Low Component Count Research Articles

Design and control of a reconfigurable high‐gain battery integrated dc‐dc boost converter for time‐varying loads

SummaryIn this paper, a reconfigurable, low component count high‐gain battery integrated dc‐dc boost converter (HGBIBC) is proposed for power management of time‐varying loads (TVLs). The battery is integrated between the two switches and the two diodes, which provides an inherent feature of pulse‐charging and pulse‐discharging of the battery, thereby increasing its lifetime. The converter operation, in various modes, is explained, and the steady‐state and time‐domain analyses are performed to establish the high‐voltage gain feature of the converter, which makes it suitable for interfacing sources with low output voltages. The guidelines for the design of converter parameters and selection of switching devices are presented. Small‐signal models are derived, and the relative gain array (RGA) analysis is performed, which revealed that the control loops are of decoupled nature and hence the controllers, for each loop, can be designed independently, as in the case of a single‐input single‐output (SISO) converter. The PID controllers are designed to simultaneously regulate the load voltage and source current. The theoretical concepts developed in the paper are validated experimentally using the laboratory prototype of the converter. The experimental results, demonstrating power management, at load voltages of 60 and 48 V are presented, which are found to be in close correlation with the theoretical and simulation studies.

Interleaved Totem-Pole ZVS Converter Operating in CCM for Single-Stage Bidirectional AC–DC Conversion With High-Frequency Isolation

In this article, a new bidirectional single-stage interleaved totem-pole electrolytic capacitorless ac-dc converter with high-frequency isolation and low components count is proposed. The proposed converter is constructed using nonregulating two-phase interleaved totem-pole converter switched with a fixed 50% duty on the grid side and a full-bridge on the dc-side for active power and dc output regulation. This switching method results in a ripple-free grid current regardless of the magnitude of the input inductances. Consequently, a proper design of input inductance secures soft switching for all switches under wide voltage and load ranges without an auxiliary circuit or resonant tank. Hence, the proposed topology overcomes the reverse recovery issue, thereby enabling the use of Si devices in CCM. Moreover, the current spike around the ac main zero-crossing is avoided in the CCM operation due to small rectified voltage around zero-crossing. Furthermore, the instantaneous powers at the grid side and dc-side are identical since the proposed topology is electrolytic capacitorless with inherent second harmonic ripple current at the dc-side. PFC is inherently performed in the proposed converter without a current shaping control loop, and the phase-shift angle is the only control variable. Hence, the control system is simple and reliable. A 3.3 kW prototype of the proposed converter is built and tested in order to verify the performance and the theoretical claims.

Voltage Source Multilevel Inverters With Reduced Device Count: Topological Review and Novel Comparative Factors

Multilevel inverters (MLIs) have gained increasing interest for advanced energy-conversion systems due to their features of high-quality produced waveforms, modularity, transformerless operation, voltage, and current scalability, and fault-tolerant operation. However, these merits usually come with the cost of a high number of components. Over the past few years, proposing new MLIs with a lower component count has been one of the most active topics in power electronics. The first aim of this article is to update and summarize the recently developed multilevel topologies with a reduced component count, based on their advantages, disadvantages, construction, and specific applications. Within the framework, both single-phase and three-phase topologies with symmetrical and asymmetrical operations are taken into consideration via a detailed comparison in terms of the used component count and type. The second objective is to propose a comparative method with novel factors to take component ratings into account. The effectiveness of the proposed method is verified by a comparative study.

