Hello. Could you help me understand how to create a threephase EMI filter? For example, I chose a fullbridge inverter with parameters P = 100kW, f_switch = 100 kHz. The noise measurement is performed using the LISN.
The results of the simulation (calculation time 050ms)
In this graph, I don't like the presence of peaks for the differential and common mode noise. Could you answer, this is how it should be?
The results of the simulation (calculation time 4550ms)
Differential and common mode noise spectrum (calculation time 4550ms)
Next, I want to design an input filter. If I understand correctly, the main condition for filter design is that the filter impedance should be less than the input impedance of the inverter (about 10 dB). Question: How to plot the input impedance of the inverter?
I simplified the circuit and set AC = 1 for the Vg source.
The inverter input impedance graph is
I chose a filter frequency of about 100Hz. From the previous graph, I determine that at a frequency of 100Hz, the input impedance of the inverter is 21dB. This means that the impedance of the filter should be 21dB10dB = 31dB (0.028Ω). Could you correct me if I am wrong? I think the plotted input impedance plot is wrong. Maybe I need to add a PFC in front of the inverter circuit?
The results of the simulation (calculation time 050ms)
In this graph, I don't like the presence of peaks for the differential and common mode noise. Could you answer, this is how it should be?
The results of the simulation (calculation time 4550ms)
Differential and common mode noise spectrum (calculation time 4550ms)
Next, I want to design an input filter. If I understand correctly, the main condition for filter design is that the filter impedance should be less than the input impedance of the inverter (about 10 dB). Question: How to plot the input impedance of the inverter?
I simplified the circuit and set AC = 1 for the Vg source.
The inverter input impedance graph is
I chose a filter frequency of about 100Hz. From the previous graph, I determine that at a frequency of 100Hz, the input impedance of the inverter is 21dB. This means that the impedance of the filter should be 21dB10dB = 31dB (0.028Ω). Could you correct me if I am wrong? I think the plotted input impedance plot is wrong. Maybe I need to add a PFC in front of the inverter circuit?
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