# Questions tagged [switching-losses]

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1answer
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### Power loss calculation question

Recently I am working on power loss calculation, there are two components I need to calculate, the MOSFET and Diode, and I have some questions I would like to ask you. What's the most accurate ...
1answer
78 views

### Flyback diode choice

I am curious about how to determine the turn ratio to get the minimum power loss. Assuming n=Np/Ns Vin=380, Vo=40, different turn ratios can get the same output because Vo =VinD/(n(1-D)). When the n ...
2answers
93 views

### MOSFET Selection criteria considering conduction losses, switching losses and working frequency

I am trying to choose a suitable MOSFET for my full-bridge resonant converter for wireless power transfer. The circuit topology is something like the following. Specifications: rated power $-~500 W$...
1answer
44 views

### Junction temperature calculation

I have a question regarding the calculation of the junction temperature of MOSFETs and IGBTs. An estimation is possible with: $$T_j = P \times R_{th} + T_a$$ Let us assume that the thermal resistance (...
0answers
68 views

### Can a voltage peak detector circuit detect square wave overshoot voltage?

I'm building a simple inverter with an inductive-capacitive load. I wonder if I have overshoot voltage like this on my IGBT: I want to detect this overshoot, but since I don’t have an oscilloscope I'...
0answers
57 views

### High efficiency pwm current limiter for charging supercap from alkaline battery

I'm designing device which uses two alkaline C-batteries in series as power source, and sends SMS messages using SIM800. On average 1 message per day is sent. Goal is to maximize battery life. Allowed ...
1answer
36 views

### How does the buck regulator soft start condition reduce the unwanted voltage drops from high impedance power sources?

I have been studying the functionality of the soft start function. I understood how it will help to reduce the overshoot of the output voltage as well. Here, my intention is to understand the meaning ...
0answers
115 views

### How to determine Vds(on) and Vds(off) for switching loss calculation?

In the Infineon Application Note, two of the parameters they've used to calculate the switching loss of the MOSFET are Vds(on) and Vds(off). Is the Vds(off) the blocking voltage? Where do they obtain ...
1answer
69 views

### Can a thyristor regain its forward/reverse blocking capability if the current through it is “instantly” brought to zero?

I am imagining a situation where we have several series-connected thyristors, say 10, each that can block a voltage of 100V. So, the ten series-connected thyristors together can block a total voltage ...
0answers
95 views

### Low efficiency buck converter

I've seen the circuit below on YouTube. But it has low efficiency and the p-chnnel MOSFET gets hotter as the output & input voltage difference increases (it goes above 100c with heatsink). I don't ...
2answers
76 views

### Lower duty cycle less efficient?

Assume you have a DC voltage V, ideal switch (no switching losses) operating at some frequency f and duty cycle ...
2answers
54 views

### Any advantage in AC-DC or DC-DC with past, large form factor semiconductors?

I want to clarify this question with my real-world example: Say you have a device which contains some AC-DC converter (or DC-DC) for rather high power specs (10 kW up to 300 kW, not in the same ...
0answers
143 views

### Eon and Eoff IGBT losses

I have read several documentations about switching losses in IGBT. Most of documents indicates to use Eon and Eoff curves to calcul the switching losses through the IGBT. Nevertheless, the Eon and ...
0answers
273 views

### Calculating switching loss of diode - unknown Qrr

I would like to calculate a switching power loss of BY203-20S diode, in following conditions: Vr = 1600 V, fsw = 65 kHz Switching loss of a diode is given by equation: $Psw = Vr*fsw*Qrr$ We can ...
0answers
75 views

### Turn-on and turn-off switching energy

Is it possible to calculate the turn-on and turn-off energy of SiC-MOSFETs with datasheet parameters? The method with ½ * U * I * tr (or tf) cannot be used here. Let us take the C2M0080120D from Cree ...
1answer
180 views

### Does supply voltage affects stepper motor driver heat dissipation?

Below is a block diagram of a stepper motor controller with an external mosfet h-bridge that drives one of the stepper's coils. Let's say that the coil has 2ohm DC resistance and 3mh inductance, the ...
0answers
34 views

### Is zero loss turn-off possible for thyristors?

Consider this very basic circuit: simulate this circuit – Schematic created using CircuitLab Don't mind the values - they don't matter, as this question is conceptual. Imagine that Vcomm is ...
0answers
295 views

### How to add thermal model on SOAtherm-Nmos block in LTspice

I would like to analyze the junction temperature of a SCT3022AL MOSFET during switching operation on LTspice. Followint the Spice model and the thermal model of the MOSFET: https://www.rohm.com/...
1answer
307 views

### Linear power supply vs SMPS (losses in transformer)

We know that, in a power supply, there are always losses taking place. If we have a linear power supply, the major source of loss is the core loss in the transformer. But in an SMPS, where we have a ...
3answers
2k views

### Baker Clamp application for PNP Transistor

I have an issue related to Baker Clamp application for PNP Transistor. I know how to implement the Baker Clamp for NPN Transistor. However I do not know how to do it for PNP. So could anyone can ...
1answer
73 views

### How to calculate the switching loss of an OR Gate?

This is the datasheet of the OR gate. Current consumption as per the datasheet is 25 uA. (Electrical Characteristics table - Page 4 Input current Icc = 25 uA). I am wondering how power consumption ...
2answers
980 views

### Speeding up turn-on and off with VOM1271 Photovoltaic MOSFET Driver (/optocoupler)

It's my first post here so please do not hesitate to tell me if I'm not doing it right :-) A bit of context : we need to switch an array of power resistors (1,3kW, 1ohms) in order to test under load ...
0answers
2k views

