Sliding mode control of boost rectifiers operating in discontinuous conduction mode for small wind power generators

This paper presents an approach to design the sliding mode control for an AC-DC converter, consisting of a diode rectifier in series with a boost converter. The results obtained show that this converter with the proposed control law can be used to control the extraction of mechanical power when connecting the permanent magnet synchronous generator (PMSG) to a wind turbine. The boost converter operates in discontinuous conduction mode (DCM) in order to reduce the total harmonic distortion (THD) of the currents in the PMSG. To verify the performance of the proposed method, a simulation study is performed.

Modelling of SEPIC, Ćuk and Zeta Converters in Discontinuous Conduction Mode and Performance Evaluation

High-order switched DC-DC converters, such as SEPIC, Ćuk and Zeta, are classic energy processing elements, which can be used in a wide variety of applications due to their capacity to step-up and/or step-down voltage characteristic. In this paper, a novel methodology for analyzing the previous converters operating in discontinuous conduction mode (DCM) is applied to obtain full-order dynamic models. The analysis is based on the fact that inductor currents have three differentiated operating sub-intervals characterized by a third one in which both currents become equal, which implies that the current flowing through the diode is zero (DCM). Under a small voltage ripple hypothesis, the currents of all three converters have similar current piecewise linear shapes that allow us to use a graphical method based on the triangular shape of the diode current to obtain the respective non-linear average models. The models’ linearization around their steady-state operating points yields full-order small-signal models that reproduce accurately the dynamic behavior of the corresponding switched model. The proposed methodology is applicable to the proposed converters and has also been extended to more complex topologies with magnetic coupling between inductors and/or an RC damping network in parallel with the intermediate capacitor. Several tests were carried out using simulation, hardware-in-the-loop, and using an experimental prototype. All the results validate the theoretical models.

Design and Implementation of a Single-Stage PFC Active-Clamp Flyback Converter with Dual Transformers

This paper proposes an AC/DC single-stage structure by integrating a boost topology and an active clamp flyback (ACF) circuit with power-factor-correction (PFC) function. The PFC function can be achieved by controlling a boost PFC topology operated in the discontinuous conduction mode. With the coordination of active clamping components, a resonant technique is obtained and zero-voltage-switching (ZVS) can be achieved. The proposed converter is combined with the advantages of: (1) compared with two-stage circuit, a single stage circuit decreases the component of the main circuit and reduces the complexity of the control circuit; (2) a boost topology with PFC function operated in discontinuous conduction mode can be accomplished without adding any current detecting technique or detecting input signal; (3) by using the inductor from the PFC stage, ZVS function can be achieved without any additional inductor; (4) the increment of switching frequency facilitates the optimization of power density; (5) the conducting loss at the secondary side can be reduced by adding the synchronous rectification; (6) in this proposed scheme, the dual transformers with series-parallel connection are utilized, the current at the secondary side can be shared for lowering the conduction loss of the synchronous transistors. Finally, a prototype converter with AC 110 V input and DC 19 V/6.32 A (120 W) output under 300 kHz switching frequency is implemented. The efficiency of the proposed converter reaches 88.20% and 0.984 power factor in full load condition.

A PI + Sliding-Mode Controller Based on the Discontinuous Conduction Mode for an Unidirectional Buck–Boost Converter with Electric Vehicle Applications

This paper solves the buck–boost converter operation problem in the discontinuous conduction mode and the feeding a DC bus of a combined battery/solar-powered electric vehicle grid. Since the sun’s radiation has a very important effect on the performance of photovoltaic solar modules due to its continuous variation, the main task of the system under study is the regulation of the output voltage from an MPPT system located at the output of the panels in order to obtain a DC bus voltage that is fixed to 24 V. This is ensured via a double-loop scheme, where the current inner loop relies on sliding-mode control; meanwhile, the outer voltage loop considers a proportional–integral action. Additionally, the current loop implements an adaptive hysteresis logic in order to operate at a fixed frequency. The closed-loop system’s performance is checked via numerical results with respect to step changes in the load, input voltage, and output voltage reference variations.

Paralel Flyback Converter sebagai PFC pada Lampu LED menggunakan Fuzzy Type-2

ABSTRAKPeralatan elektronika umumnya memerlukan catu daya berupa sumber tegangan DC yang berasal dari sumber tegangan AC 220 V yang disearahkan menggunakan penyearah gelombang penuh. Pemasangan filter kapasitor pada sisi output penyearah menyebabkan bentuk gelombang arus masukan terdistorsi sehingga menimbulkan arus harmonisa yang mengakibatkan nilai faktor daya menjadi rendah. Artikel ini membahas mengenai paralel flyback konverter sebagai PFC (Power Factor Correction) pada lampu LED 36 V/60 W menggunakan algoritma fuzzy type-2. Flyback konverter pertama sebagai regulator tegangan DC bekerja dalam kondisi CCM (Continuous Conduction Mode). Flyback konverter kedua sebagai PFC bekerja dalam kondisi DCM (Discontinuous Conduction Mode) sehingga konverter bersifat resistif. Hasil simulasi menunjukkan bahwa paralel flyback konverter dapat memperbaiki faktor daya dari 0.597 menjadi 0.903 dan dapat menjaga tegangan keluaran konstan sebesar 36 V menggunakan algoritma fuzzy type-2 serta arus input yang dihasilkan memenuhi standar internasional hamonisa IEC61000-3-2 kelas C.Kata kunci: PFC, flyback konverter, IEC61000-3-2, lampu LED, fuzzy type-2 ABSTRACTElectronic equipment generally requires a DC voltage source that comes from a rectified 220 AC voltage source using full-wave rectifier. Installing capacitor filter on the output of rectifier makes the input current waveform becoming distorted that cause harmonic current which results in low power factor value. This article discusses parallel flyback converter as PFC (Power Factor Correction) on 36 V/60 W LED lamp using fuzzy type-2 algorithm. The first flyback converter as voltage dc regulator works in CCM (Continuous Conduction Mode). The second flyback converter as PFC works in DCM (Discontinuous Conduction Mode) to make the resistive converter. The simulation results shows the parallel flyback converter can improve the power factor from 0.597 to become 0.903 and can maintain a constant output voltage of 36 V using fuzzy type-2 algorithm and the input current meets the international harmonics standard of IEC61000-3-2 class C.Keywords: PFC, flyback converter, IEC61000-3-2, LED lamp, fuzzy type-2