DC Voltage Gain Research Articles

Single switch Z source/quasi Z source DC-DC converters

<span>This paper analyzes a family of high step up single switch switched capacitor boost converters and Z-source/quasi Z-source dc-dc converters to provide high output dc voltage gain, a proper choice for photovoltaic applications. The operating principles, parameters design guideline of these converters are presented along with simulation results.</span>

Novel high voltage gain dc–dc converter with dynamic analysis

This study proposes a non-isolated dc–dc converter based on a coupled inductor and switch-capacitor–boosting techniques. The goal of the proposed topology is to increase the voltage gain with low-duty cycle, so voltage stresses are decreased across power switches and diodes. The power switches are controlled by pulse width modulation. The common ground of input and output of the proposed converter makes it suitable for many applications such as photovoltaic systems. The proposed converter topology is discussed in continuous and discontinuous operation modes. A dynamic analysis of the proposed converter is also provided. Simulation and experimental verifications are presented to prove the effectiveness of the proposed topology.

Ultrahigh Voltage Gain DC–DC Boost Converter With ZVS Switching Realization and Coupled Inductor Extendable Voltage Multiplier Cell Techniques

In this article, a novel ultrahigh voltage gain dc–dc boost converter with expandable diode-capacitor voltage multiplier (VM) cells is presented. The diode-capacitor VM cells and coupled inductors are employed in the presented topology to provide a higher voltage gain. Also, the main and the auxiliary power switches of the presented converter operate with zero voltage switching. The coupled inductors' leakage inductances control the rates of the current drop in the voltage multiplier diodes, which decreases their reverse recovery losses markedly. Moreover, the voltage stresses on all capacitors and semiconductors are reduced significantly. In this converter, the number of voltage multiplier cells, and the coupled inductors turn ratios provide three degrees of design freedom. These degrees of freedom are used to set the desired voltage stresses of the semiconductors within the desired range and to provide a high voltage gain at optimum duty cycles. The design and theoretical analysis of the presented converter are discussed. Finally, the performance of the presented converter is validated using a 500 W, 40 V/380 V laboratory prototype converter, and the experimental results confirm the theoretical calculation.

Voltage gain improvement of the operational transconductance amplifier designed with silicon-on-insulator fin field effect transistor after being exposed to proton-irradiation

In this work, the influence of proton-irradiation in the voltage gain of two-stage operational transconductance amplifier (OTA) designed with silicon-on-insulator (SOI) fin field effect transistors (FinFETs) is studied. The OTA simulations were performed using Verilog-A approach based on experimental data extracted from the SOI FinFET electrical characterization, before and after proton-irradiation. The OTA is designed with SOI FinFETs of fin widths (W fin) of 20 nm, 120 nm, and 870 nm, all in the same predefined inversion region (g m/I D = 8 V−1). All evaluated OTA circuits exposed to proton-irradiation presented a voltage gain increase (compared with pre-irradiation circuits), of 0.87 dB, 1.19 dB, and 6.16 dB for fin widths of 20 nm, 120 nm, and 870 nm, respectively. The results show that despite the typical radiation effect of degradation of the individual transistors (it being more severe for larger fin width SOI FinFET), these effects combined in OTA circuits result in an unexpected improvement in DC voltage gain, especially for wider fins. Focusing on the fin width impact on the OTA voltage gain, before and after proton-irradiation, it is much greater for narrow fin width SOI FinFET thanks to the better Early voltage.

Non-Isolated n-Stage High Step-up DC-DC Converter for Low Voltage DC Source Integration

The dc-dc converters with high step-up DC-voltage gain play a vital role in integrating low voltage DC sources. Though several converter topologies are reported in the recent past, attempts have been made to reduce the components, especially the switching devices, passive elements, converter losses, etc., of the converter. A novel DC-DC converter topology, viz., single switched impedance network (SSIN)-based converter with n-stage is proposed in this paper. The operation of the SSIN based converter in continuous and discontinuous conduction modes are discussed. The effect of parasitic elements on DC-voltage gain and efficiency of the SSIN is carried out. The small-signal model of the SSIN converter is derived. The performance of the SSIN converter is compared with the similar converter topologies. The 500 W prototypes of the SSIN with n = 1 and n = 2 are fabricated, and the experimental results are presented in this paper. To improve the converter performance, SiC-based semiconductor devices are used. The SSIN converter with two-stage has low switch loss at 500 W load, improved efficiency during high power and high output voltage operation, the switch stress of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> /2, etc.