### MOSFET switching losses in LTSpice

I've made a simulation of three-phase MOSFET rectifier in LTSpice. I am simulating different conduction angles and calculating efficiency. However, I would like to also take a look at the switching ...
1answer
160 views

### Problems sharing data on a common uSD between a camera and micro; - Switch (TS3A27518E)

Having a lot of difficulties sharing a uSD card between two devices (Atmel micro which uses the SPI, and the camera). We used to do this using relays and all worked fine but cards got faster and ...
1answer
130 views

### Strange behaviour while simulating switching loss

I am trying to simulate gate charge profile and switching loss curves of transistor as in the circuit below. I used ideal current source (30uA) for load, clamp diode (piecewise-linear model with ron = ...
1answer
130 views

### How to replace microswitches with electronic switches in a voltage / resistor ladder circuit

Hello everyone, I am relocating a pair of transmission control levers to a different location within a car. At present each lever actuates a pair of SPST microswitches (at the same time) ...
2answers
2k views

### Dynamic and Active Leakage in CMOS

I studied various techniques to reduce the leakage power consumption in CMOS design. Leakage currents can be static and active. I understand the meaning of static (standby) leakage, but I am ...
4answers
3k views

### Why are switching losses proportional to switching frequency?

Actually in soft switching converters an increase in frequency increases switching losses? Can anyone explain why?
4answers
8k views

### How to increase mosfet switching speed, and decrease switching losses?

I hope this is not a too broad question, but what are the best practices to achieve fast switching on a MOSFET driven by a PWM signal? My current knowledge tells me I can do two things: 1 - To use ...
1answer
927 views

### MOSFET inverter switching losses/events - 3-phase motor

To keep this simple, let's focus on one half-bridge which supplies sinusoidal current to the motor. Q1 is the high side MOSFET and Q2 is the low side MOSFET. SPWM outputs change twice per period - so ...
3answers
718 views

### N-Mosfet switch circuit strange behavior laboratory power supply

I'm dealing with an N-Mosfet switch circuit to control, through PWM, the temperature of a heater resistor. The mosfet is a IRFS7430-7PPBF. The load is driven at 12V and has a power rating of 80W. ...
1answer
658 views

### switching power loss calculation in sinusoidal pulse width modulation

How do i calculate the switching power loss in sinusoidal pulse width modulation SPWM in a H bridge inverter (4 IGBTs), and precisely is it linearly proportional to the frequency switching or to the ...
2answers
1k views

### Why does this circuit speedup the switching time and reduce losses?

I am a little confused as to how this circuit works: According to this website its function is to speedup charge time of the MOSFET as well as reduce losses. How does D1 and Q2 actually work to make ...
1answer
663 views

### MOSFET fast turn-off not enough

I have a PWM bridge driving a higher than 1k load from 200V supply. The simplified, equivalent schematic is this: The drivers I'm using are slow turn-on/fast turn-off and, in the schematic, it's a 50%...
1answer
1k views

### PWM motor heating

Every man and his dog are controlling DC motors with PWM. Nowadays microprocessors are popular and offer more flexibility than 555 timers and general mixed signal analog electronic. The song remains ...
1answer
8k views

### 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 ...
4answers
49k views

### Difference between High- and Low- side switching of power?

Is there any real difference between high- and low-side switching? Assume: Switching is for on/off control of an object (My case RPi) Base/Gate can be driven to Vcc and GND
1answer
2k views

### Is there a formula to figure out power loss of a power inverter?

Is there a formula that will give me a ball park idea of how much power I will lose when I run my DC battery bank through a power inverter? Is this something that varies depending on the inverter? ...
2answers
8k views

### Diode losses in switching power supply

I couldn't find a simple approx formula for calculating diode reverse recovery losses! I am not doing any rocket science, so I just need an approx formula (not worried much about temperature effects ...
1answer
4k views

### Dual active bridge converter

I'm having issues calculating the power losses associated with the operation of a bidirectional isolated Dual Active Bridge DC/DC converter. The converter is controlled using Phase Shift Modulation (...
2answers
20k views

### How to determine maximum PWM frequency for transistor (2SK2554)

How can I determine (estimate) maximum reasonable PWM frequency for 2SK2554 transistor? I found timings in datasheet: I could estimate frequency from this (and make sure that all these times are 20-...
1answer
20k views

### How to use “Voltage controlled switch” in OrCAD?

In this OrCAD project, I tried to build really basic DC-DC Converter with use of "S" or "SBreak" parts in OrCAD's Analog Library. But, According to analysis (picture below), the blue DC line should ...
2answers
808 views

### synchronous buck ls-FET switching losses and dead time minimization

I'm designing a Synchronous buck converter. I'm having doubts regarding the following: In the rectifying period of the converter, using a Schottky diode in parallel with the low side MOSFET will ...
3answers
24k views

### Which has better efficiency: step-up or step-down switching voltage regulator?

I have a Lithium battery pack circuit that converts 4.2V (two 4.2V cells in parallel) to 5V. Another option is to use a step-down converter from 8.4V (two 4.2V cells in series) to 5V. Considering ...
1answer
4k views

### How to determine BJT switching time

Is there some standard way to get information about BJT (Bipolar Junction Transistor) rise and fall times (the high power ones) ? In essence a IGBT is a BJT being driven by a FET, so there should be ...
1answer
174 views

### What are the implications of a MOSFET not listing switching losses in the data sheet?

Many MOSFETs do not specify switching losses in their data sheets. Does this imply that the losses are too low to worry about? Too high for the device to be used in a switching application? Variable ...