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Increasing a 12/24v alternator to 36v

vulcanworks

Joined: 31-01-17

Topics: 11

Replies: 15

Posted: Tue 4th Jul 2017, 11:24am
Increasing a 12/24v alternator to 36v

Hi,
Just about there with all the puzzle pieces for "Mary May" our name for our Diesel powered Tug. One fly in the ointment has come up though - the need to regulate the voltage to the PWM.

The easiest way is probably to use an alternator instead of the first 800W motor, but I've not been able to find a 36V alternator. Plenty of 24V ones are available and I know it's possible to increase the voltage output on an alternator, but I've only found methods to increase the voltage by a small amount (say 0.6 or 1.5v). I need to increase the voltage by 12v. I'm assuming the method is identical but using different diodes.

If anyone knows, or could point me in the direction of a diagram etc that would be great.

Thanks
Mike
 

Replies To This Post

vulcanworks

Joined: 31-01-17

Topics: 11

Replies: 15

Posted: Tue 4th Jul 2017, 11:43am

Could this work ?

A 24V Alternator -> Step Up Voltage Regulator -> 36v 800W 28A Motor

I've found one which would step up the voltage from 24V to 48V 15A, so I assume I'll be able to find something suitable.

Mike
 

MartynRedfearn

Joined: 1-01-94

Topics: 16

Replies: 107

Posted: Tue 4th Jul 2017, 12:37pm

Mike a 12v alternator is capable of very high voltages if you remove/disable the voltage regulator we measured the one in Spuggy at 96v before altering the drive ratios. I suggest reading this article http://www.smex.net.au/Reference/AlternatorTraction02.php
 

vulcanworks

Joined: 31-01-17

Topics: 11

Replies: 15

Posted: Tue 4th Jul 2017, 3:49pm

Perhaps I'm overthinking this. So long as I can regulate the voltage going to the PWM, it's not going to matter whether I use a motor as a generator or an alternator. Maybe the simplest solution (a motor connected through a buck-boost module) is the way to go.

I've seen a 1200W High Power DC-DC Converter Boost Step-up Power Supply Module which can vary its output current up to 20A, has a variable input voltage of 8-60V and a variable output voltage of 12-80V. With that I could literally connect anything on one side, any PWM on the other, configure the module and it "should" work...shouldn't it ?
 

colinedmondson

Joined: 9-08-09

Topics: 3

Replies: 82

Posted: Mon 17th Jul 2017, 12:01am

I agree with Martyn. Take the regulator off the alternator and replace with a small PWM controller (say 10A). Depending on the speed of the alternator, the output voltage can then be varied from 0v to the chosen maximum voltage, which is set by the engine pulley diameter and speed. I have a 75mm pulley on a 5hp engine to give 51v max, I am running two 24v motors in series, ie 48v. All the details on how to do it are in the SMEX article. From the driver's point of view it drives like a battery electric except for the need to set the throttle first.
 
 
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