Pulse-width modulated (PWM) Z-source converter plays an important role in industrial/power electronic systems. Steady-state and dynamic modeling of the power-stage of PWM converters is essential for envisaging a closed-loop regulated power supply.
Steady-state analysis of pulse-width modulated (PWM) Z-source dc-dc converter operating in continuous conduction mode (CCM) is presented. Voltage and current waveforms, and their corresponding expressions describing the steady-state operation of the PWM Z-source dc-dc converter have been presented. The input-to-output dc voltage transfer functions, both for ideal and non-ideal PWM Z-source dc-dc converter have been derived. The minimum Z-network inductance required to ensure CCM operation is derived. The voltage ripple due to filter capacitor and its ESR, and their individual effects on the overall output voltage ripple have been derived and analyzed. Expressions for power loss in each of the components of the PWM Z-source dc-dc converter has been determined. Using the expressions derived to determine the power losses, an expression for the overall efficiency of the PWM Z-source dc-dc has been derived. An example PWM Z-source dc-dc converter is considered. A laboratory prototype is built and the theoretical analysis is in good agreement with the experimental results.
Ac small-signal modeling of pulse-width modulated (PWM) Z-source converter in continuous conduction mode (CCM) by circuit-averaging technique is presented. Averaged dc, low-frequency-large-signal, dc, and ac small-signal models of PWM Z-source converter operating in CCM have been presented. Open-loop power-stage transfer functions corresponding to the capacitor voltage-loop and inductor current-loop are derived. The transfer functions derived take into account the ESRs of the inductors and capacitors. Experimental validation of the derived small-signal models is presented for a laboratory prototype. The theoretical predictions are in good agreement with the experimental results.