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# Questions tagged [control-system]

A control system regulates the behavior of other devices or systems, usually using a control loop. Examples are a home heating controller using a thermostat, a regulator keeping a drone stable, and industrial control systems used for controlling processes or machines.

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### Deriving PI controller transfer function when input is reversed

I'm developing the compensator for the linear DC Bench Power Supply I'm designing. As I've come to deriving the transfer function for the op amp-based compensator, I realize I've been depending on a ...
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### DC Motor Difference Equation Digital Control System

This shows a DC motor drive with the voltage input. And the discrete-time model is like this The difference equation should be something like this: Where the C_1T is the inverse laplace transform of ...
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### Control system with one setpoint, one process variable, and two outputs?

I asked a version of this question before and got some unhelpful answers, I think because 1) the minutiae of my question distracted from the core concept, and 2) I didn't adequately describe the ...
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### How can I explain contradictory damping performance between linear and nonlinear systems?

I have a 3rd order nonlinear dynamical system, representing a power system. After linearizing the system, it turns out that by increasing the parameter L_g, damping is reduced and thus the overshoot ...
2 votes
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### Why do we prefer a cross over slope of -1 (20 dB/decade) for bode plot of power converters?

The video mentions (@12:45), we should ensure the slope at cross over should be around -1 (20 dB/decade). He mentions we can apply phase margin test if this condition is satisfied. As far as I know we ...
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2 votes
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### What is the integral variable of a PIDF written as a digital biquad in transposed direct form 2?

I have a PIDF written as a digital biquad in transposed direct form 2. Omitting the construction of the a and b constants the guts of the filter look like: ...
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2 votes
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### AC analysis of SMPS shows instability. How to modify the analysis to reflect the transient stability?

Background I have designed a switch-mode power stage with voltage-mode control that uses an LCLC filter in its output to obtain a very low ripple output voltage. I have empirically arrived at a ...
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2 votes
1 answer
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### Stability analysis of hybrid discrete-continuous systems

I'm trying to derive the overall state-space system model for a hybrid system, in order to plot its eigenvalues. The system is shown as follows: Which is originally from this paper: Modeling and ...
2 votes
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### How do I control the speed of a simple DC motor based on the output of a machine learning algorithm using a Raspberry Pi?

Let's suppose there is a simple machine learning algorithm for detecting speed limit signs using image recognition and it detects a 30 km/hr sign. Is there any way to send instructions to my motor ...
2 votes
0 answers
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### Underlying reasoning behind lead and lag nomenclature of compensation

If $0<z, \;p$, the Laplace transform transfer function $\frac{s+z}{s+p}$ constitute two distinct types of compensators. If we look at this schematic, $0<z<p$ (lead compensation) implies ...
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### Buck converter with state feedback: does changing the input voltage changes the dynamic of the converter?

Short question: in a buck converter with state feedback, do changes in the input voltage cause changes in the dynamics of the output voltage (and inductor current)? The problem: let's say we have a ...
2 votes
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### Standard for electrical schematics in the UK

I'm trying to find out whether there is an accepted standard for electrical schematics in the UK. From my research so far, I've come across IEC 60617 however this appears to have been withdrawn. I ...
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2 votes
1 answer
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### 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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### Simulation of field oriented control of three phase induction motor

I have been developing a simulation of the field oriented control algorithm of the three phase squirrel cage induction motor in the Xcos (equivalent of the Simulink). The simulation consists of ...
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2 votes
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### Controllability and observability from given transfer function

Is it possible to determine whether system is uncontrollable or unobservable or both from given transfer function in which there is pole zero cancellation? for ex.transfer function like this Or it ...
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### Problem understanding transfer functions of second order filters

The transfer function of any second order filter can be found by analyzing the circuit using the Laplace transform. For example the transfer function of a second order low pass passive RLC filter ...
2 votes
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### Mixed sensitivity controller design

I am defining a controller using the mixed sensitivity approach, and I have the following specifications: a low frequency attenuation of 60 dB a maximum resonance peak of 2 and I have chosen to use ...
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181 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 ...
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2 votes
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### Why gain crossover frequency must be lower than phase crossover frequency for stable systems?

As far as I understood from here, phase margin means the amount of phase that needs to be added in order to coincide with 0 db gain and -180 degrees phase. Likewise for the gain margin it means means ...
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### Why are complex valued zero and pole not used in lead or lag compensation design?

Consider the compensation transfer function $\frac{s+z}{s+p}$ so that the inequalities $0<z<p$ and $0<p<z$ correspond to lead and lag compensation respectively. It can be seen that ...
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1 vote
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### 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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### Multi-cell LiPo charging while still powering system?

I'm working on a control system PCB design that's powered by 2, 3.7V LiPo batteries in series to achieve a higher voltage output. I would like to integrate charging via a mini-B USB connector with ...
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### How to design a PI controller for fourth-order transfer-function?

Fourth-order systems may render very complex characteristic equation that are difficult for tuning. Is there any method to tune controllers for these systems easily?
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### PID controller simulation in Scilab/Xcos

I have been attempting to resolve following issue related to the simulation in Scilab/Xcos. I have been developing a control software and at the time being I have been developing a library of the ...
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1 vote
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### How do I plot the root locus when there are multiple controller gains?

I am trying to design a closed loop system with a PI controller. I have plotted root loci before, but in those, I had assumed that the controller was only Proportional. This gave a characteristic ...
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### Controller design

I was reading controller design using State space model from book by Norman S. In that topic, the author suggested to design controller by converting given state space represention into phase variable ...
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