Asymmetrical Duty Cycle Control Research Articles

Multioutput Wireless Charger for Drone Swarms With Reduced Switch Requirements and Independent Regulation Capability

This paper develops a cost-effective and efficient wireless charger with multiple outputs based on newly proposed H3 bridge inverter, which has the benefits of reduced switch requirements and independent regulation capability. The output power of each channel is regulated by asymmetric duty cycle control. With the help of auxiliary LC branch, soft switching is ensured in spite of load variations. The sequential logic of driver signals is analyzed in detail to explore the independent regulation characteristic. For arbitrary 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> (or 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> +1) outputs, the total number of required switches is only 3 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> (or 3 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> +2) and the voltage stress of switches is the input voltage, which can reduce switch requirements. Simulation and experimental results are in good agreement with each other, proving the proposed wireless charger as a feasible solution for drone swarms.

Fault Current Control of Three-Phase Dual Active Bridge DC–DC Converter Employing Modified Asymmetrical Duty Cycle Control Modulation

Fault Current Control of Three-Phase Dual Active Bridge DC–DC Converter Employing Modified Asymmetrical Duty Cycle Control Modulation

An Independently Controlled Two Output Half Bridge Resonant LED Driver

In this research work, an independently controlled two output half-bridge resonant LED driver is proposed. Half bridge series converters will be providing power to two LED lamps. The devices in half-bridge converter are switched at zero voltage using LC resonant circuit. Therefore, switching transition power losses are minimized which increases the LED driver efficiency. Each LED lamp’s ripple current is decreased by adding an inductor in series with it, eliminating the need for an electrolytic capacitor and extending the life of the resonant LED driver. Both regulating and dimming operations use asymmetrical duty cycle (ADC) control. Numerical simulations are conducted to examine the suggested resonant converter topology’s steady state performance as it sources LED applications. Using the OrCAD/PSPICE tool for universal AC mains, 25 W and 29 W LED driver analysis, design, modeling, and simulation are carried out. The proposed driver needs to provide high efficiency even at reduced illumination.

Dual Output and Dual-Frequency Resonant Inverter-based Induction Heating Using ADC Control

A dual output dual-frequency (DODF) resonant converter-based AC-AC induction heating (IH) by using asymmetrical duty cycle (ADC) control is presented in this paper. The proposed scheme gives two outputs with independent power control, which improves input power factor and achieves zero voltage switching (ZVS) with a wide range of operations. It includes two pairs of two half-bridge series resonant converters, each pair having one common capacitor along with various resonant frequencies. These converters are modulated with the ADC control scheme to obtain smooth operation. The proposed topology doesn’t use the DC stage; it is directly connected to the power supply to produce high-frequency AC output. With the use of direct connection, the converter components are reduced when compared to conventional converters. There will be a reduction in voltage drop, power losses, cost of the converter and which will result in improved efficiency. Simulation results are obtained from PSIM 11.1.7 software. This scheme controls two different loads with an efficiency of 98.25%.

Backflow Power Optimization of DAB Based on Asymmetric Duty Cycle and Internal Phase Shift Control

Dual active bridge (DAB) converter with single-phase-shifting (SPS) control would produce large backflow power when voltage regulation ratio deviates from 1 or under light load, an asymmetric duty cycle and internal phase shift (ADIPS) control was proposed which controls the transmission power by duty cycle and internal phase-shift ratio and the backflow power can be eliminated under light load therefore improves the efficiency of DAB converter. By establishing mathematical models of inductor current and transmission power, the working principle of the proposed control method was given as well as the cause of backflow power was analyzed. The constraints of zero backflow power and an optimization control method of zero backflow power under ADIPS control was presented. At last, an experimental prototype is used to obtain the validation results, simulation and experimental results verify the excellent performance of the proposed control strategy in eliminating the backflow power of DAB converter under light load.

