Inductively coupled power transfer (ICPT) is a technology that is implemented to charge electric vehicles (EVs) wirelessly. Some developments from the past years indicate that this promising charging method has the potential to replace wired charging methods. Thus, some aspects of designing ICPT need to be discussed and considered to develop an optimal system. However, most reviews from the previous articles focused on the developments of ICPT systems in the scope of EV charging. This study not only reviews current developments and topical issues and challenges in high-power ICPT systems, but also presents several techniques for analysing the system as well as further developments for wireless EV charging adapted from the other electromagnetic field applications. This study will assist readers to analyse any proposed ICPT systems using current methods of analysis and to tackle highlighted topical issues presented from the previous technical papers.

In this study, the third harmonic injection method based on analogue circuit is applied in the interleaving parallel three-phase four-leg (3P4L) inverter, the adverse effects of injected signals on the circulating current are found, and the corresponding control strategy solution is proposed. At the beginning of this study, by using the large-signal model of leg, it is proved that four legs can be decoupled, on the basis of this conclusion, the current sharing control strategy based on dual-loop scheme and third harmonic injection can be applied in paralleled 3P4L inverter, however, peak value of circulating current is increased by zero-sequence component which is caused by injected signals. Therefore, output impedance analysis method is applied, and the control strategy including zero-sequence component feedforward loop is proposed, which can be implemented with analogue circuit, and is suitable for the 400 Hz synchronous/interleaving paralleled inverter systems. Finally, the effectiveness of the control strategy is verified by simulation and experiment.

In this study, a new isolated high-gain switched-boost DC/DC converter employing two symmetrical switched-boost networks along with a modified control algorithm based on the combination of the pulse-width modulation (PWM) and phase-shift modulation is proposed. Utilising symmetrical switched-boost networks increase the voltage gain of the proposed converter, significantly. Moreover, applying the proposed switching algorithm on the proposed isolated switched-boost DC/DC converter leads to the following advantages: (i) high-voltage gain, (ii) zero voltage switching (ZVS) turn-on of two switches, (iii) ZVS turn-off of two switches and (iv) appearing three controllable parameters (the shoot-through duty cycle, the phase shift and the transformer turns ratio) in all of the equations including the voltage gain equation, which enhances the flexibility of the converter. In this study, the steady-state analysis, design procedure of the elements, and voltage and current stress of the semiconductors are given. Then, the proposed converter and the proposed switching algorithm are compared with similar converters and modulation techniques in order to highlight their features and drawbacks. Finally, experimental results are obtained to substantiate the theoretical analysis accuracy.

Finite control set model predictive control (FCS-MPC) has been widely used in the control of grid-connected converters with the advantages of fast dynamics, multi-objective control, and easy implement. However, the conventional FCS-MPC bears with variable switching frequency, high current ripple and computational burden. An improved current model predictive with the cost function-based modulation scheme (CFM-MPC) is proposed for a three-phase three-level VIENNA rectifier to improve the power quality. First, the mathematical model and voltage vector are given according to the principle of deadbeat control. Then, the voltage vector of different voltage vectors are selected according to the location of the voltage vector reference, and the switching action time of the selected are directly calculated by the inversely proportional with cost function value of the selected vectors. It remains the merits of both the conventional MPC and space vector pulse width modulation schemes to track the optimum voltage vector without increasing the computational burden. Finally, a comparative study with the proposed CFM-MPC and conventional FCS-MPC has been conducted to verify the superiority of the proposed scheme. The results show the proposed CFM-MPC has the advantages of lower power ripple, fixed switching frequency, lower total harmonic distortion and neutral point potential balance.

A novel high gain three-state switching hybrid boost (TSS-HB) converter for DC microgrid applications is proposed in this study. The TSS-HB converter is developed from a conventional boost converter with voltage lift technique. The high voltage gain is achieved by the inclusion of an additional semiconductor switch. Further, this structure reduces the voltage and current stress of the switches and diodes. The proposed TSS-HB converter operates in three switching states with the help of two different duty ratios (k ₁ and k ₂). The power circuitry, continuous conduction mode (CCM) and discontinues conduction mode (DCM), and characteristics waveform are discussed in detail based on the theoretical background. The voltage gain and efficiency analysis of TSS-HB in CCM is presented with consideration of non-ideal circuit components. While boundary condition and voltage gain in DCM is discussed with ideal components. The comparison sections highlight the advantages of TSS-HB over existed topologies with the same number of components. Further, the selection of semiconductor devices and the design of components are discussed in detail. Finally, the hardware results are presented which validate the predicted characteristics of TSS-HB converter.

