Created Date: July 10,2012

Created by: plcnut

An alternators voltage output is varied by increasing the field current. A standard external voltage regulator will either pulse the field or vary the field voltage(thereby varying the field current). Some regulators are sinking and some are sourcing, all depending on the type of alternator you have. Yours may have a floating field where both ends of the field winding are accessible, or it could have one end grounded internally, or it could have one end tied to positive internally, a good auto-electric shop should be able to tell you what yours is (or you could do some probing with a ohmmeter and figure it out), and you can probably just use a generic external regulator that will handle everything. (I'm not a professional on this so if someone knows better please feel free to correct me, this is just a little of what I learned in one of my escapades to do what nobody else seemed to be doing). :)

Created Date: July 10,2012

Created by: dieseltwitch

Thanks! after continuing my research today I have contemplated going to a PM wind turbine alternator. This would allow me to use a purpose built wind MPPT Charge controller. Im not sure if this will do any thing for me or if its easier o vary the field voltage on a normal alternator. with so many variables in the system Im trying to figure out what would actually control the engine speed. normally the MPPT is designed to maximize a normally uncontrollable source of power (wind or sun) here I have control of the power source so Im wondering if the MPPT would be over kill.

Created Date: July 11,2012

Created by: Cap

The Problem with a PM wind generator, is the Magnetic feild is always there.. so you can NEVER cut back the Alternators out put to RPM Ratio... so the charge is always RPM Dependant..

I think you were on the right track with the Alternator trick..

I'd Go this route..

Remove the Internal Regulator from the Alternator, and mount Most of it External.. or at least the Regulator smarts of it..

Have the Alternator set up to have Charge Targets for Voltage.. these will be selectable by the PLC Outputs..

Target One is NO selected Out put Voltage.. this is used for Engine testing and Starting/Warmup.. the Alternator will still be connected to the Batery bank, but no chage voltage will be produced... ( Free Spinning )

Target Two is 13.5 Volts.. this is the Float Charge.. selectable by the PLC and usually will kick the Engine to a Moderate Idle State..

Target three is 14.2 to 14.5.. this is the Absorption Charge.. for Hiting the Batery bank after the Bulk Charge Phase..

Target Four. is set at about 14.8 to 15 Volt.. this is the pound the charge Phase.. for getting the battery back up to a point where you can start the absorption phase..

In Practice, the Outputs would look something like this..

NO PLC Output will have NO Output to the Regulator.. this is the No Output Range..

PLC 1 output will be the Lowest Setting.. 13.8

PLC2 will be the Next Step Setting.. 14.5

PLC3 will be set for 14.8 to 15 Volts

OR you can wire it so the Stage One Output is PLC1

Stage Two Output is PLC1 and PLC2

Stage Three is PLC1, PLC2, PLC3..

Depends on how you run your Feedback Resistor Bank

By having the regulator, or at least the Voltage Matching parts of it mounted remotly, you can switch between the Various Charge Voltages, and MOST Alternators have some sort of Current Limit Sensing built into the Regulator/Alternator Combo to keep the Alternator from Poping the Diodes when you are hitting it hard..

You can do a Tempature Monitor for the Diode Pack to see if you are getting them too hot..

Then you can do a Voltage Monitoring of the Rectofied ( Check Local Spelling ) voltage on the Flywheel Alternator of your 10 HP motor to get an aproximation on the Engine Speed, and adjust the Governed Engine Throttle to keep the desired speed.. using Staged Pull Coils with Loading Springs to Pull on the Engine Govenor..

See how Simple that is??.. :)

Cap

Created Date: July 13,2012

Created by: dieseltwitch

The Problem with a PM wind generator, is the Magnetic feild is always there.. so you can NEVER cut back the Alternators out put to RPM Ratio... so the charge is always RPM Dependant..

I think you were on the right track with the Alternator trick..

I'd Go this route..

Remove the Internal Regulator from the Alternator, and mount Most of it External.. or at least the Regulator smarts of it..

Have the Alternator set up to have Charge Targets for Voltage.. these will be selectable by the PLC Outputs..

Target One is NO selected Out put Voltage.. this is used for Engine testing and Starting/Warmup.. the Alternator will still be connected to the Batery bank, but no chage voltage will be produced... ( Free Spinning )

Target Two is 13.5 Volts.. this is the Float Charge.. selectable by the PLC and usually will kick the Engine to a Moderate Idle State..

Target three is 14.2 to 14.5.. this is the Absorption Charge.. for Hiting the Batery bank after the Bulk Charge Phase..

Target Four. is set at about 14.8 to 15 Volt.. this is the pound the charge Phase.. for getting the battery back up to a point where you can start the absorption phase..

