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151 Threads found on Stability System
Only PM is necessary but insufficient condition for the stability of a system.Root Locus and Bode Plots should also be examined.Overshoot is a kind of stability fact and generally not desired.
Hello Friends, I am designing a Charge sensitive amplifier and would like to study about the stability. we know, A/1+AB where AB is the open loop gain. If AB is equal to -1 then the system will oscillate. How would I know that AB will be equal -1. Please tell me the process to calculate. A= G sCdRf/ 1+sRf( Cd+Cf) B= 1+sRfCf/sRfCd... P
Considering that the cable is already constituided by metal on its compostition, your detector should be able to determine a differential variation in the EM field, so the threshold adjust aswell stability of analog circuitry could be an issue. In continous prodution processes, QC is better achieved by visual system sensors, although on this approa
Define feedforward system, define absolute stable... Commonly, ffwd system means an open loop control system without any feed back. As far as I'm aware of, "absolute stability" is an algebraic rather than control theory term. In so far I'm not sure what's it's expected to mean in this context. For control (...)
Hi All, After a some survey in control systems, it seems that relative gain array(RGA) criteria is used for tuning MIMO feedback systems. Has anyone closed MIMO systems using this technique? But this method doesn't look at the classical phase margin(PM), modulus margin(MM) and gain margin(GM) criterias, so I have my doubts on this. (...)
A system can have any number of poles and zeros below the unity gain crossover. For stability, we need only a good first order roll off around unity gain crossover. Your example of (1+s/wz)/s^2/wu^2 is perfectly stable. This is what happens in a pll or in a multipath opamp/feedforward opamp. Another example (1+s)^2/s^3. One cannot determine stabil
How to do stability analysis for multi loop system? Any suggested Papers for this? As far as I know - it is really a problem to find suitable answers. According to my experience we can say the following: * A multi-loop feedback system has more than one single feedback loop (that`s logical). In most cases, we c
Hi i have attached an image of a very simple op-amp. I am learning the basics of op-amp. 130712 The 1st image we have the opamp amplifying the difference of the two inputs and therefore the output voltage, X = 0.99 which is depicted in figure 2. I was taught (just a simple example as such) that now if you take the diffe
You must have > 2 samples per Hz of loop bandwidth for frequency accuracy and much more for phase stability. Try 960 samples per cycle but only compute 60 times per second using algorithm to process incremental delayed samples. or get a fast Linux OS real time simulator. Which Uni are you at? - - - Updated - - -[/SIZ
The stability of any feedback system for voltage and current is challenging from no load to full load or dynamic non-linear loads, lab supplies with these features tend to be more complex. This is similar to the feedback gain going from 0 to
Hi All, I am a newbie in the field of electronics but have enthusiasm to learn and build. I have a project I am involve in which needs from us to build a high-resistance sensor measurement system. The sensor, because of the in-stability of fabrication, can have a baseline resistance between 10MOhm to 70MOhm. The quest here is to measure the abo
Hello everybody I have a problem, about stability region of the continues system that's has been discreted. I would appreciate if you could answer my question. I have a circuit that including several capacitance, inductance, and resistance. I get the A (state space matrix) of the system and then discrete this matrix by Backward Euler (...)
You can model everything as linear blocks to perform an AC (small signal) stability analysis (either by calculation or simulation). For example, the PWM part of the circuit converts the error voltage to a PWM duty-cycle which generates a voltage at the converter output as determined by the input voltage and the duty-cycle. So you calculate what t
Don't care about the phase near switching frequency and above. The system can't be described as time-continuous and analyzed with bode plot in this range. The results above 50 kHz are effectively meaningless for stability analysis. The basic problem is that you have no phase margin according to bode plot. Step response is respectively bad. You s
Which is better ? mikroElectronika's mikroMedia for PIC32 or mikroMedia for STM32 ? I need speed and stability. I am making a security system and want to use TFT and Touchscreen. mikroMedia boards have TFT+Touchscreen and they are stackable. I will be also using mikroBus Shield for mikroMedia and I will be plugging GSM2 Click and GPS Click to th
stability is criteria that begs a requirement for functional performance on overshoot, ripple, jitter etc. This is what drives the stability gain and phase margin. But also note that the margin changes with opearting conditions that affect SNR or load/capacity ratio or some other gain factor. If you know how to generate worst case conditions,
Hi, I am designing a Flyback converter. I want to understand the inference of stability analysis related to power supply. 1.What is the meaning of a stable system? Stable means a step load won't cause lots of ringing or oscillation from a non-linear or capacitive load or any desired load it
Alexandra - it seems that you are simulating the closed-loop system, correct? However, because you were speaking about stability margins - are you aware that stability margin simulations require loop gain analyses?
