Continuous Inductor Current Mode Research Articles

Hybrid approach for 3 phase bridgeless AC to DC Cuk converter for WECS

ABSTRACT This manuscript proposes a novel hybrid method based on a single-stage three-phase bridgeless alternating current (AC) to direct current (DC) Cuk converter for wind energy conversion systems (WECS). The proposed hybrid method is the combination of Mexican Axolotl Optimization (MAO) and Fuzzy Wavelet Neural Network (FWNN), hence it is named as MAO-FWNN method. Moreover, the proposed method enhanced the system performance by distributing the defined reactive-power to harmonic reduction and doubly fed induction generator (DFIG). The proposed converter is modelled under a discontinuous mode of the inductor current. The converter’s output inductor is modelled as a continuous inductor current mode, and it functions to provide enhanced power quality (PQ) and low DC (Direct Current) voltage ripple. At that point, the MATLAB platform is used to execute the performance of the proposed method, and it is compared with existing methods. The performance of the proposed method provides the 0.095 to 0.096 times/sec, which is higher than the existing methods. As a result, the proposed technique is well established compared to the existing techniques.

Use of Boost Power Stage for Static Voltage Gain Improvement of a Non-isolated Continuous Input Current Three-Level DC-DC Converter

The work presented in this paper describes the steady state analysis of a non-isolated and continuous conduction mode (CCM) operated three-level DC-DC converter with input boost power stage for achieving high static voltage gain. The proposed converter configuration is a double boost DC-DC conversion scheme. A boost power module consisting of a power switch, an inductor, a pre-charge diode, and a diode rectifier is introduced as the input stage in the conventional three-level DC-DC converter configuration to obtain the DC-DC converter topology suggested in this research work. The role of the input boost power stage is to extend the voltage gain of the conventional three-level boost converter. The proposed topology employs two power switches in addition to a boost power switch with simple control strategy so that the switching losses are reduced. The switches are subjected to low voltage and current stresses. The suggested non-isolated converter is operated under continuous inductor current mode in open loop configuration. The converter configuration has been simulated in MATLAB / SIMULINK platform. The input boost power stage receives a voltage of 24 V from a DC source. With low duty ratio (= 0.8) of the power switches, a DC voltage of around 208 V is obtained at the load end. The passive components of the converter are so designed that the filtering requirements on the DC output voltage and current waveforms are reduced. The voltage gain of the proposed converter is compared with that of the three-level boost converter without input boost power stage. The various modes of operation of the suggested converter are discussed with relevant equivalent circuits. The proposed system is validated using a developed hardware prototype model of 100 W converter with a low cost KA3525A PWM controller. Both simulation and prototype model results demonstrate that the proposed converter suits high voltage gain applications.

Regenerative Braking in Electric Vehicle Using Quadratic Gain Bidirectional Converter

The manuscript proposes a quadratic gain bidirectional converter (QGBC). The proposed converter is operated in two different stages—step-up (motoring) and step-down (regenerative braking)—which can be employed in electric vehicle (EV) applications. The converter is operated in the continuous inductor current mode (CICM). For regenerative braking (RB) of permanent magnet brushless DC (PMBLDC) motor, the self-inductance of the motor is exploiting to step up the back electromagnetic force (EMF) of the motor to extract the energy even at low rotor speed. The design parameters of the converter are selected as battery voltage V s = 48 V , output voltage V o = 200 V , output power P o = 1 kW , and switching frequency f s = 20 kHz . The design system is simulated using MATLAB/Simulink. Finally, a 1 kW prototype is developed for validation and performance analysis of the converter. The converter operates at maximum efficiency of 95% during step-up operation of the converter. A DSP microcontroller TMS320F28335 is used to control the switches of the converter in the experimental setup.