In Practice, the Outputs would look something like this..

NO PLC Output will have NO Output to the Regulator.. this is the No Output Range..

PLC 1 output will be the Lowest Setting.. 13.8

PLC2 will be the Next Step Setting.. 14.5

PLC3 will be set for 14.8 to 15 Volts

OR you can wire it so the Stage One Output is PLC1

Stage Two Output is PLC1 and PLC2

Stage Three is PLC1, PLC2, PLC3..

Depends on how you run your Feedback Resistor Bank

By having the regulator, or at least the Voltage Matching parts of it mounted remotly, you can switch between the Various Charge Voltages, and MOST Alternators have some sort of Current Limit Sensing built into the Regulator/Alternator Combo to keep the Alternator from Poping the Diodes when you are hitting it hard..

You can do a Tempature Monitor for the Diode Pack to see if you are getting them too hot..

Then you can do a Voltage Monitoring of the Rectofied ( Check Local Spelling ) voltage on the Flywheel Alternator of your 10 HP motor to get an aproximation on the Engine Speed, and adjust the Governed Engine Throttle to keep the desired speed.. using Staged Pull Coils with Loading Springs to Pull on the Engine Govenor..

See how Simple that is??.. :)

Cap

Thanks for the detailed reply! You gave me a lot of food for thought! After thinking about how to deal with the inconsistent relationship between voltage and amperage. If I'm not mistaking during the initial bulk charge the amp load will be higher and so is the voltage. Once the bulk cycle is done the voltage stays the same but the amp load drops and remains low. So I'm thinking that I can vary the field strength only to adjust voltage using a PID loop to maintain the voltage and another PID loop to load the battery and maintain a target amp load.

I'm thinking of Making the system analog and not just use switches. I was trying to find out how the control of the field windings would work. What voltage equals what output.... I do like your idea of some type of tacho reading back into the computer for overall engine control.

One advantage I can think of in doing the different amp/voltage control is that I can add and subtract batteries at will and the computer will adjust with out problem.

I could also run multiple alternators and turn one on or off if it's not needed to help save fuel.

I will also put on a battery temp sensor of some type to make sure I don't overheat them.

I love these projects!:D

Created Date: July 13,2012

Created by: Cap

If I remember all my Old School Stuff.. . the Unloaded output Voltage of the Alternator will be something like the Square of the Alt Speed, untill the Magnetic Hystresis starts kicking in big time.. then the Losses start taking over.. and you reach some point that no matter how fast you spin it ( Unloaded ) it will not make any more Voltage..

Current Output into a Dead Short will also be the Sq of the Speed with simular relationship to the Voltage Output, and Mag Losses..

What you will find in Practice, is the Speed and Exciting Curent of the Rotor are completly inter-related.. and good control over BOTH will make a Good Steady Charger.. Usually the Regulator is All Electronic, for Fast Feedback in the Loop Performance.. And the Good Speed Control is done with Rotating Mass, and as good a governor as you can get.. with that said, Early Regulators for Generators and Alternators were Relay Coils tugging upon Springs, to ballance out the Forces.. so how fast can that be.. usually the Alternators relied on the Batteries to even out the Voltage to the System..

I'd run the Output Charge through Curent Transducer/Transmiter to get a Ma reading as to actual charge Curent..

Think the PID loops of the PLC would work for output to the Alternator.. but the Problem is the Interface to the Rotor Curent.. You want to stay out of the Linear Range of Analog Devices for heat generation.. so that will put you in the PWM stuff for Driving the Rotor Curent.. MANY PWM controllers are avalable,( In chip Form and as Charge Controllers ) but I'm not thinking anything off the Shielf will pug into the Alternator, and the PLC output of 4-20 or 0-10 Volt and get you charging Batteries.. that is why I sugested using a Switchable Resistor bank to Modify the Sample Voltage the Built In( or Replacement ) regulator will 'see ' for its Feedack Checking..

The Next Hurdle to jump over is the Engine Speed.. Pull Coils on Springs is Cumbersom.. but Functional..

Cap

Created Date: July 13,2012

Created by: dieseltwitch

If I remember all my Old School Stuff.. . the Unloaded output Voltage of the Alternator will be something like the Square of the Alt Speed, untill the Magnetic Hystresis starts kicking in big time.. then the Losses start taking over.. and you reach some point that no matter how fast you spin it ( Unloaded ) it will not make any more Voltage..

Current Output into a Dead Short will also be the Sq of the Speed with simular relationship to the Voltage Output, and Mag Losses..

