Continuous Current Conduction Mode Research Articles

A Single-Stage Isolated Battery Charger Using Nonbridged Positive Cuk Converter Configuration

This article presents a nonbridged isolated positive Cuk (NB-IPCuk) converter-based single-stage battery charging system (SSBCS). The architecture of the suggested charger ensures the intrinsic advantage of power quality improvement in discontinuous current conduction (DCC) mode at the supply mains. The suggested NB-IPCuk converter scheme has fewer components than other bridgeless/nonbridged Cuk converter schemes. This is because the NB-IPCuk converter is a partial integration of two Cuk converters. The usage of the Cuk converter garnishes the system with input and output inductances, which lessens supply current harmonic distortion and, thus supply terminal low pass filter requirement is eradicated. The advantages of the NB-IPCuk converter are the eradication of one inductor and multiple diodes (two back-feeding diodes), which are generally used in NB converter configurations. In place of two separate inductors, the NB-IPCuk converter uses a single secondary side output inductor. The usage of BL configuration of NB-IPCuk converter eradicates the bridge rectifier (BR) stage, and thus, the BR-associated losses also got eradicated. The NB-IPCuk converter also garnishes the system with electrical isolation which adds to the safety standards of the system. DCC mode operation of the NB-IPCuk converter is used in the present work. DCC mode requires lesser sensors in comparison to continuous current conduction mode. The abovementioned benefits of the NB-IPCuk converter make the SSBCS system cheaper, compact, and more efficient. The detailed stability analysis (Bode diagram and pole-zero map) and mathematics for the NB-IPCuk converter are also included in the paper. The prototype and MATLAB/Simulink model of NB-IPCuk converter-based SSBCS system with DCC mode control has been built, and results of both prototype and MATLAB/Simulink are deployed to verify SSBCS system’s performance during dynamic and steady-state conditions.

A bridgeless configured asymmetrical alternating current–direct current converter‐based isolated single‐stage electric vehicle battery charger with supply side power factor enhancement

AbstractAn approach is presented to employ two different types of converters in bridgeless configuration for supply side power factor enhancement of the system. The isolated single‐stage electric vehicle battery charger uses two different converters in a bridgeless configuration to extract the advantages of both converters for supply‐side power factor enhancement. For the negative and positive semi‐cycles of the supply voltage, the power factor‐enhanced asymmetrical alternating current–direct current converter utilises a fourth order single‐ended primary‐inductor converter and a second order buck‐boost converter, respectively. The use of single‐ended primary‐inductor converter and buck‐boost converter in bridgeless configuration reduces the net order of the system with respect to conventional bridgeless‐single‐ended primary‐inductor converter schemes. The buck‐boost converter also needs the supply‐side filter to eradicate the unwanted harmonics in the supply current which increases the order of the system. The usage of both converters presents many benefits like input inductance of the single‐ended primary‐inductor converter can be utilised as a filtering element with a capacitor for the buck‐boost converter. The anti‐parallel diode conduction operation of both switches facilitates the elimination of extra reverse feed diodes (generally used in bridgeless schemes). The single‐stage charger itself comes with the benefit of elimination of extra stages and thus the losses associated with it. The presented charger also witnesses the elimination of the rectifier due to usage of bridgeless configuration. The isolated single‐stage electric vehicle battery charger is also garnished with electrical isolation which adds to the safety standard of the system. To attain power factor enhancement, the asymmetrical alternating current–direct current converter functions in discontinuous current conduction mode in the present work. The elimination of extra‐stages (with respect to two stage charger), a filter, a rectifier, two extra reverse‐feeding diodes, one voltage sensor, one current sensor (with respect to continuous current conduction mode), and electrical isolation not only makes the system compact and safer but also makes the system cheaper. Elaborated mathematical modelling and stability analysis of the presented alternating current–direct current converter using a pole‐zero map and bode plot have been included in the article. The prototype and MATLAB/Simulink model of isolated single‐stage electric vehicle battery charger system with discontinuous current conduction mode control has been built and results of both prototype and MATLAB/Simulink are deployed to verify isolated single‐stage electric vehicle battery charger system's performance during dynamic and steady‐state conditions.

