Currently, I have a problem about the current measurement.
I used the Hall Effect transducers, LV25-P and LA25-NP, to measure the input voltage and input current for the Buck-Boost. The details of the Buck-Boost can be seen in the first figure. The current signal is measured by the LA25-NP and sent to the signal condition circuit as shown in the second figure.
I used the PV emulator, Chroma ATE-62050H-600S, as the input source for the Buck-Boost. Some results are shown in the third figure, where the explanation of the channel 1-3by oscilloscope can be seen in the second figure.
Now, my questions are:
Thank you for your answes @Yihua Hu.
Proximity of switching elements (transistors) and unstable ground are also common problems. Windings: just use a multiple winding to set Your current (measured) closer to transducer range.
Hello, @Marcin Holub, thank you for your answers.
In my Buck-Boost, I have three ground as the figure I attached. The GND is the ground of the main circuit, D_GND is the diver's ground, and the last one (the triangle one) is the sensor's ground. I connected them together with 0 Ohm resistance. Do you think it is the problem that you mentioned "unstable ground"?
Your Schematic shows the LA 25-NP in the 5A configuration but this should have nothing to do with the noise you are seeing. That noise is most likely caused by the switching of one of your active devices. Most likely the rails are bouncing because of the circuit layout. Parasitic inductance is a likely culprit. Make sure your bypass caps are as physically close to your active devices as they can get and make your ground as close to a star configuration as you can get. You may also want to isolate the grounds for the buck-boost and the current sense circuit.
Yes, weak gound connections and no gound plane are all possible reasons, just like proximity of switches.
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