Questions tagged [control-loop]

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Dutycycle DCDC control

I will start with that, i already ask for this question in other topic but i didn't have any anwser about my question link. Please don't go too far in explaning difficult thing not realated with my ...
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1answer
67 views

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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2answers
162 views

Nyquist stability criterion for positive feedback

it is known that the stability of a system with negative feedback may be analized through the Nyquist stability criterion, which is based on observing the number of turns around the point (-1;0) in ...
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1answer
101 views

PFC controller - How does it work?

I would like to better understand how a PFC controller works, especially PFC which work in CCM mode. I found the following documentation from International Rectifier: https://www.infineon.com/dgdl/an-...
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2answers
91 views

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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2answers
180 views

MOSFET as heating element for a RaspberryPi

I developed a PID autotuning algorithm that I want to test outside of a simulation environment. For this purpose, I got temperature sensors to send data to a RaspberryPi. Now I need something to ...
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1answer
70 views

Trouble understanding Loop Filter in a PLL

I'm currently trying to understand the function of a loop filter. But where I'm stuck is that I know the output of the charge pump is a series of current pulses whose width is proportional to the ...
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2answers
126 views

What does Dominant pole/Pole mean related to capacitors and filters or Electronics in general for intuitive understanding

I am trying to understand the feedback compensation techniques of DC-DC Buck converters. And I drift to more and more small questions which make me want to understand the basics of poles/zeroes/...
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2answers
335 views

Cascaded current control

I have a actuator capable of measuring motor current and position via an encoder on the output shaft. The motor is a brushed DC motor running through a gearbox. My questions is in regards to the use ...
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2answers
642 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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2answers
346 views

Loop bandwith and open-, closed- loop gain in ADIsimPLL

I'm want to use ADIsimPll to calculate the loop filter properties for a PLL I want to build. I read some things in the programs help topics which I find somehow strange. Maybe you guys can help me out ...
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1answer
71 views

Any transfer function has the same denominator 1+T

Sometime ago, I came across some theory saying that in a control loop any transfer functions such as ...
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2answers
122 views

What exactly am I messing up in this control loop?

I am creating a simple control loop for a safety door for a machine. When the door is opened, the machine turns off. When its closed, the machine can operate. The way I have it set up now is that we ...
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1answer
128 views

feedback loop for a single stage offline flyback that is powering 2 independent LED strings

I have a design that is a offline, single stage flyback, powering two different LED strings. The output of this converter is about 50W and the output voltage can range from 20V-45V. I'm using ST ...
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2answers
553 views

How to find the closed loop transfer function of the LT1619 current mode controller

I am trying to figure out what would be the closed loop transfer function of the LT1619 controller. This is the first step I want to make in order to design the feedback loop. What I already know ...
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3answers
408 views

Interpreting the open loop gain of a linear power supply

This question is related to a question asked earlier regarding a linear power supply build. It turns out that the circuit is oscillating quite badly; an issue not uncommon in feedback circuits. I've ...
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1answer
512 views

How do I get a closed-loop PID controller from a transfer function?

I have the transfer function below: $$T_c(s) = \frac{s+k_i}{m_0s^3+s+k_i}$$ It is assumed that \$k_p=1\$ and \$k_d=0\$. I am given that \$x_l(t)=[x_l(t),y_l(t)]^T\$ is the trajectory and the ...
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2answers
596 views

Positive feedback with constant transfer functions

If I have a control loop with positive feedback, the closed loop transfer function expression is: $$\frac{Y(s)}{X(s)} = \frac{P(s)}{1-P(s)H(s)} $$ where \$P(s)\$ is the direct loop transfer function ...
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1answer
175 views

What is a Jaffe-Rechtin PLL?

Eberhardt Rechtin and Richard Jaffe (both involved in NASAs DSN) published this paper (paywalled) on PLL-design and -performance back in 1955. It is referenced quite often, so I wanted to understand ...
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0answers
67 views

Digital PLL reference noise rejection

I have a fully digital implementation of a PLL. The problem that I have is the white noise coming from the PFD (you can view it as input jitter). I would like to filter it a lot, but an implementation ...
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3answers
12k views

Why does the opamp output voltage saturate?

simulate this circuit – Schematic created using CircuitLab Vout = Vin (1 + R2/R1) According to this positive feedback topology - made an error here, it's Vout = Vin(-R2/R1) (edit) Now I read ...
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1answer
731 views

DC-DC boost converter using multisim. Output voltage keeps changing with input voltage

Link to circuit schematic simulation The circuit is from the above link. There is some problem with the control loop. The output voltage doesnt stay constant within the input range of 12-24v for ...
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1answer
494 views

Loop Bandwidth of PLL

How is the loop bandwidth of a PLL calculated? Is it the area under the Transfer Function vs. Frequency plot?
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1answer
817 views

Loop compensation design of buck converter

I am trying to design loop compensation with type-3 error amplifier for a buck converter. I'm a student and very inexperienced in this subject. Please bear with me. Here is the general procedure ...
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2answers
757 views

Root locus of discrete time system

I have a question about a probably easy task, but I can't find the right K. I have the loop with an adjustable gain element given: $$Q(z) = \frac{H(z)}{1+ K\cdot G(z)H(z)} $$ I have given: $$H(z) ...
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2answers
256 views

Where is the pole introduced by the RC circuit?

I've implemented a circuit under a suggestion which solves stability issues when driving a MOSFET with an high capacitance, using an OpAmp. Now, the circuit suggested is this one, in which is modeled ...
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4answers
8k views

How to achieve very accurate/fine rotation with motor

I am running an experiment where I need to rotate a lightweight dial (<5 grams, so very low torque requirement, and fairly slowly), but need to do very accurate, fine steps of 0.03 degrees. ...
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1answer
80 views

Software control system. Which one is it?

I wrote a software which replaces a discrete closed loop PI control circuit and now I was wondering what kind of control system is this equivalent to? This code drives the PWM which regulates the R_DS,...
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1answer
2k views

How to improve current control loop in power supply?

I'm working on MCU programmable bench power supply. Its range is 0-50V and 0-3A programmed in 10mV and 10mA increments. It will be published as open hardware and source code that anyone can use it if ...
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1answer
657 views

loops with C18 Compiler on mplabide for 18f4550

I am facing trouble with glowing multiple LED simultaneously on a 18f4550 micro-controller under the same " while(1) ". I am new programming. [C18 compiler with Mplab ide.] I was able to alternate ...
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2answers
502 views

Confusion in feedback for switchmode dc/dc converter

I have a slight confusion in how the feedback pin works. The "\$V_{ref} \times (1 + R_1 / R_2)\$" seems like a shortcut to me, and I have trouble understanding how to feed a voltage in to it, to say ...
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4answers
6k views

Does this voltage regulator use “on-off” control, or is it a voltage follower?

In Electronics A2 (GCE), we are currently studying voltage regulators. An example voltage regulator circuit is provided using an op-amp and a power MOSFET. I would judge this to be a voltage ...