Implementation of chaotic oscillator by designing a simple Chua’s diode using a single VDTA

A simple Chua’s chaotic oscillator circuit using voltage differencing transconductance amplifier (VDTA) is presented in this paper. The circuit is implemented by designing a straightforward and compact Chua’s diode using only one VDTA and one resistor. The proposed chaotic oscillator offers the advantages of low component count and increases the frequency spectrum having a dominant frequency in the range of tens of MHz. It is simulated in Pspice using both macro model of commercially available operational transconductance amplifier (OTA) integrated circuit MAX435, and 0.18 µm CMOS TSMC Technology parameters. The simulated chaotic responses at different nodes and the various attractors are observed conforming to the theoretical predictions. The responses with a dominant operating frequency of 20 MHz is shown, which is much higher than the earlier implementations of Chua’s circuit. The power consumption of the circuit is found as 0.243 mW. The workability of the circuit is also verified experimentally on a breadboard by assembling VDTA using MAX435. Non-ideality analysis has also been carried out in detail. Finally, the paper concludes with the comparison of various aspects with the earlier implementations.

Interleaved Ultrahigh Step-Down Converter With Low Component Count

An ultrahigh step-down converter with a low number of semiconductor devices is presented in this article. Important features of this converter are simple structure with low size and cost, low voltage and current stress on components, low output current ripple, and low conduction and switching losses. In this converter, the power switches are turned on under zero current switching (ZCS) condition, whereas the output diodes commutate under ZCS condition without any auxiliary circuit. Thereby, in addition to the converter efficiency improvement, the diodes reverse recovery problem is alleviated. The proposed topology has employed a two-phase interleaved structure to reduce current stress, three windings coupled inductors to further decrease the voltage gain, and two series capacitors to diminish the voltage stress on the semiconductors elements and recover the leakage inductances energy. The experimental results of an implemented prototype are provided to evaluate the effectiveness of the proposed topology at 100 kHz and 200 W, which converts a 400-V input voltage into a 12-V output voltage.

Interleaved bidirectional DC–DC converter for electric vehicle applications based on multiple energy storage devices

Hybrid electric vehicles (HEVs) and pure electric vehicles (EVs) rely on energy storage devices (ESDs) and power electronic converters, where efficient energy management is essential. In this context, this work addresses a possible EV configuration based on supercapacitors (SCs) and batteries to provide reliable and fast energy transfer. Power flow among the aforementioned energy sources and the EV occurs through a dc link associated with an interleaved bidirectional dc–dc converter. This topology presents low component count and high efficiency over a wide load range, consisting of an adequate choice for high-power, high-current levels. A detailed design methodology is presented, which comprises the qualitative and quantitative analysis of the converter and the control system implementation using a simple strategy, i.e., average current mode control. A 2 kW laboratory prototype of the converter using microcontroller dsPIC30f4011 by Microchip is implemented and the system performance is evaluated in terms of some key waveforms. High power density, low component count and increased robustness can be stated as the main advantages of the proposed approach, which can be considered as a viable alternative for practical EV applications.

Photovoltaic-Wind and Hybrid Energy Storage Integrated Multisource Converter Configuration-Based Grid-Interactive Microgrid

In this article, a new dc–dc multisource converter configuration-based grid-interactive microgrid consisting of photovoltaic (PV), wind, and hybrid energy storage (HES) is proposed. Control structure along with power sharing scheme to operate the system under various operating modes, such as: 1) grid-connected mode; 2) islanded mode; 3) state of charge of battery ( $SoC_{b}$ ) less than or greater than specified limits; and 4) operating renewable sources (PV and wind) at maximum power point, is presented. The detailed analysis, modeling, and design of the proposed configuration and control structure are presented. The key highlights of the proposed configuration are: 1) low component count; 2) voltage boosting, voltage regulation of supercapacitor and power-sharing among the battery and supercapacitor are inherent; and 3) simple control structure with a reduced number of sensors. Supercapacitor-battery-based HES is interfaced which effectively handle the power fluctuations due to the wind, PV, and sudden load disturbances. Integration of supercapacitor to respond to high-frequency fluctuations increases the lifetime of battery storage and reduces the sizing of the storage unit. The proposed system is verified through digital simulation and experimental results.

