Power metal-oxide semiconductor field-effect transistors (MOSFETs) are increasingly used in the space probes where the environment is composed of various kinds of particles. Thus, it is essential to study the influence of the natural radiation environment on the electrical behaviour of MOSFETs in space. This study presents two-dimensional numerical simulation results, which investigates the sensitive volume, triggering criteria and characteristics of single-event burnout (SEB) and single-event gate rupture (SEGR) for the split-gate enhanced power U-shape MOSFET (SGE-UMOS). In addition, the comparison of the standard Trench-UMOS and SGE-UMOS for both SEB and SEGR simulation results is investigated. The SGE-UMOS shows an improved SEB performance than the standard Trench-UMOS with a larger safe operating area. The SGE-UMOS can also contribute to protect against SEGR compared with standard Trench-UMOS.

A novel buck–boost converter is presented in this study. This converter is based on Cuk converter. Therefore it inherits all the advantages of Cuk converter such as low output voltage ripple and minimal radio frequency interference. In addition, some implementation problems of KY converters are solved. The proposed converter has higher voltage gain in step-up mode in comparison with Cuk converter. Moreover, this converter expands the continuous conduction mode (CCM) operational region. In the suggested topology, the gate of the switch is referenced to ground, so this converter does not need a floating gate drive. Simulation results of the suggested converter are presented in different operational conditions. To verify the operation of the proposed converter, experimental results are provided using a hardware prototype that operates in both CCM and discontinuous conduction mode.

Recently, multilevel converters have received the largest amount of attention because of some advantages such as high quality output waveform, lower harmonic distortion and reduced electromagnetic interference. A novel cascaded multilevel inverter topology is proposed in this study. First basic part of inverter configuration is described and then symmetric and asymmetric form of converter is discussed. Comparison study is done between the proposed topology and cascaded H-Bridge (CHB) converter. Number of components such as switch number and gate driver has been reduced in the suggested topology compared to multilevel CHB converter. Furthermore, Peak inverse voltage of suggested topology is lower than that of conventional CHB converter. Reduction in number of on-state switches in introduced topology leads to the reduction of power loss and voltage drop. Moreover, modularity is other characteristic of this configuration. Finally, simulation and experimental results are presented. The presented results show the validity and the effectiveness of the proposed multilevel structure.

Multilevel voltage source inverters are most promising when employed in high-power and high-voltage applications. As the number of inverter levels increases, the algorithm of space-vector pulse-width modulation (SVPWM) becomes increasingly complex. Based on the intrinsic relationship between SVPWM algorithms for 2-level inverters and those for arbitrary-level inverters, here a novel SVPWM algorithm is proposed for an arbitrary-level inverter. Considering that the nearest three vectors are used to synthesise the reference vector, the on-time of the voltage vector for an arbitrary-level inverter can be acquired from that for a 2-level inverter via the use of a linear transformation. This algorithm is verified through simulation and experiments, with the latter proving that the proposed algorithm can meet the real-time requirements of multilevel inverters.

This study presents an improved hybrid parallel observer (HPO) based model predictive current control (MPCC) strategy to realise the source voltage sensorless control of grid-connected converters under inductance and resistance uncertainties. Since there is a little research on the sensorless control of MPCC-based converters, in this study, according to the linear extended-state observer theory and the adaptive filtering theory, a HPO which combines two different types of observers is constructed. With the new observer, the multivariable observation of system disturbance and model parameters is achieved. On this basis, through the combination of the HPO and the MPCC, a new HPO-MPCC control strategy is formed. The stability and parameter tuning of the HPO are analysed. To determine the initial value of the source voltage angle in the startup process of the converter, a new startup algorithm is proposed. A two-level grid-connected converter is built to verify the feasibility and effectiveness of the proposed strategy. The results show that, compared with the traditional algorithms, the new HPO has higher accuracy and stability; the HPO-MPCC achieves the source voltage sensorless control of the grid-connected converters and ensures the high precision and fast dynamic response characteristics of the conventional MPCC; the new startup strategy avoids the over-current problem of the conventional methods and improves the reliability of the whole system.

