# Pulsated DC Chopper with Inductive load

#### dasunx

Summary
Pulsated DC Chopper with Inductive load
Circuit Diagram

Components USED

1. MOSFET ( 47N60C3 ) (https://www.infineon.com/dgdl/Infin...n.pdf?fileId=db3a304412b407950112b42dff93492f)
2. Primary Transformer Coil
3.12V. 2A Switching Power Supply
4.function generator ( currently using 66kHz frequency)
5.oscilloscope
6. Schottky Diode ( PMEG100V060ELPD ) (https://assets.nexperia.com/documents/data-sheet/PMEG100V060ELPD.pdf )

oscilloscope output

The required output is mentioned with the circuit diagram.

Questions
1.how to remove the oscillatory part of output?
2. how to get full 12v across the Inductor coil?
3.any other possible ways to achieve the above mentioned required waveform across the inductor coil

Extra components Available,
extra 2 of 12v,2A power supply

Related Electrical Engineering News on Phys.org

#### tech99

Gold Member
The voltage across an inductor is equal to - dI/dt. So if you want a square wave you need to supply a sawtooth current. This requires a high resistance source.
On the other hand, if you intend to have square wave drive and a resistive load across the inductor, this must have a resistance low enough so that the time constant, L/R, is several cycles.

#### Tom.G

Science Advisor
I can't quite read the inductor value, is it 0.62mH or 0.62nH or 0.62uH?

Based on what the inductor value is, try replacing it with a resistor whose value matches the inductor reactance at the 66kHz switching frequency and see what waveforms you get. Keep the rest of the connections just the same as they were for the photos you posted. Anything other than a nice clean squarewave indicates an instrumentation or equipment problem.

I did a quick evaluation based on 0.62mH, here are some areas to look at:
1) There are long leads between the inductor and the clamping diode
2) The Power Supply may not be able to keep up with the 66kHz varying load
3) The connections to the 'scope are not directly at the inductor

Cheers,
Tom

#### NascentOxygen

Mentor
Add a 0.1uF cap across the power supply terminals to lower its impedance.
To soak up that low-energy oscillation, try a resistor parallel to the inductor, maybe 4.7 MΩ, though the oscillations may actually be attributable to the oscilloscope leads.

As Tom.G pointed out, your oscilloscope connections may not be displaying the inductor voltage alone. If you connect the probe to the "bottom" of the inductor, and the oscilloscope's earth to the common ground, then it will display inductor voltage + the supply's DC voltage, the latter merely constituting a DC offset (if stable).

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