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

Favorite low phase shift 240Vrms detector – I have a requirement for a very low phase shift, galvanically isolated, zero cross detector that will operate on UK-grid 240Vrms. What is your favorite trusted solution? Read more

Permittivity of ferrites – Various sources give different information regarding permittivity of ferrites. They seem to agree that epsr = 10 to 20 for NiZn ferrites, but for MnZn ferrites they quote values from 10 to 300. I would like to know the velocity of EM waves in ferrites, so knowing epsr would help. Read more

Inductor current exceeds its saturation rating – I am designing buck converter using MCP16301 :
Vin 14V
Vout 5V
Iout 125mAI have chosen inductor for it:
SRN3015TA-220M
22uH, saturation current 550mA
I have a concern about exceeding inductor saturation rating during buck converter startup. Read more

Need help checking the schematic –  I was making a simple buck converter using an AVR as a controller and 6n137 optocoupler as a highspeed isolator. After I bought the chip I discovered that the output voltage is only 5 volts and I need 10 volts to drive the MOSFET IRF3205 If I drive it with Vgs = 5v the R on, it will be so high (I think) and there will be more losses in the converter, so I decided to add another IRF 3205, but I am not sure of what I am doing. Can you help me and give it a check? Read more

1kW push-pull converter controller IC recommendation – I’m designing 1kW push-pull converter. Design specs are below;
60VDC input
20kHz to 100 kHz operating frequency. ( Fixed but I could change it)
400VDC-2.5A output
I’m looking for analog controllers for this converter. So far I found TL494/TL594 controllers. Is voltage mode control a problem for push-pull? Read more

Protection of 15A DC power line – I need overvoltage and reverse polarity protection on a 12V DC line, carrying a current up to 15A. I thought about using a hot swap controller like the LTC4211 as eFuse, which would work for overvoltage protection. Read more

Low voltage drop high current unidirectional diode/circuit – Need help in continuation of a circuit I was working on, for which I had great inputs from the community. This was the original post: https://www.edaboard.com/showthread….ike-controller. Referring to the above, I had managed to get an LFP battery with inbuilt BMS. That helped me create a MOSFET based switch alright (since charge and discharge connections are separate unlike the earlier circuit), but there is still one nagging issue I cannot find a solution/suitable component for. Read more

Harmonic distortion of LED driver – The below is the LED current (green) and mains input current (red) of a 15W offline, nonisolated buck LED driver. There is deliberately no electrolytic input capacitor. Do you believe that this mains input current would violate THD regulations? I mean, it does have the ringing waveform at the mains voltage zero crossings, as you can see. Read more

Synchronous motor driving – The old one motor for the machine of this type (photo) was damaged so I’m trying to change the new motor and it has only two wires. When these wires are interchanged, the motor running in both clockwise and clockwise direction.  Read more

Triac: 60 Watt bulb flickering – I am using BT136 triac, MOC3021 optocoupler, and AT89C2051 µC and AN33 with rectifier and a step-down transformer for zero crossing detection. What I am doing here is, with the AN33 is I am detecting zero crossing and firing gate trigger to triac via MOC3021. Here the Triac input voltage is 230 volts, 50Hz. According to the concept, after rectification, the pulse will be detected at 100 Hz (Zero crossing), i.e., 10 milliseconds. So, I am taking a delay 2 at millisecond and firing a gate trigger pulse of width 60 microseconds. I have varied the delay time of triggering from 2 milliseconds to 8 milliseconds, at 2 ms, the bulb is perfectly glowing, but on increasing the delay, the intensity is not decreasing but flickering. I want to dim the bulb. Can you tell me the possible mistakes I am doing? I want to dim the bulb. Read more