Steady State Behavior of a Single-Switch Non-isolated DC-DC SEPIC Converter Topology with Improved Static Voltage Gain

This paper presents the analysis of steady state behavior of a single switch non-isolated Single Ended Primary Inductance Converter (SEPIC) topology for achieving high DC voltage gain using diode-capacitor voltage multiplier. A voltage boosting module consisting of inductor and capacitor in addition with two diodes is introduced in the conventional SEPIC configuration in order to derive the DC-DC conversion technology proposed in this work. The voltage gain of the converter is extended using a diode-capacitor voltage multiplier cell. The converter suggested in this work has a single controlled switch. Hence, the conduction losses and the control complexity of the switch are very much reduced. The open loop configuration of the proposed non-isolated converter is described under continuous inductor current mode. The voltage boosting capability of the presented converter is compared with that of the existing modified SEPIC structure. The presented positive output converter topology has low switch voltage-current stress compared to the existing modified SEPIC topology given in the literature. The inductor and capacitor components of the suggested converter are so chosen that the DC output voltage and current waveforms show very low percentage of ripples. A DC voltage level of 24 V is given as input to the proposed converter. The DC voltage obtained across the load terminals is around 370 V which is achievable with low duty ratio (= 0.7) of the active switch. The voltage conversion ratio is very much influenced by the variation of the duty cycle of the power switch. In this work, the converter topology is presented and its various modes of operation are explained with equivalent circuits. The PSIM software platform is effectively and efficiently utilized to validate the performance of the converter. The obtained results convey that the proposed DC-DC conversion technology with extended voltage gain has the capability to maintain the steady-state output voltage and current profiles with almost negligible amount of ripples owing to the use of suitably designed non-dissipative elements in LC filter.

Analysis of a DC–DC quadratic type step‐down converter for wider low voltage conversion

This study proposes a new transformerless DC–DC step-down converter having the quadratic type of wider voltage gain, for point-of-load applications. In comparison to existent quadratic buck converter variants, the proposed topology offers better switch utilisation at small output voltages and reduced voltage/current stress on components. The stress minimisation benefit helps to select low ON-state resistance switch in the proposed converter, thereby decreasing its conduction losses. Qualitative steady-state analysis is carried out under continuous inductor current mode and design criteria for L-C components are established. State-space average model is derived and subsequently, an equivalent sliding mode control law based on just source side inductor current dynamics and integral of load voltage error is constituted to regulate the output. Salient operational characteristics of the converter are studied analytically and illustrated thereafter using experimental outcomes on a laboratory prototype.

Parallel-charge series-discharge inductor-based voltage boosting technique applied to a rectifier-fed positive output DC-DC converter

The conventional power electronic boost converters have inherent limitations that they are not able to increase the low DC input voltage level into sufficiently high DC output voltage level. This is because of the fact that (1). the inductor used in the converter has certain amount of internal resistance, and (2). the power devices used in the converter are subjected to high potential stress which led to damage of the devices. A configuration of a non-isolated step-up rectifier-fed positive output power converter capable of converting low DC voltage into high DC output voltage-based on the concept of parallel-charge series-discharge inductors is proposed in this paper. The proposed converter is fed by an uncontrolled diode bridge rectifier to which an input sinusoidal AC voltage of magnitude 30 V (rms) is given. The converter is configured such that the input AC voltage of 30 V (rms) is stepped-up to around 900 V (DC) at the output of the converter, with extremely low duty ratio. The proposed converter configuration employs only two high power semiconductor switches with reduced complexity of control. In this work, the converter topology is presented, and its steady state behavior and dynamic modeling are discussed for continuous inductor current mode operation. Further, it is revealed that the voltage gain of the converter is influenced by the variation of the duty cycle of the power switches. The effectiveness of the converter is better understood through simulation in MATLAB/SIMULINK platform. The results demonstrate that the converter is able to maintain higher constant output voltage profile with significantly reduced overshoot and settling time. 
 

