# 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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### Calculation of diode switching losses

I am an Electrical Engineering student. I'm in my final year and doing a thesis about soft switching. I am trying to grasp the calculation of diode switching losses. I'm having the impression that ...
157 views

### Auxiliary circuit to reduce power losses in idle stage of this oscillator (wireless power application)

I am trying to implement the following resonant oscillator for wireless power transfer application. There will be a secondary coil coupled with Lp. . Reference - WPT Application Note One of the ...
319 views

### Why would someone prefer halfwave rectifier over bridge rectifier? [duplicate]

The other day, out of curiosity I was measuring the current wave shape of a laptop charger. The wave shape indicated a spike only in one half cycle. I'm guessing half wave rectifier here. One thing ...
3k views

### How Long Will This Battery Keep My Fridge Powered For?

I have an interesting mathematical/electrical dilemma and I'm not sure where to start. I am considering buying this fridge (specs on page). I will be hopefully buying a battery pack with it to ...
1k views

### MOSFET body diode conduction

Does the body diode in MOSFET conduct current in backward direction when the MOSFET is switched OFF? If yes, can we build rectifier-bridge using 4 non-driven MOSFETs?
491 views

### Mechanical Switch in parallel to the Micro Controller working in Sync

Here is the image for my requirement,want to operate Load Lamp of 230V AC with Mechanical Switch in parallel to Controller where one can 'ON' the Load Lamp from the Mechanical Switch and 'OFF' from ...
159 views

### Meanings of some symbols in electronics

I am new to electronics and i want to get about what do the symbols encircled in red signify? Can anyone tell me what is happening in the diagram. Please help me. Regards .png
6k views

### SMPS: What is current mode instability (aka “sub-harmonic oscillation”)?

In peak current controlled switching power supplies, there is a phenomenon called “current mode instability” aka “sub-harmonic oscillation”. What is that? Can't seem to get a good explanation of this.....
842 views

### Working and simple applications of PLL [closed]

Recently I am studying about Phase Locked Loop. My professor said that it is an amazing device with a variety of application. I understood the basic working of a PLL. But I couldn't appreciate his ...
734 views

### IGBT transistor with auxiliary emitter

Recently I discovered, that some IGBT transistors in IGBT modules have the second pin for an emitter, called auxiliary emitter. In the picture above 2nd and 4th pins are auxiliary emitters. This is ...
406 views

### Logic-level converter FET

I have been using the BSS138 level converter circuit for a while now and today it struck me I get how the voltage is stepped up by the FET or the BSS138 when you are applying say 3.3 V on the LV side. ...
428 views

### Can I drive a three phase induction motor with this method?

I have an idea to drive induction motors in a new way. I call it Variable Torque Drive (VTD). You are all familiar with VFD which utilize variable frequency and try to keep the torque constant. This ...
452 views

### What is the technical name for fan that produces electricity?

I'm wanting to create a wind powered LED similar to this one, but weather proof. I know there's tons of them out there, but I'm wanting to build it from scratch. My issue is that I'm completely ...
69 views

### How to extract minimum supply voltage from the datasheets

I am relatively new to electronics and need to know What is the minimum supply voltage (Vcc) for LM1875 and for LF347 and how do I extract it from the datasheets? In LM1875 it is written that the ...
360 views

### How do designers know about kilowatt power of wind turbine generators like 1.5 MW?

Generators and transformers are always designed in kVA because designers never know about the load it will provide power to. Then how do we know the wind turbine generator will deliver 1500 kW or 2 MW ...
437 views

### Difference between Vth and Vge?

What is the difference between the threshold voltage (Vth) and gate-emitter voltage (Vge) for IGBT devices? How can I calculate Vth of an IGBT chip?
938 views

### Why does hysteretic current-mode control have variable switching frequency?

This figure below is from Raymond B. Ridley Dissertation "A New Small-Signal Model for Current-Mode Control". Here is an except from the document: The general implementation of hysteretic current-...
291 views

### pulse width modulation versus amplification

If I want to make a sine-wave inverter where the output AC voltage is lower than the input DC input voltage, how can I see that using pulse-width modulation will be more efficient that just using a ...
949 views

### Connecting wind generator to 12V battery without regulator

I've been doing a DIY Wind energy generator. I'm also a newbie in this field. I would like to ask what will happen if I connect my wind turbine to a 12V rechargeable battery without a voltage ...
31k views

### How to identify orphaned power cords? [closed]

We are doing a massive purge of "stuff" from home and storage. I am accumulating a large quantity of random, unmarked power cords. Some will have "Nintendo" or "Norelco" on them - so I know to go ...
125 views

### Is Inductive Kickback Protection not necessary for AC?

For DC inductive loads, typically a flyback diode is placed over the motor so that when the current changes instantaneously it doesn't have a chance to build upon the switch contact and then create a ...
137 views

I had a quiz on power electronics and the following questions were asked: Question 1: Consider the buck chopper in Figure 1, operating at 100 kHz frequency, with the switch duty ratio of 0.5 and ...
366 views

### 5V 1A Solar panel only delivering low power

So I bought this 5V 1A solar panel that can be used e.g. to charge your smartphone accroding to the product description. When I measure the voltage using a multimeter I measured 6.9 V. A little bit ...
9k views

### why is noise always a high frequency signal ? what then is frequency of a noise?

while designing signal conditioning circuits for sensors , we design low pass filters to remove high frequency noise. why can't noise be a low frequency signal or what will its frequency be ?
7k views

