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# 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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28k views

### Where does electricity go after being used?

For a very long time I have been wondering, where does electricity go after being used? When I use my tablet it runs from a battery. Where does the power go?
233 views

### Full Bridge VSI problem

The above problem was asked in GATE(Graduate Aptitude Test in Engg) 2015 in India. I have no idea where to start so I can't show my attempt. But through google, I got solution by 2 different coaching ...
38k views

### What is Overmodulation?

The Wikipedia article is very short and doesn't explain the concept very well, and there aren't any other sites that I can find that give a simple explanation. What does it mean by 100% modulation? I ...
4k views

### How is the gate trigger resistor value calculated for a triac

As per the application notes of bta08-600cw, to control a three phase induction motor, for triggering the triac gate, the value of resistor is shown as 510 ohm. How is this value arrived at? What ...
2k views

### what the best way to calculate Rg gate driver for Mosfet

I need to drive a MOSFET IPW90R120C3 from Infineon here the Specification of MOSFET VDS @ TJ=25°C 900 V Rdson @ TJ=25°C : 0.12ohm Qg = 270nC Specification of ...
9k views

### Why is flyback air gap needed for energy storage?

Why do so many sources say something along the lines "since a flyback transformer stores energy, an air gap is needed"? I have seen this reasoning in textbooks and app notes. I thought air gaps ...
566 views

What is a ferrite bead? How is it different from an inductor? How is it rated? What are its important parameters? What allows me to chose between an inductor or ferrite bead to filter out frequencies ...
1k views

### Why do we want higher power factor in ac motors?

Here is a simplified 3P electric motor below: This motor is simply combined of three coils facing toward to the rotator (in the center) 120 degree apart to each other. The user wants his rotator to ...
669 views

### SPWM vs 6-step PWM vs SVMPWM

While learning 3-Phase scalar control of ACIM using STM32F407 MCU I could not clearly understand the diffrence between the following terms: 1. SPWM 2. 6-step PWM 3. SVMPWM How do they differ from ...
86k views

### Why does the USA use 110V and UK use 230-240V?

Why does the USA use 110V and UK use 230-240V? What are the advantages? Explain me with calculation. Why do they use different frequencies like 50Hz, 60Hz? What is the reason?
1k views

### How to limit current of an AC signal

For my project, I'm trying to work with the principle of electrovibration. This principle is about simulating textures using low current electricity on an insulated conductive surface (see Wikipedia). ...
3k views

### What does it mean that a resistor has value of 56E?

I found on one schematic that has resistor with value 56E. I don't know what does that mean. Can you give me some information, please.
1k views

### How to use the same antenna to receive and transmit on the same frequency with an SDR [Half-Duplex]?

Considering that the SDR board has one TX/RX output/input and one RX input, I am wondering how could I use one antenna for a half duplex communications on the same frequency. The idea is to use the ...
943 views

### IR2110 max duty cycle

I'm using the high side of an IR2110 driver. If I set the duty cycle to 100% the circuit burns out, I haven't how can I calculate the max duty cycle for the driver in a given circuit?
3k views

### TRIAC Angle of Firing vs Power Delivered to Load, how calculate?

I'm building a phase control system for simple power control to a given load (heater for example). I need an equation to find the relationship between angle of TRIAC firing vs power delivered to load ...
558 views

### Hacking DSLR battery to power camera from power supply [closed]

I would like to power my DSLR for long captures with a power supply. I know the voltage and inner structure of the official batteries. The battery has 2x 3,7V cells inside with a circuit. People ...
88 views

### can you explain me the working of this circuit in detail? [closed]

this circuit is a occupancy light circuit i want to know the working of the transistor regarding base,collector and emitter in the transitor
18k views

### What to plug in first to usb charger when charging: wall outlet or cell phone and why? [closed]

I asked this question on Physics StackExchange but was advised to ask it here. When I charge me cell phone or notebook or whatever device what should I plug in first? Should I at first plug in usb ...
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 ...
383 views

### How to define working voltage class net to calculte the creepage?

I work of a project of single phase PFC converter and I need to define the working voltage to each each NET of Schematic to calculate creepage distance. I have a question about the low voltage of NET ...
435 views

### Capacitor Voltage Rating

How to find the voltage rating of a capacitor after knowing the capacitance value. Example, For a power supply, If the input voltage is 60V and output is 5V. The input capacitor(C1) value is 100uf ...
622 views

### High power pulse generator

I'm designing a relatively high power pulse generator. Basically I have a microcontroller generating a clean square wave (0-3.3 V or 0-5 V) which then goes into my amplification circuitry. I want to ...
423 views

### Resistor values for a Voltage- Controlled Current Source Circuit

simulate this circuit – Schematic created using CircuitLab Hi Folks, During my bachelor thesis, I am learning IGBT gate driver cricuits. I am struggling with understanding the following ...
79 views

### Harmonics in power system [closed]

I have seen in some text books that power converters produce harmonics in power systems. How do power converters inject harmonics in a power system?
240 views