Optimal IP Current Controller Design Based on Small Signal Stability for THD Reduction of a High-Power-Density PFC Boost Converter

This paper presents an optimal design for the inner current-control loop of the continuous current conduction mode (CCM) power factor correction (PFC) stage, which can be used as the front stage of the two-stage AC/DC telecom power supply. The conventional single-phase CCM-PFC boost converter is implemented with proportional–integral (PI) controllers in both the voltage and current-control loops to regulate the output DC voltage to the specified value and to ensure the input current follows the input voltage, which offers a converter with a high-power factor (PF) and low current total harmonic distortion (THD). However, due to the slow dynamic response of the PI controller at the zero-crossing point of the input supply current, the input current cannot fully follow the input voltage, which leads to high THD. In this paper, we investigate a digitally controlled PFC converter with an optimally designed inner current-control loop using a doubly-fed control loops integral-proportional (IP) controller to reduce the THD and to offer an input current with a unity PF. For the economic design of a digitally controlled PFC converter, two isolated AC and DC voltage sensors are designed for interfacing with the microcontroller unit (MCU). PSIM software as well as experimental prototype was used to test the converter performance using the proposed designed current controllers and isolated voltage sensors. We achieved a high-power-density, digitally controlled, telecom PFC stage with a power factor more than 99% and THD of about 5.50%.

DCM-Based Bridgeless PFC Converter for EV Charging Application

This article proposes a single-phase switched-mode bridgeless ac–dc buck–boost derived converter that can serve as a front-end converter for the on-board electric vehicle (EV) charging application. The bridgeless scheme rules out the orthodox bridge rectifier and the affiliated losses. The proposed converter operates in discontinuous current conduction mode (DCM), thus achieving natural power factor correction for variable ac input. In addition to this, sensing of input voltage and input current is fended off because of DCM operation making the converter reliable, cost-effective, and robust compared with conventional continuous current conduction mode converters. Furthermore, the control becomes simple with the employment of a single sensor and the elimination of the phase-locked loop. The proposed front-end converter is well suited for low-voltage battery chargers ranging between 1.0 and 3.3 kW installed in golf-carts and E-rickshaws. A comprehensive steady-state analysis for one switching cycle and the design equations of the proposed converter are presented. The small-signal model of the proposed converter is presented for the implementation of the closed-loop control. Experimental results from a 1.0-kW concept-proof hardware prototype have been demonstrated, which upholds the converter analysis.

Four-Channel Buck Converter in Asymmetrical Continuous Current Conduction Mode

This article is concerned with the asymmetrical control strategies of a four-channel dc/dc buck converter in the continuous current conduction mode (CCM). The converter has two input and four output channels. Energy equations of the converter are studied, and asymmetry of input voltages, output voltages, and loads are examined in the CCM. The proposed control strategy allows us to directly control the power flow in each channel without any unwanted consequences for the rest of the channels among these conditions. The main advantage is the direct control of the total transferred power by the positive sequence of the capacitor voltage, the power exchange among the input channels by the negative sequence of the capacitor voltage, and the power exchange among the output channels by the inductor currents. Calculating these currents also helps to determine whether the converter at a certain point operates in the CCM or in the boundary mode (where zero current switching is possible). Feasibility of zero-voltage switching is simplified by this method. Converter efficiency is showed to be 83% at asymmetrical output voltages in the CCM. Theoretical studies are confirmed by both numerical simulations and laboratory experiments on a 100-W prototype. The studied converter can be applied in supplying multilevel inverters.

