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

Designing 600 watts synchronous buck  – I want to design the synchronous buck with LTC3858-1 with the below specifications
Vin=13 volts to 35 volts
Vout=1 volts to 12 volts
Iout-max=50 ampere
How can I modify this file for higher output power? Read more

BLDC: where is my BEMF? – These days I’m trying to identify my BEMF (BEMF=voltage induced in the coil by the moving magnetic field) in my BLDC system, but I can’t seem to find it. This is the circuit diagram. Read more

Quadrant-1 Motor PWM: Where does the BEMF hide? – I was reading this rather informative blog from Texas Instruments called So, Which PWM Technique is Best? but it didn’t quite answer my question. My assumption is that the BEMF is looping around the diode and the motor, if I’m right in my assumption, then how to prevent the BEMF from circulating and thereby aiding coasting? Is it possible to persuade the BEMF to pick another route? I mean other than going full H-bridge and Quadrant-4? Wouldn’t this be possible? The BEMF is dissipated in the resistor? Read more

Conducted emission voltage failed at switching frequency of boost – I have a conducted emission voltage failure at the switching frequency of BOOST circuit. The circuit below is the power rail filter, and the UBATT was connected to the BOOST input. The switching frequency of BOOST is 400KHz, it has two phase and is delayed 180 degree, So I get the failure at 800KHz, it exceeded 6dB. I tried to change the 470nH inductor to 3.3uH, it gets worse. I also add more caps, such as 10uF, 4.7uF and 470uF, there is no improvement. Read more

Contactor CA7-30 – I got a faulty contactor CA7-30 (Sprecher + Schuh brand). I want to replace it, but I found difficulty in searching for a replacement because its contactor coil has 3 terminals….it has A1, A2, and 3rd coil terminal. I am looking for a replacement. All the contactors I found online have 2 coil terminals only A1 and A2. Read more

Simetrix/Simplis elements help – I am looking for someone who has more than my novice level of knowledge onSIMetrix/SIMPLIS elements software. I am trying to construct a Bridge rectifier using an ideal transformer at a ratio of 10:1 or any transformer to work at a 10:1 ratio with an AC RMS input of 230V 50hz. I keep getting 10 individual primary transformers to 1 secondary which is not exactly what I want. Read more

Spikes in the output of IR2110 – I was trying to implement an inverter with an h-bridge configuration using IR2110 (the standard configuration of this). But I got spikes during the transition. Switching frequency was 50kHz. Read more

PLECS: op amp not regulating – I have a PSFB converter done in PLECS from Plexim but I can not make it work, even though theoretically looks good. I can not see any mistake in my implementation, so I need someone else to look at it. The problem is that the voltage feedback implemented by the Op-Amp is not regulating, i.e., it sets the “control signal” for the CPM controller so high, that the current never reaches it and hence the SR flip flop never resets => never switches the bridge leg. Read more

BLDC: flyback recovery – I want to recover as much flyback current as possible from my BLDC, so far I have 200mA going in and I’m only able to recover 1-3 mA’s before the voltage after the (hand drawn) diode drops below supply voltage, which is disappointing. This is the driver stage of my BLDC controller, and I have taken phase 1 as an example. Read more

Switching power supply with Lnk304 – I use the below circuit to build 12Volt 100-200mA from 220V AC with lnk304. But the problem that I have encountered is that some of these circuits explode after a while. But some of them are still working for 3-4 months. What can be the reason for this problem? Read more