0-7 Ampere PWM Actuator to control the Lever of mechanical Diesel Pump.

Thread Starter

Ali_Nassereddine

Joined Apr 25, 2018
3
Greetings Everyone,

I am trying to control the Lever of a mechanical Diesel Pump. i Found a rotary actuator that operates 0-7 Ampere PWM which can control the lever of Mechanical diesel Pump. My control system sends a speed Up and Speed Down Pulse ( 2 Outputs) which energizes 2 relays to increase or decrease the speed of the Diesel Engine (Control the movement of lever). Please could any one help support with suitable Circuit to help operate the Rotary actuator by Just Closing a switch for Speed Up or closing a switch for Speed. there for as my controller sends a pulse and the Speed up relay energizes and its switch will close (Closing a switch in Suitable Circuit) and the speed of rotary actuator will increase :D same goes for speed down.
 

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Thread Starter

Ali_Nassereddine

Joined Apr 25, 2018
3
Dear Dana,

Many thanks for your kind reply.
well it is designed but the price is very high and i am looking for a shipper solution. i found the attached device that controls the rotation however it has a mechanical rotating potentiometer that i need to replace by a digital potentiometer to control the up and down through external Gen-set controller that has an output of speedup speed down which energizes a relay which in return act as a 2 push button for up or down direction.
so any help will be appreciated.
 

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dendad

Joined Feb 20, 2016
3,069
Do you have any experiance with electronics, Arduinos.....?
There are some instrucables on how to make your own servo, like..
http://www.instructables.com/id/DIY-Servo-Motor/
that could be a starting place. But a lot depends on your capability.
It may be wise to find a ready built solution if you can.

For a DIY solution, you could use the up/down signal to alter a count in an Arduino to generate a PWM out.
It would be fairly simple to do. A watchdog singal of some sort is a good idea so if the controller dies, the motor speed drops to zero.
 
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shortbus

Joined Sep 30, 2009
7,074
May be wrong about this, but to me it looked like there is a position sensor in the servo it's self, the 5V 3 wire plug shown in the first post. So some type of window comparator circuit could be used to control the motor position of the servo. When the generator is putting out to much voltage the servo would run one direction. When not enough voltage it would turn the opposite direction. When withing the "window" no movement at all.

The PDF for the factory governor is here -
https://www.huegli-tech.com/fileadmin/Dateien/pdfs/products/gasmanagement/Governor/HT-HSG100-MN-EN-V1.2.pdf
(edit fixed link)



It seems to use motor speed from a hall sensor on the ring gear of the flywheel, to measure motor speed.
 
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Thread Starter

Ali_Nassereddine

Joined Apr 25, 2018
3
Thank you Dendak and Short bus....
ShortBus:- The Diesel Gen-set controller in my application is already reading the speed from a magnetic pick-up installed on a flywheel. therefore no need to get a feedback . The Gen-set controller will request a speed and by that it starts activating 1 of the 2 Binary outputs (Speed Up or speed Down) which in return energizes 1 of 2 relays (Either Speed Up relay or Speed Down Relay) and as the controller is requesting a certain speed, it is also measuring the speed reached through the magnetic pick-up signal. Based on the attached document (a cheap solution ), i connected the actuator to the motor output and as in rotate the Potentiometer clockwise the actuator moves to a direction and as i rotate anticlockwise the actuator rotates opposite direction. Maybe its not the best solution. its kind of acceptable but unfortunately i am stock in the part of replacing this mechanical potentiometer by a circuit (DIGITAL Potentiometer). Will appreciate any help with that.

Dendak:- I like what you mentioned. please could you elaborate more on your solution (up down signal) and if i can use a microcontroller to perform this job instead of the arduino, is there apossibility to come out with a circuit that can be controlled similar to the above using a relays for speed up and speed down which in return can generate PWM 0-7 A.

Thank you again .. its well appreciated all of you guys
 

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dendad

Joined Feb 20, 2016
3,069
I am not a great programmer, and this has not been tested. But using an Arduino, a couple of inputs that can be the relay contacts, a pot to set the response time, and a power FET to drive the servo, something like this, but fleshed out a bit...
SpeedControl.jpg

// Speed Control
const int speedOut = 9; // Analog output pin that the FET is attached to
const int UpIn = 10; // up signal in. Active Low
const int DnIn = 11; // down signal in. Active Low

const int LED = 13; // indicator LED
const int Time = A0; // set speed of response.
int speedValue = 0; // variable used as the speed count
int Stop = 0;

void setup() {
// put your setup code here, to run once:
speedValue = 0;
pinMode (UpIn,INPUT_PULLUP);
pinMode (DnIn,INPUT_PULLUP);
pinMode (LED,OUTPUT);
digitalWrite(LED,LOW);
analogWrite(speedOut,Stop); // start with the output off.
}

void loop() {
if (digitalRead(UpIn)==LOW) {
speedValue++;
if (speedValue >= 255) {
speedValue=255;}
}
if (digitalRead(DnIn)==LOW) {
speedValue--;
if (speedValue<= 0) {
speedValue=0;}
}
analogWrite(speedOut,speedValue);
delay((analogRead(Time))+10); // read pot and set the response loop time. Min 10mS
}


I think there will need to be a min loop delay set, and maybe a max one too, but this will need to be tested. And a watchdog so the PWM defaults to 0 out if the control signal is lost. Lots of other stuff too!

I'm sure there will be plenty of help to get this or something like it going. I may even breadboard it and test it ;)

(As others my be able to tell, and this just proves it, "My favorite programming language is solder")
 
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shortbus

Joined Sep 30, 2009
7,074
i connected the actuator to the motor output and as in rotate the Potentiometer clockwise the actuator moves to a direction and as i rotate anticlockwise the actuator rotates opposite direction.
Hi, I would measure the voltage going out to the pot used with that controller. If it is 5Volts I'd then try to see if the signal from the 5V section of the servo is the same. The section in the servo PDF called, "Rotary position IC wiring". Measure the resistance between the 5v in(red wire) and the feedback position out (yellow wire) and see if they are the same as the pot used with the speed controller. Because I think that you will find that a pot is what is used in the servo as a position detector.

That said none of this will keep the voltage output of the genset correct, without using a measurement of the genset output voltage. It will only keep the speed of the engine constant with in a range, because the servo is only working as a governor not a voltage "regulator", which is what I'm assuming you are really wanting.
 

danadak

Joined Mar 10, 2018
3,607
Something like this, attached.

Basically two switches, debounced, captured by a polled status reg.

Whenever status reg shows a request of up or down SAR ADC is used to detect the
position by reading the position sensor voltage, and calculating a conversion to PWM
to seek the new position.

Extra channel on SAR (you can have up to 8) for monitoring something else.

If you need relay drive outpouts thats just adding a pin for each relay driver.

Uses PSOC 4, board you would use to do the coding and application ($4)
would be - (you will need external power MOSFET for actuator as shown on schematic)

http://www.cypress.com/documentation/development-kitsboards/psoc-4-cy8ckit-049-4xxx-prototyping-kits



One thing not clear to me is actuator PWM driven or Voltage driven, did
not see in datasheet clear indication of this. If V driven, or current, you
would add PSOC DAC to project and some interface for power.

Regards, Dana.
 

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