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

MOSFET switchover for E-Bike controller – I’m working on a prototype of an Electric Bike. I am trying to use regenerative energy from the electric motor during freewheeling to charge back the battery. I want this to be semi-automated and hence I’m trying to use high power MOSFET switches to smoothly switch between charge and discharge configurations. Read more

Overcurrent and precharge circuits – How do overcurrent protection circuits and precharge circuits work? Please explain a circuit for 100A current with 48V rated voltage using MOSFETs. I need a precharge/predischarge circuit to limit the inrush current that occurs when the board is powered on initially. Read more

SMPS battery charger control IC UC3842 – Please let me know that I am repairing a (Chinese) SMPS based car battery charger I have changed the MOSFET (10N60) three times and source resistor 1-ohm and UC3842. But now I increase 1-ohm to 3-ohms but output current reduce to 1 Amp and before it was 6 Amps. And now UC3842 slightly heat-up. Read more

Voltage sampling in high power high voltage buck converter – I have designed a DC/DC converter 3kW, 300V input /150V output buck converter that for now works in open loop fashion using a microcontroller. Now I wanted to implement a voltage loop control. What I do not understand is that since this a buck converter with no need for isolation and the ground of power stages and microcontroller are the same, then why should I use isolation amplifier to sample the voltage and feed it to the ADC? Read more

Charge pump switch runs current in opposite direction – Divide by 2, H-Bridge, step-down, switched-capacitor, charge-pump – Operation principle of is shown the attached jpg.
Suppose we look at node “bottom”. In steady-state, it toggles between voltages (Vin+ε)/2 and 0V, while Vout is at ~(Vin-ε)/2. Should the bottom right switch be realized by a PMOS?
And if yes, do you agree it will run negative direction current through its diodes?
Is it OK? Should it work like that? Read more

LM317 as a high current voltage regulator – Please let me know that I made this attached circuit but 10 ohms resistor gone very hot and I connect Halogen bulb of 100W 12VDC but it can not glow. Read more

Heat generator simple circuit – I am looking for a simple circuit to generate heat to keep my device inside an enclosure above 0 deg C, in outdoor application winter time. I’m thinking about a resistor and MOSFET controlled by a GPIO of a processor. Read more

Offline flyback SMPS diode at 120 degrees C – We have designed a 60W PFC’d flyback LED driver. Output is for 60V LED string. VAC input is 240VAC. The output diode is STTH3010D. When the LED driver is in its plastic enclosure, which is itself inside a metal enclosure, we record 120 degrees on the tab of the diode. This is with the equipment in 22 degrees centigrade ambient. We cannot afford to buy a bigger heatsink than the one that we have for it. And in any case, we couldn’t afford to re-do the board so we could fit a bigger heatsink in. Read more

H-bridge inverter circuit using IR2110 MOSFET driver – I have built the circuit attached herein on a PCB. The driver section and the half-bridge circuit were tested individually and worked fine. But when I try to combine them the IR2110 always blows up. And the output of the 12v supply that I used to power the VCC pin of the IR2110 gets messed up as well. I used 80v ac coming from a variac. How do I fix this problem? Read more

Building a 12V DC to 120V AC converter – I have a transformer which I took out of an inverter for computer use. This transformer has a 12VAC input with 120/220VAC output. I know there are many diagrams on the internet but I wanted to use a PWM TL494 (I have many of them) and looking for a schematic to build the converter with the parts I have, I have always found push-pull configurations (for center tap transformer) but mine has no center tap. I am thinking of using a full bridge converter but I am not sure about that. Read more