Improved Power Quality Transformerless Single-Stage Bridgeless Converter Based Charger for Light Electric Vehicles

In this article, a bridgeless switched inductor Cuk (BSIC) converter based charger is presented to provide the low-cost and reduced-size charging solution for the light electric vehicles, i.e., LEVs, with enhanced performances at the supply side. Generally, the chargers of LEVs such as E-Rickshaws, E-Bike, and E-Cycle, are equipped with an additional converter to charge the batteries at low voltages (24–72 V). The switched inductor configuration improves the step-down dc voltage gain of the charger with only one stage and also improves the reliability at such low voltages. It is noteworthy that the cost associated with the sensors along with the size of the magnetic components is considerably reduced by operating the charger in discontinuous current mode condition. Moreover, the high-gain transformerless configuration further improves the cost, size, and efficiency of the charger. The effectiveness of the charger is tested on a laboratory prototype, for an 850 W rating with 220 V, 50 Hz nominal supply voltage conditions. The steady state and dynamic behaviors of the charger are analyzed under different operating conditions. Moreover, the behaviors of the charger during the initialization of charging process are analyzed for ensuring the soft starting of the charger. A basic comparison of the presented charger configuration with existing LEVs chargers is presented to highlight its advantages over the existing one.

A New High Voltage Gain DC to DC Converter with Low Voltage Stress for Energy Storage System Application

Increasing energy demand globally has led to exploring ways of utilizing renewable resources for sustainable development. More recently, the integration of renewable distributed resources in small- and large-scale grid has been seriously researched. Development in renewable power sources and its integration with the grid require voltage level conversion to match the grid/micro-grid level. The voltage level conversion is brought about by employing Direct Current-Direct Current (DC-DC) converters with boosting features. The paper presents a wide gain range DC-DC boost converter with a low-stress on switching devices. The proposed converter’s voltage gain is high compared with the conventional quadratic boost converter and other recently developed high gain boost converters. The topology has been compared with recently proposed topologies, and comparative analysis based on various performance parameters has shown that the topology is suitable for renewable and sustainable energy storage and grid integration. The power loss analysis has been done by incorporating the switching and conduction losses. A hardware prototype of 150 W has been developed to validate the converter’s performance in steady-state as well as in dynamic conditions.

Bidirectional DC–DC Converter with Coupled Inductor Fordc-Bus Regulation in Microgrid Applications

&#x0D; This paper presents a theoretical analysis and the experimental results of the bidirectional coupled inductor dc-dc converter for dc-bus voltage regulation and power compensation in dc-microgrid applications. In dc-microgrids, a power distribution system requires a bidirectional converter to control the power flow between dc-bus and batteries. Furthermore, the dc-bus needs to be kept stabilized within certain limits and the converter handles a large range of voltage variation in the accumulators. The proposed topology is also relatively feasible for low-input-voltage applications for interfacing energy storage elements, such as batteries, ultracapacitors with the high voltage dc-bus in electric vehicles. The converter allows greater voltage gain compared to classic non-isolated topologies and can better deal with the wide range of voltage variation imposed by the source/load. The operation principles, the DC voltage gain, the design of the filters, the voltage/current stresses and a comparison are discussed. The experimental results confirmed and validated the theoretical study as well as the converter performance so that the measurements performed obtained from a 600 W laboratory prototype.&#x0D;

Sliding mode controller-based switched-capacitor-based high DC gain and low voltage stress DC-DC boost converter for photovoltaic applications

High-gain DC-DC power boost converters blocks have been converted to the main transitional topologies for the PV applications to enhance the level of the generated voltages of these panels for grid applications. The single-switched and transformer-less converters due to their higher efficiency, and cheaper and light-weighted features are the first selection for these converters design. This study presents a transformer-less DC-DC power boost converter with a switched-capacitor structure with a sliding mode controller (SMC) to increase the DC voltage gain and decrease the voltage stress on the power switch. This advantage is doing based on the preamplifier block by using an extra inductor at the input side. Also, the switched-capacitor block easily decreases the voltage stresses on the main power switch and other diodes. Presenting high voltages under the small duty cycles is one of the most important features of the proposed converter that allows longer off-time duration for power switch for Continuous Current Mode (CCM) operations. This leads to lower amounts of the dynamic losses for the power switch and higher efficiency. On the other hand, the control process of the proposed converter under the different input voltages and output powers and loads due to using only one power switch is simpler compared with multi-switched topologies. All calculations for obtaining the gain, currents follow through the components, voltage ripples through the capacitors, and efficiency is presented. The hardware prototype with 300 W power is tested and the results confirm the theoretical calculations.