FLC and PWM SMC for KY Boost Converter

This paper presents a design and implementation of fuzzy logic controller (FLC) plus PWM sliding mode controller (SMC) for 2nd order-d KY positive output voltage boost converter (KYPOVBC) operated in continuous inductor current mode (CICM). It is more suitable for steady power source in liquid crystal display (LCD), I-pad, CCTV camera, computer parts, light emitting diode (LED), renewable energy and industrial application. The 2nd order-d KYPOVBC always works in CICM and replica of synchronous rectification characteristics. The ON/OFF nature of the 2nd order-d KYPOVBC is nonlinear and their dynamic performance becomes poor. The classical linear controllers are noncapable of output voltage regulation of this converter during the high input supply voltage and load disparities. With the purpose of improving dynamic performance, an output voltage and inductor current regulation of the 2nd order-d KYPOVBC, a SMC plus FLC is designed. The state-space equations of the 2nd order-d KYPOVBC are arrived and then, SMC parameters are calculated. The FLC rules are framed according to the working nature of the 2nd order-d KYPOVBC without mathematical modeling, which is one of the major advantages of the FLC. The SMC acts as an inside loop of this converter to regulate the inductor current, whereas the FLC and proportional integral (PI) controllers act as an outside loop of the same converter for controlling the output voltage. The performance of the designed model is investigated at various operating regions by developing both the experimental and matrix laboratory (MATLAB)/simulation link (Simulink) models in comparison with the SMC plus PI controller. The results are presented to show the best performance of the designed model.

Design, modelling, and implementation of a modified double‐switch flyback‐forward converter for low power applications

This study proposes a modified double-switch flyback-forward (DSFF) converter for low-power applications with a reduced number of windings in its transformer. This circuit has resulted from the combination of the two-switch flyback and two-switch forward converters. It includes a simple transformer with one set of secondary side windings, and it is not necessary to design two separate sets of windings for the desired output voltage which is the main problem of other flyback-forward converters. An auxiliary winding has been designed for self-biasing, and consequently, it improves the overall efficiency in the no-load condition. Due to the modifications on the previously presented two-switch flyback-forward converter, the circuit model has changed. This study, first, analyses the operation of the proposed converter in detail, then it explains a method to design this converter in continuous inductor current mode. Also, a start-up voltage regulator circuit and a modified bootstrap gate driver will be investigated, and the DC and AC model of the converter will be presented. Experimental results validate the proposed DSFF converter. The tested circuit includes a DSFF converter, a pulse generator circuit, a start-up voltage regulator, and a modified bootstrap gate driver.

A Single-Switch Quadratic Buck–Boost Converter With Continuous Input Port Current and Continuous Output Port Current

A single-switch quadratic buck–boost converter with continuous input port current and continuous output port current is proposed in this paper. Compared with the traditional buck-boost converter, the proposed converter can obtain a wider range of the voltage conversion ratio with the same duty cycle. Moreover, the proposed converter can operate with continuous input port current and continuous output port current compared to the existing counterparts with inherently discontinuous input port current and discontinuous output port current. The operating principle and steady-state performance of the proposed converter under continuous inductor current mode is analyzed in detail. Then, the comparison between the proposed converter and the existing quadratic buck–boost converters has been conducted to demonstrate the unique features of the proposed one. Finally, experimental results from a prototype built in the lab are recorded to verify the effectiveness and validity of the proposed quadratic buck–boost converter.

Control of SRM drive for photovoltaic powered water pumping system

The aim of present study is to develop a `Luo' converter-based low-cost solar powered water pumping scheme utilising a switched reluctance motor (SRM). The speed of SRM drive is controlled by adjusting the DC-bus voltage of split-capacitor converter. The converter is electronically commutated at fundamental frequency for low switching losses. A `Luo' DC-DC converter working in continuous inductor current and capacitor voltage modes (continuous inductor current mode and continuous capacitor voltage mode) is utilised to feed power to SRM drive through a split-capacitor converter. It also provides the limitless sector of maximum power point tracking (MPPT). The elimination of current and voltage sensors on the motor side owing to variable speed operation of the motor drive makes the system cost-effective and reliable. The soft-starting of SRM drive is also achieved through the proper step size and initial duty cycle selection through MPPT algorithm. The performance of SRM system is validated by both Simulink/MATLAB platform-based model and responses of developed prototype.

