The “ PWM Switch ” concept included in mode transitioning

Vatché Vorpérian, from the Jet Propulsory Laboratory (Passadena, CA), introduced his PWM Switch model concept in the 90’s. At that time, he derived an invariant three-terminal model that could be inserted in any converter featuring a power switch and a diode. Thanks to his approach, solving ac transfer functions of complex converters became easier, compared to the former State-Space Averaging technique (SSA). Based on his original work dedicated to current-mode control (CM) and voltagemode control (VM), several SPICE models have been constructed. In the VM domain, for instance, Vorpérian adopted two different configurations to derive his Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) models. SPICE subcircuits built on these two different models, were forced to use mode switches that complicated the implementation and seriously hampered the converge friendliness. Also, in current-mode control, Vorpérian never published the DCM case. This paper will first quickly introduce the PWM Switch model to further derive two novel simple auto-toggling VM and CM models.