Auto alternator used as motor

[tcmtech]

I have considered a similar concept but I would just go with a stock BLDC motor driver designed for the high powered RC BLDC motor applications. My brother plays with them all the time and I have seen a few of his can top 100 amps at 20 volts input.

**broken link removed** $23.80.

 

[dr peppers]

This is an interesting article, some redneck connected the 3 phase output of an alty in a vehicle to an alty outside the vehicle with the exciter windings connected to 12v, a simple way to get an alty to work as a motor.

Not much use if you want to battery power the motor though, still interesting.

https://www.youtube.com/watch?v=SdeQgOZqC78

 

[shortbus=]

The Saturn VUE hybrid used an alternator/starter like this. Also a lot of newer inboard boat motors are going to this. They are called "BAS" (belt alternator starter). They don't really use AC to run them, its actually "bipolar" DC.

A search on DIYelectric car forums, Endless sphere .com and RCmodeler forums will get a lot of information on 'alternator to motor' conversion

 

[dr peppers]

Dynostarts were around in the 60's on small marine vessels if thats whay you mean, allthough they were dc and had a commutator, sounds like theres another later version.

The method I was suggesting was using the 3 phase output of a standard alty to drive another alty as a synchronous motor, the motor would try and follow the speed of the alty, depending on load.

 

[Jules_Theone]

So do you think a stock BLDC motor driver will be able to run a car alternator? Or give up with the alternator idea - The hub motor I was looking at was like £200 and would probably be the easiest thing to do mechanically.

With the back-back alternator idea, firstly I guess its not all that efficient and it's also bi-directional. I was thinking could that concept be used to de-couple the drive so I don't have to have a 9" long chain going from front to back? And what about having an alternator on each wheel powered from one alternator?

Jules

 

[dr peppers]

Yes it would, whether its a good idea or not I dont know, never done it, do a search on you tube theres a few examples of where folk have a alty turning off a r/c type bldc motor driver, in theory if the driver can provide enough amps then it'll work.
One thing about r/c type bldc motor drivers, I'm not an expert but the ones I've seen are 3 wire, this means that either they use armature coil feedback or are open loop type drivers, as I understand it the most efficient drivers use positional feedback like hall effect switches, these are used on pushbike motor hubs, at least the ones I've looked at.

If you were powering the cycle from an engine then the alty generator/motor idea might be worth a try (I've recently seen a pushbike on ebay that had the chinese hub motors front and rear and they were powered by a 2 stroke petrol engine hidden on the back rack), and it'd probably work with one per wheel, youre right though its not efficient, not only is power wasted genrating the fields (you can replace the field winding with magnets), I've a suspicion that at low speeds efficiency will not be good as alty's only output high currents at high speed so its logical to assume the reverse.

To be honest seriously think about saving a whole load of hassle and get the chinese wheel hub motor, they are made for the purpose, you can even get them that have regen braking.

 

[Jules_Theone]

So do you think a stock BLDC motor driver will be able to run a car alternator? Or give up with the alternator idea - The hub motor I was looking at was like £200 and would probably be the easiest thing to do mechanically.

With the back-back alternator idea, firstly I guess its not all that efficient and it's also bi-directional. I was thinking could that concept be used to de-couple the drive so I don't have to have a 9" long chain going from front to back? And what about having an alternator on each wheel powered from one alternator?

Jules

Sorry, double post, my connection is rubbish. How do I remove this?

 

[shortbus=]

Dynostarts were around in the 60's on small marine vessels if thats whay you mean, allthough they were dc and had a commutator, sounds like theres another later version.

The method I was suggesting was using the 3 phase output of a standard alty to drive another alty as a synchronous motor, the motor would try and follow the speed of the alty, depending on load.

No these are true alternators. They also have a driver circuit that gives the sequence to drive as motors. When the 'motor' is engaged the alternator circuit is cut out.

 

[pilko]

You could try something like this:- http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyyuzu.pdf

 

[Jaguarjoe]

A lot of people make "RPC's", rotary phase convertors. Mostly basement machinist's who need 3ph power for various industrial machines they buy.
One single phase or DC motor of adequate capacity drives a 3ph motor which generates the 3ph power. Lots of info on the web, eBay sells the control portion of RPC's.

 

[tcmtech]

Lots of info on the web, eBay sells the control portion of RPC's.

Or you could just go here and skip all the complicated AC - DC - AC stuff. https://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

 

[dr peppers]

That was in the back of my mind, I've tried a similar method only with a manual switch instead of a relay, it works, starting torque wasnt great with mine, but that might have been the way it was done.
I've seen machines supplied from manuafturers with similar setups, saves the cost of a 1 phase motor.
I didnt post the idea in case lurkers were waiting, some folks reckon its less than ideal.
I think this thread has gone a little off topic, the op wants ideas for an electric vehicle.

 

[shortbus=]

Yeah, don't know how it became about phase converters?

Every one wants to use a micro-controller for a BLDC, when it can be done with one of the MC33033 or MC33035 BLDC motor control chips. And no programing.

https://www.electro-tech-online.com/custompdfs/2012/04/MC33033-DPDF.pdf

 

[pilko]

@ shortbus,--both the OP salty9 and Joules_theone are looking for a method to run an automotive alternater as a motor, not to run a BLDC. That is why I posted the Microcontroller salution in post 29.

pilko

 

[dr peppers]

The only problem with that ic is that it uses positional sensors, micro's come in handy when you want sensorless.
I'd like to come accross a readily available ic that will do sensorless bldc control, and that also might be of use to the op if an alty motor is what he's gonna go with.

 

[shortbus=]

Effectively, running the alternator as a motor is making it into a BLDC motor. Removing the diodes is the first step. Giving the slip-ring brushes ~6VDC is the second, this makes the rotor segments magnetic, every other one the opposite pole. Just like in a BLDC motor.

None of the sensor-less motor drivers will make as much power from a given motor as a sensored one will. Sorry but its a given fact. An ESC works on the BLDC motors as long as the load is not too high. In the situation a ESC is made for, driving a propeller in a model plane, If it looses its place in the commutation of the motor it will pick it up again in the next set of commands. The props inertia keeps it moving till the controller catches up.

 

[shortbus=]

The only problem with that ic is that it uses positional sensors, micro's come in handy when you want sensorless.
I'd like to come accross a readily available ic that will do sensorless bldc control, and that also might be of use to the op if an alty motor is what he's gonna go with.

Like this? Or one of the others Allegro offers. **broken link removed**

 

[dr pepper]

Yes just like that, but none of my suplliers list it.
The datasheet says its good for hydraulic pumps, must have a good starting torque then, I thought start up was an issue for sensorless.
Yes it makes sense that sensorless motors arent gonna have the same power than a sensored, not untill someone comes up with a fancy new technique.

 

[ClydeCrashKop]

This topic inspired me to post this one.
https://www.electro-tech-online.com/threads/alternator-as-a-stepper-motor.127094/

 

[dr pepper]

I have tried a similar thing with a hard disc motor, wasnt having any of it, couldnt get the rotor in lock.

Microchip do an application note and code for a sensorless bldc driver, I'm gonna play with that when I get chance.