Analysis of Zeros in a Boost DC–DC Converter: State Diagram Approach

This brief presents the analysis of zeros present in boost dc–dc converters that are operating in continuous inductor current mode. It proposes the utilization of the concept of multiple forward pathways from input to output to analyze the origin of the resulting zeros and determine their locations. This brief provides insight into the various zeros present in the boost converter through a state diagram approach.

Power Factor Correction With a Modified Sheppard–Taylor Topology Operating in Discontinuous Capacitor Voltage Mode and Low Output Voltage

In this paper, a modified Sheppard-Taylor converter operating in continuous inductor current mode and discontinuous capacitor voltage mode (CICM/DCVM) is studied and implemented. The operation sequences are described and the averaged model of the converter over a switching cycle is developed. With the obtained, the dc characteristics of the converter were derived, and design criteria for components selection to ensure DCVM operation were reported. The converter is then used for power factor correction in a single-phase rectifier with a front-end diode-bridge. This mode of operation provides the converter some desirable features: zero-voltage turnoff switching and natural purely resistive behavior at low dc output voltage level. This can be achieved by simply using an open-loop control, which offers better reliability than the CICM/CCVM previously reported in the literature, where feedback control is required. The theoretical study of the converter is presented and validated through experimental measurements carried out on a 500 W laboratory prototype. It is shown that this rectifier exhibits an input power factor higher than 99.7% and a source current distortion lower than 6% at small output voltage level.

Modeling of DC–DC Buck Converters for Large-Signal Frequency Response and Limit Cycles

A zeroth-order-hold equivalent discrete-time model of the buck converter for computing its large-signal frequency response is developed and experimentally verified. It is shown that, with a dc bias and a sinusoidal variation of the input duty cycle, the frequency response of the output voltage from the converter shifts from underdamped behavior to damped behavior with increasing amplitude of the input sinusoid. It is observed that, with a given dc input bias and a given input amplitude beyond the range of the state-space linearized small-signal model, the converter behavior varies from exclusively continuous inductor current mode at low frequencies to behavior with continuous and discontinuous inductor current modes at high frequencies. The use of this sinusoidal input large-signal frequency response in predicting limit cycles induced by feedback of the output voltage using proportional and integral controllers for such converters is studied. Experimental results confirming the use of this large-signal frequency response are presented

Small-signal analysis of multiphase interleaved boost converter with coupled inductors

The small-signal analysis of the multiphase interleaved boost converter with coupled inductors operated in the continuous inductor current mode is addressed. It is very difficult to design a dynamic feedback controller when the converter phase is expanded since there are no general and compact expressions for the small-signal analysis for various inductor couplings. Analytical and concise frequency models are derived and the dynamic characteristics investigated according to the inductor couplings and the number of phases. The small-signal analysis is verified experimentally. The proposed frequency models will be very useful to design the dynamic controllers of the multiphase interleaved boost converters.

Generalised steady-state analysis of multiphase interleaved boost converter with coupled inductors

The generalised steady-state analysis of the multi-phase interleaved boost converter with coupled inductors operated in continuous inductor current mode is addressed. The analytical expressions for efficiency, inductor and input currents, and output voltage are derived from the transformed average state-space model. Generalised expressions for the input and inductor current ripples and the output voltage ripple are also derived for various inductor couplings and the characteristics are analysed according to the inductor couplings. The steady-state performance is verified experimentally.

Fuzzy-controlled individual-cell equaliser using discontinuous inductor current-mode Cuk convertor for lithium–ion chemistries

An intelligent battery equalisation-scheme based on fuzzy-logic control (FLC) is presented to adaptively control the equalising process for series-connected lithium–ion batteries. The proposed individual-cell equalisation scheme (ICE) is a bidirectional DC–DC convertor based on the Cuk convertor operated in the discontinuous inductor current mode (DICM). The proposed method can be used to achieve a zero-current-switching (ZCS) cell-balancing control scheme to reduce the switching losses in MOSFET switches. Further, a fuzzy-logic-controlled strategy is constructed with a set of membership functions to prescribe the cell equalising behaviour within a safe equalising region for reduced cell-equalisation time. The simulation and experimental results show the advantage of the predicted equalising performance for lithium–ion battery stacks. The proposed fuzzy-logic-control battery-equalisation controller (FLC-BEC) abridges the equalisation time by about 30% compared with the equaliser without FLC. The power losses of the MOSFET switch are significantly reduced by about 33.8%, and the equalisation efficiency is increased by about 8.5% compared with the same equalisation scheme in continuous-inductor-current mode (CICM). The proposed equalisation method maintains safe operations during the charge/discharge state to increase the charge capacity of lithium–ion battery-pack cells.

