Multiple-output Converter Research Articles

Solar powered high gain DC-DC converter with FPGA controller for portable devices

A solar-powered converter design is necessary for portable devices with increased gain and reduced ripple in overall operation. This research presents a photovoltaic-powered Field Programmable Gate Array (FPGA) based on increased gain multiple output converter design and analysis. The dynamic panel input makes it difficult to operate the load. To control and make the input static to satisfy the demand, perturb and observe with a load balancing algorithm technique are used. The converter gained output is high, and batteries are used to balance the loads when solar irradiance is low. Simulation results were carried out with the presented converter circuit that can be operated with a 12 V supply as input from a renewable power source. The output gain ratio of 14 to a minimum of 40 % duty cycle operating at a switching frequency of 20 kHz has been achieved. The proposed methodology is transferred to hardware by connecting with the reconfigurable FPGA Spartan-6 development board to manage the dynamic load control system's complex logic and high processing ability. The overall performance is compared with various pre-existing systems, tabulations are made with the analysis, and experimental results are also illustrated at the end.

Grid Strength Impedance Metric: An Alternative to SCR for Evaluating System Strength in Converter Dominated Systems

Short circuit ratio is an outdated measure of system strength in converter dominated systems as the useful behaviour of inverter-based resources is not represented. While still useful for determining fault current provision, converter connected generation contributes to short circuit level and system strength in a different way to traditional synchronous generation. Additionally, traditional measures only account for system strength at the fundamental frequency while converters possess complex interactions across a frequency range. A novel method of determining system strength across this frequency range from the network impedances is proposed in this paper. The approach known as the Grid Strength Impedance Metric, calculates the system strength independently from short circuit level. The unique contribution of grid-following and grid-forming converters is represented by including the multiple-input multiple-output converter output impedances in the calculation. Small-signal impedance models are employed, and the metric is largely concerned with short-term voltage stability, but some inferences can be made for longer timescales. The approach is validated using time domain simulations to check for any identified areas of weakness in the frequency range. The Grid Strength Impedance Metric successfully represents the useful behaviour of grid-forming converters, indicating an enhancement in voltage stiffness in locations of deployment.

Design and analysis of multiple input single output converter for hybrid renewable energy system with energy storage capability

This paper proposes the design and analysis of a multiple-input-single-output (MISO) DC-DC converter suitable for a hybrid renewable energy system with energy storage capability. The converter design and control strategy validated in this research can be used to regulate the output dc voltage obtained from multiple-source renewable energy systems. The design is realized using a non-isolated double boost converter as it can handle bidirectional power flow at the storage port and has other advantages like compact structure, reduced number of components, and double boosting capability. The converter can also work without transformers, enabling the input renewable energy sources to operate individually. An inverted decoupler control strategy is adopted in the design of this novel converter. Mathematical models were developed to obtain the decoupler matrix, and the proposed control strategy is utilized to analyze the output. Simulations were performed on MISO converters with load and reference variations and is validated with the prototype. The current ripple percentage at the dual source side is found to be reduced by 2.6%. Also, the rise time, settling time, and percent overshoot of the output voltage were reduced by 0.03 s, 45 ms, and 3.6%, respectively. The performance of the proposed MISO converter is validated on a 50 W hardware prototype. The results validate the MISO converter's superior dynamic performance, output voltage regulation and reduced dual source ripple current, all of which are in agreement to the results of the simulation. A comprehensive comparison with the traditional controller is also conducted to further illustrate the advantages of the proposed inverted decoupler. The inverted decoupler validated in this work can be effectively used in hybrid renewable energy systems with energy storage capability, as it is found to be immune to the disturbances from the source end.

Single-Inductor Multiple-Input–Multiple-Output Converter for CubeSats Electric Power System

State-of-the-art CubeSat electric power system (EPS) architectures employ multiple dc-dc converters to regulate the load voltage and maximize the solar energy harvest. However, this leads to the use of multiple bulky inductors in the CubeSat EPS which is much constrained by strict volume and weight restrictions. With the aim of achieving smaller EPS footprint, this paper presents a new single-inductor based multiple-input multiple-output (MIMO) converter for CubeSat EPS. The operational principles of the proposed converter and its steady-state analysis are discussed, and converter modeling is performed. A control strategy is developed to achieve voltage regulation of the CubeSat loads and maximum power point tracking (MPPT) for the PV panels under a wide-range of irradiation conditions. An experimental prototype based on the 1U CubeSat specifications is developed to validate the performance of the proposed MIMO converter.