This study presents a proportional resonant current control scheme for three-phase grid connected voltage source converters without any grid voltage sensors. Towards this goal, the grid voltage sensors are replaced by a voltage estimation scheme based on the Newton–Raphson algorithm. In the proposed method, the grid connected converter behaviour is converted to an optimisation problem which relates the instantaneous grid voltage value to the filter parameters, the generated converter voltage and the exchanged powers in each sampling period. The proposed optimisation problem is then solved in each sampling period by means of the Newton–Raphson optimisation technique. Afterwards, the reference current for the current control loop is generated from the estimated grid voltages. Using an estimator instead of the voltage sensors not only reduces the size and cost of the converter system but also improves its reliability and protects it from grid voltage disturbances and noises. The excellent performance of the proposed grid voltage sensorless scheme is confirmed through experimental and simulation results.

This study proposes an embedded control for an off-grid single-phase multistring inverter with front-end DC–DC conversion stage followed by a synchronised H-bridge. In this inverter, the duty cycle of DC–DC converter is varied in the form of fully rectified sinusoidal fashion to produce a similar output voltage across the DC-link capacitor. This unidirectional voltage is converted into an AC voltage by the synchronised H-bridge. An application of this inverter topology with the proposed control scheme in micro-grid is investigated in the present study. The proposed control scheme not only possesses better steady-state performance with both linear and non-linear loads but also provides fast dynamic response during a step change in load. A digital controller based on field programmable gate array is utilised for the simultaneous generation of high-frequency switching pulses for DC–DC converter and synchronised fundamental frequency switching pulses for H-bridge. The entire system is simulated in MATLAB/Simulink® environment and its functioning is verified with linear and non-linear loads. The hardware prototype of inverter is also built in the laboratory and its performance is validated. Further, the better performance of the proposed system for supplying household appliances is ascertained in the laboratory.

In this study, a way of operating a double split-gate resurf stepped oxide (DSGRSO) UMOS has been proposed. The n-drift region is divided into two parts by the double split-gate: the upper one and the lower one, which enhances the resurf active effect and binges in an electric field peak in the middle of the n-drift region, and decreases the width of split-gate trench, resulting in an increase of figure of merit (FOM). The simulation results show that the DSGRSO UMOS has improved the saturated breakdown voltage by 25.7% and FOM by 108% as compared with SGRSO UMOS at the certain aspect ratio.

The aim of this study is to investigate the natural voltage balancing dynamics of the single/three-phase stacked multicell converters (SMCs). First, explicit analytic solutions for switching functions’ implicit equations, which are, utilised in modulating of the SMCs operated under phase disposition phase shifted carrier pulse width modulation (PD-PSC-PWM) technique whereas being initiated from the Kepler's transcendental equation, are derived. Next, utilising above-mentioned calculated Kapteyn (Fourier–Bessel)-based infinite series, a time-variant differential equation-based analytical model for single/three-phase SMCs is suggested. This strategy reduces to a model that can facilitate the analytic investigation of the start-up behaviour, dynamic response and natural voltage balancing phenomenon for SMCs owning any number of voltage-levels and phase numbers. Furthermore, it is also inferred that under the PD-PSC-PWM modulation technique, the flying-capacitor (FC) voltages balance naturally for higher number of stacks and cells, hence substantiating that the natural balancing exists for high-level SMCs. Moreover, precise analysis of the experimental observations reveals that settling time of the FC voltages in the positive and negative stacks positioned in the immediate vicinity of the SMC's midpoint is higher than the settling time of the FC voltages in the correspondent positive and negative stacks outlying the SMC's midpoint.

In this study, a power factor (PF) control for an AC–DC boost converter operating in light load condition has been presented. A passivity-based current control able to operate in either continuous conduction mode (CCM) and in discontinuous conduction mode has been implemented. A voltage proportional integral-based control with input feed-forward has been implemented in order to increase PF and regulate the DC output. A current observer, suitable for both operating modes has been adopted in order to eliminate the need for expensive current sensor. The proposed mixed conduction mode control scheme has been numerically tested using a powerful software simulation platform and compared with classical CCM control scheme. Experimental tests have been finally performed on a real boost converter controlled by a Texas Instruments microcontroller in order to validate the results and to prove the feasibility of the algorithm.

