Questions tagged [power-factor-correction]

A circuit that compensates the reactive characteristics of a load to make behave as close as possible to a resistive load in order to maximize the power consumption efficiency.

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73 views

PFC inductor calculation

I have a question about PFC inductor calculation. Please see the below figure. This is my answer, but I don't know how to only let Lmin equal to Vrms, P, fs. There is a V (output voltage) in there. I ...
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30 views

Reactive power compensation

For a solar power plant with a capacity of around 800 kW AC, the night time power factor reading was around -0.13 noted from the meter at interconnection. Night time reactive power consumption of the ...
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1answer
111 views

GFCI tripping when using hair trimmer, but only when using an extension cord

I have a GFCI socket in a recently-build bathroom. My hair trimmer trips it often when stopping under some conditions and while I have a fix I'd like to better understand what exactly is going on here....
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1answer
68 views

Does the PFC stage adjust its output power depending on the load requirements of downstream converters?

I am trying to calculate the overall efficiency of a PFC+flyback converter. The PFC boost converter has an efficiency of 0.9 and the flyback an efficiency of 0.89. Depending on the load which requires ...
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3answers
118 views

X2 polypropylene capacitor for DC smoothing after AC rectification

Can a X2 polypropylene film capacitor be used for dc smoothing at the output of a bridge rectifier? I want to use this capacitor at the input of a power factor correction circuit with a switching ...
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1answer
31 views

Is a power system acting in leading mode after power factor correction bad?

I am modelling a simple power system with two generators. The power system is initially assumed to be operating with a lagging pf (the generators are providing reactive power). However, some ...
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1answer
44 views

Splitting output power of a PFC stage to three flyback converters

I want to design three flyback converters whose input is taken from a single power factor correction circuit based on boost converter topology. The PFC stage delivers 200 W (400 V, 0.5 A), and I want ...
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2answers
48 views

Power factor leading and lagging effect on power

Why doesn't power factor leading or lagging bring any effect to apparent power? While for reactive power, lagging will result in a positive answer and leading will result in a negative answer?
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3answers
216 views

What can happen if the power factor of one generator becomes leading?

Please help with this. I have a generator which I loaded in parallel with other generators. I noticed that the power factor became exactly one and after a while leading. The other two generators had a ...
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1answer
68 views

Current specifications of the boost inductor

The following calculations refer to the boost inductor of a PFC boost pre-regulator. ILac is defined as the ac inductor current.as it says "ac inductor current" and its value is calculated ...
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2answers
115 views

Can a PFC work without feedback?

I want to test my PFC using MC33262. How can I be sure that it works? I see any signal on GD pin, yet I powered it correctly with 10-12 Vin the Vcc pin. Vac = 230 Vrms Does a PFC emit a frequency by ...
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1answer
68 views

How does this supply network for Vcc work?

The following schematic refers to a PFC driven by L6562A. What is the current flow in the supply network of this IC in the two different statuses of MOSFET=ON and MOSFET=OFF?
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Are three-phase bridgeless boost, three-phase totem pole and active 6 switch rectifiers different names of the same topology?

I keep coming across these topologies in several references and they look similar but the names are used interchangeably. I wish to know if these are same, and if not, what is the difference between ...
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1answer
47 views

LTV and NLTI capacitors and inductors' basic relations

Are the famous differential relations of inductor and capacitor true for Linear time-variant (LTV) inductors and capacitors? How about non-linear time-invariant (NLTI) ones? $$V_\text{L}=L\frac{dI}{dt}...
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191 views

How does the "zero current detection circuit" work?

This question refers to the L6562A PFC driver. My problem comes from the following highlighted text from the AN2761 application note. I can't understand the reason for 1.4V. What's the meaning of &...
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1answer
392 views

How is this "current sense resistor" selected?

I attempt to design a PFC by L6562A. In the corresponding application note is mentioned that the amount of current sense resistor should be calculated from the following relation. My problem is the &...
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3answers
313 views

What does "leading-edge blanking" do exactly?

