Questions tagged [power-electronics]

Refers to the conversion of electric power by using solid state components such as semiconductors. Can also generally apply to the field of electrical engineering which works with power electronics.

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18 views

Low Dropout Regulator Enable Delay

I have a main buck DCDC 5V that feeds to five different LDOs(3.3V). To create power sequencing, I would like to use a resistor and a capacitor at the input of the enable pin of each LDOs and by ...
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23 views

How stable is USB powerbank to power your circuit? [on hold]

If you have a circuit that requires 5 volts and 1 ampere. How stable do you think is a USB powerbank? Is there a possibility that the voltage can fluctuate when it's near the end the its life? What's ...
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21 views

Charge and power distribution circuit with multiple batteries

I’m looking for solution for electric vehicle charge and power distribution system PCB. For some reasons I want to split battery to several Li-Ion packs in separated units (hulls). I see the next ...
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22 views

How to adjust the switching speed of Totem-Pole Bridgeless PFC? [on hold]

How can I vary the switching speed of the totem pole PFC? Increasing the MOSFET gate area can vary switching frequency of the MOSFET. So does it mean it also vary the PFC rectifier switching speed? ...
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2answers
102 views

Voltage doubler and power

Lets consider for instance this voltage doubler: It was told that a practical limit of this circuit is the fact that we cannot absorb too much current from it. But I wanted to verify (if it is true) ...
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1answer
163 views

Transformer Design Using AP Method and Construction

I am designing a transformer for a traction inverter using the AP method. 1) I have chosen a Metglas core with a saturation flux of 1.56 Tesla. I have chosen a operating flux density of 0.6 Tesla. ...
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83 views

How to supply either 5V or 0V without the gradual PSU voltage bleed?

I have a 200W 5VDC power supply (Meanwell LRS 200-5). When I shut off the AC it takes about 60s for the supply to drain fully through the connected sensitive components (processors and storage drives)....
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67 views

Current delivered by the vehicle alternator

I have a vehicle alternator with following parameters: 14V, 140A. In parallel to this alternator is connected 14.4V vehicle lead acid battery. The alternator is used as a power source for a load which ...
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1answer
281 views

dq0 Transformation Interpretation

What is the physical interpretation of dq0 axis transformation in electrical machines and power systems? How does this transformation helps? Thanks
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1answer
38 views

Buck converter step response

I am simulating a current step in a buck converter with a resistive load that I designed. I am measuring the response while stepping the current up from 5A to 10A and stepping the current down from ...
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1answer
30 views

Should I charge an in-series 6-pack of Li-ion batteries at 4.2v 1A or 25v 1A?

I have a 6-pack of 18650 Li-Ion cells connected in series, so it gives around 22v dc output. To charge a single Li-Ion cell I need a 4.2v 1-1.5A charger, simple stuff. But to charge the whole 6-pack, ...
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2answers
88 views

How DIAC works?

I edited my whole post for more refreshed information I learned about DIAC. Let's consider the following circuit and how it works. First of all the Vs must be higher than break voltage of diac, so ...
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1answer
75 views

Why don't we worry about reverse recovery voltage and current of a diode in a simple circuit application?

When the diode goes into reverse recovery, why don't we worry about the power supply in that specific time since the current will be increased? Will it not damage the power supply or is it since it is ...
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32 views

How to calculate V/f value for an Induction motor?

I want to implement constant V/f in variable speed Inverter of a 3-phase Induction motor, 1500 rpm, 4-poles. I also know the equation: V/f = 4.44 × N x Phi Phi is maximum value of flux, f is ...
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72 views

Control of battery charging

I have been developing a control software for charging and discharging battery in a dc grid. The system consists of: 01) Three phase alternator with three phase diode bridge rectifier at its output ...
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3answers
1k views

Calculating the ESR of Capacitor

I try to calculate the ESR of a capacitor. I checked this datasheet: http://www.farnell.com/datasheets/2245214.pdf?_ga=2.167304311.817060034.1534770853-676261198.1531404202 I can see from the ...
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1answer
544 views