In this study, a circulating current suppression strategy is proposed using high-frequency voltage compensation when asynchronous carriers exist between modules in modular and scalable inverter systems (MSISs). In MSIS, an inverter and a control unit constitute one module. Because each module is connected in parallel, the power capacity and efficiency can be increased. However, according to the switching state in the parallel module, a circulating current can be generated. This current causes stress on the switches. Furthermore, the circulating current not only deteriorates the current control performance but also increases the difficulty of load sharing. In this study, a novel method is proposed to suppress high-frequency circulating current caused by asynchronous carriers. This current can be reduced by generating the same switching pattern in two modules using high-frequency voltage compensation. Simulation and experimental results are presented to verify the proposed method.

Charging of electric vehicles (EVs) from solar energy provides a sustainable means to power EVs in the future. A comparison of topologies for a three-port converter to charge EVs directly from photovoltaic (PV) panels is presented in this study. The grid-connected EV charger has a nominal rating of 10 kW and is bidirectional, enabling vehicle-to-grid operation. The topologies are optimally designed considering different switching frequencies, silicon carbide devices, magnetic cores and number of interleaved stages. Nine topologies are compared using a comparison framework, and the best topology is chosen based on the number of components, converter efficiency, volume, controllability and current ripple. The analysis shows that the best topology is a three-port converter with a central direct current link with a 3-leg interleaved boost converter (IBC) for the PV, two-level inverter with sinusoidal modulation for the grid and a 4-phase interleaved flyback converter for the EV. The loss models built are experimentally verified using a 3-leg IBC.

This study proposes a discrete-time integral terminal sliding mode controller (DITSMC) integrated with a sensorless maximum power point tracking (MPPT) method for a permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS). The effects of the parameters of the proposed DITSMC on the convergence-time and the error-bound are investigated by the simulation studies. The dynamic performance of the DITSMC has been evaluated experimentally on a test bench for step-type wind changes. The optimum coefficient between the output voltage of the generator and the extracted power from the WECS is determined only for a wind speed by offline studies. Then, the MPPT can be provided using this coefficient for all wind speeds in the operating range of the WECS without any mechanical sensor. Additionally, the experimental studies show that DITSMC has better performance than the PI controller in terms of the settling time and thus the efficiency of the WECS.

In this study, a novel control scheme for the discontinuous conduction mode (DCM) operation boost power factor correction (PFC) converter is proposed. Instead of adopting constant duty cycle (CDC) control, variable duty cycle control or frequency control, the magnetic control or variable inductor control is adopted to regulate the output voltage, so CDC and switching frequency can be implemented for the switch. The operation principles of the proposed control scheme are discussed in details, and the analysis of the input current, power factor, boundary condition and design considerations are presented. In addition, the modelling of the variable inductor and the DCM operation boost PFC converter with variable inductor are derived in detail, by linearising the non-linear components, the model of the DCM operation boost PFC converter with the proposed control scheme can be obtained, and the design procedures of the PI controller are presented. Finally, a 70 W experimental prototype is built to verify the theoretical analysis and the effectiveness of the proposed control scheme.

In this research work, a multipurpose power electronic interface (PEI) competent of utilising dual sources during charging process has been proposed for plug-in electric vehicles. Based on the requirement, the battery can either be charged from solar photovoltaic (SPV) or from the grid. Moreover, when charged from an SPV source, converter can extract highest available power with maximum power point tracking (MPPT). The intrinsic novelty of the proposed PEI is that no additional components/switches are employed to achieve dual sources in charging or for MPPT. The proposed PEI consists of a converter derived from a conventional isolated secondary ended primary inductance converter (SEPIC). It is designed to operate effectively in all vehicular modes (charging, propulsion (PP) and regenerative braking (RB)). During battery charging from the grid and SPV, it operates as isolated SEPIC. While, in PP and RB, it operates as a flyback converter. Therefore, the proposed converter keeps isolation in each mode, which results in better safety for battery as well as vehicle users. Further, all vehicular modes are achieved through a single converter. As a result, compactness of the charger increases and making it best solution for on-board battery charging application.