### Maximum power transfer and Thevenin

I am trying to find the thevenin resistance value and the Vth for maximum power transfer. I have tried to find Rth by calculating R3 and R2 as parallel resistance and same for R4 and R5 and then ...
117 views

### Explain the equation [closed]

Explain the following equation... $$r^{\prime}_d = \dfrac{26\mathrm{mV}}{I_D} + r_B$$ Explain from where and how this equation comes out . Also elaborate the terms used in above mentioned equation....
4k views

### What kind of hardware implements Fourier transform?

I looked around online but I found nothing relevant. It is very difficult for an electronic device to decompose a signal in different frequencies. How this is done at the bare metal level? Any ...
5k views

### Why do devices stop operating properly in extreme cold?

I have noticed that a lot of smart phones say that they won't operate under -4 degrees F (-20 degrees C). Can anyone explain to me what happens when the phones get cold that stops them from operating?
6k views

### What is a good power electronics textbook? [closed]

I really want to learn as much as I can about power electronics, switching mode power supplies, and overall analog design. Unfortunately my universities computer engineering program is still ...
3k views

### IGBT vs. Power MOSFET for switching applications. Where to draw the line?

For lower breakdown voltages, a power MOSFET is clearly the device to go for, in view of its higher efficiency, higher commutation speed and lower price. Where should the line be drawn, upwards of ...
20k views

### Arduino 230v Light bulb dimming

Hey guys i have done a lot of research and testing on different circuits for 230v(50hz) or 220v light dimming, but i cant get my arduino to dim my light. This is the last thing i tried. made this ...
13k views

### Parallel MOSFETs and Gate Drive Capability

I'm trying to design a Full-Bridge which can handle upto 330 A (@ 12V). I'm paralleling 3 MOSFETs per leg, and I think I've found a low enough RDS(on) MOSFET to make this somewhat practical. Here's a ...
30k views

### Q-Point of a circuit

In a BJT or MOSFET circuit we have this curve: What is that q-point? From my research I have the following information: The operating point of a device, also known as bias point or quiescent point ...
5k views

### How can I size the DC link capacitor of a 3 phase inverter?

I have come across the Salcone-Bond paper Selecting Film Bus Link Capacitors For High Performance Inverter Applications (PDF), which shows equations for single-phase inverters. But I can't seem to ...
15k views

### Average output voltage of a fully controlled full wave rectifier

What is the average voltage for a fully controlled bridge rectifier with firing angle $\alpha$ ? In a lot of web resources it is said to be: $$\frac{V_{max}}{\pi} (1+ cos(\alpha))$$ For example ...
13k views

### Calculating a burden resistor for a current transformer

Background: I follow a reference design for a single phase power meter (230 V, max 3 A). The below circuit is to measure current via a current transformer. A current transformer will be ...
2k views

### Generating electricity by moving a door

I'm entirely new to electrical engineering. This is for a hardware/software project I have in mind, where I need electricity without having to plug the device into a power source. My intention is to ...
2k views

### Does output voltage of a boost converter depend on load current in CCM?

In the thread below, there are different opinions whether output voltage of a boost converter operating in continuous conduction mode (CCM) depends on load current or not. Boost Converter Output ...
1k views

### How does this FM transmitter work?

I'm an electronics student and I have been trying to understand this FM transmitter diagram (taken from electronicshub.org) for a long time. I had put efforts to learn it by surfing the web but parts ...
2k views

### wiring AC switch with DC led

This is a follow up to a previous question I had answered. I'd like to show the following diagram. Here, I have laid out (crudely) a diagram that has 120v-110vAC from the wall going to a push button ...
7k 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.....
958 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-...
1k views

### Which informations do I need to calculate the efficiency and horsepower of a 3 phase induction motor?

As far as I know the magnetic force is responsible for the motor rotation. So, horsepower of the motor is mostly related to magnetic flux on the coils (windings). Also magnetic flux is directly ...
449 views

### Transformer dimensioning for SMPS (not the Aw Ae way)

There's a lot of documents that talks about dimensioning of the transformer for a SMPS power supply (in this case one quadrant only is not of my interest). this site cites the following: The main ...
1k views

### What are the adavantages of neutral vs. isolated grounding?

While studying "Neutral grounding" I've come to know that advantage of neutral grounding is Voltage to ground are limited to phase voltage. The high Voltages due to arching faults or transient line ...
7k views

### Can I use TI's cc2541 BLE as micro controller to perform operations/ processing instead of ATmega328P AU to save cost?

I am using arduino pro mini (which contains Atmega328p AU) along with cc2541(HM-10) to process and transfer data over BLE to smartphone. I am wondering if I can use cc2541 itself for processing data ...
2k views

### Induction heater circuit problem

I am trying to build induction heater with the help of the following schematics(taken from this page): So I am using 220:10Vrms(15Vpeak) transformer with fullbridge rectifier and a capacitor to get ...
4k views

### How to control power to a water heater

My water heater element is rated at 3.6kW at 240V. To use solar power efficiently, I would like to use excess solar power (in a grid-tied arrangement) to heat our domestic hot water. Our electricity ...