This below-highlighted block is in the L6562A PFC controller. In its application note is mentioned that the CS pin is equipped with 200 ns leading-edge blanking to improve noise immunity. What is it ...
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2answers
194 views

Different levels of SPICE models

I wanted to model some components operated in a switching boost power converter at LTspice and i realized that different levels are available for power mosfets. Do all components have different levels ...
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71 views

Convert a through-hole type circuit board to SMD type

I want to replace the through hole parts of the following circuit with SMD parts (control section.) This is an 80W FPC using L6562A. Is this a straightforward action or does it require further ...
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1answer
177 views

What is the correct approach to simulate a predesigned circuit?

I want to simulate the following circuit with LTspice, but all the operating parts in the circuit (highlights) are not available in the library. I also couldn't find their spice models on the internet....
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26 views

What is the definition of ILac in following diagram and calculations?

The attached diagram and calculations refer to following application note: AN2761 Application note Solution for designing a transition mode PFC preregulator with the L6562A I don't have any idea about ...
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2answers
222 views

What's the difference between the D and DTR parts?

Is DTR just the same as D which is packaged in tape and reel? If so, was it really necessary to categorize them like this?
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4answers
121 views

Loss-free resistor model

Can someone use a simple explanation to tell me what a loss-free resistor model is? I googled it but it is hard to understand. When I study power factor correction circuits, I see some papers use this ...
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58 views

Reduce the effect of half wave rectifier on transformer

I have an electromagnetic feeder drive which is supplied from a transformer. When I see the catalogue of the drive I noticed it using just the positive pulse of the AC source (half wave rectifier.) ...
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1answer
136 views

Vienna rectifier Matlab simulation

I am trying to simulate the following case: A three-phase source in a Matlab is connected to a Vienna Rectifier which is supposed to supply power to a resistive load of 50KW. Output DC voltage to be ...
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33 views

Does active power factor correction help with internal radiated/conducted noise?

I am choosing parts for the supply of a device. The case will be a metal chassis and there will be an AC-DC (12 V) converter module inside mounted on the chassis. The total AC power draw will be less ...
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1answer
39 views

Generator Power factor Calculation with varying Output Power

We are operating a generator (Stirling engine in particular) that outputs a certain active power in the range of 6.5-8.9 kW. The power output is adjusted with pressure variation. The electrical ...
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64 views

Boost PFC Control

I am learning the Boost PFC control, and I read this Master thesis and I have some questions I want to ask you guys. 1.)In the PFC control why we need to multiple 1/x^2, can someone tell me? I think ...
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178 views

Current sensing in boost PFC controllers

I was going through the datasheets of a few active PFC controller ICs (like this: https://www.ti.com/lit/ds/symlink/ucc28019a.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1619350669153&...
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24 views

Boost PFC with large leakage inductance

I would like to implement a boost PFC stage for an alternator that has a large leakage inductance (~40mH). When looking at the schematic, we can see that the boost inductance ...
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8answers
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Need device with poor power factor

I'm looking to calibrate an energy meter. As a part of that process, I need to cheaply find a device that can create a power-factor of 0.5, in order to calculate the required phase correction. The ...
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48 views

PFC formula for calculating conduction losses across MOSFET

I am not able to demonstrate the formula above where Vin is the input voltage of the PFC, Vout is the output voltage, Po is the output power, and Rds(on) is the on resistance of the mosfet. This ...
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1answer
74 views

Power factor requirement for SMPS just above 75W

What is the power factor (PF) requirement for an SMPS or even just a standalone power factor correction (PFC) stage with a power level above 75W? I know that in some cases the customer will specify ...
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28 views

Inaccurate differential voltage measurement

I tested 3-level PFC voltage initialization event in practice using 1 x single ended probe to measure the output voltage as well as 3 x differential probes to measure the precharge voltage levels of ...
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2answers
61 views

Current values after power factor correction

I am a student tasked with correcting the power factor of an RC circuit to unity with a parallel inductor... Vrms = 240V, 50Hz R = 12ohm C = 220uF. I have calculated the inductor value by calculating ...
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1answer
115 views

Why shouldn't I use a Zobel network to improve the power factor of an electric motor?

