# Tagged Questions

A system that may be electronic circuits or even software that uses control theory (principally differential equations) to control an output by monitoring various aspects of the system under control and varying inputs all towards meeting a defined goal. Some famous examples are controlling a ...

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### Distribution of Control in Modern Electrical Grid SCADA Systems [on hold]

I have a few questions regarding the structure of modern SCADA systems, in the context of the electrical grid. Specifically, what controls the state (either open or closed) of circuit breakers on ...
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### Estimating Frequency in PLL from phase

Assume I have a digital PLL that outputs phase estimate of the reference signal, however I am wondering can I estimate the frequency of reference signal according to the given phase estimate? I know ...
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### Is a Variable Frequency Drive (VFD) a Secondary Element or Final Control Element (FCE) in a control system? [closed]

I'm confused with some concepts about instrumentation in a control system. I'll use a Variable Frequency Drive (VFD; PowerFlex 70) to control a pump to change the process fluid level. It's clear in ...
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### How to learn Control systems? [closed]

I have been astonished by Control theory and, its applications like the inverted pendulum, and the various control projects that use gyroscopic effect for stabilization, and i am avidly trying to ...
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### How to test PLL for step input change in phase

I wrote a simulation for second order PLL and I would like to test it with a input to see whether my PLL can track the phase. I would like to change phase of my sinusoidal signal with step with ...
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### Phase lock loop frequency of reference signal

I am writing a Matlab code for phase locked loop and up to now I assumed that frequency of input signal is given (known) and I choose frequency of my VCO close or exactly the same as reference signal. ...
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### Park/Clarke Transform and Power

I'm looking to determine the electrical power input to a 3-phase BLDC motor, driven by TI's DRV8305 motor controller. I can't use the DC power flowing into the system because I'm trying to capture the ...
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### Control Engineering - Root Locus

Please see attached Question & Answer screenshot. I have managed to answer up to part 4 of the questions however in part 5, after countless working out and re-evaluating my approach, I still can't ...
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### VSC-based multi-terminal HVDC Control

I came across multi-terminal HVDC based VSC Simulation in MATLAB/Simulink. The control (using vector control ) for such a system is very tough for me because I have little experience in this field (...
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### How do I go about identifying a thermal system with multiple inputs and outputs? MIMO system

I have a lot of measurements of a thermal system that I would like to model using a state space model. How do I go about identifying and modeling the system? The system has 2 inputs and 5 outputs. ...
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### Output type of incremental rotary encoder

I have been trying to choose incremental rotary encoder for speed control of three phase induction motor. My problem is that I am not sure what type of output should I choose. There is following ...
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### Phase Margin and Damping Ratio Approximation

I have read in many texts that the closed loop system damping factor can be approximated as: Phase Margin = 100 times Damping Factor. The actual relation between the two is more complicated and i ...
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### Types and regulation schemes LDOs

LDOs, or low-dropout linear regulators, come in various types, but it can be difficult to distinguish them, and to the novice engineer, this regulator is often made to seem deceptively simple. Some ...
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### Select sampling frequency to closed loop control in a DC-DC converter

For a DC-DC converter in current mode control the control variable is the inductor's current, which at steady state is periodic. which is the ratio between the switching frequency and the sampling ...
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### Why non repeated poles at imaginary axis makes LTI system marginally stable?

I understand that stability for an LTI system is defined with respect to Bounded input bounded output condition. However I'm not clear on why non repeated poles on the imaginary axis makes the system ...
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### Why is impulse response of LTI system important

Why is the impulse response for a LTI system also called its system response? What is special about the output when the input is impulse signal? I understand that impulse signal contains all the ...
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### Efficient low current buck controller topology

In SMPS there are two sources of loss: parasitics, and the controller. Usually, the load consumes more power than the controller, and the parasitic losses dominate. I have the opposite situation. I ...
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### PID Control: Controller of the type $\dfrac{1}{s+k}$

