Discrete low-voltage power metal-oxide-semiconductor field effect transistors are used in a wide variety of applications with each application relying on different aspects of device behaviour. The conflicting requirements of these applications along with constraints such as legislation, industrial base, and intellectual property have resulted in a diverse array of technologies available in the market. This study outlines the many considerations that are faced when designing a high-performance silicon power MOSFET technology contrasting the trade-offs involved as factors such as on-state resistance, switching performance, reliability, and robustness in the application are optimised.

Up to now the vast majority of insulated gate bipolar transistors (IGBTs) has been produced on silicon (Si) wafers out of the float-zone (FZ) process. FZ crystals can easily be used for this application, but are only available with a diameter of up to 200 mm. However, the use of wafer substrates with a diameter of 300 mm offers a significant increase in productivity and is therefore the diameter of choice for the high-volume production of CMOS devices. In order to benefit from this advantage also for the manufacturing of IGBTs, material out of the magnetic Czochralski process, which is available in 300 mm, had to be adapted. Key issues include crystal originated particles, dopant segregation along the crystal axis, and the higher concentration of oxygen. In particular, the implementation of the field-stop zone by the implantation of protons will lead to the additional formation of hydrogen-decorated C_IO_I complexes which can act electrically as donors. However, by an appropriate adjustment of the processing parameters the electrical characteristics of IGBTs on FZ substrates can be well reproduced.

A new soft-punch-through (SPT) buffer concept for 600–1200 V insulated-gate bipolar transistors (IGBTs) based on thin wafer technology is proposed. The new SPT structure employs an epitaxial layer for the lightly doped n-type drift region, which is grown on a thick starting material or substrate. The n-type substrate serves as the SPT buffer region. The doping concentration of both drift and buffer regions are comparably low with the buffer region having a higher doping level. The design options of this new concept are discussed based on experimental data and 1200 V IGBTs using the new buffer concept are compared to IGBTs employing previously published buffer technology.

From the power loss reduction and safety operation points of view, the direction of power device developments is simply one-way. However, from the application point of view, the direction is wide-ranging. There are a variety of requirements to be considered, such as switching waveforms, operational environments including not only the temperature range but also the combination of the humidity, the cosmic ray endurance, the package compactness and so on. In this study, several efforts are explained as the latest technologies.

This work investigates modification on the top-side aluminium (Al) metallisation of 1.2 kV insulated-gate bipolar transistors (IGBTs) under repetitive short-circuit (SC) type-I measurements for two different parasitic inductances of 45 and 380 nH. The presence of current–density filaments starting at the collector side during SC leads to local temperature increase of the emitter metallisation and thus to modification of the top Al surface in the pattern of the current filaments. Here, two techniques thermo-reflectance microscopy, which can detect the surface temperature during repetitive short circuits directly and Al modifications after repetitive SC with analysis under optical microscope after the test have been considered. At 45 nH, with different DC-link voltages from 300 to 600 V, the Al modification pattern is non-uniform and it becomes uniform for V _DC>600 V. However, for 380 nH parasitic inductance and for DC-link voltages 300 and 400 V, the Al reconstruction shows a non-uniform pattern and becomes uniform for V _DC≥500 V. The SC simulations were performed by using a simplified front-side IGBT structure using variable DC-link voltages and inductances to reproduce the filament behaviour.

An accurate temperature estimation is a substantial necessity to evaluate the outcome of a power cycling test. For devices with a forward biased pn-junction in the main current path, there is a well-known and understood method using its forward voltage drop at a small sensing current. Since metal–oxide–semiconductor field-effect transistors (MOSFETs) do not provide a pn-junction in forward mode, this method cannot be applied directly. A similar method to estimate the junction temperature of a MOSFET is the V _SD(T)-method, which uses the junction of the reverse body diode. While this method is gaining wide acceptance for junction temperature estimation during power cycling of silicon carbide MOSFETs, no comprehensive investigation on its accuracy, stability and susceptibility towards degradational shift has been performed so far. In this work, the results of an investigation on the V _SD(T)-method with an evaluation of its precision and suitability for temperature estimation during power cycling tests of silicon carbide MOSFETs are presented.

A comprehensive study of displacement damage and total ionisation dose effects on 4H-silicon carbide power devices is presented. Power diodes and transistors produced by different manufacturers were irradiated by high-energy particles (protons, alphas, electrons and neutrons). The influence of radiation on device characteristics was determined, the introduced radiation defects were identified, and the main degradation mechanisms were established. Results show that radiation leads to the creation of acceptor traps in the lightly doped drift regions of irradiated devices. Devices then degrade due to the removal of the carriers and the decrease in carrier mobility and lifetime. For unipolar devices, the gradual increase of the forward voltage is typical while the blocking characteristics remain nearly unchanged. In bipolar devices, high introduction rates of defects cause a sharp reduction of carrier lifetime. This results in shorter carrier diffusion lengths and subsequent loss of conductivity modulation leading to a sharp increase of the forward voltage drop. The irradiation also shifts the threshold voltage of power switches. That is critical, namely for metal–oxide–semiconductor field-effect transistors. According to the authors’ study, the junction barrier Schottky diode and junction field-effect transistor (JFET) can be considered the most radiation-resistant SiC power devices.

