There is a trade-off between transient performance and line current distortion of the DC bus voltage control of single-phase grid-connected voltage source converters. This paper presents an improved DC bus voltage control scheme of such converters using a proportional-integral controller in series with a first-order low pass filter. The extended symmetrical tuning method was adopted in the design of a regulator parameter, which greatly reduced the oscillating component at the double line frequency. The proposed control methodology allowed the loop bandwidth to increase without distorting the line current. Consequently, the DC bus voltage fluctuation or DC bus capacitance was reduced with a shorter settling time during a step load, compared with the conventional scheme. The proposed voltage scheme was found to be robust to the grid voltage variation and was less susceptible to the line voltage harmonics. Simulation and experimental results of a 1.5 kVA PWM rectifier verified the proposed methodology.

This article reports an investigation into ferrite and nanocrystalline materials for the medium-frequency transformer of a dual active bridge DC-DC converter, which plays a key role in the converter’s efficiency and power density. E65 MnZn ferrite cores and toroidal and cut nanocrystalline cores are selected for the construction of 20-kHz transformers. Transformer performance is evaluated with a 1.1-kW (42–54 V)/400 V dual active bridge DC-DC converter with single-phase shift and extended phase shift modulations. The experimental results indicate that the toroidal nanocrystalline transformer had the best performance with an efficiency range of 98.5–99.2% and power density of 12 W/cm3, whereas the cut-core nanocrystalline transformer had an efficiency range of 98.4–99.1% with a power density of 9 W/cm3, and the ferrite transformer had an efficiency range of 97.6–98.8% with a power density of 6 W/cm3. A small mismatch in the circuit parameters is found to cause saturation in the nanocrystalline toroidal core, due to its high permeability. The analytical and experimental results suggest that cut nanocrystalline cores are suitable for the dual active bridge DC-DC converter transformers with switching frequencies up to 100 kHz.

This paper presents an analysis on the effect of a parasitic capacitance full-bridge class-D current source rectifier (FB-CDCSR) on a high step-up push–pull multiresonant converter (HSPPMRC). The proposed converter can provide high voltage for a 12 VDC battery using an isolated transformer and an FB-CDCSR. The main switches of the push–pull and diode full-bridge rectifier can be operated under a zero-current switching condition (ZCS). The advantages of this technique are that it uses a leakage inductance to achieve the ZCS for the power switch, and the leakage inductance and parasitic junction capacitance are used to design the secondary side of the resonant circuit. A prototype HSPPMRC was built and operated at 200 kHz fixed switching frequency, 340 VDC output voltage, and 250 W output power. In addition, the efficiency is equal to 96% at maximum load. Analysis of the effect of the parasitic junction capacitance on the full-bridge rectifier indicates that it has a significant impact on the operating point of the resonant tank and voltage. The proposed circuit design was verified via experimental results, which were found to be in agreement with the theoretical analysis.

This paper presents high step-up push-pull resonant converter based on current source class-D rectifier, it provides high of voltage for a 12 V DC from battery via isolated transformer and current source class-D Rectifier. The main switches of push-pull and diode full-bridge rectifier operated under zero current switching condition. The advantaged this technique is used leakage inductance for zero current switching of power switch and leakage inductance used designing resonant tank secondary side. A prototype high step-up push-pull resonant converter was built and operated at a 200 kHz fixed switching frequency, a rate 340 V DC output voltage and 250 W output power. The objective analysis the effect of parasitic junction capacitance of full-bridge rectifier which has significant impact of this purpose is to operating point of resonant tank and voltage. The circuit proposed and designed was verify by experimental result. From a result are presented in agreement with the theoretical analysis and experimental work.