A Three Switch Resonant Inverter for Multiple Load Induction Heating Applications

Induction heating (IH) is a trending technology in the domestic applications due to its advantages related to high efficiency, better control, and fast heating. Present research focuses on developing cost-effective and highly efficient solutions. In this article, a three-switch inverter (3SI) for multiple load IH applications is proposed, which meets previous requirements. Reduced component count and high efficiency are the key benefits of the proposed inverter. Asymmetric duty cycle control is used to obtain independent control over two loads simultaneously. The operation of the proposed 3SI has been verified by rigorous simulations in Orcad PSpice software and by experimenting with designed hardware prototype. The simulation and experimental results are in good agreement with each other, proving the proposed 3SI as a feasible solution for multiple load IH applications.

Investigation on Performance of Various Power Control Strategies with Bifilar Coil for Induction Surface Melting Application

In recent years, induction heating applications assisted by electronic power control have been very appealing. For melting applications, induction heating is widely used as it seems to be appropriate and provides higher efficiency, zero pollutants, non-contamination of material, etc. in comparison with conventional heating. The conventional variable frequency control scheme is not sufficient for melting applications because of its high switching loss, low efficiency, and lower heat rate. A superlative control technique is required to control the output power smoothly, for a high heating rate with minimum power loss, and to lower the number of components. In this paper, a capacitorless self-resonating bifilar coil is proposed for induction surface melting applications. The performance of the system in terms of modular losses, heat rate, and efficiency is analyzed for various power methods such as pulse duty cycle control, phase shift control, pulse density modulation control, and asymmetric duty cycle control. An experimental validation is performed for the 1 kW prototype, and the heating rate, efficiency, and modular losses are calculated. The control technique is digitally validated using a PIC16F877A microcontroller with 30 kHz switching frequency. The temperature distribution is analyzed using a FLIR thermal imager. Among the tested methods, pulse density modulation-based control provides smooth and varied power control from 0% to 100% with minimum modular losses. The efficiency of the system is 89% at a rated output power and is greater than 85% for pulse density modulation control with a fast heating rate.

Independently Controllable Dual-Output Half-Bridge Series Resonant Converter for LED Driver Application

This article presents a dual-output series resonant converter (SRC)-based light-emitting diode (LED) driver, which utilizes three switches to form two half-bridge networks. The proposed three-switch two-half-bridge structure provides reduced switch count and independent control. It uses asymmetric duty cycle control to regulate the LED operating currents and utilizes a low-frequency pulsewidth modulation (PWM) dimming scheme for each half-bridge to control the illumination of each LED load independently. All the switches in the proposed converter operate with zero-voltage turn-on to reduce the switching losses. The operating principle and detailed analysis of the proposed converter is presented and verified with experimental studies for a total load of 50 W (i.e., LED load-1 26 W and LED load-2 24 W). Also, a comprehensive comparative study of the proposed LED driver with recent counterparts is presented.

Photovoltaic Cell Energy Transfer System Using Series-Connected Bidirectional Resonant Converters

This paper presents an energy transfer system for a photovoltaic module with solar-powered panels, batteries, and a grid-tie inverter that uses series-connected bidirectional resonant converters. The purpose of this study is to investigate the asymmetrical duty cycle control and frequency control techniques for increasing and controlling the input voltage of the grid-tie inverter. Prior to the experiment, the performance of the bidirectional resonant converters was evaluated using a simulation program. By adjusting the asymmetrical duty cycle by 50%, the input voltage of the grid inverter was found to be 48.2 V. However, by adjusting the asymmetrical duty cycle by 10%, the input voltage of the grid inverter was 150.4 V. Furthermore, when turning on the switch in the zero-voltage switching (ZVS) mode, the converter circuit was controlled and operated within an appropriate frequency range. The results revealed no switching losses when the converters were turned on. As a result, the bidirectional resonant converters were able to properly transfer energy and regulate the input voltage of the grid inverter.