Control features of a four channel resonant buck converter

This study presents the steady-state behaviour of a new four channel resonant DC/DC buck converter in symmetrical operation both in continuous current conduction mode (CCM) and in discontinuous current conduction mode (DCM). Having two inputs and four outputs, one of the most important advantages of this converter is its capability to provide four identical or arbitrarily different output voltages, while power exchange between the input channels facilitates the smooth operation even when one of the inputs falls out (security power supply). The converter can be operated in zero-current switching and zero-voltage switching conditions that results in enhanced efficiency. The quasi-sinusoidal waveforms help to lower electromagnetic interference. The analysis revealed the relations among input and output voltages as well as the effect of control variables on the steady-state operation. The obtained theoretical results are verified by both computer simulations and measurements on a recently built experimental prototype. The analytical results and control characteristics are devoted to design such converters and develop control strategies for them.

Control of Chaotic Behaviour in Parallel-Connected DC-DC Boost Converters

Chaos control means to design a controller that is able to eliminating the chaos behaviour of nonlinear systems that experiencing such phenomenon. In this paper, a delayed feedback control mode is presented. The paper describes the control of the bifurcation behaviour of a modular peak current-mode controlled DC-DC boost converter which is used to provide an interface between energy storage batteries and photovoltaic (PV) arrays renewable energy sources. The parallel-input/parallel-output converter comprises two identical boost circuits and operates in the continuous-current conduction mode. A comparison is made between waveforms obtained from a MATLAB/SIMULINK model for open-loop converter and the controlled one. The study shows the effectiveness of the designed delayed feedback control mode.

Small-signal modelling of current-programmed N-connected parallel-input/series-output bridge-based buck dc–dc converters

A procedure is established for the small-signal modelling of n-connected current-programmed parallel-input/series-output pulse-width modulated bridge-based buck dc–dc converters operating in the continuous-current conduction mode. State-space averaging is used to represent the power stage while current-mode control is modelled using a modified new continuous-time technique. Approximate analytical expressions of the major small-signal transfer functions that include the number of modules as a variable are proposed. PSpice simulations are carried out to validate the analysis.

An Improved Non-isolated LED Converter with Power Factor Correction and Average Current Mode Control

A new type of high power LED drivers is proposed by adopting an improved two-stages non-isolated configuration. In order to improve power factor and achieve accurate average current control under universal input voltages ranging from 100 Vrms to 240 Vrms, the power factor correction and average current mode control methods operating in continuous current conduction mode are designed and implemented. With the LUMILEDS emitter type LEDs, a laboratory prototype is built and measured. And from the measured results, it could be concluded that the proposed driver has many better performances such as high power factor, low current harmonic, accurate average current control and switch protection.

Adjustment and stability control for wide range input voltage Boost converter with small sinusoidal perturbation

The Boost converter with wide range input voltage, operating at both stable section and unstable section, the chaos phenomenon makes the system work unsteadily. Based on continuous current conduction mode, the adjustment and stability control with small sinusoidal parameter perturbation for Boost converter are discussed. The transition process between stable state and unstable state for different perturbation amplitudes are analyzed in detail, the critical transition conditions between stable state and unstable state are deduced, and the stability conditions are also determined. It is shown by digital simulation that sinusoidal parameter perturbation can not only suppress the chaos phenomenon, but also cause the converter originally in steady state to turn into unsteady chaos state. The consistent and appropriate perturbation amplitude range can be selected for the wide range input voltage, so as to ensure the Boost converter to start, be adjusted and operate steadily and reliably.

Experimental study of controlling chaos in a DC–DC boost converter

This paper presents a delayed feedback control scheme for eliminating chaotic behaviour in a peak current-mode controlled DC–DC boost converter operating in the continuous current conduction mode. Experimental results and FORTRAN simulations show the effectiveness and robustness of the scheme.

