Not with a PWM

See if this helps.

http://www.electrical4u.com/starting-methods-to-limit-starting-current-torque-of-dc-motor/

Your dc motor is low voltage and draws a lot of current at start up. A series resistor, series inductor, or shunt capacitor would have to be quite large, depending on how long your motor need to get started.

Thank you very much! It did not since Id have to get inside the windings, but it was very informative and interest.

What do you dislike about using a simple PWM controller? This will be the easiest and most efficient way to vary the current into an inductive load. I admit that 100 amperes will be a hefty controller but a 1.5 horsepower DC motor is not a little motor.

Id love to use a micro controller and a couple of Mosfets to handle the current, but that adds cost and complexity to the project. The product manager doesn't want to add any controllers or cost!

The product manager doesn't want to add any controllers or cost!

You can't do anything without cost except ask for advice.

"If you can't get what you want during a negotiation, kick the table over." - Anon.

• "The product manager doesn't want to add any controllers or cost!"

So he is looking for a magical solution then?

You had better call this guy...

I would just add a reverse biased flyback diode parallel to the inductive load of the motor.

That costs a bit more. Fail.

Good point thanks.

That costs. Fail.

R1 would need to be switched s/c after start interval. 10kΩ continuously in series during run......

Why do you say that?

The 10K and 100K are only connected to the gate (during steady state operation).

Incidentally the FET is only about $3 from Digikey and the other components will be almost negligible.

I see that now. "Switched ground" as you say bypasses the arrangement during steady state.

You didn't show the 0V rail.....I looked too fast.

The hefty relay for that switch could cost more than $3.

OP wants (OP's masters' want) a zero cost solution, remember?.....he'll be looking for a while.

The switched ground is only driving the 10K into the gate of the FET.

Ok, get it now. I have senior moments, thanks for the patient explanation.

So, $3 plus what ever is used for the switch. Switch would need to be timed and coordinated with the existing "go" button, right?

I have an electric winch on my site truck and the zero cost way I get around the rapid winch drum acceleration is to just not care about it and let the rope/sling-stretch/slip provide a bit of give in the unloaded rigging during the initial inching and loading. Once the winch is loaded its startup acceleration characteristics change too. I think some one here already suggested a brake....

Thanks again. I like your circuit. Simple, but still needs to be made. I don't think there really is a zero cost solution.

Thanks, I used the circuit years ago to replace the power relays on some of the cards in a 19" shelf because we found that when we turned on a card it sometimes "dipped" the 5V power rail on the shelf enough to cause nearby cards to reset.

I used an SI4463 FET (about 11 Amps max) and the two capacitors were 100nF and 220nF.

I have to admit that I was surprised at how well the voltage on the card ramped up linearly: the blue trace is the 5V rail on the card, and, the black trace is the gate voltage.

The OP will clearly need to slow down the ramp much more than this but I can't see any reason why the same principle wouldn't work.

You could use a golf cart style step resistor. If this involves a brake system, you might have to take that into consideration.

That costs. Fail.

But... but... but... those involve adding PARTS, and thereby the dreaded COST!

You violated the edict.

Even a large bungee cord? Forgettaboutit....

That costs. Fail.

What about going to the junkyard for a variable speed controller off an old treadmill?

http://www.ebay.com/bhp/treadmill-parts

You would need a lot of old junkyards if you start the production!

That costs. Fail.

Lift only heavy objects with the winch (weight just under design capacity)....

That's it! Well sort of.

The mechanical load is undersized for the winch so the mechanical load needs to be increased. The OP should take the disc brake from the frugal manager's vehicle (Cavalier?) and bolt the disk to the spool of the winch. The caliper then gets mounted to the winch frame and bingo, an adjustable mechanical load. A little simple mounting of a master cylinder and brake lines from the vehicle and the task is done.

I guarantee if the OP surprises this manager with this modification the problem will be solved.

You could run the line over a spring mounted pulley that would act as a shock absorber...

Why bother with the diversion pulley arrangement? Just install the strut (spring and damper) in line with the load. Or use one of those Snatchem straps.

How about mounting the winch on a sliding sprung and damped cradle mount....easier than a PWM....... NOT!

..but this won't do due to cost.....

Can't be done without any cost.

you could run it with a lower voltage or use a resistive switch they use to use them on electric forkfifts. limits current through the contacts .

could cycle the switch really fast... manual PMW

cheap untill switch/relay wears out or it sticks.

Try a thermistor.

A series inductor, say 10 Henry, might do it, but finding one that would take 100 amp might be difficult. Also the cost might be more that the electronics suggested. I would suggest a reverse EMF diode rectifier across the inductor & motor to prevent switch arcing.

That costs. Fail.