Questions tagged [control-system]

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 rockets thrust angle to ensure directional control.

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1answer
221 views

Calculating discrete-time transfer function

I have a continuous function \begin{equation}G_p(s) = {1\over s^2} \end{equation} which I am trying to combine with a zero order hold (with a sampling time of 1 second) to produce a discrete function....
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73 views

Why is my zero and pole frequency of this transfer function wrong?

So I have this transfer function: $$\begin{align} \dfrac{g_m-sC_{gd}}{s(C_{gs}+C_{gd})}=\dfrac{-C_{gd}\left(s-\dfrac{g_m}{C_{gd}}\right)}{(C_{gd}+C_{gs})\left(s-\dfrac{0}{C_{gd}+C_{gs}}\right)}=-\...
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2answers
84 views

Why is the closed gain loop -3dB from the open loop gain rather than some other value?

I am reading the book Op Amps for Everyone and in the chapter of feedback loop theory, I have this quote (see picture) where it says in reality the closed loop gain is down by 3dB at the point X as ...
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17 views

Controllability and Observability of SFG by intuition

For the below block diagram is it possible to conclude controllability by tracing the path from inputs to state variable , similarly to conclude observability by tracing path from state variable to ...
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45 views

Nichols plot confusion

The transfer function is \$F(p)=10/(p^2+2p+1).\$ Using Wolfram Alpha, the Nichols plot shows that the argument \$\to -\pi\$ when \$\omega \to +\infty\$. However, calculating the argument on paper ...
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138 views

Determine the maximum value reached by the system output signal

Consider the 2-order system, without zero, whose transfer function is $$H (s) = \frac{51}{s^2 + 2s + 17}$$ An input signal $$u(t) = 4\varepsilon(t)$$ is applied to this system Determine the maximum ...
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231 views

Cascade vs series?

Is there any difference between cascade combination and series combination in terms of control system? Or they both same? Since in control system literature,sometimes at some places,we find the word ...
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65 views

How to stabilize this system?

I'm trying to understand system stability basics. Let us say I have a system $$ G(s) = \frac{500}{s^2 - 500} $$ Since it has two poles in the right half s-plane, it is unstable. How can I ...
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36 views

PID Control: Is adding a delay before the next loop a good idea?

I am implementing PID control in c++ to make a differential drive robot turn an accurate number of degrees, but I am having many issues. Exiting control loop early due to fast loop runtime If the ...
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1answer
53 views

PID controller for a very wide temperature range (∆T=190°C)

I'm designing temperature control system based on Peltier elements. And it's needed to work on a very wide temperature range - from below zero to more than 100°C. So there is two work modes - cooling ...
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1answer
56 views

Small signal model of a forward converter operating in current mode control

By knowing that I do not know the plant transfer function of the forward converter operating in current mode control, I can be suspicious on the result provided by the following document : https://...
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2answers
264 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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Confusions regarding swing up hybrid control?

I am trying to learn about swing up hybrid control and i came across a figure shown in attached snapshot. I have two confusions in this regard: 1)Both "swing up energy control"(u1) and "...
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Supposed to be a trapezoidal BLDC Back-EMF waveform?

INTRO: The project bellow was designed in simulink to drive a BLDC motor. It has a matlab function that basically receives the rotor's angular speed (w) and using N = 6 (N is the number of pole pairs) ...
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2answers
60 views

Infinite Phase Margin

I have been assigned a control systems problem, where I am supposed to stabilize a system using a controller technique from the frequency domain. When I implemented the system on Matlab and calculated ...
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26 views

Finding \$\small K\$ for a given \$\small\zeta\$ value when \$\omega_n\$ (frequency) is not given

Here \$\omega_n\$ (frequency) is not given. Then upon plotting the Root Locus, how will we find \$\small K\$ at \$\small\zeta = 0.5\$ if we're not using a graph sheet and want to find everything ...
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3answers
125 views

How loop gain is related to complete transfer function?