Three-Phase Three-Level Isolated DC-DC Soft Switching Converter For Solar Applications

Three-level isolated DC-DC converter is an attractive topology in high input voltage applications, which can provide the voltage stress of the power devices to only a half of the dc voltage and also reduce the size of dc filter requirement. But major limitations in the existing three level ZVS converter topologies are brought out with an increased inductance in the primary side and it required to provide complete ZVS of all primary devices down to light loads. By employing an external inductance in the primary of the transformer, total leakage inductance of the transformer increases which is required for realization of soft switching of the converter switches but there are some disadvantages of connecting external inductance in the primary of the transformer. To overcome all these drawbacks, the three-phase three-level isolated DC-DC soft switching converter has been proposed in order to reduce voltage and current stresses. This converter topology requires less number of control switches and operates with an asymmetrical duty cycle control. The proposed three level DC-DC converters provide two- level voltage waveform before dc output filter, which significantly reduce the size of dc output filter. The proposed work has been implemented using MATLAB/SIMULINK and the performance of the proposed converter is verified through simulation results.&#x0D;

Closed-Form Asymmetrical Duty-Cycle Control to Extend the Soft-Switching Range of Three-Phase Dual-Active-Bridge Converters

The three-phase dual-active-bridge (DAB) converter is a promising topology for high-power dc–dc conversion in dc grids and industrial applications. However, the conventional single-phase-shift modulation shows a limited soft-switching range and large reactive currents under light-load operation especially with large voltage variations. This article proposes an asymmetrical duty-cycle control method for the three-phase DAB to extend the soft-switching range and reduce reactive currents by realizing three-phase triangular- and trapezoidal-current-mode operation. Closed-form solutions of the proposed modulation schemes are derived that enable a simple online calculation of the control parameters. The proposed modulation schemes can substantially reduce losses of both power semiconductor devices and the medium-frequency transformer. Thus, the three-phase DAB converter can realize high efficiency over a wide operation range, especially under light-load conditions. Considering the practical implementation, a compensation method is presented to correct the distorted current waveforms caused by the dead time and ensure the desired soft-switching operation. Besides, the power loss imbalance between top and bottom switches induced by the asymmetrical duty cycle is addressed by an active thermal balancing strategy. The effectiveness of the proposed method is validated by simulation results and experiments on a downscaled converter prototype.

Cascaded full‐bridge resonant inverter configuration for different material vessel induction cooking

This paper presents a cascaded full-bridge resonant inverter configuration for different material vessel induction cooking. The proposed inverter configuration features simultaneous heating of three different material vessels, and independent power control. In this proposed work, three different induction heating loads are simultaneously operated at their respective resonant frequencies. Vessels of iron, steel, and aluminium materials are used. The output powers are independently controlled by an asymmetric duty cycle control. The proposed inverter is designed and hardware prototype has been implemented. Experimental results are validated with simulation results.

Output Voltage Control of the SP topology IPT system based on Primary side Controller operating at ZVS

This paper presents a technique to control the output voltage of a series-parallel (SP) topology inductive power transfer (IPT) system using only a controller, located on the primary side. This reduces the cost, size, complexity and loss of the system compared to conventional IPT dual-side controllers. An asymmetrical duty cycle control (ADC) of full-bridge inverters was used to control the DC output voltage to its designed value. Additionally, a zero voltage switching (ZVS) operation can be obtained at all power levels by varying the switching frequency of the inverter. Theoretical analysis was performed through a mutual inductance coupling model and verified by computer simulation. Experimental results of the circular magnetic structure IPT system with an adjustable air-gap confirm the validity of the proposed controller. The system efficiency was improved throughout the operation and the improvement became obvious as the output power was decreased.

Three-Phase Three-Level Soft Switching Dc-Dc Converter for Industrial Applications

In high power DC applications, the single-phase DC-DC converter will face large voltage and current stress in each control switch and thereby the power handling capacity is less. To overcome this problem, three-phase DC-DC converter is used and it is suitable for high power applications with reduced number of switches as compared with the conventional topologies. The asymmetrical duty cycle control is considered to operate the switches under soft switching and hence the switching losses are reduced. The transformer leakage inductances are used along with junction capacitances in order to form resonance and hence ZVS commutation is possible in a wider load range. The modified phase shift control method is used for the proposed converter.The operational modes and design equations of the proposed converter have been observed. The simulation is carried out with a load of 1000W for validating the proposed work.

