Isolated three-phase rectifier with high power factor using the zeta converter in continuous conduction mode

This paper presents the analysis of an isolated three-phase rectifier with high power factor using a Zeta converter operating in continuous conduction mode. The structure is particularly simple and robust. Its main features are one power processing stage (which can operate as step-down or step-up voltage), lower harmonic distortion of the input current, and natural isolation. The converter works with constant frequency and pulsewidth modulation. The principle of operation, design procedure, and experimental results are presented.

This paper presents a high power factor single-stage driver powering a high-power-LED. The driver employs a PFC based on a Zeta converter, using the One-Cycled Control (OCC) technique. A design procedure for Zeta converter is presented, which is based on the flyback converter as proposed by (Lamar, et al. [1]). Through simulation results of Zeta converter working as PFC, classical OCC and exponential ramp OCC approaches are compared and discussed. Showing that the ramp OCC approach results in better performance of the PFC, in relationship to conventional OCC. This paper also presents the stages of operation of the Zeta converter in the continuous conduction mode (CCM).

This paper introduces small signal modeling of the restructured boost converter (RBC) in continuous conduction mode (CCM) by using the circuit averaging technique. The averaging technique produces linear transfer functions of the converter. The transfer functions relating the duty cycle to output voltage, duty cycle to inductor current, input voltage to output voltage, and input voltage to inductor current are obtained. To validate the converter model, power simulation (PSIM) simulations are developed, and experiments are conducted. The function of RBC is similar to a conventional boost converter, i.e., to level up the input voltage. A comparative analysis between the RBC and conventional boost converter is performed. The results highlight the advantages of RBC over a conventional boost converter.

In order to obtain more realistic characteristics of the converter, a fractional-order inductor and capacitor are used in the modeling of power electronic converters. However, few researches focus on power electronic converters with a fractional-order mutual inductance. This paper introduces a fractional-order flyback converter with a fractional-order mutual inductance and a fractional-order capacitor. The equivalent circuit model of the fractional-order mutual inductance is derived. Then, the state-space average model of the fractional-order flyback converter in continuous conduction mode (CCM) are established. Moreover, direct current (DC) analysis and alternating current (AC) analysis are performed under the Caputo fractional definition. Theoretical analysis shows that the orders have an important influence on the ripple, the CCM operating condition and transfer functions. Finally, the results of circuit simulation and numerical calculation are compared to verify the correctness of the theoretical analysis and the validity of the model. The simulation results show that the fractional-order flyback converter exhibits smaller overshoot, shorter setting time and higher design freedom compared with the integer-order flyback converter.

Taking a buck converter in continuous conduction mode as an example, the improved digital average voltage (IDAV) control technique with capacitor current compensation is presented, and the operation principle and control law are analyzed in detail. The stability and transient performance impacted by the compensation coefficient are investigated by sampled-data modeling, and the optimal compensation coefficient for the fastest load transient performance is found. The analysis results show that the compensation coefficient can be regarded as a virtual equivalent series resistor (ESR) of the capacitor, which affects the stability and transient performance of the system without increasing output voltage ripple. Experimental results are given to verify the correctness of the theoretical analysis.

Present day standards and applications require power electronic ac- dc converters that can operate over a wide range of load variations with approximately unity power factor, controlled dc bus voltage, low input current distortion, and a simple controller. Power factor correction (PFC) techniques can be a practical solution to unidirectional rectifiers since they reduce the number of devices, and improve the efficiency and power system quality as well. This paper presents a new topology of a modular three-phase AC-DC converter. The presented PFC converter can produce a controlled dc output voltage, near-unity power factor, and high efficiency. By operating in the continuous conduction mode (CCM) with an active approach which is one class of high-quality three-phase rectification, the required features are achieved. The performance of the topological structure of the presented converter is discussed and investigated under various modes of operation to identifies their merits and limitations. Extensive simulation is carried out using PSIM software to validate the explained function.

Current-mode controlled single-inductor dual-output (SIDO) switching converters have three borders in wide-range parameter variations. Based on the slopes of inductor current during the power switches being turn-on or turn-off, a unified discrete-mapping model of current-mode controlled SIDO switching converters with ramp compensation is established in this study, which can be applied to three basic SIDO switching converters, i.e. buck type, boost type, and buck-boost type. Only six parameters appear in this model after non-dimensional analysis, from which the dynamical behaviours of SIDO switching converters in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) can be effectively illustrated. The effect of ramp compensation is analysed in detail. By utilising the proposed unified model, two transition conditions and boundary equations of the converter are derived, where its operation state transits from stable period-1 to instability and operation mode shifts from CCM to DCM. The operation region with varied circuit parameters can be estimated and divided by the parameter-space map, which is significant for the design of circuit parameters and stability. Finally, taking a current-mode controlled SIDO boost converter as an example, its experimental results are carried out to validate the theoretic analysis and the non-dimensional unified model.

The growing demand on the renewable energy systems that work through battery cells has provided a high interest in the DC/DC Buck-Boost converters due to their capability to both amplify and attenuate the voltage that is supplied from such cells. An important feature in the design of these converters is the ability to operate in continuous conduction mode (CCM) so as to lower harmonic distortion and avoid the need for active control on inductors. In this paper, we investigate the design requirements for CCM operation in a reported single switch quadratic DC/DC converter by constructing a simulation model to validate the theoretical gain equations of the converter and check their agreement with the reported results. The simulation results obtained not only revealed inaccuracies in the reported gain equations but also confirmed the agreement between the proposed gain equations in this paper with the expected behavior of the converter.

