Duty Ratio Of Switch Research Articles

Switching Frequency Improvement of a High Speed on/off Valve Based on Pre-excitation Control Algorithm

The high-speed on/off valve (HSV) serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems. As the switching frequency of the HSV increases, the properties of the generated discrete fluid approach those of continuous fluids. Therefore, a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems. However, the current research mainly focuses on its dynamic performance, but neglect its FRC. This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time. The maximum switching frequency (MSF) is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio (SDR), whereas the closing dynamic performance limits the MSF when HSV operates with high SDR. Building upon these findings, the pre-excitation control algorithm (PECA) is proposed to reduce the switching time of the HSV, and consequently enhance its FRC. Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms, the closing delay time by 2.54 ms, and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms. As a result, a larger MSF of 417 Hz and a wider controllable SDR range from 20% to 70% were achieved at a switching frequency of 250 Hz. Thus, the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.

High-performance Cuk converter with turn-on switching at zero voltage and zero current

The soft-switching technique has the potential to significantly enhance the performance of the power converter. This is primarily because it allows for an increase in the switching frequency, which ultimately leads to improved modulation quality. This raises extra concerns, particularly in high-power applications, because in a standard hard-switching converter structure, components can often not function at frequencies higher than a few hundred hertz. This paper presents a high-efficiency soft switching CUK converter.When the main and auxiliary switches are turned on and off at zero voltage, the proposed converter yields zero voltage and zero current. The suggested method is ideal for a DC-DC converter based on IGBTs or MOSFETs. The recommended systems are described using theoretical analysis, the results of computer simulations, and experimental data derived from a prototype. The design parameters of the inductance and capacitor circuit for edge-resonant soft switching were obtained using the output power and the switching duty ratio. In the end, soft-switching is better than hard-switching in terms of efficiency, particularly when operating under full load.

Nondifferential AC Choppers Based Identical Bipolar Buck–Boost AC–AC Converter Without Commutation Issue

This article proposes a new H-bridge structured bipolar pulsewidth modulation (PWM) buck–boost ac–ac converter based on the nondifferential ac choppers. The proposed converter can generate simple identical noninverting and inverting buck–boost voltage outputs by modulating one phase leg with single control duty ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${d}_1$</tex-math></inline-formula> or <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${d}_2$</tex-math></inline-formula> ). It can also provide flexible identical noninverting and inverting buck–boost operations by modulating both phase legs with two control duty ratios ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${d}_1$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${d}_2$</tex-math></inline-formula> ). In the proposed topology, the use of nondifferential ac choppers eliminates the complementary switching of ac switches and related inductor open-circuit issue. Moreover, half the switching devices are configured as switching-cell units to avoid shoot-through occurrence due to accidental turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> of complementary switches. Therefore, the proposed topology is free from commutation issue and can abolish PWM deadtimes to produce high-quality output with improved utilization of switch duty ratios. It also provides continuous input current and can perform normally with reactive loads. It has the potential to mitigate both voltage sags and swells (due to bipolar operation) when used as series voltage compensator; and unlike the existing nondifferential bipolar ac–ac converters, it can provide compensation for more intense voltage sags (of above 50%) as well. In-depth analysis of the proposed topology and hardware verifications are provided in this article.

Two-Switch Boost Converter With Improved Voltage Gain and Degree of Freedom of Control

The use of renewable resources for low power generation has led to extensive research on power converters for reliable and efficient power conversion. Though conventional boost converter (CBC) remains the widely used topology, its operating range is limited due to constraints on voltage gain and degree of freedom of control (DoFoC). This paper presents a two-switch boost converter (TSBC) which improves the voltage gain and DoFoC by cascading an additional switch-diode pair to the CBC circuit. The additional switch enhances the range of voltage gain without operating CBC at high duty ratios. Additionally, TSBC offers more choices to adjust voltage gain, which enhances DoFoC. The switching interval selection is detailed considering the voltage gain and constraints on circuit variables. The design formulations of TSBC are examined to facilitate optimal choice of components. The features of TSBC are theoretically established with mathematical derivations and are validated by simulations and experiments. The experimental results indicate that for a duty ratio of 0.7 for the existing switch of CBC, an increase in voltage gain from 3.2 to 4.3 is achieved when the duty ratio of the additional switch in TSBC is varied from 0 to 0.1. Similarly, improved DoFoC is demonstrated with inductor current control as well as with constant ripple ratios while maintaining the required output voltage. The proposed converter can easily replace the commonly CBC to improve the gain and DoFoC by simply cascading a switch-diode pair at the input-side of CBC.

