Ćuk Converter
Overview
This example demonstrates an unregulated, non-isolated Ćuk converter.

Electrical model
The Ćuk converter is a DC/DC converter that, like a buck-boost topology, can be configured to produce an output voltage either lower or higher than the input voltage. However, it always produces an output voltage whose polarity is opposite of that of the input.
The non-isolated Ćuk converter uses a capacitor for energy storage, rather than an inductor like most switched-mode supply topologies.
The converter has an ideal transfer function of:
Vout ⁄ Vin = -D⁄(1-D), where D is the duty cycle.
This means that a duty cycle value of 0.5 will create a unity gain of 1 with opposite polarity, and values higher or lower than 0.5 will step-up or step-down the output voltage, respectively.
Simulation
Run the simulation with the model as provided to view the signals and verify that the load voltage of both topologies has an absolute magnitude of Vin * 0.6⁄(1-0.6) = 10 V * 3⁄2, or approximately 15 VDC.