A new scheme for high boost trans-z-source inverter with continuous input current is proposed. Because of the high boosting capability of the proposed inverter, the modulation index will be higher with lower shoot-through duty ratio. Higher modulation index will lead to improved total harmonic distortion of the output voltage. This topology has one inductor, three diodes, two transformers, and three capacitors. Comparison between the new schemes with the previously proposed trans-z-source topologies is made based on the voltage stresses on capacitors, efficiency, and voltage boost factor. To verify the effectiveness and validity of the new inverter, experimental and simulation results are provided.

This study proposes a multilevel inverter with optimised structure from switching device number point of view. Configuration of the presented multilevel inverter is modular and extendable. Three different methods are introduced to determine the magnitude of DC voltage sources. Characteristics of inverter topology based on suggested methods are given and compared with each other. Also, the proposed multilevel inverter is compared with some similar topologies in terms of controlled switches, driver circuits, DC voltage sources and total blocking voltage to verify its advantages and probable disadvantages where the results show the superiority of the proposed topology in the comparison items. Selective harmonic elimination pulse width modulation technique is applied to achieve output voltage with high quality. Finally, a laboratory prototype of the proposed multilevel inverter is implemented and then, the experimental and simulation results are derived to validate the inverter capability in generating staircase waveforms.

A single-switch high step-up boost converter based on a novel voltage multiplier (VM) has been proposed in this study. Compared to traditional boost converter, not only the voltage conversion ratio has been increased, but also voltage stress across semiconductor devices has been decreased. Moreover, the voltage conversion ratio and voltage stress of switch of the proposed converter can be adjusted by the number of the VM cells. The control and drive circuits for the proposed converter is as simple as boost converter as there are no additional switches. Working principles and performance characteristics of the proposed converter have been analysed in detail. A 200 W experimental prototype with three VMs has been built to validate the theoretical analysis.

A universal and robust wireless power transfer (WPT) system crossing insulators to feed monitoring terminals on power towers of overhead transmission lines is presented in this study. Analyses of the WPT system crossing high-voltage insulators string indicate that system characteristics and energy loss vary under different insulation conditions. Transfer characteristics of the WPT system with different relative positions between the coils and insulators are analysed to find an insensitive scheme. To achieve a non-interacting and relatively efficient operation under the scenarios, magnetic shielding layers are designed to further isolate the WPT system and insulators. Moreover, the resonant frequency point tracking method of this specific WPT system is studied and implemented to achieve robust transfer efficiency. Experimental results prove the feasibility, and the system displays a robust transfer performance with various high-voltage insulators. Such energy feeding system can be used in disc or composite insulation towers universally with simplified installation methods.

This study presents a non-isolated step-up inverter without leakage current for low-voltage renewable energy generation such as photovoltaic (PV) cells grid connection. From the structure of the proposed inverter, the negative terminal of the PV array is directly linked with the grid neutral, so the common mode voltage of the parasitic capacitance can be kept constant and the leakage current will not be generated in theory. Moreover, this transformerless inverter can produce an AC output voltage higher than the input DC voltage, which will reduce the sizes of the generation system. A switching modulation strategy carrier-based is analysed in detail when the input inductor current is operated in discontinuous conduction mode. The operation modes of the proposed inverter are also discussed, respectively, in positive and negative half line cycles. Finally, a digital experimental prototype is tested in the laboratory, and the experimental results are consistent with the theoretical analysis.

This study proposes a speed sensorless vector control strategy for the six-phase linear induction motor (SPLIM) based on the dual reduced-dimensional serial extended Kalman filters (DRDSEKFs). Firstly, the low-order mathematical model of SPLIM is obtained according to the equivalent transformation of primary voltage, current and flux components in the stationary coordinate system. Then, the state equation is derived and the speed estimation based on the five-dimensional extended Kalman filter (EKF) is realised. To reduce the computation cost and improve the accuracy of speed estimation, a DRDSEKFs algorithm is proposed, with one two-dimensional EKF and one three-dimensional EKF operating serially in every control period. As the real-time performance of the algorithm is guaranteed, it is possible to overcome the hysteretic nature of the traditional EKF and improve the dynamic estimation performance. Simulations and experiments show that the proposed sensorless control strategy is feasible and effective.