I am trying to understand how loop gain of system determines the stability of a complete system. Loop gain is given by 1+GH where G is forward transfer function (TF) and H is feedback factor. If we ...
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29 views

S domain transfer functions of full bridge inverter

I need to design an inverter circuit as in the schema. It is driven by the unipolar PWM method. I have a problem with the circuit. It would be great if anyone can help me. I want to get the s domain ...
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45 views

Stabilizing plot using root locus method

"Design a PI controller to stabilize the plant \$ G(s)= 1/(s-1)\$ using only root locus method." Since there are two variables \$K_p\$ and \$K_i\$ ,i.e. one for proportional and one for ...
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1answer
140 views

Determine the impulse response of the following discrete system

I'm not sure how they got the answer (provided below) for the following discrete system y[n] = x[n]- 2x[n-2]+ x[n-3]- 3x[n-4] the answer is given as .... h[n] = [1 0 -2 1 -3] why is this? any help ...
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2answers
738 views

Transfer function of phase change controlled with capacitance

We have an RLC series circuit with sinusoidal voltage source of frequency \$\omega\$. The normal transfer function of current to voltage is: $$ G(s) = \frac{I(s)}{V(s)} = \frac{1}{R+s L+ \frac{1}{s C}}...
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117 views

Help with identifying a transfer function - with neuroscience application

This is a question for you electrical network engineers. The problem has arisen in a neuroscience study I am working on, but I hope to be able to glean some insight from other domains that deal with ...
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2answers
508 views

Controller vs compensator?

Both these terms: controller(forexample PID controller) and compensator(Lead compensator) are often encountered in control systems,but what is difference between these two? Brain douglas in this ...
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3answers
147 views

What does this switch symbol with a triangle on the contact stand for?

I found this symbol in one of my control circuits. It is a part of a suction valve operated by a motor overload relay. I have been pulling my hair out trying to find the meaning of this symbol and ...
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56 views

What is the effect of addition of a compensator(either Lead or Lag) to a system?in terms of addition of poles and zeros?

When we add a compensator(either Lead or Lag) to a plant in series, what is the effect in terms of addition of poles and zeros? A pole-zero pair is added(meaning one pole and one zero)? or a pair of ...
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1answer
51 views

Two different expressions for lead compensator?Why?

I am trying to learn about lead compensators from an online resource,but two different articles of same resource mention different expressions of lead compensator, i have also attached snapshots for ...
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2answers
200 views

How do integrator circuits serve as memory devices in continuous time system?

I didn't understand the yellow-marked sentence clearly, and even I did, what does it have to do with the conclusion that follows it? (marked in green). Thanks in advance.. Source: Modern control ...
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1answer
121 views

Steady error control system sinusoidal disturbance

Consider the control system closed-loop represented such a block diagram below: Given that: \$G_C(s) = K\$ and \$G(s) = 1/s\$ a) Determine the values of \$ K\$ which the closed-system loop is stable....
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52 views

How would the pole and zero frequency expression look like for this transfer function I derived?

This is a practice problem in deriving the transition frequency function for mos and part of the set of questions is to determine the pole and zero frequency expression but this transfer function i ...
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2answers
69 views

How to calculate wattage required to heat up air inside an enclosure to 50°C?

I've got a polycarbonate enclosure and I'm going to place a heating element inside it to increase the air temperature in it from room to 50°C, plus a fan to maintain temperature. I need to find out ...
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1answer
46 views

Could somebody clarify the phase angle and gain of this transfer function?