Drain-Source Voltage-Controllable Three-Switch Active-Clamp Forward Converter for Wide Input/Output Voltage Applications.

Active-clamp forward converters are applied to various medium-capacity power systems because they have a relatively simple structure and are capable of zero-voltage switching. In particular, there is the advantage that a stable output voltage can be obtained by controlling the duty ratio of the power semiconductor switch even in applications with wide input and output voltage ranges. However, the voltage stress on the power semiconductor switches due to the application of active clamp is higher than the input voltage, especially as the duty ratio increases. A three-switch active-clamp forward converter is proposed, which can overcome such shortcomings and can reduce the voltage stress of the power semiconductor switches, but it causes an increase in the DC bias of the magnetizing current and the additional conduction and switching losses. Therefore, in this paper, a voltage-stress-controllable three-switch active-clamp forward converter that can utilize both advantages of the conventional active-clamp forward converter and three-switch active clamp forward converter is proposed and verified through a prototype for 800 W battery charger.

An Enhanced Modified Multiport Interleaved Flyback Converter for Photovoltaic-Shunt Active Power Filter (PV-SHAPF) Applications

This paper presents a newly designed modified multiport interleaved flyback converter (MMPIFC) to transfer the photovoltaic (PV) power to the DC bus of the parallel-connected multilevel inverter-based shunt active power filter (SHAPF). The proposed modified multiport interleaved flyback converter (MMPIFC) is designed to interconnect N number of input power sources into the DC bus of the SHAPF to fix the problems with the partial shadow and improve the SHAPF’s ability to compensate. Compared to the commonly used interleaved flyback converter (IFC), the proposed MMPIFC has a larger boost factor toward the DC voltage input. The flow of power between the different power sources and SHAPF is controlled by varying the duty ratio of the main switches. The working principles of the proposed MMPIFC-operated PV-SHAPF are explored in this paper, and essential design concerns are highlighted. A prototype model with 1 kVA, 400 V, and 50 HZ is built and tested under various conditions to validate the theoretical analysis, design, and control method.

Integrated Quadruple Output Synchronous Buck Converter for E-Mobility Application

A nonisolated integrated multiple output synchronous buck converter is proposed in this article to cater the auxiliary power supply requirements of e-mobility. The converter provides independently controlled multiple outputs with reduced switch count as compared to conventional separate buck converters as well as conventional synchronous buck converter. The operating principle and working of the proposed converter are discussed in detail for better understanding. As the dynamic behavior of the converter is similar to the conventional buck converter, a simple controller is designed and implemented in this work. The converter is simulated in MATLAB-Simulink. A laboratory prototype of single input–quadruple output (SIQO) converter is developed and operated under closed loop condition to validate and demonstrate its advantages. The prototype is developed by designing two inductors on a single core for increased compactness and reduced cost of the converter. Each output of the converter can be independently controlled by varying the duty ratio of the related switch, thereby eliminating the effective cross regulation problem. The efficiency of the proposed SIQO converter is 93.6%, with four output ports, which is higher than its category of converters reported earlier. A significant improvement in the calculated efficiency is observed with the replacement of conventional switches and diodes of the converter by SiC switches (96.1%).