A Family of Single-Stage, Buck-Boost Inverters for Photovoltaic Applications

This paper introduces a family of single-stage buck-boost DC/AC inverters for photovoltaic (PV) applications. The high-gain feature was attained by applying a multi-winding tapped inductor, and thus, the proposed topologies can generate a grid-level AC output voltage without using additional high step-up stages. The proposed topologies had a low component count and consisted of a single magnetic device and three or four power switches. Moreover, the switches were assembled in a push-pull or half/full-bridge arrangement, which allowed using commercial low-cost driver-integrated circuits. In this paper, the operation principle and comparison of the proposed topologies are presented. The feasibility of the proposed topologies was verified by simulations and experimental tests.

Switched-LC Based High Gain Converter With Lower Component Count

A compact high step up dc–dc converter with continuous input current and lower device voltage stress is a prime requirement for renewable application. In this article, a high gain dc–dc converter is proposed, which combines the concept of switched inductor and switched capacitor along with a unique interconnection of input–output. This arrangement reduces capacitor voltage stress. The proposed converter has reduced conduction losses, reduced components count, and low voltage stress across the devices. Besides, the proposed converter has lower inductor current ripple, which is suitable for renewable integration. The operation and steady-state analysis of the converter are done in continuous current mode. For the proposed converter, voltage and current stress and the losses are calculated analytically. A comparative analysis is presented to prove the potential of the proposed converter. The dynamic analysis of the proposed converter is performed to regulate the output voltage. Finally, an experimental set up is designed to test the converter under both distinct power ratings and closed loop.

A New Single-Phase Direct Frequency Controller Having Reduced Switching Count without Zero-Crossing Detector for Induction Heating System

Induction heating (IH) is an environmentally friendly solution for heating and melting processes. The required high-frequency magnetic field is accomplished through frequency controllers. Direct frequency controllers (DFC) are preferred to dual converters as they have low conversion losses, compact size, and simple circuit arrangement due to low component count. Numerous frequency controllers with complex switching algorithms are employed in the induction heating process. They have a complicated circuit arrangement, and complex control as their switching sequences have to synchronize with source voltage that requires the zero-crossing detection of the input voltage. They also have a shoot-through problem and poor power quality. Therefore, this research proposes a novel frequency controller with a low count of six controlled switching devices without a zero-crossing detector (ZCD) having a simple control arrangement. The required switching signals are simply generated by using any pulse-width-modulated (PWM) generator. The performance of the proposed topology is verified through simulation results obtained using the MATLAB/Simulink environment and experimental setup.

A Self-Oscillating Flyback Converter with Primary Feedback Control

Due to its simplicity and low component count, a self-oscillating flyback converter is an ideal topology for cost sensitive applications, such as mobile phone chargers and auxiliary power supplies. To regulate the output voltage, the conventional self-oscillating flyback converter employs a secondary feedback current mode control scheme whose major components include a TL431 error amplifier and optocoupler. These two components nonetheless contribute significantly to a total cost of the self-oscillating flyback converter. A further cost reduction can be achieved, if the error amplifier and optocoupler can be eliminated altogether. This paper proposes a self-oscillating flyback converter with primary feedback control. In the proposed converter, the error amplifier and optocoupler are replaced by a Zener diode, and the output voltage from the auxiliary winding is used as a feedback variable, instead of the actual output voltage from the secondary winding. In the paper, the operation of the proposed converter is described. The prototype converter operating from a 220 V AC main and producing an output of 24 V/0.5 A is fabricated and tested. Experimental results are presented to verify the converter performance as well as to validate the principle of operation.

Highly Efficient Wireless Power Transfer System With Single-Switch Step-Up Resonant Inverter

In this article, a highly efficient wireless power transfer (WPT) system is realized by employing the proposed single-switch step-up resonant inverter with a series–series-compensated network. This resonant inverter has the merits of a simplified circuit structure, low component count, inherent voltage boosting, zero-voltage switching (ZVS), and high efficiency. Based on the equivalent circuit model, the two-coil WPT system is analyzed in the frequency domain, which shows that a quasi-constant current (CC) in the primary side and a corresponding quasi-constant voltage (CV) in the secondary side can theoretically be achieved. A systematic top-down design methodology of the entire WPT system is also provided, which serves as a practical design guideline. The proposed solution benefits real WPT applications by generating a clean and stable dc voltage for the built-in dc–dc battery management system of the receiving device. The experimental results show that the maximum efficiency of the WPT system at the rated output power of 11 W is around 86.4%.

