolated pairs, and there is about half an ohm between every combination / pair of terminals. Here's the backplate :
You cannot view this attachment.
The wires are led through fat copper tracks to spade-type terminals which are spot-welded onto tags from the electronics package, in the visible groups of 2, 2, 1. This is turns out is so they can be led into the regulator/manager in the right places. The regulator package is large! and heavily potted/sealed so was a devil to get apart. It looks like this :
You cannot view this attachment.
Forgive the fragments of plastic from my ham-fisted and exasperated attempts to open things up. There was a LOT of potting, spot-welding, and sharp-edged connectors and my pain levels got to a point where the red mist descended and the hammer and screwdriver came out. I was reflecting that I didn't really want the control package, just the main body of the device, so I wasn't concerned about re-using it.
You can see five small boards with golden components on them - this is where the five stator leads come in. The prominent gold components are precision resistors, so something is monitoring current very precisely. I can't see the rectifiers but I think they're potted-in up the top of the picture.
The rotor has a small magnet attached to the end, which I suspect is driving a hall-effect sensor in this package so the system knows where the rotor is, rotationally - it needs this for the Motor mode, I think ? Because it has to generate / synthesize a waveform to move the rotor around based on where it is relative to the stator coils. Some controllers do this by sensing the change in inductance as the rotor moves past stator coils, but this appears to use a sensor. I guess that gives it more control.
The control harness comes in at the top-right, it's a six-way connector but only four of them are used, you can just see four little loops of wire coming onto the central processor board.
So it is WAY more complex than I need, but if I could figure out the stator windings I could perhaps use it. The sliprings/rotor connections are very accessible. So I'm posting this (a) because people might like to see inside these things and (b) to ask if anyone knows what the five stator tags signify and whether it's possible to three-phase rectify this.
I might try tearing-down the manager a bit more to try and find the heavyweight rectifiers, and there must be some chunky switches in there (FETs or a relay maybe?) to switch between Motor and Alternator modes.
Thoughts appreciated !
Richard