Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around power electronics. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com

Cross related switching losses (Eoss) – I saw this Infineon advertising product video:
https://www.infineon.com/cms/media/e…0VCoolMOSCFD7/ In the section “Technical features and benefits”  “Improved switching losses Eoss II”, at the end of the video they show how they calculate switching losses. They add to the “Eon” energy (based on drain-source voltage overlap with drain current) the “Eoss” one. Infineon and some other well-known manufacturers do this, while others stop at the overlap between drain voltage and drain current in order to estimate switching loss. The explanation why Eoss should not be included in the overall switching loss is this (please tell me if I am mistaken).  Read more

Driver circuit for IGBT – I want to design circuit FOR driving Gate_IGBT (GT60N321) to control the speed of dc motor (180 volt _ 2 HP) I want to control the IGBT gate by PIC microcontroller (pwm_pin) this is the circuit but it is not working.  Read more

What are the limitations of switching power supply to enhance its frequency? – There is a paper entitled the working principle of high-power adjustable switching power supply and it mentions a new design of high-power adjustable switching power supply which using Buck-type switching power supply topology, with a single PWM output, MC33060 as a control IC, and dual output IR2110 driver chip and then designed a high-voltage high-power switching power supply as an effective solution to adjustable high-voltage switching power supply circuit, which can solve the problem effectively that in the non-isolated topology, the common switching power supply can not reach high limits, and attached with over-current protection usage. But my question is what about medium and small power devices? What is the bottleneck for medium and small power devices to increase their frequencies of switching power supply?  Read more

LED working but relay not working with BC547 – I want to drive 5v single channel relay by BC547, I am using a 1k resistor at the base but the relay is not working. I replaced the relay with an LED and it works fine. So can anyone tell me why led is working but the relay is not working? Also, I tested the voltage by replacing relay at the terminal and it was 5v but still relay not working. Read more

Low power high-efficiency switching regulator (5V to -28V) – I have a 5V power supply from which I want to produce -28V, @500uA max load current. I’ve tried using LT1617-1 from Linear Technology but the simulation at LTspice shows an RMS current consumption of about 7-8mA, which is not acceptable for my application. Any ideas on improving the circuit attached to lower overall current consumption (ideally around 1-2mA) or suggestions of any other implementations  Read more

Deciding flyback converter IC – I’m trying to build an offline converter that has an input 150Vac-250Vac and outputs 24V 0.3A (about 7.2W). This converter will be used as an adapter to feed other digital and analog circuitry components on a PCB and is not used as a charger. I have TI’s UCC28911 (CV/CC controller) and Power Integration’s LNK626PG (CV controller) in mind. Both are primary side regulator flyback ICs, are opto-less and can provide the output power required. Read more

IGBTs burned  – I’m trying to do an inverter based on Sine Pulse Width Modulation (SPWM). I did two stages, control and power. The first, done with AmpOp 741 and comparators LM311 generates 4 signals which would be injected on the gates of a bridge of IGBTs (G4PC50K IR 022P), these receive a DC signal to be modulated by them. Read more

Common mode noise issue in offline LED driver (150W) – We have designed an Offline 240VAC LED driver which is linear regulator based. (86% efficient). It does, however, contain a 1W buck converter for its bias supply. For cost reasons, we are not allowing ourselves to use any through-hole components on the PCB. We are also not allowed any custom made components (only off-the-shelf allowed). We are also not allowed to take an earth wire connection to the PCB, as its more cost due to the greater assembly effort. (the Earth wire does, however, connect to the earthed heatsink on which the PCB sits, and is held onto by metal screws). Read more

Wind a 2.2uH torroid inductor – I’m new to inductor winding. When I searched in google I found the methods to wind, But I want to know
1. How can I select a toroid core ?. I found some codes T30-10 etc.
2. Is the wire gauge a factor?. If I selected one core, How to determine which gauge wire need to use?
3. How can I know whether the 2.2uH inductance reached?
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12V 10A SMPS topology – I want to design an SMPS with an input of 220V 50Hz, an output of 12V 10A. Can you help please choose the topology? Which will be simpler? Which is more effective? And can you help to choose the conversion frequency? Read more