Memristor-Based Edge Detection for Spike Encoded Pixels.

Memristors have many uses in machine learning and neuromorphic hardware. From memory elements in dot product engines to replicating both synapse and neuron wall behaviors, the memristor has proved a versatile component. Here we demonstrate an analog mode of operation observed in our silicon oxide memristors and apply this to the problem of edge detection. We demonstrate how a potential divider exploiting this analog behavior can prove a scalable solution to edge detection. We confirm its behavior experimentally and simulate its performance on a standard testbench. We show good performance comparable to existing memristor based work with a benchmark score of 0.465 on the BSDS500 dataset, while simultaneously maintaining a lower component count.

Zero-voltage Zero-current Transition Network for Dual Phase Interleaved Converter

In this article, a zero-voltage zero-current transition scheme suitable for a family of dual-phase interleaved converters is proposed. The transition network consists of an auxiliary transformer, a switch, and a clamp diode. This network uses a low component count structure, and yet achieves effective soft-transitions (zero-voltage turn-ON as well as zero-current turn-OFF) for the main switches. It facilitates zero-current turn-OFF of all the diodes along with zero-current turn-ON of the auxiliary switch. Additionally, the auxiliary transformer self-adjusts the current in the auxiliary network depending upon the loading conditions and thus the reactive energy during the soft-switching is low for the entire range of loads. A detailed theoretical analysis is presented by considering a high step-up dual-phase interleaved boost converter as an example. The feasibility of the proposed soft-switching scheme is implemented on the same and its effectiveness is demonstrated through experimental results which are obtained on a 400-W converter prototype.

Neutral point clamped quasi Z source inverter for photovoltaic systems

<p>Multilevel inverters are becoming popular for power conversion in renewable energy systems, AC-DC hybrid micro grids etc. The voltage stress and inrush current through these inverter leg switches are quite higher as compared to the load ratings which increase the chances of inverter leg switch failure. A three level neutral point clamped quasi Z source inverter topology is discussed in this paper which has the features of lower component count, reduced capacitor voltage stress, and it can be operated at different control strategies to achieve wide range of voltage boosting ability, suited for photovoltaic (PV) systems. It also ensures continuous input current irrespective of the DC supply voltage variations and injects stable and smooth power to the load/grid. The effectiveness of the proposed inverter is verified by simulation results in MATLAB Simulink model as well as performing experiment with the help of a laboratory prototype.</p>

Improved Transformerless Grid-Tied PV Inverter Effectively Operating at Twice the Switching Frequency With Constant CMV and Reactive Power Capability

In this article, an improved single-phase transformerless inverter is presented, which obviates the leakage current issue to a great extent. The proposed solution uses the dc-bypass (H6 type) topology with a diode clamp circuit, operated by a modified unipolar pulse-width modulation (PWM) scheme. An advantage of reduced switching losses comes with the use of the modified unipolar PWM, which produces effective double switching frequency at the inverter output. Due to the PWM strategy and diode clamp circuit, the common-mode voltage (CMV) of the inverter is constant throughout the operation. Consequently, the ground leakage current is negligible even in the presence of high parasitic capacitance of photovoltaic (PV) panels. Further, the other desirable features of the grid-tied inverters, such as reactive power injection for grid stability and low-voltage ride through (LVRT) are not compromised with the proposed scheme. A combination of high efficiency, constant CMV (and hence, negligible leakage current) and reactive power feeding capability with low component count stand the proposed system out among the existing transformerless grid-tied systems. The design and working principle of the proposed system are discussed and analyzed in detail. Simulation and experiment results are included to validate the proposed solution and its merits.