Analysis, simulation and experimental study of chaotic behaviour in parallel-connected DC–DC boost converters

The paper describes an experimental study of the bifurcation behaviour of a modular peak current-mode controlled DC–DC boost converter. The parallel-input/parallel-output converter comprises two identical boost circuits and operates in the continuous-current conduction mode. A comparison is made between the results obtained from an experimental converter with those obtained from bifurcation diagrams generated from previous work and waveforms from a new MATLAB/SIMULINK simulation presented in this paper. Another comparison is made between the modular converter diagrams with those of the single boost converter.

Small- And Large-Signal Modelling of a Modular Boost-Derived DC-DC Converter For High-Output Voltage Applications

A procedure is established for the small- and large-signal modelling of modular current-mode controlled (CMC) pulse-width modulated (PWM) boost-derived transformer-isolated DC-DC converters. A three-module converter employing full-bridge topology is taken as an example. The converter is intended for high-output voltage applications and works in the continuous-current conduction mode. It consists of DC-DC modules whose inputs are connected in parallel and outputs in series across a common resistive load. Cycle-by-cycle simulations using PSpice are performed to aid the analysis.

Application of Theory to Current Mode Controlled Parallel-Connected DC-DC Boost Converters

AbstractThis work describes the bifurcation behaviour of a modular peak current-mode controlled DC-DC boost converter. The parallel-input/parallel-output converter consists of two identical boost circuits and operates in the continuous-current conduction mode (CCM). A nonlinear mapping in closed form is derived and bifurcation diagrams are generated using MATLAB. A comparison is made between the modular converter diagrams and those of the single-boost converter. The effect of introducing mutual coupling between the inductors of the constituent modules is also addressed. Results are verified using the circuit analysis package PSPICE.

Application of Theory to Current Mode Controlled Parallel-Connected Dc-Dc Boost Converters

This work describes the bifurcation behaviour of a modular peak current-mode controlled DC-DC boost converter. The parallel-input/parallel-output converter consists of two identical boost circuits and operates in the continuous-current conduction mode (CCM). A nonlinear mapping in closed form is derived and bifurcation diagrams are generated using MATLAB. A comparison is made between the modular converter diagrams and those of the single-boost converter. The effect of introducing mutual coupling between the inductors of the constituent modules is also addressed. Results are verified using the circuit analysis package PSPICE.

Small-signal modelling of peak current-mode controlled buck-derived circuits

Two averaged techniques are compared for the small-signal modelling of constant-frequency pulse-width modulated peak current-mode controlled buck-based DC-DC converters operating in the continuous-current conduction mode. Both techniques are employed to derive explicit expressions of the major small-signal transfer functions for the modular-converter examples taken. Large-signal transients predicted using the more accurate pulse-by-pulse simulation are also presented to aid the comparison. The two techniques are the new continuous-time technique and the unified technique.

Small-signal and transient behaviour of a two-module DC-DC converter using mutually coupled output filter inductors

Small-signal characteristics and output voltage transients of a voltage-mode controlled two-module DC-to-DC converter feeding a common resistive load are investigated. The parallel-input/series-output converter system works in the continuous current conduction mode (CCM), and uses magnetic coupling between the separate output filler inductors to reduce converter size and weight. A damping circuit can be designed to ensure that the natural frequencies of the output filter are well damped and adequate stability margins are achieved. The converter model is implemented using ‘MATLAB‘ and results are varified against ‘PSPICE’ simulations.

Steady-state and dynamic analyses of high-order parallel resonant convertors

The steady-state and small-signal dynamic analyses of a four-element, high-order parallel resonant DC-DC convertor operating in the continuous-current conduction mode are presented. The analyses are based on the concepts of describing function and harmonic balance. Other lower-order parallel resonant DC-DC convertors are analysed using modified versions of the equations for the four-element convertor. For output voltage control based on variation of switching frequency, convertor characteristics are determined and in some cases are compared with experimental and simulation results. It is shown that this analysis approach does not only provide an accurate unifying technique for convertor steady-state and small-signal dynamic analyses and design, but can also be used for the prediction of the output filter ripple components.< >