This study deals with the analysis, design and control of single voltage source converter (VSC)-based grid connected doubly fed induction generator (DFIG) for wind energy conversion system (WECS) with maximum power point tracking capability. This proposed system uses stator flux-based model reference adaptive system algorithm for the sensorless rotor position estimation. In this proposed topology, grid side converter is replaced by a battery energy storage system (BESS) in the dc link. The designs of all the components such as BESS, VSC and wind turbine are explained in detail. This proposed topology is implemented using a digital signal processor. This developed WECS is tested extensively in sub-synchronous, synchronous and super-synchronous speeds regions and test results are presented in all these cases. The performance of this proposed topology is demonstrated for the dynamics in wind speed by the experimental verification. A comparative study of proposed single VSC-based WECS system is made with the conventional double VSC-based DFIG.

This study presents a hybrid technique that offers constant power operation for single-phase grid-tied photovoltaic (PV) systems while performing maximum power point tracking function. A boost converter and a line commutated inverter (LCI) have been used for interfacing PV array with utility grid. Fixed firing angle of the LCI keeps the dc-link voltage constant and the boost converter extracts maximum power from the solar PV array by simply adjusting the duty ratio of the boost converter. A low-capacity battery bank connected at the dc link is used to deliver constant power to grid. Harmonic filter is eliminated as the system inherently delivers quality supply with reduced current harmonics. PIC microcontrollers have been programmed for generating pulses to the inverter and the boost converter. The system has been simulated in MATLAB/Simulink and the simulation results are presented. The parameters of a PV panel rated for 100 W, 21.5 V and 6.83 A have been used for the simulation. Experiments have been conducted on the 21.5 V, 6.83 A PV panel for obtaining a constant power of 80 W with varying irradiation and the results correlate with the simulation study.

Circuit analysis of the wireless power transfer (WPT) system with one source and multiple receiving devices is presented. An equivalent circuit model for the WPT system with one source and multiple receiving devices is proposed and formulae for calculating the maximum power efficiency and the optimal loads of the receiving devices are derived analytically. The tuning scheme for optimising the WPT system is deduced and expressed in terms of empirical equations for load networks. The circuit analysis of the WPT system is validated by the experimental results and circuit simulations. The proposed circuit modelling scheme provides an efficient way for designing and optimising the multiple-device WPT systems.

Fuel cells are used as a power generator in distributed generation and aircrafts applications. This paper proposes a new high step-up DC–DC converter with zero-voltage switching (ZVS) of switches and zero current switching (ZCS) of diodes, to be used as fuel cell's power conditioner. To have a ripple free input current, a coupled inductor can be used at the input side of the converter. The voltage gain of the converter is calculated and required conditions for soft switching have been presented. The voltage stress of elements of the proposed converter is discussed, the efficiency of converter is derived and finally experimental results have been used to validate the properties of the converter.

A non-isolated bidirectional DC–DC converter is presented in this study. The configuration of the proposed converter is simple. The voltage gain of the proposed converter is higher than the conventional bidirectional DC–DC buck/boost converter in the step-up mode. In addition, the voltage gain is lower than the conventional buck/boost in step-down mode. Because of better gain performance of the proposed converter in comparison of the conventional converter it can work in wide voltage range than conventional converter. Therefore the proposed converter is applicable than the conventional bidirectional converter. Owing to simple structure, the control of the proposed converter is quite easy. The operation principle and steady-state analyses of the proposed converter in step-up and step-down modes are explored. Finally the laboratory prototype circuit is implemented to justify the validity of the theoretical analysis.

This study proposes a high efficient series resonant ac–dc converter. The proposed series resonant converter has a structure integrated with an ac chopper. The proposed converter provides turn-on with zero-voltage switching of all switches and performs direct power conversion without several power conversion processes. Therefore the proposed converter can achieve high efficiency by minimising losses during ac–dc power conversion. In addition, it achieves high power factor without an additional circuit. The concept and operation principle of the converter are analysed and verified. A 300 W prototype is implemented to show the performance of the proposed converter.

A new multilevel DC-link three-phase five-level voltage source inverter topology is introduced here. A multilevel DC-link formed from single DC voltage supply and two cascaded half-bridge (CHB) power cells is connected to 12-switch three-phase bridge in such a way that the proposed inverter produces five levels in the output voltage waveform. Compared to comparable inverters, such as symmetrical CHB and hybrid multilevel inverters, the proposed topology maximises the number of voltage levels and reduces the number of utilised DC voltage supplies, switches, gate driver circuits and installation area. A modified fundamental frequency modulation technique based on determination of switching states of inverter is developed, to generate the appropriate switching gate signals. Furthermore, to validate the proposed topology, a low power prototype inverter has been built. The obtained simulation and experimental results ensure the feasibility of the suggested topology and also the compatibility of the used modulation technique.

