How does a motor controller, control a PMG for charging LFP?

[Ohms_Cousin]

I am a little confused - but my knowledge of motor controllers is almost zero, so not surprising.

I am interested in fitting a PMG to the flywheel of a diesel engine. The PMG uses a motor controller to control the charging of LFP batteries. I really dont understand how a motor controller is controlling the PMG for charging LFP.

The PMG is here : https://www.pmgenerators.com/dc-generators/ and here ; https://www.pmgenerators.com/engine-mounted-generator/48v-engine-mounted-generator/

The controller they tell me that is needed to control the PMG for its output for charging LFP is here : https://www.dmcde.de/pms-controllers/ - PMS480T4

Does anyone have any insights into this ? I am intrigued by the concept of a PMG doing 48vnom as a diesel generator but how is that motor controller fitting into all this?

 

[BentleyJ]

If you look at the specification sheets for the PMG Generator they produce unregulated 3 phase AC which is then rectified, filtered and regulated to output DC at 48 to 56V. Apparently the output is user adjustable. This is really no different than an Inverter style generator which does exactly the same thing but has the additional step of Inverting the filtered DC back into Regulated single or 3 phase AC.

The motor controller is simply adjusting the throttle to maintain specified RPM depending on the electrical load which translates to flywheel load.

 

[Ohms_Cousin]

Thanks Bentley - its still a mystery but you have shed some light on this.

 

[BentleyJ]

Thanks Bentley - its still a mystery but you have shed some light on this.

There is no mystery. Traditional generators had a mechanical governor with spinning weights that fly apart as RPM increases. Movement of the weights is linked to the carb via a rod or linkage. As the electrical load on the generator changes, engine RPM will change and the movement of the governor will either open or close the throttle to compensate and maintain a relatively steady RPM.

Many of the newer PMG inverter generators use an electronic stepper motor attached to the carb to adjust throttle position instead of a mechanical governor.

 

[Ohms_Cousin]

When I say mystery, i mean a mystery to me - no one else. I totally understand how a mechanical governor works - just was not aware how it was done in a solid state controller.

 

[doing it different]

Rectify the 3 phase AC, then run it through a charge controller... like a solar or wind controller.
Assuming generator is making higher voltage than the battery... use the charge controller to regulate for the battery voltage you want

 

[Ohms_Cousin]

Rectify the 3 phase AC, then run it through a charge controller... like a solar or wind controller.
Assuming generator is making higher voltage than the battery... use the charge controller to regulate for the battery voltage you want

But the PMG manufacturer specifically states that the PMG Head needs the motor controller referenced - there is no option to substitute this motor controller with a solar or wind controller.

If they stated that the PMG needs a solar or wind charge controller it would make perfect sense to me, but since they specify a motor controller then there is some complex interplay going on to control RPM for voltage output. Its all solid state - no mechanicals involved at all.

 

[doing it different]

Seems to me they are controlling voltage by the engine????? Then you are going to need some type of accurate throttle control.... you also probably will need an injection pump designed for a generator... (with small govenor drift.)

 

[doing it different]

Don't know how big, cheap or fancy you are trying to build this.
But an old inverter generator could easily be modified to work. Think of it a engine powered wind turbine.

 

[Vigo]

Any motor controller that can do 'regenerative braking' could potentially harvest power from a PMG and charge batteries with it.

Probably the only reason they specifically reference THAT controller is because they've tested it and know it works and how to instruct someone to set it up.

A lot of companies are loathe to even admit the full range of possibilities because it very quickly gets into 'if you have to ask'. Which is why you ask on a forum instead.

 

[Ohms_Cousin]

Any motor controller that can do 'regenerative braking' could potentially harvest power from a PMG and charge batteries with it.

Probably the only reason they specifically reference THAT controller is because they've tested it and know it works and how to instruct someone to set it up.

A lot of companies are loathe to even admit the full range of possibilities because it very quickly gets into 'if you have to ask'. Which is why you ask on a forum instead.

Yeah...how did we do this before the Internet?

They do specify an RPM - so the engine is running at a given RPM (2000/2200/2400 that they spec for a given output at a given voltage etc) - but I dont think it is a strictly governed per se. As the rev's go up and down a little the output is adjusted electrically - another interesting thing about this setup - the PMG head can be used as a stater for the engine itself. So can ditch the starter motor, which is a good thing. One very interesting point about being able to ditch the starter motor is that then there is no need to maintain a 12v Pb battery just for starting the engine. Not sure how they do this but it will be interesting to learn more about it.

 

[doing it different]

China is way ahead... I am sure they stole it from somewhere
Used for there little 3 wheel carts.

C$429.84 | Electric Start 4/5/6/7KW Range Extender Generator 48V-72V Multifunction Bass Battery Range Gasoline Range Increas Electric Vehic

https://a.aliexpress.com/_m0Ghqdv

 

[Ohms_Cousin]

China is way ahead... I am sure they stole it from somewhere
Used for there little 3 wheel carts.

C$429.84 | Electric Start 4/5/6/7KW Range Extender Generator 48V-72V Multifunction Bass Battery Range Gasoline Range Increas Electric Vehic

https://a.aliexpress.com/_m0Ghqdv

That is interesting - i wonder what the life span of something like this is?