TPSF12CX-MATHCAD

This Mathcad file is offered to predict the stability of a voltage-sense current-inject AEF circuit, in particular with respect to TI's TPSF12C1/3/-Q1 family of common-mode (CM) AEF ICs, and to assist with component selection. The model is inclusive of most parasitic effects and can be used as a quick check of the loop gain and insertion loss prior to simulation, bench measurement and fine tuning. The worksheet functions for single- and three-phase AC systems and facilitates two ways of entering the CM choke parameters:

1. Using a CM choke behavioral model with
   • Resistive and capacitive parasitics – suitable for ferrite-core choke
   • A ladder network of three parallel RL circuits – suitable for nanocrystalline chokes
2. Using measured impedance data (magnitude and phase)

• Examine the CM choke impedance versus frequency behavior
• Select components for the compensation and damping networks
• Optimize the loop gain for stability based on the passive filter components
• Inspect filter attenuation performance with AEF enabled and disabled