Effective low‐cost solution using cascaded connection of two modified notch filters to mitigate the second and third harmonic currents in single‐phase dual‐stage half‐bridge microinverter

On the grid side, the half-bridge topology of the microinverter is of interest for solar rooftop applications because of its high efficiency, low component count, and cost-effectiveness. However, it has an inherent double-line frequency ripple voltage on the dc-link, which causes the injection of a third-order harmonic current when the voltage control loop is closed. Furthermore, in practice, different average voltages or different capacitances of the two capacitors at the dc-link produce a second-order harmonic current that flows into the grid. In this paper, the analytical details of these harmonics are comprehensively described, and a simple and effective low-cost technique using the cascaded connection of two modified notch filters is proposed in the voltage control loop to mitigate their effects. The simulation and experimental results of a 300 W microinverter indicate that the proposed filters represent an effective low-cost solution and perform well in accordance with the IEEE 1547 standard, even if the capacitances at the dc-link are mismatched by 20%. Besides, the prototype is tested when occurring of the changing +1% of the line frequency, or appearing of the distorted waveform of grid voltage with the composition of 6% of fifth-order harmonic.

Coupled Inductor Based Boost and Hybrid Bidirectional Converter for PV Applications

Increase in the cost, world global energy consumption and use of conventional energy sources, Photo-voltaic installations are being increasingly used in distributed power generation and stand alone systems. They are Clean and green energy sources. But the output of the solar PV is very small hence high gain DC-DC converters are required and to obtain maximum power MPPT techniques are used. In this paper a high gain coupled inductor based DC-DC converter and a Hybrid bidirectional converter with low component counts are presented which is used for battery charging and discharging in the absence of solar. Simulation results obtained using MATLAB/Simulink show the performance of the converter control strategy for power flow management under various modes of operation. The effectiveness of the topology of both converters are validated through detailed experimental studies, to demonstrate the capability of the system operation in different modes.

Design and Implementation of a New Transformerless Bidirectional DC–DC Converter With Wide Conversion Ratios

A new transformerless bidirectional buck-boost converter is proposed in this paper. The proposed converter has a simple circuit structure, low component count, low voltage stress on the power transistors, and a wide voltage gain range. This makes it applicable in the energy storage charge/discharge systems, such as electric vehicles (EV), microgrids and nanogrids with energy storage units, and uninterruptible power supplies. In addition, synchronous rectification between the complementary transistors is employed to improve the converter efficiency. A comprehensive analysis of the steady-state operation, small-signal model, component parameters design, and efficiency analysis of the proposed converter operating in a continuous conduction mode is given. Finally, a 1.6-kW scaled-down prototype was built using Silicon Carbide MOSFET S to validate the effectiveness and feasibility of the proposed converter.

Novel current mode universal filter and dual-mode quadrature oscillator using VDCC and all grounded passive elements

ABSTRACTThe paper introduces a universal filter operating in current mode and a quadrature oscillator operating in current and voltage mode, employing Voltage Differencing Current Conveyor as active device along with all grounded passive elements. Apart from providing all five filter responses, i.e. low pass, high pass, band pass, band reject and all pass, the filter configuration also supports independent tunability of quality factor. The oscillator configuration can be easily realised with slight modifications in filter circuit, and features like low component count, use of grounded capacitors for supporting efficient integrated circuit implementation and availability of explicit current outputs are witnessed in both the devised networks. In the oscillator, network’s condition and frequency of oscillation can be independently tuned. For practical validation of the proposed network, PSPICE simulation software is used. The simulation results include two sets of outputs, one using CMOS (Complmentary Metal Oxide Semiconductor) implementation of Voltage Differencing Current Conveyor (VDCC) and another using off the shelf IC (Integrated Circuit) implementation of VDCC.