This paper presents efficiency comparison of quadratic boost converter in continuous conduction mode (CCM) and discontinuous conduction mode (DCM). Analytical expression for the DC component and RMS component of currents in CCM and DCM is derived. Total losses incurred in quadratic boost converter are calculated. Discontinuous conduction modes in three cases are discussed. The simulation result in software MATLAB/SIMULINK is presented for validating the results obtained by mathematical theories.

Due to the simple structure and low cost, the primary-side-regulation (PSR) flyback converter is widely used in small power applications. As the output voltage is sampled from auxiliary winding in PSR flyback converter, some sampling error exists, especially when continuous conduction mode (CCM) is introduced for higher power. To improve the constant voltage accuracy, a novel digital controlled sampling strategy is proposed. This scheme uses a digital ramp sampling method to sample output voltage in both discontinuous conduction mode (DCM) and CCM, and proposes a voltage adjustment strategy to adjust sampling errors in CCM without weakening the stability in the load-switch process. Finally, the experimental results validate the presented scheme and show that the output voltage error is less than 0.6% in a 20-V, 5-A PSR flyback prototype.

This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance, fractional differential of state variables is converted into linear operations of exponential functions, and different harmonic are separated. Thus the main transient oscillation components of state variables can be obtained according to Grunwald-Letnikov's definition of fractional derivation, and the data are processed approximately by polynomial fitting of triangular functions. The results are introduced back to the model to obtain the values of the rest harmonic magnitudes. So the final solution of state variables is in the form of the summation of harmonic contents. To confirm the correctness of the results of the proposed method, waveforms of the analytical solution are put together with those from circuit simulation in PSIM. These results demonstrate the high effectiveness of the proposed method.

Memristors (MRs) have been used in integrated circuit design due to their nanoscale size and low power consumption. In this study, a flux-controlled binary MR emulator is designed by using off-the-shelf circuit components. Then, two MR-based multi-vibrators are constructed and applied to pulse train (PT) controlled Buck converters. Compared with traditional PT controlled Buck converters requiring two pulse train generators, only one single memristive pulse generator with controllable duty cycle is used to regulate the output voltage. To suppress the low-frequency oscillations of the PT-controlled Buck converter in continuous conduction mode (CCM), an inductor current based PT (IC-PT) control method is devised with the proposed MR-based pulse generator. Simulation and experimental results both show that the IC-PT-controlled Buck converter with the MR-based pulse generator can achieve fast transient response and minimum low-frequency voltage oscillations in the CCM.

Small-signal modeling of switched-mode converters has been developed in early 70s, when the state-space averaging (SSA) method was introduced for assessing the dynamics of direct-duty-ratio controlled converters in continuous conduction mode (CCM). It turned out that the direct circuit theoretical approach could not be applied to get accurate models also for discontinuous operation mode (DCM). We present in this paper a unified and consistent method for the modeling of switched-mode converters under direct-on-time control applicable to fixed-frequency and variable-frequency operation in DCM and CCM. The method is based on the direct estimation of the state-variable derivatives using their physical and circuit-theoretical dependence on the corresponding circuit elements.

PurposeThe purpose of this paper is to propose a mathematical model for voltage super-lift dc-dc power converter in continuous conduction mode (CCM). Using the presented mathematical model, the analysis of dynamics of power stage for voltage super-lift dc-dc power converter can be performed.Design/methodology/approachThe proposed method is based on the average state space model using the state equations of the dc-dc power converter. In the proposed method, the converter is represented as a set of differential equations derived for each switching state of the power switch in terms of inductor current and capacitor voltage. The proposed method describes the dynamic behaviour of the system. The controller is designed to meet performance requirement of the system such as to maintain the dynamics such as stability, steady-state accuracy and the speed of response of the system. Using the obtained model, the analysis of dynamic response of the voltage super-lift dc-dc power converter can be performed.FindingsThe converter is modelled and verified using conventional circuit analysis method employing state-space averaging technique, and their corresponding transfer function is also derived. The dynamics of the converter is investigated using frequency response characteristics obtained using MATLAB programming environment. In addition, to improve the stability of the converter, proportional-integral controller is designed using Ziegler–Nichols tuning rules, and the effect of the compensator in the plant is also investigated.Originality/valueThe proposed method can be used for analysing the dynamics of power stage for voltage super-lift DC-DC power converter.

A new triple‐input DC–DC converter with bidirectional ability is proposed in this paper. This converter is an interface between two unidirectional ports, one bidirectional port for the battery, and a DC link. This makes the proposed converter suitable for hybrid energy systems (HES). The load power can be provided by each input source separately or simultaneously. Also, the battery can be charged by input sources as well as with the energy returned from the output. These features provide a high degree of flexibility for the proposed converter. Boost and buck‐boost operation and low‐voltage stress on semiconductors are other advantages of the proposed converter. The performance of the converter in continuous conduction mode (CCM) is given along with the governing mathematical equations. The experimental results on a laboratory prototype confirm the theoretical calculations.