This is a homework question, so I would prefer something that would make me think and maybe promote discussion. I understand the use cases for a Zobel network in an audio setup, but I struggle to see ...
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2answers
69 views

Finding the kVA loading after improving the power factor

This is a homework question I've been attempting. But the answer I get doesn't match with whats given and I don't understand why my method is wrong. This is the question with answers. Here's what I'...
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1answer
86 views

Calculating PF of a transformer

Consider a one-phase transformer rated at 20 MVA, 13/2 kV and 50 Hz. It goes through a short-circuit test with |V1|=11 kV applied on the primary side. During the test, the primary side draws rated ...
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When changing rotor current in alternators, the pf and inductive part of the current changes but the resistive part does not. Why is this so?

Given a current for an alternator $ I = I_R - jI_X $ When the rotor current changes, the excitation changes so the magnitude of the generated voltage changes. The current changes, but only the ...
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131 views

Impact of PFC output impedance on the regulation of a converter

I have determined the transfer function of my converter operating in closed loop configuration. Nevertheless I saw on the web that the transfer function is not the same if my converter follows a PFC. ...
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2answers
38 views

Formula for non - active power of capacitors connected in a star?

There is a common question in my coursework that we are asked to : Let's say we have an inductive 3 - phase load that consumes $$S=15 + j10$$MVA "If , we connect parallel to this load, 3 ...
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1answer
57 views

High power factor but maximum current at resonance in series RLC circuit

In a series RLC circuit, at resonance, the power factor is unity but the current is high. But since in high power factor the current drawn is low, then isn't this a paradox? High current is ...
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Is my solution to this power factor question correct?

I'd be very thankful if it would be possible for someone to check my solution to this question and highlight any mistakes which I may have made in the working. I have checked through it myself several ...
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2answers
74 views

Power factor in a power system

Will a system necessarily have an increase or decrease in power factor with a change in frequency of the system?
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1answer
86 views

How can Kill-a-watt show .1A, 12VA, but 0 watts?

I'm trying to verify whether a 10W aquarium heater is failing. It has a safety fuse that renders it permanently inoperable if it overheats by running unsubmerged, which is suspected in this case. My ...
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3 phase 208v leg balance and observed KVA

I have a cluster computer system in a small server room, fed by an 80 kva capable double conversion (480v 3-phase in, 208v single phase out) UPS. This UPS has an LCD display showing voltage, leg ...
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1answer
189 views

How can a boost PFC (Vienna rectifier) lower the voltage?

I found a Vienna rectifier circuit as a PFC. Output range: +350...+500VDC and -350...-500VDC. Input: 400VAC (three phases). To begin with, I simulated a basic three-phase rectifier: Here's the 561V ...
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1answer
139 views

Confused with the formula for Power Factor Correction

The formula provided in my lecture notes: $$C=\frac{Q_c}{\omega \:V_{RMS}^{\:2}}$$ Where $$Q_c=Q_{old}-Q_{new}=P\left(tan\left(\theta _{old}\right)-tan\left(\theta _{new}\:\right)\right)$$ Such that \$...
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3answers
492 views

What is the significance of UPS output power factor?

A UPS's output rating is shown as 2000VA/1800W. I understand that the power factor here is 0.9, but the device or load I will connect to the UPS might have pf<0.9 or pf=1 (for light bulb.) From my ...
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Power Factor Circuit

I am currently working on an energy meter that requires to know the Power Factor in order to get the Actual Power in the circuit. The circuit diagram attached shows my circuit diagram and it is ...

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