CLLLC Analyzer

Analyze CLLLC DC-DC Converter waveforms

The CLLLC_app finds steady-state solutions for fixed input and output voltage over a range of output current. Initial conditions for inductors and capacitors are numerically solved at each operating point. Converter gain is displayed for a range of output load.

After selecting the "Waveform" button, results appear in 2 tabs depending on buck or boost operation. Generally, boost mode results from operating below resonant frequency of L1 and C1. In buck mode, output voltage is below input voltage and reduces monotonically as switching frequency increases from resonance. Primary (L1 & C1) and secondary (L2 & C2) components are equal and transformer turns ratio is set to 1. Magnetizing inductance is k times L1. Characteristic impedance, Zo, and resonant frequency, wo refer to L1 and C1.

Bridge waveform phase timing is plotted over the range of operating frequencies, w. Theta_1 is the duration of phase when the output rectifiers conduct current. Theta_2 is post conduction and theta_3 (if applicable) preceeds conduction.

DC Transfer Function shows load current plotted versus switching frequency. Additionally, buck mode current gain can be compared to combinations of capacitor voltage and inductor current as would be used in an inner-current feedback loop.

Data from the plots can be copied from the 2 text windows between the plots.

If "Invalid w" is displayed in the Errors window, change the "Waveform: w" entry to a value on the w axis of the Bridge Waveform Timing graph.

If "Out of range" is the error, the analyzer cannot find a steady-state solution for the circuit settings. Unity gain operation is not solved in this analyzer. Move converter gain away from 1 to resolve the error.

For more information on the operation or algorithms, feel free to contact the author.