stability is a time domain measure of overshoot with oscillation from either stimulus; step or impulse. However Control system design is usually done in frequency domain. It is a result of negative feedback network with a sensor based on rotational or linear position, velocity and acceleration compared with desired profile. Current contro
PID control needs specs to define , system step error response, overshoot under worst case gain and time lag and rate of change of disturbance response Impulse error response ( like opening door on ice cold day) For stability , frequency / phase margin is used to determine correct feedback signal conditioning and gain to optimize speed, (...)
Dear Friends...... i am ph.d Scholar in power system ....i need to write a code in embedded system to improve the power system stability... is there any link or ebook to write a code in embeedded system....(or) any other courses in embedded system need to do means also say that details (...)
It's possible with industry standard analog multipliers like AD633. As you are designing a feedback system with variable gain, achieving stability for all operation conditions isn't quite easy, but basically possible at the cost of bandwidth.
The influence of a small amount of positive feedback - as long as the system remains stable - can be found using the same formula as for negative feedback, however using a POSIVE sign for the loop gain. (stability limit for unity loop gain). Example: Voltage controlled feedback (as for operational amplifiers): Zout=Zol/(1-A,loop) with Zol=open lo
1. PFM mode loop is open loop or close loop? 2. Is it required to do stability Analysis for PFM loop ? If No Why ?
Hi, I understood what you told me now. Let me explain what I understood. First I have a system a(s) and a feedback=1. For this case the phase margin and gain margin are bad or really small, so what I want to do is to compensate the system, that means increase the value of phase and gain margin. Am I correct ? [COLOR="#0000
Can you help me compare these results? They're the simulations of a closed loop system . When we change the poles, (in this case, there are 4 poles), the response system also changes. The 4 poles involves 2 complex numbers and 2 integers, but I don't see the relationship between the poles and the response. I don't see an exact description. I mean,
stability is primarly discussed in small signal analysis. As you'll know, it uses a simplified linear OP modell and doesn't care for signal magnitude. Thus it can't answer your question. When advancing to large signal analysis, you have to notice the various nonlinear effects of a real system. To consider a simple case, the OP might show an
Hey , what's should be differenciated , error term or main signal ? The output should be time domain signal in 1D monitor in this case. the system should have more than one loop circuit , the output will have more dimension, ND for good stability take care when the excident emerge.
Whats the need of studying control system in electronics? Feedback is one of the basic principles applied in electronics. Connected with the principle of feedback are the terms "feedback loop", "loop gain", "closed-loop gain", "stability", "stability margin". The theory behind all these parameters is provided by s
i know for stability we need positive PM GM . that means at -180 degree gain should be negative(in decibels) for stable systems . From where this arrives i mean why -180 ?? i read somewhere that after -180 degree NEGATIVE FEEDBACK BECOMES POSITIVE FEEDBACK and if at that time gain >1 than system will oscillate and become unstable ?? why (...)
