Abstract
Single-stage voltage step-up inverters, such as the Dual Boost Inverter (DBI), have a large operating range imposed by the high step-up voltage ratio, which together with the converter of non-linearities, makes them a challenge to control. This is particularly the case for grid-connected applications, where several cascaded and independent control loops are necessary for each converter of the DBI. This paper presents a global current control method based on a combination of a linear proportional resonant controller and a non-linear sliding mode controller that simplifies the controller design and implementation. The proposed control method is validated using a grid-connected laboratory prototype. Experimental results show the correct performance of the controller and compliance with power quality standards.
Highlights
Two-stage power converters are generally used for connecting low-voltage DC sources, such as photovoltaic modules, batteries, fuel cells, and super-capacitors, to AC grids
This paper is organized as follows, a detailed description of the Dual Boost Inverter (DBI) topology is presented in Section 2, the control strategy proposed in this work is introduced in Section 3, the experimental validation and main results of the grid-connected DBI are presented in Section 4, and Section 5 presents the main accomplishments and conclusions of this work
The fast non-linear inner control loop, based on sliding mode control, regulates the difference of the current in the inductors of DC–DC boost converters, while the linear and slower outer control loop, manages through a proportional resonant (PR) the current injected to the grid
Summary
Two-stage power converters are generally used for connecting low-voltage DC sources, such as photovoltaic modules, batteries, fuel cells, and super-capacitors, to AC grids. Experimental validations of grid-connected DBIs can be found in [7,8] In both cases, the cascaded linear strategy is used to control individually each boost converter, including an additional control loop based on active and reactive power. One external linear control loop that regulates the grid current through a PR controller, and an internal non-linear control loop that is composed of a switching surface to control the difference between the current of the DBI inductors This is feasible due to the symmetry of the DBI allowing the control of both DC–DC converters as a single system by means of a unique control signal, based on an extension of the theoretical derivation of the SMC presented in [13]. This paper is organized as follows, a detailed description of the DBI topology is presented in Section 2, the control strategy proposed in this work is introduced in Section 3, the experimental validation and main results of the grid-connected DBI are presented in Section 4, and Section 5 presents the main accomplishments and conclusions of this work
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