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

XFMR winding optimization for DC resistance – I am asking about the design of the windings of a high-frequency transformer. The point is to see whether or not using round untwisted conductors can get rid of the expensive Litz wire. The optimization parameter then is the DC resistance.  Read more

Supply with one 12v 4A boost or two 12v 2A boosts – Supposing you make a box with 12v going in and 2 outputs each offering 2A at 24v. You could use a single 4A boost converter. Or you could use two 2A boost converters, one for each output? It seems that 2A boost converters are much smaller, lighter and cheaper than 4A converters. The inductor is much smaller, the capacitors much smaller and the switching components too. Read more

How much time required for the varistor to fail? – I want to understand the varistor selection for the continuous current. I am not going to use the varistor for the impulse operation. All the datasheets mentioned here are mostly 8/20μS but my application is that where I have fuse and MOV where I want to calculate the time of varistor to fail and accordingly select the lesser rating fuse so only fuse fail and Varistor will sustain. Read more

What is output voltage of 3-phase VFD? – I have a question regarding VFD. What is the output voltage of 3-phase VFD (input 400v)? And what is out voltage for single phase 220 V to single phase VFD for PSC motor? In a 3-phase VFD phase angle the difference between each phase is 120 degrees and in case of single phase VFD for Psc is 90-degree from each phase. Read more

Input filter design for 1KW SMPS – I want to design input filter for a 1 kW full-bridge converter. The SMPS consists of a PFC unit working at 100KHz and a full bridge phase shift convert. I need high order line filter. Is there any tool available for filters? Read more

Boost PFC stage should NOT provide an almost perfectly sinusoidal mains input current – The theoretical idea of a boost PFC stage is to make mains input current sinusoidal and in phase with the mains input voltage. However, in practical terms, that is not the ultimate goal. The ultimate goal is to make a boost stage which passes the regulations on PFC (EN61000-3-2), without necessarily providing a perfect sinusoidal input current. In fact, what you really want is a boost stage which passes the PFC regulations and yet has a fast-as-possible transient response, and also stays stable under all conditions. And in fact, if your boost PFC stage is producing an almost perfectly sinusoidal mains input current, then it will not be properly optimized in these practical terms. Do you agree? Read more

170 V Dquasi-resonant supply – I have made a circuit using the design note – DN06014/D  but the circuit is not working on the output at both 12v and 170v. I have traced the circuit three times and the connection is all good I don’t know where the problem is in the circuit. Read more

Waterproof LED lighting system with no contacts – We have been tasked with lighting up another huge system of outdoor architectural water fountains with colored LED lamps. Therefore, for this build, we are going to use our new contact-less LED lighting system. For this, there is a single power supply, which puts a high frequency (100khz) sinusoidal current into a 30 metre cable (twisted pair). Its only the power supply we have to keep waterproof. All the downstream LED lamps have no metal contacts, and so they are waterproof. Each LED lamp comprises a ferrite coupler which “clips” over the 30 metre cable wires, and the secondary is embedded in this ferrite as a PCB “printed” secondary. –No contacts! – each lamp can very simply be clipped or unclipped, from anywhere on the cable that we like. It’s a perfect system. Why is no one else doing this? Read more

Is a multi-phase buck-boost converter possible? – I have been reading about multi-phase synchronous buck-converters and there benefits compared to an ordinary buck-converter, and I have seen but not really read about multi-phase boost converters. Multi-phase converter means that instead of having a synchronous buck-converter built with one power stage(high-side & low-side MOSFET switches, inductor and possibly capacitors) you make several individual buck-converters that are connected parallel and by some means share the current load, which is a scheme that offers a whole load of useful results. What about a multi-phase buck-boost converter? Read more

Mechanical relay to photomos relay –  I would like to ask if there’s anything I need to consider to convert mechanical relay to photomos relay. Read more