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Motor Starter Stage Simple Circuit

jwalton1

Apr 3, 2014
1
Joined
Apr 3, 2014
Messages
1
Hello, Any help would be brilliant with this!
I need to create a method of taking a variable input from a 230V@10A dimmable socket in a theatre to convert it to a variable 180VDC to control a DC motor built into a treadmill the other side of the room with a constant run power requirement of 5 Amps. So far all I am using is a bridge rectifier and running the dimmer at a low level to convert it into DC but as you can probably imagine as soon as the motor is started the load on the motor causes the inrush to trip the 10A dimmers (the motor only has one run coil and no start).

Can anyone recommend a circuit that could be at the motor end of the setup using either capacitors or a resistor system that would require no human interaction apart from the dimming control to adjust the speed after start up.

Preferably cheaply!

Again, any help would be greatly appreciated.
 

Fish4Fun

So long, and Thanks for all the Fish!
Aug 27, 2013
481
Joined
Aug 27, 2013
Messages
481
jwalton1,

Welcome to the forum!

First: Line powered 2.3kW speed controls are NOT:

1) Cheap
2) Easy
3) Good DIY projects.

Things to consider:
1) 230Vac is an RMS value so the DC voltage after being rectified will be ~325Vdc.
2) Any passive means of dropping 325Vdc to 180Vdc @ 10A will require dissipating ~1.4kW of heat.
3) If this 'theatre' is "open to the public", then it is almost certainly subject to electrical and safety codes that need to be complied with. Attempting to DIY a 2.3kW power supply is almost certainly going to be out of compliance.
4) Dimmers designed for lighting are typically NOT designed to handle highly inductive loads like DC motors.
5) Many "DC" Treadmill motors are in-fact not mechanically commutated, a clue that the one you are using may NOT be mechanically commutated is the "constant 5A power requirement"; this type of rating is more typical of a stepper motor or a BLDC motor. If the motor is NOT mechanically commutated then attempting to vary the speed by current or voltage regulation will likely fail.

Since most treadmills include a built in speed controller, I would suggest you attempt to use it as it was designed specifically for the motor in question. This would be by far the easiest and cheapest solution...even if it meant searching Craig's List or going to some garage sales looking for a complete treadmill to salvage parts from.

Fish
 
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