This study suggests a non-linear output voltage tracking controller for DC/DC boost converters in the form of a classical cascade control structure. Non-linearities in the converter dynamics as well as parameter uncertainties and load variations are considered. The first contribution of this study is the design of an auto-tuner, which automatically adjusts the control gain according to the output voltage error to enhance transient performance. The second contribution involves proving that the closed-loop system ensures the performance recovery without any steady-state errors in the presence of parameter and load variations. The effectiveness of the proposed algorithm was verified through experimental investigations using a 5 kW prototype DC/DC boost converter.

This study proposes a carrier-based PWM strategy with zero-sequence voltage injection for T-type three-level inverter to a tolerant open-circuit fault. The half-bridge and NP bridge open-circuit faults are analysed. The faulty switch can be identified by the average phase current and the deviation of neutral-point (NP) voltage. In the case of half-bridge failure, the fault-tolerant control reduces the distortion of phase current and the amplitude of line-to-line voltage is decreased. In the case of NP failure, the faulty pole voltage becomes two-level instead of three-level and the phase voltage is not reduced. By using the novel zero-sequence voltage injection, the NP voltage is balanced in both half-bridge and NP bridge failures, which do not require additional hardware and complex calculations. The effectiveness of the proposed fault-tolerant PWM strategy and injection of zero-sequence voltage is validated by the simulation and experiment results.

For many distributed power systems (DPSs) such as light-emitting diode lighting and battery management, communication is essential. This study presents an improved method of integrating power transfer and communication through a common bus by applying the concept of power/data time division multiplexing transmission (PD-TDMT). The proposed method employs power electronic topologies as the basic circuits to create the power transfer system and utilises the power transmission intervals for communication. Compared with conventional communication techniques in DPS, the proposed method has the advantages of simple implementation, enhanced noise immunity and higher output power capacity. The general structure of PD-TDMT systems is presented, which includes power sourcing equipment (PSE) and powered devices (PDs). A series of PSE and PD circuits are derived based on dc–dc topologies. The timing sequence of power transfer and communication is given. To suppress the common-mode interferences under the high-power condition, a balanced power transmission system is also proposed. Besides, the termination circuits are discussed in detail under the long-distance transmission condition. Finally, the proposed method and theoretical analysis are verified by experiment.

In this study, a modified single-switch bridgeless power factor correction (PFC) single-ended primary-inductor converter (SEPIC) structure is proposed. The major practical drawbacks of the existing structure are the presence of circulating current and high maximum current stress at the input capacitor and line diodes. Therefore, to overcome these problems, the existing structure is restructured by repositioning the line diodes in series with input inductors. Besides, the principle of design parameters optimisation is used based on the balancing energy compensation between input capacitors and output inductor. This structure is designed to operate in discontinuous conduction mode in order to achieve almost a unity power factor. The operation principle and design consideration of the modified structure is introduced in details. The experimental results demonstrate that the total harmonic distortion current is reduced from 56.3 to 4.9% after the optimisation process is performed, and at the same time the dead zones are inherently eliminated. Furthermore, it is shown that the output voltage ripple frequency is always double from the input line frequency of 50 Hz and the output voltage ripple is constantly lower than the maximum input voltage ripple. Thus, the designed parameters of the experimental converter are verified with ∼160 W of the converter output power.

The performance analysis of modified multilevel DC link inverter (MMLDCLI) operating with various carrier-based pulse width modulation (CB-PWM) techniques is studied. In MMLDCLI, seven-level is achieved with six controllable switches only, making it an attractive option as a reduced device count multilevel (MLI, multilevel inverter) topology. MMLDCLI operates with two different levels of voltage source, and the absence of transformer makes this topology suitable for photovoltaic (PV) applications. Two different levels of sources can be achieved with two different combinations of PV panel arrangements. The CB-PWM is reputed modulation approach for MLIs. In this study, various CB-PWM techniques are implemented for MMLDCLI to evaluate performance parameters such as harmonic analysis, device losses and device stress. All the simulations are performed in SIMULINK, and hardware prototype is developed to validate the results.