A Parallel-Connected Single Phase Power Factor Correction Approach With Improved Efficiency

In this paper, a new parallel-connected single phase power factor correction (PFC) topology using two flyback converters is proposed to improve the output voltage regulation with simultaneous input power factor correction and control. This approach offers lower cost and higher efficiency by parallel processing of the total power. Flyback converter-I primarily regulates output voltage with fast dynamic response and processes 55% of the power. Flyback converter-II with ac/dc PFC stage regulates input current shaping and PFC, and processes the remaining 45% of the power. This paper presents a design example and circuit analysis for 200 W power supply. A parallel-connected interleaved structure offers smaller passive components, less losses even in continuous conduction inductor current mode, and reduced volt-ampere rating of dc/dc stage converter. TI-DSP, TMS320LF2407, is used for implementation. Simulation and experimental results show the performance improvement.

Signal flow graph modelling of interleaved buck converters

AbstractThis paper presents a systematic development of unified signal flow graph model for an interleaved buck converter system operating in continuous inductor current mode. From this signal flow graph small, large‐signal and steady‐state models are developed, which are useful to study the converter dynamic and steady‐state behaviour. Converter performance expressions like steady‐state voltage gain, efficiency expressions and other small‐signal characteristic transfer functions are derived. Development of unified signal flow graph is explained for a 3‐cell interleaved converter system. Derivation of large, small‐signal and steady‐state models from the unified signal flow graph is demonstrated by considering a 2‐cell interleaved buck converter system. Large signal model was programmed in TUTSIM simulator, and the large‐signal responses against supply, load disturbances were predicted. Signal flow graph analysis results are validated with PSIM simulations. Further, the mathematical models obtained from the signal flow graph modelling are in agreement with those obtained from the state‐space averaging technique. Copyright © 2003 John Wiley & Sons, Ltd.

Input filter interactions in peak-current-mode-controlled buck converter operating in CICM

Peak-current-mode (PCM) control is a widely used method to control switched-mode converters. Most often an input filter is necessary to meet electromagnetic interference requirements. The input filter can cause instability and degradation of input and output dynamics if not properly designed. The input filter design from the output dynamics viewpoint has been addressed in numerous papers, resulting in well-agreed results in the case of direct duty-ratio control. The same methods and criteria have also been applied to PCM control, but the results have turned out to be conflicting. This paper shows that the adverse effect of the input filter on the output performance of a peak-current-controlled buck converter in continuous inductor-current mode is insignificant. The input performance is, however, significantly affected, necessitating the use of proper damping. It is also shown that the instability is caused solely by the instability of the input filter under negative incremental resistance. The methods used are unified in nature, but the results obtained in this study cannot be generalized to be valid for types of converters other than a buck converter.

A novel single-phase ZCS-PWM high-power-factor boost rectifier

This paper presents a novel single-phase high-power-factor (HPF) pulsewidth-modulated (PWM) boost rectifier featuring soft commutation of the active switches at zero current (ZC). It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques. The input current shaping is achieved with average current mode control and continuous inductor current mode. This new PWM power converter provides ZC turn on and turn off of the active switches, and it is suitable for high-power applications employing insulated gate bipolar transistors (IGBTs). The principle of operation, the theoretical analysis, a design example and experimental results from a laboratory prototype rated at 1600 W with 400 VDC output voltage are presented. The measured efficiency and the power factor were 96.2% and 0.99%, respectively, with an input current total harmonic distortion (THD) equal to 3.94%, for an input voltage with THD equal to 3.8%, at rated load.