Fourier Series Expansion of the phase current of a three phase full wave bridge rectifier

I am really struggling with this homework problem where I am asked to calculate the harmonic components as a ratio of the first fundamental harmonic of the phase current of a three phase rectifier ...
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50 views

Improvising for a 5v 2A device [on hold]

My 5v 2A charger got damaged, my phone is a 5v 2A device. So I was wondering if connecting two 5v 1A chargers in parallel to give me 5v 2A to charge my phone will be a good idea?...
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30 views

How to measure correctly efficiency at high load with LT8646

i'm trying to measure efficiency of a LT Part LT8646 at high load with the attached schematic. i'm using a dynamic load and a power supply to give 12V. I'm using a digital multimeter to read the ...
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42 views

Current Transformer Rated primary current vs Max. Primary current

I've been reading up alot on how to work with a CT. Basicly you have a primary current (eg: 100A) and a turns ratio (eg:1:2500) and a load resistance (eg:5 ohms) so now things are straight forward we ...
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2answers
117 views

How do I connect an LED with floating DC voltage?

I want to connected an LED at the output of 500V DC. This DC power supply is made by 3phase DC rectifier and is floating. I would like to have a display on the front panel of the supply which will ...
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1answer
37 views

LTSpice buck converter output voltage too high

I am designing a 311V to 48V buck converter in LTSpice using ideal components for now. I am using a 48V/311V = 15.434% duty cycle in V2 which controls S1: This is the simulation output: Below is ...
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2answers
52 views

MOSFET pinchoff reduce current

I understand that in an n channel MOSFET as Vgs increases, electrons are attracted towards the gate forming an n channel. These electrons are responsible for the conduction of the MOSFET. As Vds ...
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24 views

Can I use a soft switching IGBT (FGA 25n120: given in specification) for my variable frequency drive power circuit (frequency around 10-20kHz)?

I am building a variable frequency drive from scratch. The design worked well with switching MOSFET. Now I need to increase the power output and DC bus voltage so that I would like to implement ...
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1answer
335 views

Safety Capacitor Selection

When selecting an X2 safety capacitor what must be taken into consideration. There are only a few types of capacitance ranges and seem to be chosen based on voltage rather than capacitance. Take ...
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1answer
39 views

Power devices max voltage, current, power, speed, etc. .. ratings

I want to know how to get the real world or the most recent or the reliable information about power devices max ratings in volt, ampere, power, speed .. etc., parameters. I found this picture that is ...
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16 views

How to change V and F in constant V/F control of an ACIM?

If I generate 3-Phase PWM outputs to drive a 3-phase ACIM and use constant V/F method for speed control then how will I change V and F of the generated PWM outputs? I will generate PWM's using LUT ...
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3answers
76 views

CAN BUS electrical characteristics

I know that CAN bus has two states. Dominant states where CANH goes 3.5V and CANL goes to 1.5V and in recessive state, both CANH and CANL goes to 2.5V. My question is, how much current does it draw in ...
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1answer
93 views

Ic and Vce equations of IGBT

I know in IGBTs while operating, parameters Ic (collector current) and Vce (collector-emitter voltage) are Tj (junction temperature) and Vge (gate-emitter voltage) dependent. Is there anything else ...
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2answers
58 views

How triac acts as a diode and two transistor?

I'm constantly reading this fact that a Triac acts as a diode and two transistor. Can someone explain it.
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1answer
40 views

Using a Main Surge Protector for only branching out other surge protectors

Whenever I try to find information about this question it always says that it is not good to plug in a surge protector into a surge protector because you can overload or overheat the protector or ...
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2answers
86 views

Ic-Vge IGBT Curve

In the figure below, presented in the manufacturer datasheet, you can see the Ic-Vge curve of an IGBT device. As mentioned, it has been drawn at Vce=20V. What does this equality mean? Can we have such ...
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1answer
41 views

Characteristic Impedance without transmission lines

let's consider this three port power divider: I saw somewhere that the reflection coefficient Г11 can be calculated with the formula Г11 = (Zin - Z0)/(Zin + Z0), where Z0 = 50 Ohm. Now my questions ...
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4answers
548 views

Voltage drops when load connected to ld1117a

Package: LD1117A (package sot223) Power: USB adapter( mobile charger ) 5.3 V 2 A When these is not r1 resistor present and adj is connected to ground, Vout is 4.9 V for Vin 5.3 V. r1 is 120 ohm ...
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2answers
74 views

How to classify power electronics components in 2 main groups?

