Primary side regulation (PSR) technology has the characteristics of lower cost and standby power losses. However, there is no algorithm suitable for discontinuous conduction mode (DCM) and continuous conduction mode (CCM) operations of primary side control for flyback converter because of the difficulty in estimating the output voltage correctly. In this paper, a PSR control algorithm suitable for DCM/CCM flyback converter is proposed and implemented with digital micro controller. The voltage drop on the secondary winding and output diode at CCM operation is compensated by sensing the secondary side current at the instant when primary side switch is being turned-on. The secondary side current is zero at the voltage sensing instant and equal to the current at the instant when primary side switch is being turned-on as flyback operated at DCM. In addition, the proposed algorithm can be used to regulate either the output voltage or current very well. An experimental prototype with 150 W rated power is built to verify the feasibility of the proposed control. Experimental results show that the output voltage can be controlled with error less than 0.25%, and the output current error is less than 5%. The conversion efficiency is up to 92.8%.

This article proposes a high step-up dc–dc converter with a continuous input current that is suitable for sustainable energy systems. A three-winding coupled inductor, two power switches, three diodes, and three capacitors are utilized to perform the functions of active switched inductor and switched capacitor. By charging the two primary windings in parallel, and discharging the two primary windings in series to the intermediate capacitor and the output, the conversion ratio can be further improved with lower voltage stresses and current stresses on its power switches. In addition, the energy stored in the leakage inductance is recycled to reduce the voltage spikes of the power switches. Eventually, a laboratory prototype with an input voltage of 36–48 V, and output voltage of 400–600 V with a rated power of 600 W is implemented to validate the correctness and effectiveness of the theoretical analyses. The maximum efficiency and full load efficiency are 97% and 96.2%, respectively.

In this paper, a high step-up dc-dc converter is presented. The proposed converter features a with high voltage conversion ratio and high efficiency with a reasonable duty cycle by adopting an active switched inductor and a coupled inductor. The voltage stresses on the power switches are lower, and with the energy stored in the leakage inductor being recycled, its efficiency is improved. Moreover, current stresses of the power switches are greatly reduced as caused by inductors parallel charging and series discharging on the active switched inductor. Loss analyses of its components are also presented. A comparison including component counts, voltage gain and voltage stresses of power switches with other relevant converters are analyzed. Eventually, a laboratory prototype with an input voltage of 24 V-36 V and an output voltage of 400 V with 400 W rated power is implemented to validate the correctness and effectiveness of the theoretical analyses.

The output voltages of renewable energy resources are relatively low for practical applications. Hence, a converter with high voltage gain is needed. This article proposes a high voltage gain nonisolated three-port converter for a renewable energy source with energy storage applications. A coupled inductor with three windings is used for transferring energies among photovoltaic (PV), battery, and the load. When the battery provides energy to the load, two primary windings with opposite polarities are connected in series. Thus, the effective primary turns is reduced for improving the voltage gain. In addition, the energy stored in the leakage inductor is recycled to the output so as to suppress voltage stress on the power switches and improve system efficiency for energy transference from either PV or battery to the load. Both PV and the battery can provide power to the load independently, thus sharing the load power coordinately. The operation principles, steady-state analyses and key parameter design of the proposed topology are then described in detail. Finally, an experimental prototype is implemented to verify the theoretical analyses with PV, battery, and load voltages of 48 V, 24 V, and 200 V, respectively.

In this paper, a high voltage gain non-isolated three-port converter with a three-winding coupled inductor is proposed for renewable energy system. By implementing a cascoded structure where a photovoltaic (PV) source is stacked on top of a battery voltage source, the high output voltage can be achieved with a reasonable duty cycle, resulting in higher efficiency when both sources provide energy to the load. Furthermore, only three power switches are needed to regulate the energy flows among the three ports. When the low-voltage PV source provides energy to the load, the primary winding and the secondary winding of this coupled inductor are connected in series with opposite polarities to increase the voltage gain of the proposed converter. The use of a clamp circuit allows for the recycling of leakage inductance energy, which helps to reduce voltage spikes on the power switches. This results in the selection of low on-resistance switches and leads to higher converter efficiency. The proposed topology’s operations, steady-state analyses, and key parameter designs are then discussed. To validate the performance of the proposed converter, a 300 W laboratory prototype is implemented.