High‐efficiency duty‐cycle controlled full‐bridge converter for ultracapacitor chargers

This study proposes a high-efficiency duty-cycle controlled full-bridge dc–dc converter for ultracapacitor chargers. By the asymmetric duty-cycle control, the proposed converter achieves zero-voltage switching of power switches without circulating currents. It reduces the output current ripple by the current-doubler rectifier. A control strategy is suggested for charging ultracapacitors. A constant current and constant voltage charging is performed. The proposed converter achieves a higher efficiency compared with the conventional phase-shift controlled full-bridge converter. The performance of the proposed converter is evaluated by experimental results for a 30 F ultracapacitor bank.

Asymmetrical Duty-Cycle and Phase-Shift Control of a Novel Multiport CLL Resonant Converter

In this paper, a novel multiport CLL resonant converter with a phase shift and asymmetrical duty-cycle control is analyzed. The power flow can be maintained with the phase shift between ports, whereas the asymmetric duty cycle manages the output voltage at the load terminals. Series connected transformers at the secondary side enable to split the power in each port and reduce the voltage stresses on the switches compared with the parallel connected transformers. Even under the unbalanced input conditions, the power flow between ports can be managed by the central control without any need for communication devices. In order to investigate the power distribution in each port, two different isolated dc sources and a variable load are used. The converter operation is tested at 40, 80, or 120 V inputs, with the output of 200 V at a full power of 1 kW with a maximum efficiency of 97.4%. The experimental results show that the multiport CLL resonant converter with the proposed controller is an appropriate topology for sustainable energy platforms, which are supplied by different types of energy sources, such as photovoltaic, fuel cell, wind, and so on, at various power capacities.

Three‐leg inverter configuration for simultaneous dual‐frequency induction hardening with independent control

Parts of certain objects need hardening. Hardening is a heat treatment process which can be achieved by induction heating. Certain objects like gears require alternating source with two different frequencies. Simultaneous application of dual frequencies is desirable for proper hardening of a gear. This study proposes a three-leg inverter topology with a load resonant circuit which can provide independent and simultaneous control of low-frequency (LF) and high-frequency (HF) currents through the load coil. The load circuit is a combination of two series resonant circuits which operates at the desired LF and HF. Power control is achieved with phase modulation and asymmetric duty cycle control techniques. A 240 W prototype of the proposed dual-frequency inverter is implemented and tested. Experimental results obtained are in good agreement with the simulation results.

Dual frequency inverter configuration for multiple‐load induction cooking application

Induction cooking application with multiple loads powered by suitable power converters and appropriate control technique needs attention. This study proposes dual frequency operated full-bridge inverter for multiple-load induction cooking. This inverter simultaneously powers two series resonant circuits. Each series resonant circuit is for one induction cooking load. This technique provides constant switching frequency operation for individual loads with asymmetrical duty cycle control. Output power of each load is independently controlled. The proposed inverter configuration and control technique is simulated and experimentally tested for two loads. Simulation and experimental results are in good agreement. This technique can be extended to more than two loads.

Buck-Boost Interleaved Inverter Configuration for Multiple-Load Induction Cooking Application

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of VDC, one more VDC is derived using buck- boost converter giving 2VDC as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of 2 VDC and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

Modified Three-Phase Three-Level DC/DC Converter With Zero-Voltage-Switching Characteristic-Adopting Asymmetrical Duty Cycle Control

In the applications for high-power dc/dc conversion, the power devices usually suffer high voltage and current stress in traditional single-phase dc/dc topologies such as forward, half-bridge, and full-bridge converters, which limits the power level of converter to reach higher. As a superior alternative solution, a three-phase three-level (TPTL) dc/dc converter was investigated in this paper, which has the advantages of lower voltage and current stress on switches, as well as fewer power devices. Adopting a symmetrical control strategy, the input current and output current frequency can be increased by a factor of six compared to the switching frequency, resulting in a reduced filter requirement. However, all the switches are hard-switching, leading to a considerable switching loss. In this paper, an asymmetrical duty cycle control strategy was proposed to the TPTL dc/dc converter. The modified converter remains all the advantages of original control strategy; meanwhile, soft-switching can be achieved using the energy stored in output filter inductance and leakage inductances of transformers (or resonant inductances). The theoretical analysis was presented in details, along with the characteristics and soft-switching condition of the converter. Experimental results from 540 to 600 V input and 48 V/20 A output were presented to verify the theoretical analysis and the performance of the modified converter.