In PID control an integrator action is represented by $\dfrac{1}{s}$ Does anyone know what would be the effect of using $\dfrac{1}{s+k}$ instead of $\dfrac{1}{s}$, where $k$ is a constant? ...
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### Getting the Wrong Transfer Function for Controls Problem

Background So admittedly, it's been about 5 years since I've dealt with any kind of circuits and now I am going back and taking a controls course. On the very first problem I am doing, my answer is ...
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### How to determine the transfer function for 2nd order, over-damped system

My question is related to this one asked previously. The chosen answer says to find the poles "a" & "b" for a 2nd order, overdamped system one would first set the derivative of the impulse ...
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### Discretization Using ZOH, FOH and Tustis bilinear Transformation

I am very new to this forum, so excuse me if i do not write the equations properly. And I'm pretty new to DSP too, so this might be very basics for most of you, but it's pretty complicated to me. I ...
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### Choosing accelerometer or displacement sensor for system

I am working on an electro-servo motor system which can be seen as a similar in here! It is a shaketable system which converts acceleration input to displacement output. My question involves a bit ...
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### A quick question about system identification

I am trying to identify a temperature controller system. I have chosen my inputs to be a PRBS signal for the actuator and I am reading in the output from my thermistor. I am using atmega328 to read in ...
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### interchangeable operation of two electric motors without PLC

I have two motors that drive an air compressor. I have a pressure switch to turn the motors on/off. The sequence I want is: when pressure switch turns ON - motor 1 starts, when pressure switch ...
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### if i have a pole in (0,0i), is the system stable for k=0?

KGH(s)=k/s(s^2+4s+7) Is my system stable for k=0 ? If i have a pole in 0,0i does it automatic says that my system is not stable
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### What is the natural frequency of a 3rd order system with 3 real roots?

I know the the structure of a 3rd order system is: $Q_s=(s+a)(s^2+2\xi\omega ns+\omega n^2)$ but what do I do if I have something like this? $Q_s=(s+4)(s+5)(s+3)$ How do I measure its natural ...
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### Root Loci Breakaway points

my question is regarding if the breakaway points exist or not. Do they only exist if 2 poles or 2 zeros are next to each other? Example if their are poles at -1 and -2 the breakaway point would be at -...
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### Control Systems Stability

So I asked this question previously in the control theory section and got no responses. Ill try it here. Basically I need to find the ranges of k and $\beta$ such that the steady state error will be ...
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### Switching on and off a LED light if a AC is passing through a wire or not

This is the basic setup of what I'm going to do. Have a wire plugged into the mains that is then connected to a ON/OFF flip switch then goes on to the rest of my project. Want I want to do is to add ...
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### How to make a sound-controlled variable resistance?

So I have those old analog video equipements (Panasonic WJ-AVE5, Videonics Video Equalizer) and I'd like to have some of the parameters (video crossfade, superimpose function, brightness level, etc.) ...
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### Heat exchanger identification

I have been developing a digital controller for water cooling system of power electronics converter. This system consists of plate heat exchanger, pipe with demineralized water flow (this fluid is ...
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### Closed Loop 4 Sensor Control System

I have 4 on/off motors running individually (call them M1, M2, M3, M4) and 4 ping sensors (call them X1, X2, X3, X4) with a board placed in front of the motors and sensors. As the motors move forward ...
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### proportional control offset

I understand that with proportional only control you have to have error or the control output goes to zero. The answer to this question Proportional controller was very informative. Mr. Lathrop ...
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### How an equation in s domain is converted into z domian using zero hold method

I am just reading a research paper on matrix converter and i came through transfer function conversion from s domain into z domain. which i am unable to understand. how the equation 3.4 is transferred ...
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### Is feedforward used in boost converter operating in DCM mode?

Is feedforward used in boost converter operating in DCM mode? I saw some examples where feedforward is used to control boost converter in CCM but not DCM mode. So I am wondering if it can be used in ...