Robust output voltage control of a high gain DC–DC converter under applied load and input voltage uncertainties

In this study, using robust and adaptive approaches, two controllers are designed to compensate for the applied load and input voltage uncertainties of a high voltage gain dc–dc converter. These controllers are designed based on measuring only the output voltage of the converter. The permissible ranges of the uncertainties are calculated using dynamics equations analysis while practical limitations are considered. In the first approach, an input multiplicative uncertainty is considered for the model of the converter by linearisation of non-linear equations as well as using permissible ranges of the uncertainty. Then, a robust H∞ controller is designed. In the second approach, the converter model is considered as a first-order dynamics model with the unknown parameters and an unknown additive term while a direct robust model reference adaptive controller is designed for it. Finally, the non-linear equations of the converter are simulated and the performances of the controllers are compared with each other. The control methods are then implemented on a 200 W prototype of a converter for evaluating the simulations results.

Wide Input Voltage Range Operation of the Series Resonant DC-DC Converter with Bridgeless Boost Rectifier

The series resonant DC-DC converter (SRC) can regulate the input voltage in a wide range at a fixed switching frequency. In this work, the bridgeless rectifier, which is utilized intensively in the applications of the power factor correction, has been integrated into the SRC as a voltage step-up cell at the output-side of the SRC. It is shown that the conventional overlapping pulse-width modulation (PWM) of the two metal oxide semiconductor field-effect transistors MOSFETs in this rectification cell limits the input voltage regulation range of the converter due to excessive power losses in abnormal operating conditions. The abnormal operating conditions occur when the instantaneous voltage across the resonant capacitor is larger than the secondary voltage of the isolation transformer. This happens at high values of the DC voltage gain, i.e., low input voltages and high currents, which causes the resonant current to flow in the reverse direction in the same half-cycle through a parasitic path formed by overlapping PWM of the rectifier MOSFETs. The abnormal operation results in additional conduction loss in the converter as the MOSFETs of the bridgeless boost rectifier turn on at high current at the beginning of each half of the switching period. Accordingly, the overall efficiency of the converter significantly deteriorates. This paper proposes the hybrid PWM aiming to improve the efficiency of the SRC with a bridgeless boost rectifier in a wide input voltage regulation range. The converter swaps between the overlapping and the proposed short-pulse PWM schemes to drive the MOSFETs in the bridgeless boost rectifier. The transition between the two PWM schemes is defined according to the boundary condition that relies upon the operating point of the converter power and the input voltage. The proposed hybrid PWM scheme is analyzed and compared to the overlapping PWM at different levels of the input voltage and the load power. A 300 W prototype was studied in the laboratory to show the feasibility of the proposed hybrid PWM scheme with the closed-loop control system to switch between the two PWM schemes.

Improved Hybrid Switched Inductor/Switched Capacitor DC–DC Converters

High voltage gain dc–dc converters are widely used in various applications like low-voltage sustainable sources. In traditional boost converters, the voltage gain is limited by high voltage stress, high current ripple, and low efficiency due to employing a high duty cycle ratio. In this article, we propose converters that are a combination of four substructures, namely active switched inductor, passive switched inductor, switched capacitor cell, as well as an auxiliary switch with nonisolated configuration. The proposed structures have high voltage gain compared to the conventional either switched inductor-based or switched capacitor-based ones in addition to a low duty cycle ratio. By adding an auxiliary switch, the efficiency is improved, particularly for high voltage gains. The principle of operation and steady-state analysis are discussed in detail. Also, simulation results from PSCAD/EMTDC software are validated by a prototype built for experimental examination. The results demonstrated that the voltage gain and efficiency could be improved by utilizing the auxiliary switch.

A High Voltage Gain DC–DC Converter With Common Grounding for Fuel Cell Vehicle

The essential features of a DC–DC converter for fuel cell vehicle are to ensure the higher voltage gain to meet out the higher DC link voltage demand, continuous input current to improve the life span of the fuel cell, presence of common grounding to avoid electromagnetic interference issue and lower voltage stress with reduced components. This paper presents a high voltage gain DC–DC converter by combining the switched capacitor and quasi switched boost network modules. The proposed high voltage gain converter provides the continuous input current, lower voltage stress, utilizes a fewer number of elements and common grounding feature. The operating characteristics, steady-state analysis both in continuous current mode (CCM) and discontinuous current mode (DCM), comparative analysis with contemporary converters are discussed. The theoretical claimed analysis is validated by the simulation and experimental study. The proposed converter is operated for 200 W output power rating and tested for providing the voltage gain in the range of 5–8 times the input voltage gain by varying the input voltage from 25 V–40 V. The efficiency of the proposed converter is also reported for different output power rating which is in the range 91.3%–93.7%.

