B-H curve plotting circuit for ferromagnetic material

[ltvsmano]

Hi everyone,

I need to study about the magnetic characterisation of electromagnetic material, so i have made the circuit as per attachment.
When i am giving power supply to primary winding of core , i measured the current flowing through primary coil by shunt resistor 1ohm and the resulted waveform is looks very noisy. What could be the reason for this?

 

[FvM]

1. There's no attachement with your post
2. to plot a B-H curve, you need to integrate windings voltage
3. "Noise" can be expected to be sourced by your power supply. What is it?

 

[ltvsmano]

1. There's no attachement with your post
2. to plot a B-H curve, you need to integrate windings voltage
3. "Noise" can be expected to be sourced by your power supply. What is it?

I think in my company server they blocking upload facility. If u dont mind can you give your email id so that i can send image.

 

[FvM]

I think in my company server they blocking upload facility. If u dont mind can you give your email id so that i can send image.

I don't intend to start a private discussion on this topic. Other edaboard members are interested as well. You'll need to find a way to participate in edaboard in a regular manner.

 

[ltvsmano]

I think in my company server they blocking upload facility. If u dont mind can you give your email id so that i can send image.

k... i will try to find a way to upload images.

---------- Post added at 16:15 ---------- Previous post was at 14:38 ----------



---------- Post added at 16:28 ---------- Previous post was at 16:15 ----------

k... i will try to find a way to upload images.

---------- Post added at 16:15 ---------- Previous post was at 14:38 ----------

In that image the waveforms were measured at a place as below

channel 3 - Input power supply from variac
channel 1 - Voltage across 1ohm resistor at primary winding
channel 2 - Voltage at opamp output

 

[powermanonboard]

in some magnetic materials, saturation is the state reached when an increase in applied external magnetizing field H cannot increase the magnetization of the material further, so the total magnetic field B levels off. It is a characteristic particularly of ferromagnetic materials, such as iron, nickel, cobalt and their alloys. Saturation is most clearly seen in the magnetization curve (also called BH curve or hysteresis curve) of a substance, as a bending to the right of the curve (see graph at right). As the H field increases, the B field approaches a maximum value asymptotically, the saturation level for the substance. Technically, above saturation, the B field continues increasing, but at the paramagnetic rate, which is 3 orders of magnitude smaller than the ferromagnetic rate seen below saturation

 

[ltvsmano]

i agree with you. but in my circuit it is not the case. am supplying primary coil current of 0.3A to circuit and am measuring across 1 ohm resistor so the value should be 0.3V only but am not getting that value and also the resulting waveform is not pure sinusoidal. Link for the circuit am using is given below.

info.ee.surrey.ac.uk/Workshop/advice/coils/BHCkt/index.html

 

[FvM]

The voltage level measured at the shunt resistor looks very low compared to what I would expect from the shown circuit. If it's due to the high inductance of your DUT, you should simply increase the resistor values. There's no problem to use the 68 Ohm series resistor as shunt instead. In addition, there may be a problem of unsuitable grounding and signal connection. Increasing the driving voltage is another option.