In this study, novel multilevel inverter structures for medium and high-voltage applications are proposed. The proposed topologies can generate a great number of output voltage levels with more advantages. Firstly, a new symmetric cascade topology is presented which can be used in medium voltage applications. Then, based on the proposed symmetric structure, a new hybrid structure is recommended. The proposed hybrid structure can be used in high-voltage applications. The comparison between the proposed symmetric topology with conventional symmetric cascade topology and other non-conventional symmetric topologies are presented in terms of the number of insulated gate bipolar transistors (IGBTs), anti- parallel diodes, gate drivers and blocked voltage by switches. Moreover, the proposed topologies can be used in bidirectional power flow applications. The validity of the proposed multilevel inverter structures are verified with experimental and simulation results.

A few advanced bus-clamping pulse width modulation (ABCPWM) methods have been proposed recently for a three-phase inverter. With these methods, each phase is clamped, switched at nominal frequency, and switched at twice the nominal frequency in different regions of the fundamental cycle. This study proposes a generalised ABCPWM scheme, encompassing the few ABCPWM schemes that have been proposed and many more ABCPWM schemes that have not been reported yet. Furthermore, analytical closed-form expression is derived for the harmonic distortion factor corresponding to the generalised ABCPWM. This factor is independent of load parameters. The analytical expression derived here brings out the dependence of root-mean-square (RMS) current ripple on modulation index, and can be used to evaluate the RMS current ripple corresponding to any ABCPWM scheme. The analytical closed-form expression is validated experimentally in terms of measured weighted total harmonic distortion (THD) in line voltage (V _WTHD) and measured THD in line current (I _THD) on a 6 kW induction motor drive.

An interleaved high step-up zero-voltage-switching boost converter is proposed in this study. The operating principle and voltage gain ratio of the proposed converter are presented. The variable inductor control method is used to regulate the output voltage and to achieve a high-voltage gain. The design procedure of the variable inductor with a double E core is also presented in detail. Finally, a 40 W prototype with a 12 V input and 100 V output is built to verify the consistency of the theory analysis. The highest efficiency measured is 84.5%.

The multilevel converter has been brought into limelight in this study; however, particular attention has been provided to the form and function of modular multilevel converter (MMC) with new controller to mitigate the circulating currents and harmonics present in the system. Till date, research in this field is very limited with circulating currents and harmonics as the major problem. The stability analysis of proposed controller has been derived and analysed with its experimental results. The system is examined before and after application of controller and results is analysed. This article effectively addresses the problem with prototype of 1 KVA implementation and attempts to make a detailed analysis with their functions in comprehensive manner with HVDC application under different conditions. Also, the applicability of zero voltage switching at turn on, zero current transition at turn off has been verified experimentally. Computer simulations and experiment on a 50 Hz power supply show that the new controller is effective and easy to implement for modular multilevel inverters.

The study proposes and analyses a new circuit of direct AC–AC converter that can perform a bidirectional energy flow. The authors calculated the equations governing the functioning of the circuit. The adequate functioning and high performance of the circuit (the efficiency and waveform of the absorbed input current) were tested both by simulation and experimentally.

In this study, a single switch soft-switching isolated converter for light emitting diode (LED) driver applications is introduced. In the proposed converter, the transformer parasitic elements are employed as resonant elements to transfer energy and to attain soft-switching condition. The converter constant output current only depends on the input voltage, resonant capacitor, switching frequency and transformer turns ratio. Thus, the converter does not require any current feedback to regulate the LED current. In addition, the adjustment of light emission can be simply accomplished which results in cost reduction and system simplicity. Experimental results are presented to justify the validity of theoretical analysis.

The high penetration of energy from wind energy conversion systems (WECSs) can have a significant influence on the stability, power quality and reliability of power systems. Therefore several countries have developed stringent grid codes in recent years in order to enhance the overall stability of power systems. In these grid codes, the capacity to fulfil low-voltage ride through (LVRT) requirements is considered an important issue for the control of WECSs. Therefore in this study, a novel voltage sag/swell generator (VSG) based on a 4-leg matrix converter is presented. This VSG can be used to generate the symmetrical and asymmetrical faults required to test LVRT algorithms in a laboratory environment. The performance of the VSG is experimentally demonstrated and compared with the operation of other VSGs conventionally used for LVRT studies.

