High (110) voltage DC motor driver with PWM / direction inputs for cheap.

James Newton wrote 12/22/2018 at 01:01 • 0 points

Hey, anyone have advice on driving high voltage brushed DC motors? E.g. treadmill motors or the lovely old ones that last forever if you change the brushes out? They are available for dirt (I got 3 for $15 each! Working!) and yes, I know the new BLDC motors poop rainbows, but doing things on the cheap appeals to some of us.

I don't need super smooth, perfect, clean drive... just power and maybe 10 levels of it. I'm thinking industrial lamp dimmers? Or just feed from the 110 volt line directly but only give it X positive cycles out of 10? (or X negative cycles to go in reverse). If I switch on and off at the zero crossing, it should limit the noise and back EMF and whatever.

Can't seem to find any DC motor controllers that can 1. manage 110 volts and 2. reverse and 3. accept digital control signals (e.g. no knobs... PWM and direction input)

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tophalfofabarn wrote 02/19/2019 at 08:58

Also, try searching for "SCR Motor Controller". They will be rated for 90V up to 120V

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James Newton wrote 02/19/2019 at 17:48

I've actually done that already... all the ones I can find are 1. Controlled with a pot or control panel (not accepting TTL control inputs) 2. Not reversible. If you are aware of one that can be connected to a uC and can support a DC motor and reversing it, please let me know.

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tophalfofabarn wrote 02/19/2019 at 08:57

The comments saying to use a TRIAC are half right. You'll actually want to use SCRs so that you can add flyback diodes and protect the semiconductors. Alternatively, rectify first and then use a TRIAC or SCR to the motor.

Either way you are looking at four switching semiconductors.

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James Newton wrote 02/19/2019 at 17:49

I'd love any help with the circuit or spec'ing the parts. I'm not an analog guy and this is where being wrong really hurts. I'm willing to buy parts and try to build it / share the results if someone provides guidance.

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tophalfofabarn wrote 02/21/2019 at 02:10

I'm a little busy this week but maybe this weekend I can help you out and draw out some schematics. Will you want to control this with a microcontroller?

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James Newton wrote 02/21/2019 at 05:41

Yeah, controlled by a PIC actually.

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Erlend Ervik wrote 12/27/2018 at 19:55

H-bridge gate-drivers + 4 FET's should do as motor driver. You can PWM the control pins.

You can even get 3-phase motor-driver chips (various in 100V-600V range) and just disregard one channel.

The whole setup should be run from DC, so a input rectifier is required for mains use.

a filter capacitor could be good to add.

You can also do triac tricks and using a DPDT relay to reverse the motor.

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James Newton wrote 12/27/2018 at 23:43

any part numbers or links would be appreciated.

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Erlend Ervik wrote 12/28/2018 at 14:38

Check for example FAN73832. There are very many different ones.

You can probably find 100+ variants if you go looking.

The suggested part is just to give an idea, and not really a recommendation.

You would need 2 of them and 4 N-MOSFET's and the support components from the datasheet:

2 capacitors, 2 diodes(can be built in), 12V supply, misc bypass capacitors.

Just be aware that the controller voltage is not isolated from the output voltage. Some optoisolators would be needed if that is a problem.

The alternative is the IGBT modules for BLDC use, where you just leave the last output unused.

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James Newton wrote 12/28/2018 at 18:25

@Erlend Ervik Any recommendations for the MOSFET's?
The BLDC drivers I can find are all pretty low voltage. If you know of one that can manage 110V, please let me know. Or were you suggesting the same sort of thing where the BLDC driver would be connected to the HV MOSFETS?

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Erlend Ervik wrote 12/28/2018 at 18:48

https://www.onsemi.com/PowerSolutions/product.do?id=FNA41560B2

Just checked the first part I found for "IGBT module" on aliexpress.

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Martin wrote 12/27/2018 at 17:49

You can use a TRIAC and feed the motor half cycles. depending on the firing angle of the TRIAC (0 to 360° referenced to the rising "edge") you get forward or reverse. Forward from 0 10 180° with decreasing power and reverse from 180° to 360° with decreasing power.

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James Newton wrote 12/27/2018 at 18:29

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James Newton wrote 12/26/2018 at 06:28

Any of those solutions would be fine, but I can't find any that already exist. The motors I'm seeing are in the area of 1/5 HP, maybe an amp at 110.

I'm very much not an analog power guy, although I do have a lot of experience with stepper motor drivers; this is a different world. Any advice / suggestions appreciated.

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Jarrett wrote 12/22/2018 at 06:17

Lamp dimmers, also many soldering irons and hot air stations, just use triacs. Two of them and a couple full bridge rectifiers would get you reversibility.

You need to specify at what level you're looking for solutions! Are you looking for discrete triac recommendations, bespoke control boards, or full commercial solutions, and for what kind of power

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High (110) voltage DC motor driver with PWM / direction inputs for cheap.

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