Single-Inductor, Multiple-Input, Multiple-Output, DC-DC Converter Based on a New Software Zero-Current Switching (ZCS) Technique

A single-inductor multiple-input multiple-output converter is proposed in this paper that can be used in low-power systems due to low output current and voltage. This converter is implemented discretely, and only one microcontroller is employed to control the system. The unique zero-current switching (ZCS) technique considered in this paper is such that only by reading the inductor’s left-side voltage the optimal value of the inductor discharge duty cycle is determined. This method can be generalized to low-power and high-power converters, whether implemented and designed as discrete or integrated. This converter works in discontinuous conduction mode. It uses pulse width modulation control and the time-multiplexing control method, which makes the system have high efficiency and makes the cross-regulation problem between the converter’s outputs tiny. The control algorithm considered in this converter is digital, which determines the optimal charge and discharge duty cycles. Also, the switching frequency of this converter is constant, relatively low, and equal to 5[Formula: see text]kHz. The efficiency of this converter has reached 91.6% by using the ZCS technique and other mentioned control methods.

MISO CONVERTER BASED CONTROL OF SOLAR PV SYSTEM

The solar photovoltaic (PV) system penetrates the global renewable energy source due to the direct energy conversion process and environmentally friendly nature. The irradiance mismatch undergoes major difficulties in the PV converters, and this algorithm has been performed under Maximum Power Point Tracking (MPPT). To solve MPPT problems, conventional soft computing methods are frequently employed. In this study, Multiple Input Single Output (MISO) converters are used to compare the Perturbation & Observation and Artificial Neural Network methods. The converter is set up as a single-inductor buck converter with numerous input ports connected to two PV panels. The output voltage and current from the solar cell are sent into the buck converter. In order to attain maximum power for various irradiances, the reference voltage and current are sent to the MPPT controller, and the duty cycle created is supplied to the MISO buck converter. The proposed system is established in MATLAB/ Simulink to evaluate the effectiveness of the system.

Analysis and Implementation of Switched Capacitor-based Multi-Level Inverter for Electric Vehicles Applications

Significant interest has been shown in switched capacitor (SC)-based multi-level inverters (MLIs), which decrease the need for a DC supply and enhance power quality. The common issues with SC-MLIs include an uneven distribution of conducting paths, increased voltage drop across capacitors, the sum of all inverter DC link voltages across the highest voltage rated switches, and a higher total standing voltage (TSV). The purpose of this paper is to create a SC-MLI with less components in order to maintain a constant voltage across the capacitors, to obtain higher voltage gain with fewer parts, fewer conducting routes, lower TSV, and to create a more affordable and effective inverter. The structure of the MLI is created by a cascade interconnection between the number of SC cells. A single input multiple output (SIMO) converter boosts the DC-link voltage over the stable DC voltage of the solar panels using a modified perturb and observe (P&O) method. Additionally, fewer switches in the conduction path and 50 % of the switches operating at normal frequency guarantee a decrease in an overall loss of power in the proposed network. The benefits of the recommended MLI are made clear by comparing them with 17-level MLIs in terms of the number of elements, stress, gain, and cost factor. Detailed experimental results are shown under various transient conditions to show that the 17-level prototype is operationally viable. The total harmonic distortion (THD) is found to be identical and is less than 5 %, which meets IEEE standards.

Systematic Synthesis of Multiple-Input and Multiple-Output DC–DC Converters for Nonisolated Applications

Multiple-input converters (MICs) and multiple-output converters (MOCs) are attractive solutions for interfacing various voltage levels. In order to reveal the intrinsic relationships among the diverse topologies and provide as many viable topologies as possible for practical applications, this article aims to analyze the topology construction principles and propose a systematic approach to derive MICs and MOCs. To begin with, the general principle of the topology derivation is analyzed according to circuit network theory. Inspired by the idea of design controllable inductor power-flow loops (IPFLs), five construction types are proposed to create multiple power-flow network (MPN) in MICs and MOCs. Then, four basic switching cells for the topology synthesis are proposed and a flow diagram for the optimal design procedure is provided to guide the topology derivation. As one example, a family of viable and optimized MICs and MOCs with various characteristics is derived from typical Buck converter. Based on the analysis of the derived converters in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), the number of magnetic components is not increased at all so that they are promising candidates for applications requiring compact size and high integration. Besides, topology comparison and selection among a family of MICs is also conducted in view of practical specifications. Finally, one derived dual-input converter is analyzed in detail and experimentally verified to demonstrate the theoretical results.

