High Gain Non-isolated DC-DC Converter Research Articles

Design of New Nonisolated High Gain Converter for Higher Power Density

A high gain nonisolated DC-DC converter using a single power semiconductor switch is proposed in this article. The operation of the proposed converter is explained under continuous conduction mode (CCM), discontinuous conduction mode (DCM), and boundary conduction mode (BCM). The mathematical expressions for steady-state voltage gain, voltage stress, and current stress of diodes and switch are provided. Also, the design of inductors and capacitors in the CCM mode is explained with appropriate mathematical equations. The proposed topology is tested with a 200 W prototype at 50 kHz and a 60% duty cycle. The dynamic behavior of the proposed converter is examined by changing the duty cycle value and also load values. The proposed converter is verified with experimental results to prove the effectiveness of its operation. The proposed converter provides higher steady-state voltage gain as compared with recently developed topologies. The efficiency and power density of the proposed converter is 90% and 1.16 kW/L, respectively.

A Coupled Inductor Based High Step-Up Converter for DC Microgrid Applications

A high gain nonisolated dc-dc converter is proposed for the distributed generation systems. High voltage gain is achieved by integrating different methods with reduced duty ratio. Inductive voltage spikes across MOSFETs are alleviated and stress is reduced with inclusion of a passive-clamp circuit. Thus, lower voltage rating (small R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds(ON)</sub> ) active devices can be adopted. Using this clamp, zero-voltage switching over wide load range is achieved for both the MOSFETs. In addition, leakage energy of the coupled inductor is recycled without using auxiliary switch and thus, the gain get further improved. Zero-current switching is obtained for all the diodes using quasi - resonance principle, which diminishes voltage spikes across the diode caused by the parasitic ringing between leakage inductance and diode's stray capacitance. Therefore, snubbers are not necessary to protect the diodes and to mitigate reverse-recovery losses. Overall efficiency improves because of lower switching and conduction losses of the semiconductor devices. A 600 W prototype working at 75 kHz is built in the laboratory to verify the performance. The peak efficiency is nearly 96.5% and is above 95% for wide load range.

Modelling, simulation and analysis of high step up DC-DC converter using coupled inductor and voltage multiplier cell using PSCAD

ABSTRACTThis paper propose a high gain non-isolated DC-DC converter using coupled inductor at input stage and capacitor voltage multiplier cell (VMC) at the output stage. The input coupled inductor is responsible for ripple reduction and the output capacitor multiplier cells are intended to improve the voltage gain. The use of VMC reduces the voltage stress across the power converter switches and facilitates to exploit low rated switches. It will reduce the conduction, switching losses and improve the converter efficiency. The charge balance between the blocking capacitor helps to achieve uniform current sharing in each phase of interleaving operation. The projected DC-DC converter is highly recommended for fuel cell application due to the low input current ripple and high gain. The mathematical model and simulation analysis has been conducted in detailed to validate the converter topology. The converter characteristics have been compared with the high conversion ratio DC-DC converter.