Accurate knowledge about the machine parameters is of utmost importance for high performance speed control of induction machines. Out of all the various machine parameters, the stator and the rotor resistances are strongly dependent on the machine temperature, which is difficult to predict without any appropriate sensor mounted inside the machine. Online identification of these parameters requires correct knowledge about the machine magnetic parameters, which are the magnetising and leakage inductances. Moreover, estimation of the resistive parameters is affected by core loss in the machine. The magnetic parameters are almost unaffected by core losses and can be accurately calculated offline at different operating flux levels with known input variables and resistive parameters. A ‘variable flux current limit test’ is proposed to determine the parameters at various input frequencies and operating fluxes. The proposed identification method can be implemented with the same hardware available for normal operation of the drive. Various simulations and experiments performed on practical machines validate the proposed concept.

A new zero-voltage switching (ZVS) half-bridge converter with three circuit modules is presented in this study to reduce the switching losses of power switches and current stress of passive components for medium power applications. Three circuit modules with the same power switches are connected in parallel at input and output sides. Thus, the switch counts are reduced compared with the parallel half-bridge converter with the same power rating. Each circuit module supplies one-third of load power to output side. Owing to the half-bridge converter leg, the voltage stress of each power switch is clamped at input DC voltage. Three centre-tapped rectifiers are adopted at low voltage side to share load current and reduce the size of magnetic cores. Asymmetric pulse-width modulation is adopted to regulate output voltage at the desired voltage level. Owing to the resonant behaviour by resonant capacitance [or output capacitance of metal-oxide semiconductor field-effect transistors (MOSFETs)] and leakage inductance (or external inductance) at the transition interval, power MOSFETs can be turned on under ZVS. The system analysis, circuit characteristics and design example of the proposed converter are discussed in detail. Finally, experiments with a 1620 W prototype are provided to verify the effectiveness of the proposed converter.

This study concentrates on the load disturbance in voltage-controlled three-phase voltage source inverter (VSI) with transformer. High power density could be obtained when the transformer placed behind the inductor–capacitor (LC) filter, but the voltage drop on transformer leakage impedance may reduce output voltage quality in high power application. Load current feedforward control is applied to reduce output impedance and suppress load disturbance. To avoid the non-ideal high-frequency noise introduced by full feedforward strategy, simplified feedforward strategy is proposed to improve dynamic performance. The feedforward strategies implemented in both stationary frame and synchronous frame are derived, and the reduction of output impedance is analysed in detail. The distinct features of the proposed feedforward strategies are error-free steady-state fundamental output, fast dynamic response and convenient implementation. Finally, simulation and experimental results are provided to verify feasibility and validity of the proposed control strategy.

In this study, a single phase thyristor-controlled susceptance (TCS) with integrated reduced power voltage source inverter (VSI) acting as a switching compensator (also known as active power filter) has been proposed to mitigate the harmonics generated by thyristor-controlled reactor (TCR). The proposed scheme has the capability to fully attenuate all harmonics generated by TCR. The proposed technique can perform efficiently even at lower switching frequency of VSIs, which is a desirable feature for higher power rating systems. This results in a more feasible implementation for comparative dynamic control characteristics. This scheme has been described in detail and has been verified through simulation and experimental results.

To realise the accurate and real-time compensation of the harmonics of a power system, this study proposes a novel control strategy for shunt active power filter (SAPF), adopting the composite strategy of neural network proportional-integral (PI) control and dual-repetitive controller (DRC). In DRC, one repetitive controller is used to ensure current tracking accuracy and the other one is used to enhance dynamic response. The neural network PI control is adopted to improve response speed by turning the PI parameters adaptively and setting optimisation parameters online. Through the optimisation of this approach and the rational configuration of the hardware and software systems, the SAPF could achieve rapid dynamic response with high tracking accuracy and excellent compensation performance. A 100 kVA industrial prototype active power filter has been developed by using this control strategy. System compensation could effectively reduce the total harmonic distortion values from 26 to 27.7%, 27.6 to 4.25% and 4.57 to 4.35% for each phase of the current. The full response time of the system is < 10 ms.

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.