This paper presents an implement 1.5 MHz induction heating for aluminum based on vacuum tube oscillator circuit. It is operated by supplying input voltage 220 V/50 Hz to transformer with 220 V/2.4 kV then rectify form AC to DC voltage, which is then supplied to vacuum tube oscillator circuit. It produce an AC voltage, which has the waveform with high frequency close to the resonance frequency. This paper shows the heat up for aluminum with 0.95 kilowatt power and switching frequency at 1.5 MHz, consequently the circulating current at the induction coil and the work piece, causing heat at the work piece. Experimental results, induction hardening had a high power factor equal to 0.993 in a heat up aluminum rod with 10-mm diameter from room temperature to 600 °C within time about 60 second at the maximum full load power.

Generally, fuel cell (FC) power supplies cannot respond fast enough to dynamic load requirements. This research presents an energy management system for hybrid power sources in dc distribution systems. A supercapacitor (SC) module was designed to be the second power source in order to supply energy in transient, which can respond well to dynamic loads. In terms of circuits, a two-phase parallel boost converter was connected to each power source for regulating the output voltage. The interleaved technique was applied for reducing the current ripples of the sources. Flatness control, which is a nonlinear estimation technique, combined with a single-loop control strategy is proposed to control the system and it responds faster than multiple-loop controls. In this research, it included a hybrid system of two power sources namely a 500-W fuel cell emulator and a 165-F supercapacitor module, each connecting to a two-phase interleaved boost converter. The control algorithm for the hybrid system was developed and validated by the MATLAB-Simulink interfacing with a dSPACE 1103 controller card. The experimental results showed the rapid response of the proposed system to the dynamic load requirement. This confirmed that the single-loop flatness control is a potential algorithm that offers stabilization of the hybrid system.

In order to achieve a good dynamical response of a full-bridge AC-DC voltage source converters (VSC). The bandwidth of PI controller must be relatively wide. This leads to the voltage ripple produced in the control signal, as known that its ripple frequency has twice of the line frequency and cause the 3rd harmonic of an input current. A Ripple Voltage Estimator (RVE) algorithm and Feed-Forward Compensation (FFC) algorithm are proposed and added to the conventional control. The RVE algorithm estimated the ripple signal to subtract it occurring in the voltage loop. As a result, the 3rd harmonic of the input current can be reduced, and hence the Total Harmonic Distortion of input current (THDi) are improved. In addition, the FFC algorithm will offer a better dynamical response of output voltage. The performance evaluation was conducted through the simulation and experiment at 110Vrms/50Hz of the input voltage, with a 600 W load and 250 Vdc output voltage. The overall system performances are obtained as follows: the power factor at the full load is higher 0.98, the harmonic distortion at AC input power source of the converter is under control in IEC61000-3-2 class A limit, and the overall efficiency is greater than 85%.

This paper proposes an average modeling of LED dimming circuit controlled by a indirect sliding mode technique. Circuit and control parameters that affect an LED dimming system's stability are studied. The dimming circuit comprises an output-capacitor less buck converter and strings of LEDs as load. The advantages of this topology are: low-part count and increment of system lifetime. This dimming circuit is connected to a 48 V power source via an LC filter to reduce the input ripple current. It is known that tightly regulated dc-dc converter might lead to unstable operation of the system due to its negative input resistance characteristic. This paper proposes the guidelines to choose the control parameters of the sliding control that includes dynamics of a DC bus due to the change of the operating point of LED. The theoretical model is validated through experimental results obtained from the test bench using two strings of 5 Z-power W42182 LEDs (V F = 3.25V, I F = 1A).

This paper presents a simplified nonlinear estimation technique based on the differential flatness control strategy combined with a single-loop feedback control. An experiment setting that is hybridized between two power sources, namely, a 500-W fuel cell (FC) emulator and a 165-F supercapacitor (SC) module, was used to validate the proposed technique. Each power source was connected to a two-phase interleaved boost converter, which distributes voltage-regulated dc supplied by the hybrid power source. A dSPACE 1103 controller card interfaced the hybrid system and the control algorithm with the mathematical environment of MATLAB-Simulink. The experimental results showed the rapid response of the proposed system to the dynamic load requirement. This confirmed that the single-loop full-flatness feedback control is a potential algorithm that offers stabilization of the hybrid system sourced by FC and SC.