In practice I have oscillation and I think that the reason for that could be multi-poles system. In practice, small signal analysis doesn't describe the system behaviour completely. The most severe point is the class B current boost stage where both MOSFETs are off for the calculated bias point. In addition MOSFET and IGBT capacita
Yes. That is what happens at the frequency for which |GH|=1 when the system is in the limit of stability. (There is an additional condition related with the slope of the phase, but let's leave that in this moment.) Suppose that at zero-frequency G and H are both real and positive . Then we have negative feedback. If increasing frequency we find tha
Dear Sir(s), I need contribution on my masters thesis, i need to know the recent challenges in power system stability that are not solved completely. Thank you in Advanced
Can a negative-feedback system ever have large positive phase shifts that causes instability? All the examples in my old textbooks deal with instances where the overall phase shift approaches -180°. How do we deal with instances of positive phase shifts near and beyond +180°? I found this reference on the web that mentioned phase an
A evryone knows, phase is cyclic with 360°. So in your diagram, presuming it's actually showing the overall loop phase, -360° would be the reference for phase margin. For valitidy of the simplified phase margin stability criterion, there must not be multiple crossings of the n*360° line. In simple words, phase margin is the distance to the osci
This seems to be temperature drifting problem,not impedance changing or something else. Check your bias circuit and temperature stability of your system.
An example of this may the hierarchical levels of stability for Stratum I,II & III clocks used for synchronous networks. The clock is derived from the data source with defined Stratum level and regenerated with best source available from multiple choices of sources. An insular network is isolated and requires no outside reference. A plesiochronous
Hello everyone. I am designing a VGA for signals up to 3Ghz. It seems that everytime I put a feedback in my circuit the K factor gets lower than 1, though the phase margin and gain margin calculations would seem to suggest that the system is stable. I was wondering whether I can still trust the K factor for lower frequencies and in systems with
If only the following data are known in a negative feedback system is it possible to make a conclusion about stability or not?
In general yes, I'd expect it to remain stable. The RHP zero frequency should increase at light load, and as your controller starts operating in DCM, its gain should decrease. Those two things should only increase stability (unless the system was only conditionally stable). The only thing it could worsen is the damping of your LC, which might ca
the Z-transform is a complex transform deals with the explanation on impedance. here in your que z<|1\a| means your system transfer function will be convergent only untill your impedance value remains between the values of -1\a to 1\a. that means your system's ROC i.e. stability is inside the circle with radius 1\a.
Hi all, I have a system that works as an analog PLL (PFD, loop filter, CO, N divider) to stabilize the phase variations of a reference. (see attachment) However, there is a significant delay ? 50 microseconds -, due to long distance transmission, in the feedback loop between the VCO and the N divider. Which is the best way to analyze the sta
Hi everyone, I am dealing with 2D FDTD simulation in Cylindrical coordinate system. I attached my matlab code but there is some problem which i dont undersand. It seems as dispersion but time and space increments obey Caurant stability condition. Can someone post me FDTD code in Cylindrical coordinates or help me about the problem. Thank
Hi, Usually a pullup & pulldown circuit is implemented in a circuit when one of the specifications of a design requires low standby current. Will this circuit affect the system stability in an LDO design? When is the proper way to design pullup/pulldown circuit? Is this circuit (pullup/pulldown) need to be designed after obtaining all other desig
i tape out one PMU chip and when it coming back , i find in one boost dcdc the output ripple is so big , and seems not stable, please see the waveform of test. i wonder if it is system loop stability issue ,and what is the root cause, can you give me some suggestion? BTY, the simulation results and small signal model caculation shows the (...)
The main reason is for frequency stability, generally using a GPS synchronized signal generator. The phase noise is not improved.
The AGC is basically a feedback system and a delay introduced inside of the feedback loop, also would increase the stability.
A bode plot is a simple, but incomplete, way to test for system stability. There are also Nichols plots, root locus, etc. The bode plot is based on the fact that the transfer function of a feedback system is T(s) = G(s)/(1+GH(s)), where G(s) is the forward gain, and H(s) is the feedback gain. By observation, one does not have to know a (...)
Hi,everyone. Please see the system showing in figure1. system background: It?s used in wireless digital repeater including local unit and remote unit. And there are 2 different reference clocks in whole system, so it will cause the system output frequency offset badly if the 2 clocks (e.g. TCXO ) exist large frequency (...)
Use digital frequency correction to avoid stability. However, frequency lock accuracy will be limited by digital step.