Converting a PM dc motor to AC with variable speed, How?

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
I am working on a drum sander with a rotating drum, and a conveyor belt that I want to run at variable speed. I have salvaged a treadmill motor to use to run the belt. Here are it's specs

Electrical rating: 130VDC, FF 1.0
2.75 HP treadmill duty 6400 rpm 21 amps
1.75 continuous duty @100VDC FF 1.0

I am never going to approach 6400 RPM on the motor. I have been reading that I want a rectifier and a speed controller of some type, but I'm an idiot when it comes to most electrical stuff. I am very capable of doing the work to set up a system, but figuring out the components is the problem.

Is there a way to reduce the possible max rpm of the motor? Reducing voltage, perhaps?

Suggestions?
 

MrAl

Joined Jun 17, 2014
7,849
I am working on a drum sander with a rotating drum, and a conveyor belt that I want to run at variable speed. I have salvaged a treadmill motor to use to run the belt. Here are it's specs

Electrical rating: 130VDC, FF 1.0
2.75 HP treadmill duty 6400 rpm 21 amps
1.75 continuous duty @100VDC FF 1.0

I am never going to approach 6400 RPM on the motor. I have been reading that I want a rectifier and a speed controller of some type, but I'm an idiot when it comes to most electrical stuff. I am very capable of doing the work to set up a system, but figuring out the components is the problem.

Suggestions?
Hi,

Sounds to me like you need to buy a controller. I dont know how much experience you have working on electrical circuits that handle lots of current and somewhat high voltages. Some care is needed in handling such things.
Maybe you could outline what circuits you've worked on in the past that would help. This is not a beginner project for sure.
 

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
Hi,

Sounds to me like you need to buy a controller. I dont know how much experience you have working on electrical circuits that handle lots of current and somewhat high voltages. Some care is needed in handling such things.
Maybe you could outline what circuits you've worked on in the past that would help. This is not a beginner project for sure.
 

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
I've done home wiring, some minor AC motor work before, but actually doing the work isn't something I think is an issue. I am thinking it's going to go like this:. Power in> AC knob light control, rectifier, motor. Unless I'm missing something

II could also use the boards that are with the treadmill, in which case, I'd just need the pot.... But where does it go. Plus a on/off/on momentary switch for the incline that I want to use also(it's A.C). but again, where?
 

ArakelTheDragon

Joined Nov 18, 2016
1,350
I think that this motor runs continuosly at

Electrical rating: 130VDC, FF 1.0
2.75 HP treadmill duty 6400 rpm 21 amps
1.75 continuous duty @100VDC FF 1.0 => 1.75 horse power.

But it can reach the maximum of 2.75 horse power.

You need a constant 100VDC supply voltage voltage from any grid with a rectifier if you are in the US. If you are using the "230VAC" grid system, you will need a transformer to lower the voltage.

A controller would be to control the voltage as this motor seems voltage controlled. Might be some limit of minimum voltage "50VDC to 130VDC" or something like that.

Pictures of the motor and label would be useful.
 

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
I think that this motor runs continuosly at

Electrical rating: 130VDC, FF 1.0
2.75 HP treadmill duty 6400 rpm 21 amps
1.75 continuous duty @100VDC FF 1.0 => 1.75 horse power.

But it can reach the maximum of 2.75 horse power.

You need a constant 100VDC supply voltage voltage from any grid with a rectifier if you are in the US. If you are using the "230VAC" grid system, you will need a transformer to lower the voltage.

A controller would be to control the voltage as this motor seems voltage controlled. Might be some limit of minimum voltage "50VDC to 130VDC" or something like that.

Pictures of the motor and label would be useful.
A2DEB4A2-2C27-4D22-B481-DD0D6A6CC766.jpeg
 

ArakelTheDragon

Joined Nov 18, 2016
1,350

MaxHeadRoom

Joined Jul 18, 2013
21,653
There are a few options, you can get simple PWM controllers on ebay, quite cheap, there is also ex T.M. controllers such as the MC60 which is simple SCR bridge, or the MC2100 PWM version. There is also KB Drives which make similar DC drives versions.
If you are retaining the flywheel, you will need slow start to avoid blowing the controller, the T.M. versions require that you zero the control pot before applying power.
Max.
 

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
I have the old working control boards for the treadmill. They're still connected. Don't want to use the display board. I can use the old boards, (prefer) but don't know where to connect the pot for the treadmill motor, or the switch for the incline, which will be used to raise/lower the conveyer belt to the drum. If I use the old boards, I should only need a pot and switch, correct? It's also going to typically run at low RPMS. I'd like to be able to prevent the motor from being able to run at high speeds
 

shortbus

Joined Sep 30, 2009
8,062
@ ArakelTheDragon, you are usually asking people where they live but refuse to say where you live. Why do you continually answer questions you have no idea of the correct answer to? You are going to end up getting some one hurt.
 

MaxHeadRoom

Joined Jul 18, 2013
21,653
The bottom ones appear to be a Incline board.
The top, which appears to be a PWM controller has the AC in at AC2 blue & white.
The motor A+ & A-.
A 10k or 5k linear pot to L,W,H.
So that should be all you need.
Max.
 

Thread Starter

IKnowNothing

Joined Nov 14, 2018
11
A 10k or 5k linear pot to L,W,H......

The difference being??? I know that it's resistance. The more resistance decreases motor speed overall?

Fly wheel or not?
 

MaxHeadRoom

Joined Jul 18, 2013
21,653
If the drive has the zero-before-start feature you can retain the flywheel, but it is not needed for most applications other than a T.M.
Most pots for these are 10k.
Max.
 
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