Questions tagged [closed-loop]

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What micro-controllers are suitable for a closed-loop DC Motor? [closed]

I am working on a small experiment on a closed loop DC motor for speed control. The DC motor is separately excited and fed through a DC chopper. I would like to know what are the best micro-...
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2answers
67 views

Closed Loop Transfer Function - PD Control

For the following control system, I am trying to find the characteristics of the system. I have firstly found the closed loop transfer functions \$T(s) =\frac{C(s)}{R(s)}\$ , to be: \$G(s) =K_p(s+9)...
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2answers
134 views

Closed Loop system with a second order dominated response on the verge of instability

I have the forward path transfer function of C(s)G(s) = K/s(s+3)(s+7) and want to find K so that it is second order dominated on the verge of instability. But i'm not sure how to find it when it is ...
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1answer
71 views

Dominant Pole Approximation for loop gain

I have the following loop transfer function for a unity feedback system: I understand that the \$(s+2)\$ term becomes \$2\$, but what happens to the \$s\$ ?
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1answer
111 views

Closed loop vs. open loop system analysis and design

I have found questions similar to mine in the forum but none were quite answered to my full satisfaction. I have two questions: 1) Why is controller design is traditionally done with the open-loop ...
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1answer
44 views

PID controller - should terms be completely independant?

I was under the impression that the P, I and D terms of a PID controller should be calculated independently of each other. That is, they would all use the same error information, but none of the three ...
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1answer
67 views

Closed loop equation initial value

I am doing math for a closed loop equation. I know the transfer function for a closed loop system is: (Image copied from "Loop Gain and its Effect on Analog Control Systems" by Gabino ...
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1answer
90 views

Improve the performance of Buck Converter Loop Stability

The following are the specifications of my Buck Converter. Input Voltage Range : 6V to 16V Output Voltage : 5V Switching Freq : 2.1MHz Output Inductor : 22uH Minimum Load Current : 200mA Typical ...
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0answers
26 views

Drive signal (duty cycle) calculation for PI compensator

I am trying to simulate an inverter with 4 ideal switching devices in LTSpice. I have the compensator working, however I don't the correct equation in terms of calculating the duty cycle. What I ...
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1answer
44 views

Dependent vs. independent current paths

Taking the following circuit: The path on the left will be on and the same, whereas the path on the right is dependent on what is connected to the base of the transistor (not shown in the above ...
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0answers
47 views

Determining/Specing the proper stepper Motor

I am trying to properly spec a proper stepper motor for a project I am working on. I am attempting to provide roughly 3000 pounds of compressive force (about 13300 Newtons) using a p series NEMA 34 ...
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2answers
80 views

Confusion regarding root locus. Open loop or close loop?

Which transfer function ,open loop or close loop do we use/need as a pre req to perform root locus analysis? I have also attached a snapshot of the relevant webpage of university of Michigan. I have ...
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1answer
158 views

Circuit stable in the Bode diagram, unstable in step-response

I am designing a simple current control circuit and trying to simulate it in LT Spice. The circuit is not optimized for some real-world application, it's more a learning method for me to get grip on ...
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6answers
591 views

How does opamp open-loop gain affect closed-loop gain in a circuit?

The gain of an opamp circuit is basically $$A_v=-\frac{R_f}{R_i}$$ But how come the gain of the opamp itself does not appear in the equation? How is the opamp amplifying anything in the circuit? What ...
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2answers
58 views

Calculate closed loop gain with Oscilloscope measurements

Using these reading from Agilent MSO-X2012a oscilloscope: from this circuit: How do you calculate the close loop gain using these measurements. I already calculated by hand and got Av = 11V.
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1answer
238 views

Phase margin is 90 degrees but transient step response shows overshoot

The bode plot of the loop is as shown here The transient step response looks like this The block diagram looks something like this - Basically a single stage opamp(OPAMP in fig) with high gain(...
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2answers
165 views

To prove that Close Loop transfer function is sensitive to perturbation in H(s) but not to perturbations in G(s)

The feedback control system with high gain K is shown in figure
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1answer
142 views

how to display an output variable from a speed sensor to a 7 segment display in C. DSPIC33E

I have just started an electrical engineering degree and been set an assignment to create a closed loop motor speed control system in C programming language. The PIC is a DSPIC33E (BLO032) and the ...
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2answers
123 views

Proportional Control Balance Beam

Bit of an unorthodox question I'm sure, but I'm making a balance beam (two rotors on either end of a see saw) with proportional control, and I can't seem to get it to balance at 0. The proportional ...
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1answer
95 views

What is the difference between 'x' and 'plus' symbol in the block diagram

Generally speaking, what is the difference between the 'x' and the 'plus' symbol in a closed loop block diagram? For example, in (https://ieeexplore.ieee.org/document/6983570) , what's the ...
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1answer
257 views

SG3525 Closed Loop Inverter Waveform Problem

I'm using a sg3525 ic on a full bridge dc-dc converter in closed loop. The system is working fine, I don't have a problem with it. Output is just like what I want. The problem is inverter part's ...
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1answer
153 views

Sample time of PI controller

I have designed a closed loop current control (PI controller) of a DC-DC converter in continuous time domain and it is working fine. The next task is discreetization of the controller and implement it ...
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2answers
371 views

Where does the negative sign come from in this transfer function?

I have a transfer function that was given to me. It's been a really long time since I've done block diagram math, so sorry if this is a newbie question. Based on the block diagram below (I forgot to ...
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0answers
235 views

Implementing PID in PWM feedback to lower the settling time

I have created the following simple PWM feedback: The step response is: I have tried to add PID controller and I ran the following code to test it: ...
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1answer
100 views

Why doesn't current flow in the other loop?

I am just now learning about how transistors work, so please let me know if I have a misunderstanding. I ran a simulation of the circuit drawn below, and the results were that current flowed only in ...
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2answers
102 views

Closed current loop control without H-Bridge, PWM

I am trying to find a way how to control the Voice Coil Motor (VCM) or PMSM motor with a closed current loop without the use of an H-Bridge & PWM. Does anyone know how to make an analog closed ...
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2answers
240 views

Cannot predict closed-loop gain of this amplifier

This is the circuit I am currently analyzing: (link to LTSpice file) I am trying to predict each stage closed loop gain and overall gain (with all loops closed). First thing I did is calculate DC ...
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1answer
104 views

Find optimal gains transfer function

I have the following closed loop transfer function: $$G(s) = \frac{K(s^2 + 200^2)}{0.05s^3 + (1+K)s^2 + 200{K_v}s + 200K}$$ Where \$K\$ and \$K_v\$ are gains. My goal is to find the optimal gains ...
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2answers
132 views

Closed Loop control of a propeller

Hello I'm trying to control the velocity of the propeller with the pitch angle. I have a diagram from the factor cp over J and phi (see image: Draw.io diagram), but not a analytical formula. J = v*60/...
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5answers
3k views

Understanding of Dominant Pole Compensation

According to Miller Effect, within amplifying devices such as transistors that have inverting voltage gain higher that one, there should be increased input capacitance with increased voltage gain of ...