What you will find in Practice, is the Speed and Exciting Curent of the Rotor are completly inter-related.. and good control over BOTH will make a Good Steady Charger.. Usually the Regulator is All Electronic, for Fast Feedback in the Loop Performance.. And the Good Speed Control is done with Rotating Mass, and as good a governor as you can get.. with that said, Early Regulators for Generators and Alternators were Relay Coils tugging upon Springs, to ballance out the Forces.. so how fast can that be.. usually the Alternators relied on the Batteries to even out the Voltage to the System..

I'd run the Output Charge through Curent Transducer/Transmiter to get a Ma reading as to actual charge Curent..

Think the PID loops of the PLC would work for output to the Alternator.. but the Problem is the Interface to the Rotor Curent.. You want to stay out of the Linear Range of Analog Devices for heat generation.. so that will put you in the PWM stuff for Driving the Rotor Curent.. MANY PWM controllers are avalable,( In chip Form and as Charge Controllers ) but I'm not thinking anything off the Shielf will pug into the Alternator, and the PLC output of 4-20 or 0-10 Volt and get you charging Batteries.. that is why I sugested using a Switchable Resistor bank to Modify the Sample Voltage the Built In( or Replacement ) regulator will 'see ' for its Feedack Checking..

The Next Hurdle to jump over is the Engine Speed.. Pull Coils on Springs is Cumbersom.. but Functional..

Cap

When you say heat generation form the analog, could not a solid state 0-10V relay work with out generating much heat? I 've done my own PWM for controlling the speed of single phase pumps. could the same idea work for that also?

From what i got that you wrote. the exciter voltage will be (should be) less than or equal to the alternator output after its rectified? Im not so worried about what the actually voltages need to be to get the right output just what the ranges are. the PID loop should take care of the rest

Created Date: July 13,2012

Created by: Cap

If you 've done PWM on a single phase Motor using the 10 Volt solid state relay with a pulsing output from a PLC, then you 've already done most of the work..

My understanding of the Solid State Relays, is they are like the Lamp Dimer Circuits.. Once it Turns on, it will stay on till the Line Voltage Crosses Zero.. then it switches off.. so you get a Turn on at an Unknown Sign Voltage, but the Turn off, and Inductive Kick is always about the Zero Crosing Volts.. in Practice I remember it being 10 Volts or So.. not bad on a circuit rated 120 or 240 volt.. at least the Kick is not at full line voltage, like will be on the DC Circuit you will de driving..

When you are doing the 12 Volt Pulsing to the Rotor Coil, you will not be using a Triac of the 10 Volt Relay, and it will be something like a IGT.. and the Turn On Volts will be 12 ( Ish ) and the Turn Off will be 12 (ish) into a Very BIG Inductor.. and the Inductive Kick will be great.. so need to protect the stuff with some bigger than normal Diodes for the Snap Back.. You might be able to get a 10 Volt Solid State relay that has all the Protection built in.. thatd be great.. Might have a heat issue with More Switching times than the Solid State relay is built to handle .. .. Might need to mount the IGT on a heat sink.. fan cooled?

Hell, the worst you can do is make smoke and fire.. !!.. just make sure you get the Video to post..

Cap

Created Date: July 10,2012

Created by: dieseltwitch

I 've been working on my Motor/Alternator DC Generator setup and have run into a problem I'm hopping someone here can help me with. For those of you that do not know what I'm doing I have a 10HP gas motor coupled (belt drive) to a 300AMP alternator that i use as a start cart and small portable power pack with two AGM Yellow Top batteries and a 5kW Modified Wave inverter. The cool thing about it is that the motor does not have to run full out all the time. depending on the load i can slow the motor down to run quitter and consume less fuel. (still working on the controls)

The problem I'm running into now is that the battery charge is not controlled. Sure the alternator not do the 3 stage charging cycle I need (Bulk, Absorption & Float). Im trying to figure out the best way to manage this problem. So far i can find a charge controller large enough to handle my Alternator (300amps)

The alternator I have has PCM Voltage control. from my research this means the P owertrain C ontrol M odule handles all the voltage regulation.

Im wondering if I bypass what ever electronics are inside the alternator and tap directly into the rectifier if i can get the variable DC voltage and just use some type of control scheme to change the voltage to the battery bank I was thinking of running something with a DL05 or DL06 to control the churning of the battery bank. From my understanding the 3 stages go something like this

Bulk Charges the battery up to to ~14.5V once the bulk voltage has been reached the controller modulates the system voltage to maintain the 14.5V for and hour or so (the absorption stage) and then drops it to the fold voltage of ~13.5V. If this is the case can I not just run the alternator at different speeds to regulate the voltage output or is there a better way to control the voltage of the system?

Thoughts?