Step-Up Series Resonant DC–DC Converter with Bidirectional-Switch-Based Boost Rectifier for Wide Input Voltage Range Photovoltaic Applications

This paper proposes a high gain DC–DC converter based on the series resonant converter (SRC) for photovoltaic (PV) applications. This study considers low power applications, where the resonant inductance is usually relatively small to reduce the cost of the converter realization, which results in low-quality factor values. On the other hand, these SRCs can be controlled at a fixed switching frequency. The proposed topology utilizes a bidirectional switch (AC switch) to regulate the input voltage in a wide range. This study shows that the existing topology with a bidirectional switch has a limited input voltage regulation range. To avoid this issue, the resonant tank is rearranged in the proposed converter to the resonance capacitor before the bidirectional switch. By this rearrangement, the dependence of the DC voltage gain on the duty cycle is changed, so the proposed converter requires a smaller duty cycle than that of the existing counterpart at the same gain. Theoretical analysis shows that the input voltage regulation range is extended to the region of high DC voltage gain values at the maximum input current. Contrary to the existing counterpart, the proposed converter can be realized with a wide range of the resonant inductance values without compromising the input voltage regulation range. Nevertheless, the proposed converter maintains advantages of the SRC, such as zero voltage switching (ZVS) turn-on of the primary-side semiconductor switches. In addition, the output-side diodes are turned off at zero current. The proposed converter is analyzed and compared with the existing counterpart theoretically and experimentally. A 300 W experimental prototype is used to validate the theoretical analysis of the proposed converter. The peak efficiency of the converter is 96.5%.

An Overview of High-Conversion High-Voltage DC–DC Converters for Electrified Aviation Power Distribution System

This article presents the state-of-the-art review of high-conversion high-voltage (HCHV) dc-dc converters for a modern aerial vehicle's power distribution system. Higher dc bus voltages have become a trend in recent aerial vehicle development because of the potential reduction in size and weight of the rest of the power system and an increase in power density. Some front-end dc energy sources, such as fuel cells, batteries, and supercapacitors, may level at a low voltage and require HCHV dc-dc converters to integrate with the high-voltage dc bus. On the other hand, high-conversion step-down converters are required between the dc bus and various low-voltage electronic loads. A detailed review of HCHV dc-dc converters for an aviation power distribution system is limited in the literature. This article presents two main architectures of such converters. Architecture-I employs individual two-port dc-dc converters to link each source to the dc bus, and Architecture-II uses a single multiport converter (MPC) to connect all the sources to the dc bus. Architecture-I categorizes the two-port dc-dc converter topologies into unidirectional and bidirectional converters, followed by further classifications based on isolation and control schemes. Multiport dc-dc converters for Architecture-II are categorized based on port numbers and then source connection methods. This review investigates multiple topologies within each category or classification, highlighting selected circuit diagrams and their features and shortcomings. This article presents several insightful comparisons, among various bidirectional converters for Architecture-I, and MPCs for Architecture-II, for a designer to choose a proper converter. In terms of converter characteristics, this article focuses on dc voltage gain, power density, efficiency, and reliability, as these qualities are of utmost importance in an aviation application.

Homogeneous 2D MoTe2 CMOS Inverters and p-n Junctions Formed by Laser-Irradiation-Induced p-Type Doping.

Among all typical transition-metal dichalcogenides (TMDs), the bandgap of α-MoTe2 is smallest and is close to that of conventional 3D Si. The properties of α-MoTe2 make it a favorable candidate for future electronic devices. Even though there are a few reports regarding fabrication of complementary metal-oxide-semiconductor (CMOS) inverters or p-n junction by controlling the charge-carrier polarity of TMDs, the fabrication process is complicated. Here, a straightforward selective doping technique is demonstrated to fabricate a 2D p-n junction diode and CMOS inverter on a single α-MoTe2 nanoflake. The n-doped channel of a single α-MoTe2 nanoflake is selectively converted to a p-doped region via laser-irradiation-induced MoOx doping. The homogeneous 2D MoTe2 CMOS inverter has a high DC voltage gain of 28, desirable noise margin (NMH = 0.52 VDD , NML = 0.40 VDD ), and an AC gain of 4 at 10 kHz. The results show that the doping technique by laser scan can be potentially used for future larger-scale MoTe2 CMOS circuits.