I'm working on preparing a course about power electronics, and with my basic search conclusions. I thought that if it's possible or acceptable to classify the power electronics components in 2 main ...
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1answer
228 views

Average Inductor Current in RL Charging Circuit

Here's a switching circuit. The input Vs is a 24V rectangular pulse at 20kHz frequency with 75% duty cycle. Since the time constant L/R is very much greater than the pulse width, we expect the ...
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38 views

polarised condensor microphone

Sir/Madam, Kindly explain how is the following equation derived for the polarised condenser microphone? The output voltage V0 fed from the microphone to the preamplifier will be how is it derived? ...
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3answers
53 views

Input Protection Diodes Functioning with Circuit Breaker?

I was wondering if I was correct in assuming these diodes were being used for ESD protection on the input of a power circuit. I'm a little bit confused what the point of the diodes are when there's a ...
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69 views

MAX17205 battery pack fuel gauge configuration

I am working on the fuel gauge by MAX17205 for my project. https://www.maximintegrated.com/en/products/power/battery-management/MAX17205.html I am able to communicate with the chip using I2C protocol ...
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26 views

Difference between magnetizing inductance and primary inductance

What is difference between magnetising inductance(Lm) and primary inductance(Lp) of transformer?
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115 views

Multiplication of average voltage and current?

Multiplication of \$V_{rms}\$ and \$I_{rms}\$ gives average power. What things we get if we multiply \$V_{avg}\$ and \$I_{avg}\$??
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46 views

Using an X or Y rated cap in DC link

I'm wondering if I can use an X or Y rated film cap for high frequency DC link filtering/snubbering. The system will be a rectifier+inverter, so the cap in question will go on the DC link between the ...
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2answers
41 views

AD8318 Maximum Input Voltage

let's consider AD8318, a chip which contains a logarithmic amplifier, often used for power measurements. I have read its datasheet and there is a thing that I do not understand: no maximum input RF ...
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1answer
35 views

Controlling multiple floating power supplies from a single point

I have assembled a power supply from five HP dps-750rb common slot power supplies. All five units are in series. I have the first grounded electrically and have the other four units modified and ...
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19 views

Peak Current in a transmission line

Let's consider a transmission line (which drives a generic load ZL) connected to an AC voltage source. If we know that the peak voltage of the source is equal to Vp, how can we evaluate the peak ...
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1answer
47 views

Filter before or after switching regulator?

I will be passing a power line (12V-60Vdc depending on the circumstance) with a lot of noise, 300Hz and above, riding on it through a buck regulator. I want to remove this noise with a filter. I don't ...
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285 views

Clearance through pcb

I've become fairly familiar with the clearance and creepage requirements of UL/IEC/etc 60950, 60730 and derived/related standards. I've just realised, though, that they only refer to distances through ...
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78 views

Wave Propagation in Transmission Lines

let's consider this image (from AAC book, see here) The author wanted to show that a transmission line propagates not only voltage and current waves, but also an electromagnetic wave in the space ...
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2answers
86 views

How is the impedance of a circuit calculated when non linearity is introduced from a switch

What is the impedance of the following circuit if the switch operates at the same frequency with the input voltage. Since the switch introduces non-linearity to the circuit, how can I calculate the ...
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4answers
166 views

Removing output voltage ripple in high voltage outputs

I am looking to reduce the voltage ripple on a DC/DC converter operating at 5kV. I have looked extensively on the internet and have found multiple ways to reduce output voltage ripple, an ...