Controlling a DC pump with PLC/PWM

A

Thread Starter

AJ

Hello all.

I'm new to this forum, but not really new to controls and automation. I'm an IBEW Journeyman Electrician by trade and finishing my second year in college to be an Electrical Engineer. I'm helping a local race shop develop an oiling system for my turbo charged Hayabusa. We are currently using a small 12vDC pump controlled through a pwm to control the the speed of the pump which is needed to control the pressure in the turbo. In one of the oil lines we have placed a an electrical oil pressure sensor. We simply watch the gauge and turn the pressure up or down depending on what the gauge reads, pretty simple. The goal is to maintain a static pressure across the entire temperature range.

We'd like to put this on some sort of closed loop system. Currently, the pwm has to be placed under the seat and is not very accessible while riding. We have one good thing going for us. The module that controls the oil pressure sensor has 0-5v output built in. I'd like to use this as an input on a plc that has a pwm built into it to control the oil pump. I've done some research and I can't seem to find a unit that can withstand the current draw of the pump. I'm not sure exactly what that draw is, but its probably in the neighborhood of 10-15 amps. It flows 2.6 gallons per minute and can be seen here at the bottom of the page: http://www.rbracing-rsr.com/partnumbers.htm

We'd like the unit to be one piece and not have to mess with multiple pieces. The unit needs to be small as well and cost is a factor.

Any help with component selection or input on design would be greatly appreciated. Thanks in advance.
 
W

William Sturm

I think to get this in one piece, you would need to design a custom board with a microcontroller and a transistor circuit.  To use a PLC, you will probably need an external solid state relay.  I am not aware of any PLC's that have a 10-15 amp solid state relay output.

 Bill Sturm
 
I just did an Internet search and landed in eBay where there are some inexpensive PWM-based DC motor drives with potentiometers I presume are for speed setpoint/control. I would imagine you could do some manipulations with your 0-5 VDC pressure signal to use as the reference for the module to "replace" the pot. Some go as high as 50A output with 12V or 24V DC input.

The eBay category was 'Toys & Hobbies'. Or, just try searching eBay for 'DC motor speed control kit'; there were a lot of items matching that search term.

You will need some kind of "switch" for the mains power or the output power, whether that's a relay or not would depend on the application.

I think a PLC is a little overkill for this application. And would add weight and bulk to the motorcycle.
 
> I think to get this in one piece, you would need to design a custom board with a microcontroller and a transistor
> circuit. To use a PLC, you will probably need an external solid state relay. I am not aware of any PLC's that
> have a 10-15 amp solid state relay output.

Which plc and solid state relays would you recommend?
 
W

William Sturm

You would need a very small PLC that runs on 12 volts. That tends to narrow the field a lot. Automation Direct DL-05 is one.

Another idea, possibly better, is to find a small programmable board typically used for robot control. An Arduino is a good example. They tend to have DC motor drivers that can be added on easily.

Something like these:
http://www.robotshop.com/brushed-motor-controllers.html
http://www.robotpower.com/products/MegaMotoPlus_info.html
http://www.pololu.com/catalog/product/2502
http://www.pololu.com/catalog/category/11

There are many more out there, just Google around and you will find....

Bill Sturm
 
> I just did an Internet search and landed in eBay where there are some
> inexpensive PWM-based DC motor drives with potentiometers I presume are for
> speed setpoint/control.

---- snip ----

This option has been considered. We want to have the ability to change the pressure if needed and also have the a low pressure light on the bike. Using a plc really allows us a lot of freedom. Weight really isnt an issue. The rider's weight decreased by 20% smaller and the motorcycles power output has increased by 75% ;-)
 
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