Suppose a circuit with a transfer function of the form \$A(\omega)=\displaystyle\frac{A_0}{1-\frac{j\omega}{\omega_0}}\$ has \$A_0=-10\; V/V\$ and \$\omega_0=100\;rad/sec.\$ We were asked for the gain ...
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178 views

Effect of right half plane zero on bandwidth of control system

It is known that the right half zero and the delay limit the achievable bandwidth of a control system. Can someone please explain the reason, how the right half plane zero limits the achievable ...
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3answers
200 views

Stability of a two poles negative feedback amplifier

let's consider this analysis of a two-pole amplifier with negative feedback (Microelectronic Circuits by Sedra Smith 7th edition): Before showing you my doubts, let's consider this introduction made ...
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54 views

Oscillation frequency / criteria from Bode plot, negative feedback system

Got a question, which is very integral to a project that I am writing a report for (which I am to hand in soon, so in a hurry). Question: What will my oscillation frequency be? How will it be ...
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1answer
72 views

What is meant by “T” and “aT” here?

https://ctms.engin.umich.edu/CTMS/index.php?example=BallBeam&section=ControlFrequency I am trying to learn about lead compensator from above link But i have bit confusion regarding two terms,"...
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1answer
36 views

Singular interval condition for Multi input in Optimal control

The definition of singulr interval is shown in Figure. I've struggled with this problem. I think the solution of this prob is "because if the E_j matrix is not singular, it means the System is ...
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2answers
92 views

Small signal digram

According to this figure how to get qeuation(7)and(8)
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29 views

What is the relation between the control voltage and resulting pwm in a voltage-mode control system for DC-DC converters?

I'm currently learning about negative feedback and voltage mode control for various DC-DC converters. I'm very confused about how the control voltage changes the pwm signal, along with how the ...
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6answers
1k views

Why is frequency not measured in db in bode's plot?

While drawing bode's graph paper where Y axis is gain given in db while the X axis is frequency given in absolute value but scale used is log. I think the reason for log scale on X axis is to increase ...
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2answers
243 views

What's the best starting point for rotor angle estimation for FOC?

I'm driving a BLDC motor with FOC. Right now, I have Space Vector modulation working, where I can give it a magnitude and an angle, and the algorithm will drop the right values into three PWM ...
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1answer
88 views

Derivation of Feedforward Gains for current mode control in CCM converter

I recently start to read the dissertation of Dr.Ridley, A New Small-Signal Model for Current-Mode Control and I am stuck on a basic equation. First we have the function of the inductor current for ...
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1answer
648 views

Control System: DC Gain

Mostly, whenever it is asked to find the DC gain of A system; in the solutions provided, they find the steady state error coefficient (corresponding to the Type of the system). But I figured out that ...
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1answer
167 views

What is the mathematical difference between a transfer function and a state transition matrix?

I do know what the difference in meaning is between a transfer function (output over the input) and a state transition matrix $\Phi$ (describes the unforced response of the system). Yet when looking ...
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2answers
450 views

Stability of Differentiator Circuit

let's consider a generic differentiator circuit, i.e. a circuit whose transfer function is \$\text{constant}\cdot j\omega\$. For instance, you may consider this circuit with Op-Amp: I was reading ...
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1answer
355 views

How to plot root loci in z plane

How to plot root loci of loop gain G(z)= k/(z-0.5)(z-0.5)(z-0.5) in z plane?
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1answer
211 views

Linearizing hall effect sensors outputs

I'm trying to find a robust solution to linearize four hall effect sensors outout to obtain a signal that I can use in a PID control scheme. The output data is collect via 4 ADC channels on an ...
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1answer
209 views

doubt on application of stability criteria

I have only seen systems with this transfer function treated in stability criteria with this general form:$$\frac{KG(s)}{1\pm KG(s)}$$ so the $$\lvert H(s)\rvert =1$$ is it possible to apply criteria ...
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3answers
81 views

How to generate an impulse to test a system's impulse response

I just started learning some basic control theory to better understand how a transfer function is constructed from a circuit and how a system is characterize by a function. In it I found analyzing a ...
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2answers
1k views

how to find frequency of oscillations if a order three system given

Frequency of oscillation in rad/sec of a unity feedback system having open loop transfer function G(s)=K/s^3+3s^2+4s+3 is
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Here how can we find steady state error?

Here in the plot shown in attached photo, how can we find steady state error because both blue and orange waves have different amount of error at different time

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