Ultra-Low-Voltage Inverter-Based Amplifier with Novel Common-Mode Stabilization Loop

This work presents a single-stage, inverter-based, pseudo-differential amplifier that can work with ultra-low supply voltages. A novel common-mode stabilization loop allows proper differential operations, without impacting over the output differential performance. Electrical simulations show the effectiveness of this amplifier for supply voltages in the range of 0.3–0.5 V. In particular, a dc voltage gain of 25.16 dB, a gain-bandwidth product of 131.9 kHz with a capacitive load of 10 pF, and a static current consumption of only 557 nA are estimated at VDD = 0.5 V. Moreover, the circuit behavior with respect to process and temperature variations was verified. Finally, the proposed amplifier is employed in a switched-capacitor integrator and in a sample-and-hold circuit to prove its functionality in case-study applications.

Soft switching high step-down series-capacitor based converter with coupled-inductor technique

High voltage step-down converters are very popular in distributed power systems, voltage regular modules, automatic vehicles, etc. To avoid extreme duty cycles, a series capacitor-based buck converter with a coupled inductor is proposed in this paper. In this converter, the voltage stresses of the power switches are clamped to half of the input voltage. Thus, low voltage rating MOSFETs with a low Rds,on could be utilized to improve the performance of the proposed converter. Moreover, synchronous MOSFETs are also used to reduce the conduction losses of the switches. Zero voltage switching (ZVS) for the main power switches is achieved using the coupled-inductor technique. In addition, through adding a bypass flowing path, a negative current is established to guarantee the ZVS condition of the power switches. The operating principle of the proposed converter is described in this paper, and the DC voltage gain ratio, automatic current sharing, soft switching condition and design guideline of the critical parameters are also given. Finally, experimental results obtained from a 60 V/200 W prototype are presented to verify the analysis of the proposed converter.

Atomic layer deposited 2D MoS2 atomic crystals: from material to circuit

Atomic layer deposition (ALD) can be used for wafer-scale synthesis of 2D materials. In this paper, a novel, reliable, secure, low-cost, and high-efficiency process for the fabrication of MoS2 is introduced and investigated. The resulting 2D materials show high carrier-mobility as well as excellent electrical uniformity. Using molybdenum pentachloride (MoCl5) and hexamethyldisilathiane (HMDST) as ALD precursors, thickness-controlled MoS2 films are uniformly deposited on a 50 mm sapphire and a 100 mm silica substrate. This is done with a high growth-rate (up to 0.90 A/cycle). Large-scale top-gated FET arrays are fabricated using the films, with a room-temperature mobility of 0.56 cm2/(V·s) and a high on/off current ratio of 106. Excellent electrical uniformity is observed in the whole sapphire wafer. Additionally, logical circuits, including inverters, NAND, AND, NOR, and OR gates, are realized successfully with a high-k HfO2 dielectric layer. Our inverters exhibit a fast response frequency of 50 Hz and a DC-voltage gain of 4 at VDD = 4 V. These results indicate that the new method has the potential to synthesize high quality MoS2 films on a large-scale, with hypo-toxicity and enhanced efficiency, which can facilitate a broader range of applications in the future.

Push–pull based operational transconductor amplifier topologies for ultra low voltage supplies

This work presents an Operation Transconductance Amplifier with improved common mode rejection based in both Nauta’s and Vieru’s push–pull based OTAs operating at a 0.5 V power supply in the 180 nm CMOS process, with an additional biasing circuit that employs an adaptive body bias technique for calibration of output common mode voltage. Equal size CMOS push–pull pair inverter cells comprised by rectangular and trapezoidal transistor arrays are simulated and compared, showing that trapezoidal arrays designs have a higher DC voltage gain while rectangular arrays are more tolerant to process variability. Two new adaptive body bias circuits for CMOS circuits are proposed, which are used to minimize the inverter cells PVT variability and at the same time control the push–pull based OTAs common mode output voltage and transconductance. A schematic-level simulation of a hybrid Nauta–Vieru OTA prototype was run and achieved as result a differential voltage gain of 58 dB, a CMRR of 108 dB, a total power consumption of 375 nW, unity gain-bandwidth product of 100 kHz for a capacitive load of 10 pF, and a total area of 13,650 $$\upmu \hbox {m}^2$$ . The same OTA was fabricated and its DC transfer functions were measured, showing a maximum 52 dB voltage gain, 73 dB CMRR and $$11~\upmu \hbox {V/A}$$ transconductance at a 0.5 V voltage supply.