Modulated Model Predictive Control With Branch and Band Scheme for Unbalanced Load Compensation by MMCC-STATCOM

This article presents a novel modulated model-predictive control (MMPC) scheme for modular multilevel cascaded converter-based static synchronous compensator (STATCOMs) (MMCC-STATCOMs) to compensate unbalanced load current and regulate reactive power flow. By adding a common-mode voltage (CMV) to the phase-voltages of the star-connected MMCC current model, the method allows natural injection of a nonsinusoidal voltage to the neutral point of the converter, hence achieving interphase cluster voltage balance. Moreover, the imposed CMV is shown to extend the operating ranges of MMCC-STATCOMs when used for negative sequence current compensation. The proposed MMPC method incorporates a modified branch and bound algorithm to optimize the per-phase switch duty ratios. It is shown to be computationally more efficient compared to model-predictive control schemes using the optimal voltage level method combined with voltage sorting schemes. Experimental results with different weighting factors confirm the effectiveness of this control scheme and compared favorably with the conventional scheme of injecting only a sinusoidal zero-sequence voltage.

A modular isolated battery‐integrated multiport step‐up DC–DC converter for hybrid energy applications

In this paper, a modular isolated battery-integrated multiport step-up dc–dc converter is designed for simultaneous energy transfer from multiple renewable energy sources (RESs) to a load. The proposed converter offers a plug-and-play capability of input sources where each input can be connected to and disconnected from the converter. The power generation shortage/surplus can be managed by a battery inserted into a bidirectional port. Also, charging/discharging durations of battery are independent of switching duty ratios for input sources. In the presented converter, inputs are connected in parallel with a common ground through individual step-up dc–dc cells while outputs are connected in series with voltage doubler rectifiers (VDRs) to achieve higher voltage gains and lower voltage stress on output capacitors. Moreover, the leakage inductances of the isolated transformers with dc blocking capacitors provide quasi-resonant operation to alleviate high turn-off currents of switches and hard-switching in VDR diodes. Due to interactions of converter control loops, a MIMO closed-loop control system is designed to regulate the output voltage and output power of input sources at references. The simulation and experimental results obtained for three inputs verify performance of the developed converter in different modes.

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.

A Single-Stage Isolated AC–DC Converter Based on the Impedance Control Network Architecture

This article introduces a new single-stage universal-input isolated ac-dc converter based on the impedance control network (ICN) architecture. This resonant converter performs both power factor correction and output voltage regulation while operating at a constant switching frequency and duty ratio, by modulating the phase-shift between its two half-bridge inverters and the phase-shift between the two legs of its full-bridge rectifier. This phase-shift control strategy along with the ICN architecture also enables the converter to achieve high efficiency by ensuring zero-voltage-switching and near-zero-current-switching of all its inverter transistors throughout the line cycle and across wide ranges of input line voltage and output power. Power density is enhanced by realizing the three ICN inductors using a single magnetic structure with two coupled windings. This coupled inductor and a transformer constitute the two magnetic components of the proposed converter. A systematic methodology to design this ICN ac-dc converter is also introduced. A universal-input (90-265 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> ), 20-V output, 330-W, 400-kHz ICN ac-dc converter prototype is built and tested. This prototype achieves a power density of 37.9 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and peak efficiencies of 91.7%, 92.2%, 93.2%, and 93.4% at 90, 120, 230, and 265 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> input, respectively.

Efficiency Boost of a Quasi-Z-Source Inverter: A Novel Shoot-Through Injection Method with Dead-Time

A quasi-Z-source inverter (qZSI) is a single-stage inverter that enables a boost of the input dc voltage through the utilization of a so-called shoot-through state (STS). Generally, the efficiency of the qZSI depends on the utilized STS injection method to a significant extent. This paper presents a novel method of STS injection, called the zero-sync method, in which the STS occurrence is synchronized with the beginning of the zero switching states (ZSSs) of the three-phase sinusoidal pulse width modulation (SPWM). In this way, compared to the conventional STS injection method, the total number of switchings per transistor is reduced. The ZSSs are detected by utilizing the SPWM pulses and the logic OR gates. The desired duration of the STS is implemented by utilizing the LM555CN timer. The laboratory setup of the three-phase qZSI in the stand-alone operation mode was built to compare the proposed zero-sync method with the conventional STS injection method. The comparison was carried out for different values of the switching frequency, input voltage, duty ratio, and load power. As a result of the implementation of the zero-sync method, the qZSI efficiency was increased by up to 4%. In addition, the unintended STSs, caused by the non-ideal switching dynamics of the involved transistors, were successfully eliminated by introducing the optimal dead-time as part of the modified zero-sync method. As a result, the efficiency was increased by up to 12% with regard to the conventional method.

