This paper presents the modeling and control design for a high-gain step-up converter used as a power factor compensator, including a grid-tied LCL filter. The DC-DC converter is connected to the electrical grid through a full-bridge rectifier and a third-order coupling filter. The main advantage of this structure is the high-voltage conversion ratio compared to typical PFC applications. The proposed controller is based on the average model of the system, resulting in two control loops: the current tracking loop and the voltage regulation loop. The current tracking loop is designed as a proportional-resonant controller to ensure power factor compensation. The voltage regulation loop aims to maintain the output voltage at the desired reference value using a proportional-integral (PI) controller. Numerical simulations are conducted to evaluate the effectiveness of the proposed control strategy.

This paper presents the design of a control strategy for a modular high-gain DC-DC converter, based on the system’s average model. The proposed approach features a dual-loop architecture comprising an inner current control loop and an outer voltage regulation loop. The inner loop is designed to ensure accurate tracking of reference signals, achieving zero steady-state error through a proportional-integral (PI) control law applied to the inductor output current. For the outer control loop, a proportional-integral (PI) controller is proposed to regulate the output voltage. This approach offers key advantages, including accurate reference tracking and robust voltage regulation, even under varying load or reference conditions. Notably, it achieves these objectives using only two measured signals, simplifying implementation and reducing system complexity. Numerical simulations are performed to assess the effectiveness and robustness of the proposed control strategy in different operating scenarios.

This paper presents a multilevel converter for a photovoltaic transformerless application. The proposed application consists of a power converter with asymmetrical DC-link voltage, referred to as 7L-HBNPC converter, able to inject active power into the grid, producing seven output voltage levels and mitigating the leakage-ground currents. The converter uses the conventional HBNPC connection to reach seven output voltage levels. The strategy to mitigate the leakage ground currents to the grid consists of a DC-link tied LC filter. This filter is formed of two output inductors with a couple of capacitors connected to the DC-link terminals. Thus, the model of the converter based on the common-mode and differential-mode variables is presented for this filter. Besides, based on the differential-mode model structure, a control scheme is proposed. This control scheme is aimed to guarantee active-power injection to the grid despite changes in the power of the reference. Besides, the common-mode model provides information on the behavior of the leakage–ground current compensation. The seven output voltage levels are obtained by a particular design of the modulation scheme structure which produces symmetrical seven output voltage levels in a specific DC voltage unbalance-value. Finally, the performance of the proposed application is assessed using numerical simulations in a 5 kW test converter.

In this paper an improved current mode control for a three-phase rectifier is presented which is able to compensate the line currents under unbalanced operation of the supplied grid voltage. Instrumental for the controller design is the computation of the current reference, where, the key point is the use of the positive-sequence of the grid voltage to construct it. The control scheme is designed to guarantee current tracking of the positive-sequence of the grid voltage and the average voltage regulation at the output towards the desired voltage reference. The overall resulting controller is composed by two main control loops, namely, current (or inner), the voltage (or outer) control loops and additionally a positive-sequence estimator of the grid is used to compute the current reference. The current control loop is designed as a proportional controller with a couple of adaptive estimators which have been added to cope with parameter uncertainties of the filter. The voltage control loop consists of an Integral plus a Proportional controller whose output signal acts as a modulating signal of the current reference.