### What does the line to line voltage mean? [closed]

What does the line to line voltage mean? For WYE connection is Vna line to line or Van? How about Delta connection?
53 views

### What is 'Nonrepetitive Peak Surge Current' in diodes?

I just went through many datasheets of diodes but didn't understand the term "Nonrepetitive Peak Surge Current". Can someone please explain this to me?
239 views

### Why is the output from this regulator not a constant DC?

I have built a link switch. The output is DC 5V but, when measured with an oscilloscope, itis not constant. Why does this happen? How do I get constant DC output? Any design problem? ...
245 views

### Induction heating

I was reading the working principles of induction heating and I think I understand the basics. Out of curiosity, I searched the Internet for a schematic and found one. However, the thing that confuses ...
203 views

### What is torque-ampere ratio at electric machines? How it is related with machine efficiency?

When I am reading a journal about SRM (switched reluctance machines) it said that outer rotor design has better efficiency due to higher torque ampere ratio. How it is related with efficiency?
187 views

### Can i replace 3 (parallel) capacitors 16v 1800uf with 16v 2200uf?

The motherboard model is G31T-M REV:1.0 . The circuit is for the 4-pin 12v power rail coming from the power supply. I'm replacing these because they are very bloated, It's quite a miracle that the ...
294 views

### Does the source impedance of DC-AC converter always represent losses?

This is a fundamental theoretical question about power and efficiency of AC voltage source with very low output impedance, for example, a DC-AC converter; H-bridge converter or class E amplifier. MY ...
173 views

### Why the implementation of current sensing network (CSN) by sensing the switch current is simpler than that of sensing inductor current?

The excerpt below is from the book Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs by Byungcho Choi. It looks a bit long but my main question is why the ...
532 views

### What is the equation for a potentiometer with dual power supply?

simulate this circuit – Schematic created using CircuitLab Suppose we setup a potentiometer with two power supplies +10V and -10V as shown above. A digital voltmeter is setup to measure the ...
2k views

### Can a high voltage rated push-button switch be used on lower voltages?

I have a question regarding switch usage in a high voltage, very low current circuit (micro amps). Basically, we're taking the 120VAC out of the wall, converting it to DC (output can be either 5, 12, ...
1k views

### ESR in Electrolytic capacitor vs Voltage rating

I would like to know why in an electrolytic capacitor the ESR decreases as voltage rating increases. And why the current rating increases as voltage rating increases. Thank you.
2k views

### Do electronic devices consume more power when the ambient temperature is cold?

Just a casual observation: when it is winter, my personal devices such as cellphone and Ipad consume power more quickly compared when it is in the summer. But this could simply because of change is ...
561 views

### Find dBm and watts of the attenuator?

The question says "A signal of 40 dBm is passed through the first attenuator. The first attenuator has a gain of 1. The second attenuator has 20 dB output. Find the dBm and watts This is what I tried ...
3k views

### Electronic flasher with low load detection

The circuit above is an existing flasher without low load detection. I am trying to develop electronic 2-wheeler flasher with low load detection. While Googling, I got a circuit with relay in it, one ...
3k views

### Equivalent width of CMOS gate?

When setting up the gate that is defined as OUTPUT=(AB+C)' Why is the pull up network equivalent width equal to 4? I know the pull down network is counted in series, so you just add the resistor in ...
7k views

### How do I drive a MOSFET working under high voltage while keeping it insulated from the rest of the circuit?

I want to drive a MOSFET with a 50Hz, 50% duty cycle clock pulse. The voltage to be switched is as high as 300V DC. The section inside the dashed lines will stay electrically isolated from the rest of ...
1k views

### Need for thyristors in power electronic circuits?

Can anyone tell me why are Thyristors(SCRs) used in power electronic circuits? How are they more adept at handling power as opposed to other active or passive electronic components? UPDATE: As per ...
68 views

### TMS320F280049C: Unwanted pulse on GPIO during power on/off

I'm using the TI TMS320F280049C microcontroller. While testing its GPIO behavior during power on/off, I found a high to low transition on GPIO pin, on every power on/off. I'm checking the waveform ...
79 views

### Why are core losses mechanical and not electrical in an AC power flow diagram? [closed]

The power flow diagram of a generator (a) and a motor (b) are shown. But why are core losses mechanical losses?
64 views

### Isolated Power Supplies for Inverter Gate Drivers

I am using a 3-Phase IPM IGBT Inverter Module in motor driver. This module has built-in gate drivers which require 4 Isolated power supplies for their operation. In all I have to design 5 Isolated ...
203 views

### Current limit control using microcontroller

What I want is to open the MOSFET once the current passing through it exceeds 3A. A fuse is already being used, but more protection is needed. There are some options to do it. I could measure the ...
99 views

### Three phase AC machine

I have encountered a three phase ac machine whose name plate contains following information: Y/360 V/90 Hz/2,3 A. I don't know whether it is an induction machine or permanent magnet synchronous ...
333 views

### Feed-forward capacitor in SMPS feedback

I was looking at the TPS63700 DC-DC inverter datasheet and stumbled across the schematic below. It is a more or less usual buck-boost inverter topology schematic, except for the weird R4 and C3 ...
54 views

### What kind of PMIC is this?

I found this circuit in a schematic I'm reviewing, which supposedly provides a regulated +5 V supply. The primary side of the transformer includes a flyback controller that switches ~340 VDC on the ...