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.

Study on Regenerative Energy Recovery of Electric Vehicle Through Voltage Control Using Switched Capacitor

When an electric vehicle (EV) is driving at a very low or high speed, there are cases where energy recovery is not possible because the back electromotive force generated in the motor is too small or large. In this paper, we investigate the application of the regenerative electromagnetic retarder's energy recovery method to the permanent magnet synchronous motor (PMSM) of an EV. When the EV was driven downhill or coasts, L-C resonance via switched capacitor was used to control the voltage generated by the PMSM as a voltage that can recharge the battery. During regeneration, the voltage generated in the PMSM varied along with the degree of resonance through switching the duty of the proposed circuit. Through simulation, DC-Link voltage according to switching duty ratio and motor speed is plotted in a 3D map. Based on this, voltage control algorithm using PI and reverse PI duty control has been proposed. To prove the proposed algorithm, the DC-link stage of the inverter is simply equivalent to the R-C model. And, if the PMSM operates at a constant speed, the generated voltage is controlled so as to charge the battery. In addition, the discharging and charging energies of the battery are simulated when the EV with certain load torque is driving uphill and downhill. Considering the dynamics of the car, the energy recovery rate was simulated when the EV is driving uphill and downhill in a 50:50 ratio at the same slope and distance. The simulations were conducted using MATLAB Simulink, and the experiments were carried out using a motor-generator set and a small electric truck equipped with a 13 kW PMSM, respectively.

Real-time performance evaluation of two-quadrant z-source DC-DC converter for DC drive

This paper contributes to real-time performance evaluation of two-quadrant z-source DC-DC converter drive for industrial application. Regulating the switching duty ratio of the converter produces the desired output voltage level. Z-source DC-DC converter has additional qualities over a traditional buck-boost converter such as higher boost factor at low switching duty ratio, more reliable, inherent short circuit protection and impedance network that behaves as a second-order filter. Z-source converter-fed separately excited DC-drive model is developed in MATLAB/Simulink and executed in field programmable gate array (FPGA)-based real-time digital simulator (RTDS) at fixed-time step of 10 μs and the constant switching frequency is 5 KHz. The real-time simulation results present the real-time performance of the z-source converter-fed DC-drive system during motoring and regenerative braking mode. Small signal analysis is done using state space averaging approach to design a suitable controller for closed-loop drive system. A laboratory-based low voltage hardware prototype of z-source DC-DC converter system is developed utilising a real-time digital simulator (OP5600) as a rapid control prototype.

철도역사용 LED 유도등에 적용되는 플라이백 컨버터 역률개선에 관한 연구

In this paper, a simple method to improve the power factor of the conventional LED exit light with a flyback converter was proposed. Conventional flyback converters are applied to LED exit lights, which are constant loads, and 4.8[V] batteries are connected in parallel at the output stage. Therefore, by adding a passive filter between the rectifier circuit part and the primary side of the transformer, it is possible to minimize the change of the conventional circuit and improve the power factor. As a result of changing the duty ratio of the flyback main switching device from 25% to 56%, the power factor showed a high result from 95.5% to 98.3%.

