ZETA Converter Design

ZETA converter operation principle animation

On this page are presented basic design equations of the ZETA converter. Below the equations there
is an interactive online simulation circuit along with component selection steps. In addition to basic components the
circuit also contains eventual parasitic elements of the main converter components. Supposing L1=L2.



Key design equations:

Continuous conduction mode (CCM):

Current ripple ratio L1 : $r=\frac{I_{L_{ripple}}}{I_{L1_{AVG}}}=\frac{I_{L_{ripple}}}{I_{i}}=\frac{V_i*D}{I_i*L_1*f_s}$

Current ripple ratio L2 : $r=\frac{I_{L_{ripple}}}{I_{L2_{AVG}}}=\frac{I_{L_{ripple}}}{I_{o}}=\frac{V_i*(1-D)}{I_o*L_2*f_s}$

Voltage conversion ratio : $V_{o}=\frac{V_{i}*D-V_{DS_{Q1}}*D-V_{D1}*(1-D)}{1-D}$

RMS current in input capacitor: $I_{C_{i}}=I_{o}*\sqrt{\frac{V_o}{V_i}}$

RMS current in output capacitor: $I_{C_{o}}=\frac{r*I_o*D}{\sqrt{3}*(1-D)}$

RMS current in coupling capacitor: $I_{C_{c}}=I_{o}*\sqrt{\frac{V_o}{V_i}}$

RMS switch current: $I_{Q1_{RMS}}=\frac{I_o*V_o}{V_i*\sqrt{D}}$


Suggested reading:
1. Designing DC/DC converters based on ZETA topology
2. Zeta Converter Basics
3. Switching Power Supply Design and Optimization


Open project to simulate circuit, see "Notes" for component selection info - the circuit is simulatable online




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