# 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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122 views

### Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
54 views

### Stability of Buck Converter when output capacitance is variable

I am designing a buck converter for an application that has several different loads. Depending on what devices are connected, the capacitance seen at the output of the buck converter can vary ...
174 views

### Why “-1 + 0j” is critical point on Nyquist plot?

I am reading about Nyquist plot from this (http://www.cds.caltech.edu/~murray/books/AM08/pdf/fbs-loopanal_11Nov18.pdf) chapter. On page no. 10-2 its mentioned that "-1 + 0j" is critical point on ...
329 views

### How can I control TRIAC firing angle automatically with a DC voltage?

I have to build an analog proportional controller for a 127 V, 1 kW AC heating resistance. The power delivered to the heating element must be proportional to the difference between a set point ...
25 views

### Is it possible to predict the operating state of a power system (using MATLAB) if I have calculated the voltages at all nodes by state estimation?

If I have calculated all the node voltages by state estimation, is it possible to predict which operating state my system is at? By operating state, I mean any of the following: ...
137 views

### Buck-Boost converter without low side switch

Please look at the buck -boost converter below. It is 2 outputs, one buck and one boost output. Would the circuit work as describe in the picture? In what condition the circuit will it work? If so how ...
41 views

### Characteristics from transfer function

All! I am trying to figure out characteristics of a second order system The system is (for example) And its characteristics for an unit step input are I want to solve this equation by hand and ...
788 views

### Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180° is bad. If my input is a sine wave and I have negative feedback, which has a -180° phase shift, the ...
78 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....
150 views

### Why am I getting non-sinusoidal output for sinusoidal input in a mass-spring system?

A mass-spring system is represented by the following transfer function $$H(s) = \frac{s^{2} + 0.1s + 10}{s^{4} + 0.2s^{3} + 20s^{2}}$$ For a sinusoidal input I am getting a non-sinusoidal output, ...
58 views

### How do I refer the transfer function of a system from its Laplace equivalent?

I have a problem, I know how to analyze circuits in Laplace domain to get the transfer Laplace function. However, I don't know how to translate the answer to "real life" Suppose that I have a ...
362 views

### Why fast inner current loop and slow outer loop of DC-DC converter

Let say we have a DC-DC converter operates with double loop control (inner and outer) , and with switching frequency of Fs= 20000 Hz. Please ,if you could answer the two following questions: 1- ...
184 views

### PID (Arduino) Project - Determining Ki, Kp, Kd

I am working on control system project. I bought a Zumo 32U4. It has built in encoders. The project is divided into three parts: a) Move in a straight line. b) Slows down as obstacle approaches. c) ...
428 views

### Is the transfer function for the given RC network right?

For the question I arrived at the following answer (I have assumed V1 btw) Is my solution right? I just have a big doubt if whether I can use the voltage division rule at point A when there is an RC ...
206 views

### Relation between settling time and natural frequency for a critically damped system

In an article by Wie et al. (1989), for the purpose of calculating the gains of a controller, the equations of motion are approximated by the expression for a damped harmonic oscillation: \ddot{\...
78 views

### How to model a Electronic Proportional Control Valve

I am using a VSO LowPro Proportional control Valve (https://www.parker.com/Literature/Precision%20Fluidics/Miniature%20Proportional%20Valves/VSO%20LowPro.pdf) to regulate pressure into a closed ...
243 views

### What is difference between natural response and zero-input response of a system and how to find natural response?

In most books it is said that natural response is another name to zero-input response while in some resources is is mentioned that the classification is based on poles of transfer function and input....
53 views

### System Identification in a closed-loop feedback system [closed]

I have an unstable system that doesn't have a useable output when open-loop excitation is applied. Subsequently I've used a controller to control its output. I want to use the system identification ...
76 views

### Obtaining Plant Input data from System Identification (PID)

I'm trying to obtain a mathematical model from a physical plant using MATLAB. Using the system identification tool you need the plant input and output data. I'm struggling to match the theory to my ...
159 views

### Find transfer function and step function for this circuit

Can someone help me to find the transfer function of this circuit (i want to have the tension through the capacitor I think) and the step response in order to get the voltage in the function of the ...
53 views

196 views

### PI controller - DC voltage regulation

I a voltage source converter, in order to control the DC-Bus voltage a PI controller can be used. The control method is illustrated in the figure below: I would like to ask why the input of the PI ...
731 views

### Constructing bode plot from experimental data and constructing a transfer function

I've been trying for a few days to convert an experimentally obtained (frequency against magnitude and frequency against phase) graphs to a bode plot and then construct a transfer function from the ...