A ZVS-ZCS quadratic boost converter to utilize the energy of PV irrigation system for electric vehicle charging application

Finding diverse applications of installed PV based power generating unit is necessary for optimal utilization of energy produced by these units over a period of time. This paper proposes a high gain boost converter that can be used as a DC source for electric vehicle charging application in existing PV based solar pump set-up. The proposed DC-DC converter uses two-stage boosting to achieve a high voltage gain in the form of quadratic quadrupled boost factor. Low turns ratio in coupled inductor reduces the loss components of magnetic part largely. Another advantage of the proposed converter is its operation at lower duty ratio (~0.5) to achieve the desired voltage gain for photovoltaic application. Further, leakage inductance is effectively utilized to achieve ZCS of solid-state devices in conjunction with magnetizing inductance, which provides ZVS for the efficient operation of converter. To analyze the performance of proposed converter for electric vehicle charging application, simulations were carried out using PSIM/MATLAB software and results were validated using experiments conducted on a 250 W hardware prototype developed in the laboratory. A boost factor of 7.8 is achieved at a turn’s ratio of 1.9 for ~35% duty ratio of main switch. The maximum efficiency of ~93% is measured for designed converter.

Estimation of the switching losses in DC-DC boost converters by various machine learning methods

DC-DC converter circuits are topologies commonly used in power electronics applications such as renewable energy sources, electric vehicles, uninterruptible power supplies and DC transmission systems. The most important factors affecting efficiency and thus performance is the choice of the power semiconductor switching element as well as the circuit design and types of these topologies. In this context, power semiconductors are determined according to the switching frequency and current-voltage parameters. However, due to other operating modes of the circuit and load variation during the power conversion, the losses of the switching elements do not remain constant. In this study, a parametric simulation is performed in a conventional DC-DC boost converter circuit using the parameters related to the Insulated-Gate Bipolar Transistor (IGBT) power-switching element selected at a certain current-voltage capacity. These parameters are switching frequency, duty ratio and load change of the converter. Finally, using the data obtained, the loss of switching losses are estimated by the Multilayer Perceptron (MLP), Support Vector Machine (SVM), K- Nearest Neighbors (KNN) and Random Forest (RF) Machine Learning (ML) techniques.

A Novel Topology for Bidirectional Converter with High Buck Boost Gain

In non-isolated bidirectional DC-DC converters (NIBIDC), voltage output of buck/boost mode is incongruous at lower and higher end due to the existing gain. In this paper, a novel NIBIDC is designed in such a way that it enhances the gain in both buck and boost mode of operation. The proposed NIBIDC is employed with four power switches (MOSFET) with an anti-parallel diode embodied, four inductors and three capacitors used as passive elements. The current flow in parallel connected inductor improves the circuit competence. Voltage gain of NIBIDC in buck operation is lower than conventional cascaded bidirectional buck/boost converter (CCBBC) whereas the voltage gain is higher than CCBBC in boost mode. The switching stress is same while the efficiency of NIBIDC is more than CCBBC. The topology structure of the NIBIDC is simple and easy to control. The performance analysis under steady-state condition of the novel converter is carried out and a detailed comparison with CCBBC is done in connection to switching stress, converter efficiency and duty ratios to output power, etc. The operation details for proposed NIBIDC in both mode is verified/validated by experimenting with 20[Formula: see text]V input for different duty ratios in charging and discharging state of a battery and the results infer to be identical with theoretical analysis.

Single-Inductor Multiple-Output Inverter With Precise and Independent Output Voltage Regulation

In this article, a single-inductor multiple-output (SIMO) inverter with precise and independent output voltage regulation is presented. This SIMO inverter with controllable output voltage enables each individual transmitting coil in a multicoil wireless power transfer system to be driven by a tightly regulated constant-voltage source. This is especially useful for the wireless charging of rechargeable batteries when they act as a constant-current (CC) load in the CC charging phase. By precisely regulating the source voltage at each transmitting coil, a constant load current at the corresponding receiver can be achieved at a particular resonant frequency and mutual inductance between the transmitting and receiving coil. The closed-form expressions of the sinusoidal-like output voltage and resonant inductor current as a function of the duty ratio of the main switch are also analytically derived. An experimental prototype of a single-inductor three-output inverter with a single time-multiplexed analog-based controller employing the type II compensation is implemented. It is experimentally verified that the individual ac outputs can be accurately and independently controlled. The maximum error between the target and measured peak voltage values is shown to be within 1.14%.