In this study, an improved pulse width modulation (PWM) scheme was proposed for an active quasi-Z source inverter (AqZSI). Compared to the quasi-Z-source inverter (qZSI), the AqZSI with improved PWM strategy can operate in a wide range of input voltage with higher efficiency. Furthermore, the AqZSI can operate with a higher modulation index, a lower inductor current stress, and a reduced shoot-through current. A procedure flowchart is presented for the optimal selection of the shoot-through duty cycle, the switching ratio of the additional switch, and the modulation index for AqZSI. Moreover, some comparative results between the AqZSI, qZSI and conventional two-stage inverter with a boost DC–DC converter are shown in detail. Finally, 1.2 kVA SiC-based three-phase inverter prototypes are built to verify the agreement between theory and measurement.

The increasing use of medium-voltage drives and high-power equipment requires a detailed study on the switching method and topology of multi-level inverters. Asymmetric cascaded H-bridge topologies that have unequal input dc voltages with different devices in various parts of the cascaded H-bridge inverter (CHB) are representative of significant improvements in medium-voltage industrial drives. Various modulation strategies are used in multi-level power conversion applications. In the multi-carrier switching method for asymmetric CHB, the number of switches is less than carriers and is usually used in the off-line switching method. These methods of switching are not applicable to online systems. In this study, equations for combining different pulse-width modulation (PWM) to use the controllability advantage of the multi-carrier method are introduced in asymmetric topologies. Then, the dual Fourier series equations are applied to model each inverter switching relation of the asymmetric cascaded blocks. To model each inverter switching relation of the asymmetric blocks using sinusoidal PWM, the dual Fourier series equations were applied. The presented analytical modelling switching method was validated using simulation and experimental case studies.

In this study, the authors propose a method to implement a low-cost hardware-in-the-loop (HIL) system for power converters and microgrids design, test and analysis. This approach uses a digital signal processor (DSP) Texas Instruments as the HIL core. All the differential equations of the power converters are solved in real-time by the DSP and displayed in the digital-to-analogue outputs. Three different converters are modelled in this study: boost converter, single-phase inverter connected to the grid and three-phase inverter connected to the grid. Experimental results are obtained and compared to the HIL response. These results were made triggering the real converter and the HIL with the same open-loop pulse width modulation signal, showing high fidelity between the digital models over the real systems. In a second moment, a microgrid is modelled in the proposed HIL and tested with a closed-loop controller. The experiments show that the proposed hardware supports time steps as low as 1 μs or 1 MHz update rate, depending on the model. The proposed technique has the potential to reduce testing time and cost, once commercial HIL devices such as Typhoon, dSPACE and RTDS have a significant cost, not affordable or available to all the research community

Bidirectional isolated DC–AC inverters are widely used in industrial applications, such as grid-connected uninterruptible power supply, renewable power energy system, electric vehicles and so on. In order to improve the conversion efficiency, realising soft switching will become the essential technology in the research of DC–AC inverters. Based on the commonly used two-stage isolated inverter, this study proposed a novel DC–AC inverter that combines dual-active-bridge (DAB) converter, switched capacitor and full-bridge inverter. Utilising the strategy of phase-shift shoot-through control, DAB will generate a high-frequency pulse DC link cooperated with switched capacitor. As a result, during the shoot-through period, when the DC link is in zero-voltage-stage, the full-bridge inverter could realise zero-voltage switching (ZVS) through discrete pulse modulation. Principles, characteristics and implementations of the proposed inverter and its control strategy are analysed in detail. A further analysis on the operation modes and ZVS constraint of DAB's secondary bridge and switched capacitor is completed. A 250 VDC to 150 VAC (peak value) 1.13 kW simulation and experimental prototype is presented to validate the ZVS of full-bridge inverter and the analysis of DAB converter and switched capacitor.

Although interior permanent magnet brushless direct current (IPMBLDC) motors have higher torque and power density compared to surface-mounted PMBLDC motors, the reluctance torque of IPMBLDC motors generates higher torque ripples. This study introduces a new current waveform as a reference to control the IPM motors while keeping the total developed torque constant. It also helps to considerably reduce the torque ripple of the motors. The experimental results show that this method significantly reduces the damaging impact of the reluctance torque ripple without complicating computations or changing the stator and rotor structures of the motor. Additionally, the switching frequency and consequently switching losses are reduced using the proposed technique.