A Novel High-Efficiency Multiple Output Single Input Step-Up Converter with Integration of Luo Network for Electric Vehicle Applications

Concerns about pollution, climate change, limited fossil fuel supplies, and the desire to eliminate energy dependency have sparked a surge in interest in electric vehicles (EVs). EV requirements have resulted in a variety of difficulties and remedies in EV technology. One of them is the use of DC-DC converters to transfer the level of voltage from the battery in an EV to other needed voltage levels. An independent converter for each operating voltage might be used as a remedy. On the other hand, single input multiple output (SIMO) converters can be utilized to decrease costs, reduce switching loss, and thus enhance the system efficiency. In this paper, a nonisolated step-up converter with the integration of the Luo network is proposed for multiple outputs (24 V and 48 V). In electric vehicles, 48 V is utilized for battery backup, while 24 V is utilized for the horns, headlights, telematics, or the microcontroller. The experimental observations of a 36 V, 600 mA, 24 W prototype confirm the theoretic examination and demonstrate the advantages of the proposed converter over other multioutput converters. The STM microcontroller, based on an ARM cortex microprocessor, is linked into the Luo network for making pulses. The proposed converter achieves 94.2% efficiency at full power. The proposed converter’s performance is evaluated through MATLAB/SIMULINK software, and the results are validated experimentally.

Compensated Single Input Multiple Output Flyback Converter

A new single-input multiple-output (SIMO) converter is proposed in this work by incorporating flyback and buck converters in a master–slave configuration. The objective of this work is to address the cross regulation problem, achieve tight voltage regulation, improve the circuit form factor and attain a fast transient response for a SIMO flyback converter. The flyback converter maintains the output channels within 10% of their rated voltages and the SIMO buck converter is placed in series with the flyback converter such that it compensates for the output voltage deviation. Moreover, a time multiplexing switching scheme decouples output channel to eliminate the cross-regulation problem and remove the need for an additional winding transformer per each output channel. A type II compensator with a peak current mode controller was designed to achieve faster transient response which is critical for the proposed configuration. A thorough steady-state analysis was carried out on a triple output channel topology to obtain the design criteria and component values. MATLAB/Simscape modelling and simulation was used to validate the effectiveness of the proposed converter with the result yielding satisfactory transience even with load disturbance. Additionally, the result of the proposed converter is compared with previously published works.

Topology Derivation of Multiple-Port DC–DC Converters Based on Voltage-Type Ports

Multiple-port dc–dc converters are characterized by a variety of kinds and a large number of circuit topologies. In this article, we aim to reveal the intrinsic relationship among the topologies of multiple-port dc–dc converters and propose the topology derivation method. First, the voltage- and current-type ports are summarized from basic dc–dc converters, and the approach of converting current-type ports into voltage-type ports is discussed. Then, according to Kirchhoff's law, four types of multiple-input multiple-output converters named input-port-series output-port-series, input-port-series output-port-parallel, input-port-parallel output-port-series, and input-port-parallel output-port-parallel are presented. Second, the topology derivation method of multiple-port bidirectional dc–dc converters based on the voltage-type ports is studied in terms of power flow paths in various operation modes, and then the topology optimization method is proposed. Particularly, a flow diagram for the optimal design procedure is given to guide the topology derivation for some specific requirements. Based on the proposed approach, a family of multiple-port dc–dc converters can be derived, which provides lots of viable candidates for practical engineering. Furthermore, one derived converter named the parallel-type three-port bidirectional buck converter is analyzed in three operation modes to demonstrate the topology derivation. Finally, the effectiveness of the above theoretical analysis is verified by those experimental results.

Design and Implementation of Single-Input Multiple-Output DC–DC Buck Converter for Electric Vehicles

The transportation sector uses a big portion of the world’s petroleum products thus increasing the greenhouse gas (GHG) emissions. Electric vehicles (EVs) have the potential to solve GHG emissions. The requirements for EVs have brought many different problems such as the conversion of voltage level from the battery to other parts of the EV using DC–DC converters. The design and implementation of a nonisolated DC–DC buck converter with single input and dual output are presented, which is also called the single-input multiple-output (SIMO) converter. The converter is designed especially for electric cars. The battery (48[Formula: see text]V) of the electric vehicle is used as an input to the SIMO. Small-signal analysis and effective control strategy for the converter are presented in this paper. The simulation of the system is performed and compared with the experimental results.

