Questions tagged [closed-loop]

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Closed loop control of a stepper motor (i.e. servo system)

Crucial to the performance of a CNC is its ability to precisely, accurately and quickly move to the directed position. Stepper motors are perhaps the most popular (and therefore cheapest) motors ...
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On the stability of differentiator based on OP amp with an example from TI manual

I am building a proportional-Differentiator circuit based non-inverting OP-amp. But I am confused with the stability condition of OP-amp. The system will be unstable if the loop gain |T(s)|=|a(s)B(s)|...
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The output of PI controller using opamp is not working [closed]

I am designing a closed loop system for dc-dc converter for that I am using error amplifier and pi controller. For error amplifier and PI controller I am using OP177A opamp. The error amplifier ...
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How can we confirm whether the op-amp has -ve feedback? [duplicate]

Many text books show an op-amp will have negative feedback when o/p is connected back to -ve input through some discretes and under such condition V+=V- is satisfied for op-amp input terminals. In the ...
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Define input impedance of a buck converter for ideal converter (efficiency 100%) & practical converter

What I know was -The input impedance by the closed-loop buck converter in CCM mode, Zi and, in turn, that presented impedance is dependent on Zo and the duty cycle used by the buck converter below is ...
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Can any one explain what type of compensation is this

I will be using the UC3844 controller IC in combination with TL431 to achieve peak current mode control in a 150W forward converter. After some research, I found this schematic on the internet: There ...
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H-bridge class D amplfier [closed]

i am trying to make a closed-loop class D amplifier for a dissertation. I have the basics: audio signal-->pwm modulator(LTC6992)-->gate drivers->H-bridge-->LC filter--> speaker but i ...
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Ideal closed-loop gain derivation for negative feedback

Considering a negative feedback system, the closed-loop transfer function Af is given by: where A is the open-loop transfer function and AB is the loop gain. Every text I read says that if the ...
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Peltier Quick Heating and Cooling

I am using Peltier Module to quickly heat and cool down the object placed on it to a particular temperature. My target is to heat the object to 90 degrees and then cool it down to 54 degrees and then ...
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Setpoint weighting algorithm for the PI controller

Some time ago I found an interesting modification of the standard PI controller algorithm. The modification is called the setpoing weighting in the literature and regards the proportional component of ...
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4 wires encoder to 6 wires Hibrid Servo drive for closed loop stepper motor

I have the HBS860H driver and LPD3806.I wanna know if I can connect this 4 wire encoder, to this 6 wire driver. HBS860H: https://hardware-cnc.nl/images/PDF/ACT/HBS86H_English_Manuel.pdf LPD3806: (i ...
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what is the open and closed loop function of this system?

i found this in the text book. i solved by: 1- found the closed loop function of just the part of B(p) and its "feedback", let's call it B'(p). 2- after that i did H(p) = A(p) / ( 1 + A(p) * ...
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Interesting driving circuit of a voice coil actuator

I have an interesting circuit to drive the voice coil stage of an old acoustic microscope. I am struggling to understand what the different functions of the opamps in this circuit are. The circuit ...
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Determine if the system is stable [closed]

Determine if the system is stable? How is this done? Is this at one frequency? Is the Loop gain is A x B x C = 0.5 Should phase angles be added together = 173 degrees? Should I be considering the open ...
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Confusion regarding finding closed loop transfer function and damping constant from open-loop transfer function

I have second order transfer function $$ G(s) = \frac{1.247}{s^2+9.76s+23.8}$$ G(s) is in the forward path of a unity feedback system. How do I find the closed loop transfer function and damping ...
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Understanding Total Response

QUICK INFO: I am currently studying about closed and open-loops systems. BACKGROUND STORY: Imagine a big antenna is placed on a hill and there is a lot of wind. You want to turn the potentiometer so ...
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unstable systems with positive phase/gain margin

Open loop Phase/Gain margins provide information on how much margin the closed loop system have until it becomes unstable. In other words, how much you can increase the effective loop gain and or ...
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buck small signal modelling

I have a synchronous buck converter and my inductor current looks like this:- To add voltage-mode closed loop control, I need to do the small signal modelling of the converter. I am a bit confused if ...
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Bode plot in Pspice

I want to get the bode plot of the controller part of my Buck converter. For this I looked online and saw a technique that mentioned to add an AC injection source from the voltage output to the top ...
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Closed loop system stability with Bode

Stability of the closed loop system (with -1 feedback) can be assessed via Bode plot gain/phase margin analysis of its open loop system. How can one deduce stability of the closed loop system directly ...
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Why is the slope of the op amp graph 20 log (AB) in this application note

I am going through the following guide for op amps : http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf On page 87 (screenshot attached) there is a bode plot which has got me slightly ...
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Open and Closed Loop Amplifier Circuit

For example, say that a system requires an input voltage of 5V, however, you only have a source that can provide 1V. The use of a voltage amplifier is obviously the solution to the problem. However, ...
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What is the significance of phase margin in an open loop amplifier?

I know the importance of phase margin to ensure stability in closed loop systems, but what about in open loop systems? I am designing a regulated common based LNA IC that operates in open loop. Can we ...
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What is the controlled variable in this particular case?

I have a question, maybe you can help me because I am not sure of the correct definition. As an example I have a plant with a measured output y in a closed loop system. But as the feedback variable I ...
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closed loop pole of negative feedback

given w be the pole of open loop what in the pole of the closed lop shown bellow? i have found axpression for GAIN but for the pole i am not sure. Thanks.
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Can a strong electric field generate an electric current within a closed loop of wire?

I would like to know if an electric current can be generated in a closed loop of wire by using a strong electric field to circulate the free electrons within the closed loop of wire. Say that you have ...
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2 votes
1 answer
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How to deal with controling force by positioning oscillating magnet?

I am trying to code up a closed loop control system on force generated by the paring of strong rare earth magnets. I do not have much experience with PID logic but i have a weak grasp of the basics (...
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Closed-loop position control with a stepper motor

Disclaimer: I understand this might not be the optimal setup for this application, but this is what I currently have available. My controller is connected to: a stepper motor with a lead screw for ...
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2 answers
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Can an open loop system replace a close loop system

I'm thinking about a mathematical possibility how an open loop system can replace a close loop system so here is my explanation Let's say I have a plant with transfer function as given in image (1) ...
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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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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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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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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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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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2 votes
1 answer
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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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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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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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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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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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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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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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3 votes
6 answers
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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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1 vote
2 answers
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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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3 votes
1 answer
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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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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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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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2 votes
2 answers
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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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1 answer
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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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2 votes
1 answer
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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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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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