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Analog motor controller

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Grossel

Well-Known Member
Hi.

Once a time several years ago I came over some theory about a motor controller. What I remember now is this:

It contains 4 opamps. One integrator, one differentiator and a regular noninverting opamp amplifier stage. Then I think all three stages mentioned above had their input connected together and I also think that the output from the three stages went into a adder circuit.

The input comes from a frequenzy to voltage converter on the motor shaft.

However I don't know what this technique is called and therefore it's impossible to google for it. Anybody knows?
 

Chippie

Member
pulse width modulation with feedback from a tacho on the motor shaft.
 
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Space Varmint

New Member
Hi.

Once a time several years ago I came over some theory about a motor controller. What I remember now is this:

It contains 4 opamps. One integrator, one differentiator and a regular noninverting opamp amplifier stage. Then I think all three stages mentioned above had their input connected together and I also think that the output from the three stages went into a adder circuit.

The input comes from a frequenzy to voltage converter on the motor shaft.

However I don't know what this technique is called and therefore it's impossible to google for it. Anybody knows?
I don't know what all those circuits you mentioned do, but the techniques are fairly standardized these days. I think most of the motor types are single phase AC induction motors. They call them induction motors because the secondary windings (squirrel cage) have no direct electrical connection. The electricity in the squirrel cage is induced from the electromagnetic field of the primary windings. In a free running (uncontrolled) AC motor there is a START capacitor in-line with the secondary windings to shift the phase by 90 degrees so that the motor will begin to rotate, then a centrifuge switch will drop out the phase shifting capacitor after it begins to rotate.

Now days they use the same techniques as a power inverter where the motor windings are considered like a transformer. So the input AC line voltage is rectified and fed into an oscillator circuit as is done with an inverter. Then as the guy before me said, they use pulse width modulation to control the speed of the motor rotation.

Here's some good websites to get you started:

Three Ways to Control a Single-Phase Induction Motor - 2004-12-13 00:00:00 | Design News

Schematics For: 1Ø Split Phase Motors - Series 2 - ECN Electrical Forums
 

Chippie

Member
The motor could be a universal type rather than an inductive?

Just a thought :)
 

Space Varmint

New Member
The motor could be a universal type rather than an inductive?

Just a thought :)
Oh man, They even use 3 phase off the same theory. I think that they mostly use what I was describing, but I'm no expert by any means. I have never followed through with any design of this sort. It's just that I was bidding a job recently where they needed extra efficiency, and that was some of the stuff I came across in my research.
 

MrAl

Well-Known Member
Most Helpful Member
Hello,


It was a PID controller circuit.

Almost every controller (probably every one) contains a P controller, but when you add the I and D you
get better control. The P makes the basic controller, the D is so the control has a faster response,
and the I is to get lower steady state error.
 
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Chippie

Member
Proportional, Integral and Derivative are the three terms...

Derivative is commonly used in temperature control loops to reduce Dv/Dt lags.....
 

himanshusinha

New Member
Wireless robots

Well friends
i m beginner well i have made a wired racer robo car but now i want to convert it into wireless
so please guide me wat to do please from starting to end
 

Grossel

Well-Known Member
Hello,


It was a PID controller circuit.

Almost every controller (probably every one) contains a P controller, but when you add the I and D you
get better control. The P makes the basic controller, the D is so the control has a faster response,
and the I is to get lower steady state error.
Thanks a lot :)

Problem solved.

It's a "dumb" problem really, but for a no-native english it make the difference between know-how and completely confusion :confused: :rolleyes:
 
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Chippie

Member
The motor is just a regular DC. It's not important what is between the adder circuit and the motor.
Do you just want to control the speed of the motor?

A pwm cct will do that for you...search for PWM motor control.. ;)
 
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