This paper proposes a cascade voltage/current control method (vector control) for a three-phase inverter for grid connected applications. The study mainly focuses on the innovative control law based on the flatness properties for a three-phase inverter with output LC filter. Utilizing the flatness principle, we propose simple solutions to the control and stabilization problems. The effectiveness of the proposed controller is validated through experiments on a prototype 1-kVA testbed with a dSPACE 1104 controller platform. Finally, the comparative results for the proposed scheme and the conventional linear control (proportional-integral control) scheme are presented to demonstrate that the proposed algorithm achieves an excellent performance such as fast transient response.

This study presents a high-voltage gain zero-current switching (ZCS) push-pull resonant converter for small energy sources. The converter provides a high voltage from a 12 V-DC battery via isolated transformer and full-bridge rectifier. The main switches of the push-pull and full-bridge diode rectifier operate under ZCS condition. The advantage of this technique is the use of leakage inductance for ZCS operation of the power switch and in designing the secondary side of a resonant tank. A prototype high-voltage gain push-pull resonant converter was built and operated at 110 kHz fixed switching frequency, 350 V-DC output voltage, and 200 W output power to analyse the effect of parasitic junction capacitance of the full-bridge rectifier, which significantly affects the operating point of the resonant tank and the voltage. This study introduces the implementation and design using the data of a single diode to calculate the parameters. The simulation and experimental results verified the proposed and designed circuits. Both results agreed with the theoretical analysis.

This study demonstrates automatic interleaving and current sharing techniques with an automatic interleaving system of distributed power supply. Unlike the conventional current sharing techniques, this technique proposes replacing and removing one or more converter modules without interfering with the still-working interleaved converters. Besides, these techniques are expected to perform a masterless control system and to enable automatic current sharing and phase shifting. A single current waveform on the interleaving bus carries information of the number of modules and phase displacements to perform current sharing and interleaving operations. A four-phase buck converter prototype was designed, implemented and tested. The replacing and removing modules' scenarios for automatic current sharing and interleaving were demonstrated by the experimental results obtained on the prototype.

The double line frequency ripple on the DC bus voltage of single-phase PWM rectifiers causes distortion in the line current and sluggish control dynamic. This paper presents an estimating scheme for the DC bus ripple voltage, which is used to cancel the ripple component in the measured bus voltage. This results in no oscillating component circulating in the bus voltage control loop. With this, the loop bandwidth can be increased to enhance the control dynamic. The proposed ripple voltage estimator uses the line current magnitude from the virtual synchronous reference frame current control loop, and the line voltage amplitude and frequency from the Park-based PLL as the input variables. Simulation and experiment of a 1-kW single PWM rectifier validate the proposed methodology. Experimental results show that under a load change of 960 W the proposed ripple cancellation scheme reduced the bus fluctuation by 50% of the conventional scheme and the settling time decreased from 3 line voltage cycles to one cycle with the line current THD of 2.5%.

This paper presents a unified structure of the unbalanced synchronous reference current control strategies for single-phase grid-tied voltage-source converters to obtain a zero steady-state error in the line current. An arbitrary waveform is used as the orthogonal current for the stationary to rotating frame axis transformation of the reference and measured grid currents. Various choices of such orthogonal signals lead to different control structures with the same performance characteristics. This causes a temporary unbalanced system, in which double-line frequency components appear in the control loops during the transient state. The proposed method with cross-axis decoupling, tuned at the control loop bandwidth by greater than eight times the grid frequency, has better performance than the existing virtual balanced synchronous reference frame scheme. Absence of the orthogonal signal generation guarantees the stability criterion of the control scheme. A zero steady-state error is still achieved under conditions of uncertainty in the converter parameters. Simulation and experimental results of a 1.5-kVA pulse width modulation rectifier validate the proposed methodology.

