An accurate model of the harness, including its high-frequency behavior, is of great importance in designing the filter in charge of damping unwanted high-frequency harmonics caused by harness parasitics.
RFG output current (yellow) contains unwanted high frequency harmonics caused by the parasitic capacitance of the RF harness:
To improve the behavior of the RFG inverter and reduce the losses, a precise T-model of the harness was calculated based on the real harness measurements. To be able to run simulations on the time domain, an approximated simple RLC model that only models the first harness resonance was used:
After modeling the harness, a filter to damp the high frequency harmonics was designed:
Where one path is a band pass filter for the fundamental frequency and the other is a resistor in charge of damping the high frequency harmonics, with a series capacitor that increases the impedance of the resistor path at a lower frequency, reducing the losses on the resistor.
The simulations and the prototype waveforms match closely, being the differences mainly caused because of the simple model only modeling the first harness resonance:
The filter resistor current also matches the simulation:
