Ultra-high Step-up Soft Switched Quadratic DC-DC Converter with Continuous Input Current and Low Switch Voltage Stress

An ultra-high step-up quadratic converter is introduced which boosts the voltage gain by voltage multiplier cells and coupled inductors. An active clamp circuit is utilized to absorb the leakage inductance energy of the coupled inductors and provides soft switching conditions for switches. Therefore, both switches are turned off at zero voltage and turned on at zero voltage and zero current conditions which have eliminated the switching and capacitive turn-on losses. In addition, the output power diodes benefit from zero current condition at turn-off, thereby the reverse recovery problem for output diodes is mitigated. The voltage stress of switches and diodes is reduced notably, as result, switches with low on-resistance are used, and conduction losses are reduced. Regarding the mentioned advantages, the efficiency of the proposed converter is increased considerably. The proposed converter has a common ground between the input and output and continuous input current. Moreover, since the power is transferred during the main switch on time, the instability problem associated with the conventional boost converter is eliminated. The performance of the converter is analyzed in detail and to prove the theoretical analysis, a prototype of the converter for 48V to 380V at 200W is implemented in the laboratory.