This paper proposes fluorescent electronic ballast with high power factor and low line input current harmonics. The system performance can be improved by combining together with a charged pump and valley fill circuit. Details of design and circuit operation are described. The proposed electronic ballast is modified from single - stage class D electronic ballast by adding capacitor parallel with each power switch and setting the circuit parameter to operate under class DE inverter condition. By using this proposed method the DC bus voltage can be reduced around by 50% compare with conventional class DE inverter circuit. Because the power switches are operated at zero voltage switching condition and low dv/dt of class DE switching, power loss is less and EMI is generated. The experimental results are satisfied with the theoretical derivation. The experimental results show that the proper frequency of the prototype is around 40 kHz with input power factor of 0.988, THD i 8.5% at full load and efficiency of more than 90%.

Zero steady state error in the line current of a single-phase grid-connected voltage source converter is usually obtained in the synchronous reference frame with different orthogonal signal generation schemes, which may lead to slow dynamic response and stability problems. This paper analyzes a simple rotating reference frame current control of the single-phase converters using the desired steady state fictitious current as the orthogonal signal. Double line frequency components are present in the current error signals, which will be completely eliminated at the steady state condition. The control loops were tuned at the bandwidth greater than such oscillating frequency, which gave the dynamic performance even better than the ideal balance two-phase system. The generated orthogonal current was mathematically proved that no potential stability problem was found. Only two multiplications and one addition were required without stored memory for the calculation of the quadrature current. Simulation and experimental results of a 1.5-kVA PWM rectifier validated the proposed control scheme.

This study introduces a novel synchronous and encoding data technique on a single interleaving bus for automatic interleaving system of distributed power supply (DPS). Unlike the conventional interleaving techniques, this technique proposes replacing and removing one or more converter modules without interfering with the still-working converters. With encoding data technique, each controller can determine the number of modules on the interleaving bus without any communication protocol. Besides, this technique is expected to perform a masterless control system and to enable automatic phase displacement, without any additional bus. A single current waveform on the interleaving bus carries information about the number of modules in its magnitude and phase displacements in its ramp that help the DPS in overcoming module failure and maintaining the operation. A prototype of the proposed automatic interleaving technique was designed, implemented and tested. The replacing and removing modules’ scenarios with still-working modules were demonstrated by the experimental results obtained on the four-module interleaving prototype.

In this study, for application of 36 W/220 V-rms/50 Hz fluorescent lamp, a high performance of high-power-factor and low line input current harmonics of electronic ballast is proposed. The proposed ballast has a structure based on a combination of charged pump and valley fill circuit. By adding paralleled capacitors to each power switch and setting the circuit parameters, operation modes of the inverter can be modified from single-stage conventional class D to a class DE. Consequently, duty ratio can be reduced by up to 25% so that the voltage stress at power switch is lower when compared with the conventional class D inverter. Furthermore, switching power loss and dv/dt can also be reduced because of zero voltage switching condition. Details of design and circuit operation are described. The experimental results of prototype circuit, operated around 50 kHz of switching frequency at full power output, show that the proposed ballast has 94.48% of efficiency, 4.30% of THDi, 0.996 of input power factor and 1.38 of lamp current crest factor.

This paper presents an innovative control law for a multiphase interleaved converter in the distribution of power supply in fuel cell (FC) generators. Traditionally, to control the DC output power, voltage, or current in a converter, a linear multiple-loop feedback control technique is used. The nonlinear multiple-loop feedback control approach offers several techniques that help to improve the system response. In this paper, an alternative nonlinear single-loop feedback control scheme is proposed. This scheme is based on the differential flatness concept, which provides a solution to achieve the preferred response using a less sophisticated algorithm. To validate the proposed technique, a prototype of a FC power converter (a 600-W two-phase interleaved boost DC–DC converter) was constructed in the laboratory, and the control algorithm was implemented to control the prototype using a dSPACE 1104 controller card. The control scheme exhibited excellent experimental results for use with a 1.2-kW Nexa Ballard polymer electrolyte membrane fuel cell (PEMFC) regarding the steady state and dynamic responses as well as the control robustness.