Single-Inductor Multiple-Input Multiple-Output Converter With Common Ground, High Scalability, and No Cross-Regulation

Single-inductor multiple-input multiple-output (SIMIMO) dc-dc converters can integrate different input sources and supply power to multiple output loads with fewer components. This article proposed a current-source-mode (CSM) SIMIMO dc-dc converter. By virtue of the constant inductor current, the proposed CSM SIMIMO dc-dc converter can avoid cross-regulation naturally and allow the use of much simpler control strategy. The proposed configuration has the advantage of all inputs and outputs sharing a common ground and ease of expansion. Moreover, the number of the main circuit components is reduced. A CSM single-inductor dual-input dual-output (SIDIDO) dc-dc converter is constructed for illustration. The two input sources can work independently in the event of the two input sources being disconnected. A detailed comparison of the different SIDIDO dc-dc converters is provided.

Design and implementation of multiple output forward converter with Mag-amp and LDO as post regulators for space application

Linear power supplies are commonly used power supplies for many applications. They have some drawbacks such as low efficiency, difficulty in thermal management and also in regulation of the output voltage. Some of these drawbacks can be overcome by Switch Mode Power Supplies (SMPS). One of the best-suited applications of SMPS is for space applications that require power supplies which are lighter, smaller, more efficient and highly reliable. Multiple-output DC-DC converters are an important topology of SMPS that can be used for space applications. But, in multiple output converters usually, only the master output is regulated and the other outputs are left unregulated and this can result in cross-regulation. In this paper, post regulators such as Magnetic amplifiers (Mag-amp) and Low DropOut regulator (LDO) are proposed to regulate each output and also to improve load regulation. In addition to this, the input voltage feed-forward control technique is proposed to control the duty cycle of the switch, which is dynamically faster and provides better line regulation when compared to the voltage feedback controller. Besides, over current protection circuit for the converter is discussed in detail.
 Keywords: Cross regulation effect, Mag-amp and LDO, multiple output forward converter, output over current protection, voltage feed forward control.

Research on Single-Input Multiple-Output Converter for Rotorcraft Unmanned Aerial Vehicle

To satisfy the different voltage requirements of different power units in small rotorcraft unmanned aerial vehicle (UAV), we investigated two different single-input and multiple-output converters, three-output flyback converter and single inductor three-output Buck converter. The hardware components and operating principles of the two single-input and multiple-output converters were analyzed, and the control strategies of them were designed. Furthermore, operations of the two single-input multiple-output converters were simulated using Simulink in Matlab. We found that the three-output flyback converter can be used in the design of UAV when its components are settled and the voltage quality requirements are not strict. When the expansibility of component and high-stable voltage are required for the design of UAV, the single inductor three-output Buck converter should be used.

Control Strategy to Generate PWM Signals with Stability Analysis for Dual Input Power Converter System

The prime role of a renewable resource based DC hybrid power system is, to maintain the output voltage constant with higher efficiency. In order to achieve this the duty cycles of the converter switches are dynamically controlled. Multiple input single output (MISO) converter uses separate controller for adjusting the duty cycle, this complicates the design and implementation of the system. Hence, to overcome this limitation a centralized controller is used. The control strategy depends on the pattern of gating signals given to the converter switches. When independent controller is employed, then gating signals of any pattern can be used to drive the switches. However, if a single controller is used, and then a definite pattern is very much essential otherwise, the output voltage and efficiency gets affected. In this paper, an attempt is made to validate and evaluate the performance parameters of MISO converter with two pattern of gating signals; they are synchronized and unsynchronized pulses at their rising edge. The control strategy focusses on the generation of these gating pulses. PID controller is tuned appropriately to determine the gains to achieve the stability of the proposed converter. The dual input power converter validated to show how the PWM pattern affects the efficiency, ripple and regulation of the converter. Using MATLAB SIMULINK platform the simulation of the proposed concept with dual input converter in closed loop is validated. Simulation results proves that synchronized pulses gives DC efficiency of 87% at designed output of 12V output. Converter with unsynchronized PWM pulses operates at lesser efficiency of 75% and the output voltage is of 10V.

Control Strategy to Generate PWM Signals with Stability Analysis for Dual Input Power Converter System

The prime role of a renewable resource based DC hybrid power system is, to maintain the output voltage constant with higher efficiency. In order to achieve this the duty cycles of the converter switches are dynamically controlled. Multiple input single output (MISO) converter uses separate controller for adjusting the duty cycle, this complicates the design and implementation of the system. Hence, to overcome this limitation a centralized controller is used. The control strategy depends on the pattern of gating signals given to the converter switches. When independent controller is employed, then gating signals of any pattern can be used to drive the switches. However, if a single controller is used, and then a definite pattern is very much essential otherwise, the output voltage and efficiency gets affected. In this paper, an attempt is made to validate and evaluate the performance parameters of MISO converter with two pattern of gating signals; they are synchronized and unsynchronized pulses at their rising edge. The control strategy focusses on the generation of these gating pulses. PID controller is tuned appropriately to determine the gains to achieve the stability of the proposed converter. The dual input power converter validated to show how the PWM pattern affects the efficiency, ripple and regulation of the converter. Using MATLAB SIMULINK platform the simulation of the proposed concept with dual input converter in closed loop is validated. Simulation results proves that synchronized pulses gives DC efficiency of 87% at designed output of 12V output. Converter with unsynchronized PWM pulses operates at lesser efficiency of 75% and the output voltage is of 10V.

Series-Connected Current-Source-Mode Multiple-Output Converters With High Step-Down Ratio and Simple Control

In this paper, a two-stage transformerless multiple-output converter is proposed for applications requiring a high voltage step-down ratio. The proposed circuit transfers power via a current interface and the use of current-source-mode (CSM) converters, resulting in low voltage stress and drastically simplified control. The first stage of this configuration is regulated to provide a constant current to the second stage. The second stage consists of series-connected CSM boost converters. The high step-down ratio of the proposed configuration reduces the voltage stress in the switches of the second stage. The series-connected CSM converters are inherently independent of each other, leading to a very simple control scheme without the need for decoupling of the input voltage of the interconnected converters. Input voltage variation to the system will not affect the input voltage of the second stage. Load variation in one output will not affect the other outputs. If one or more CSM converters are shorted, there is no impact on other converters. These advantages enable a high scalability. Besides, the first stage of the proposed configuration can operate both in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) with the same control strategy. This feature leads to a low control complexity and elimination of inductors. The performance of the proposed converter is illustrated with a laboratory prototype driving light emitting diodes (LEDs).

Multiple-Output DC-DC Converters with a Reduced Number of Active and Passive Components

Multiple-output converters have been widely used where individual outputs are required. Compared with conventional separate converters, the advantage of multiple outputs is to have a lower number of active and passive components. In this paper, first, a pulse-width-modulation (PWM)-pulse-frequency-modulation (PFM) method is used for two-output converters that have only one coil and one active switch. Secondly, three-output converter topologies are proposed where the third output is controlled by phase delay (PD). These converters need only two coils and two active switches to regulate three outputs. How to obtain PD at different switching frequencies is discussed next, and a PWM-PFM-PD controlled five-output buck converter is presented. The proposed solution uses only two active switches and two magnetic cores to adjust five-output voltages independently. A modeling and digital control method are proposed in order to regulate the five output voltages. A prototype circuit with independent 15 V/1.5 A, 12 V/1.5 A, 5 V/0.8 A, −5 V/0.6 A and 3.3 V/0.45 A outputs is assembled to validate the analysis, and it was proved that it regulates the output voltages at different loads.

Individually Regulated Multiple-Output WPT System With a Single PWM and Single Transformer

This paper proposes a new individually regulated multiple-output wireless-power-transfer (WPT) system using single pulsewidth modulation (PWM) and a single multi-output transformer. The proposed system mainly consists of a single primary transmission channel, bandpass filters (BPFs) corresponding to each output, and a digital controller unit. The digital controller generates a single PWM signal comprising an array of distinct frequency components reserved for each output of the multi-output converter. The primary transmission channel includes a high-frequency inverter circuit and a primary transmission coil. When the inverter circuit is driven by the PWM signal, all the underlying frequency components are transmitted through the inverter circuit and the primary transmission coil. Each of these frequency components is separated at the receiver side coil by the resonant BPF connected to each of the outputs. Because the central frequencies of each BPF differ from each other, each filter allows only signals that are within their frequency band. Each output voltage of the multiple-output converter is regulated by modulating the frequency and amplitude of the frequency components corresponding to each output (or the BPF) inside the digital controller. Compared with all the other resonant topologies, the series-series resonance topology is efficient and facilitates applications involving loosely coupled WPT. However, the Q-factor of the series-series resonance topology is relatively low compared with the remaining resonance topologies. The interaction between each of the outputs increases as the Q-factor of the BPF decreases, which results in load regulation failure. The proposed multiple-output WPT system uses an efficient AM-FM hybrid control technique to regulate all the outputs independent of each other. Moreover, in order to analyze and design the proposed converter controller, an accurate and simple multiple-output wireless transformer model is proposed. The transformer model and analysis of the equivalent circuit presented in this paper simplify the conventional design of the power stage and generate a small converter signal. The technical challenges, feasibility, and the advantages of the proposed converter concept are discussed. Finally, the performance of the proposed multiple resonance-based wireless converter system has been validated using a 100-W hardware test of an independently controlled four-output resonant converter system.