Vertical silicon carbide transistors and lateral gallium nitride (GaN) transistors for power-electronic applications currently target applications with different voltage and power ratings. Meanwhile, research and development activities continue on vertical GaN transistors and new gallium oxide (Ga₂O₃) transistors. What are their perspectives in the application and how do they compete against each other and against established transistor technologies? This study discusses the specific characteristics of lateral and vertical GaN and Ga₂O₃ transistors to assess their strengths and weaknesses.

Dead-times are necessary in switching output stage to avoid shoot-through current between the high side (HS) and the low side (LS) power transistors. However, excessively long dead-times can lead to unwanted reverse conduction and power loss. Sensing the duration of reverse conductions are especially difficult for high-voltage enhancement mode (e-mode) gallium nitride (GaN) HEMTs due to their fast switching speed. High-precision sensing circuits are required for dead-time correction as the load current changes and to withstand large voltage swings. Traditional CMOS-based sensing circuits (e.g. standard logic gates) are not suitable for GaN-based converters as they can only handle limited voltage ranges. In addition, severe undershoots (up to −4 V) may damage the sensing circuit. Here, a gate driver IC for e-mode GaN power output stages capable of detecting the presence of reverse conduction with a best resolution of 0.66 ns, a dead-time adjustment resolution of 0.33 ns, and with on-chip closed-loop control is presented. In addition, a novel reverse conduction sensing circuit that can accommodate the large voltage swings at the switching node (SW) is also described.

A new analytic method to calculate the coupling coefficient including self-inductances and mutual inductance between two arbitrary-shaped coils is proposed. The proposed method is applicable for all common coil geometries such as rectangular, square, polygonal, circular coils etc. In the formula, the coil function, which is a completely a new type of function, is defined. The differences in shape and position of the coils are only on the choice of the coil function and its complex conjugate. The layouts of the two coils including separation change and lateral misalignment are discussed. An experimental setup has been built to validate the analytic calculations. Theoretical and experimental results are then compared to be in good agreement, which verify the effectiveness of the proposed method.

A two-phase interleaved buck converter (IBC) providing a high step-down conversion ratio is proposed in this study. The proposed IBC uses a switch-capacitor cell to achieve a high step-down conversion ratio compared to the conventional IBC. The cell consists of two parallel switches and two crossly placed identical capacitors. These identical capacitors are charged in series and discharged in parallel by producing a lower output voltage compared to the conventional IBC at the same duty ratio. The proposed converter provides less voltage and current stresses. The operation principle, the ripple and the average current through the inductors are described in continuous conduction mode. The boundary load condition is also determined. By describing the charging and discharging of the two identical capacitors of the cell, the capacitance value is determined. The losses and efficiency are analysed, and 96.33% efficiency is achieved. Finally, the proposed converter is implemented and experimental results are provided.

In this study, a novel nine-level modified T-type multilevel inverter (MT-MLI) with a simple capacitor balancing technique is proposed. The proposed MT-MLI circuit can generate higher levels with a single DC source and the minimum number of switching components. Each phase of the proposed topology contains ten switches and one flying capacitor (FC). The DC source voltage is divided into two parts with the help of capacitors. Phase disposition-sine pulse-width modulation technique is employed to regulate the DC-link capacitors and FC voltages. To reduce the control complexity of FC-based circuits, quarter-cycle selector is introduced to control the FC voltage within the given half fundamental cycle using redundant states, so an external capacitor charging setup is not required. Furthermore, to highlight the potential merits of the proposed MT-MLI, the comparison is made among state-of-the-art MLIs. Simulation verification of the MT-MLI is done using MATLAB/Simulink, and then hardware verifications are done using the laboratory prototype setup with Opal-RT controller. Finally, adequate results are presented to validate the proposed MT-MLI.

The matrix converter is becoming a mature technology with its specific advantages and limitations and can be effectively used as interface link in the future smart grids. In this context, the stability of the converter under different power flow conditions is highly important and needs more clarification. The input inductor–capacitor filter can significantly impact the stability of the converter when the output is tightly regulated, especially in bidirectional power flow control applications where a low-impedance source is connected to the converter output. This study investigates the matrix converter stability for bidirectional power flow control, considering the input filter and other parameters of the system. A detailed analysis of two commonly used active and passive stabilisation techniques known as digital filter and damping resistor approaches is presented, and a combination of these two methods is suggested as a better choice. The converter stability region for the proposed technique is determined by using the small-signal model of the converter. The converter performance for the methods is compared in terms of the efficiency, stability, transients, and quality of the input and output currents. Numerical simulations and experimental tests are conducted on a prototype direct matrix converter to validate the proposed method.

This study introduces an advanced DC–DC power converter with two main objectives, (i) to achieve a wide range of voltage gain, which means the converter may work over a wide range of input voltage for a fixed desired output voltage and (ii) to achieve a reduced input current ripple. Those features are highly desired in renewable energy applications, for example with photovoltaic panels and fuel cells. The proposed converter was designed in a structure in which the input voltage is composed by the difference of two inductor currents, the currents through inductors are driven with transistors that may have different duty cycle, this allows the current ripple cancellation. In addition, the structure of the converter provides a quadratic type voltage gain, which leads to a wide range of operation voltage. The converter achieves both the wire range of voltage gain and current ripple cancellation, nonetheless, the buck–boost capability is also provided. The input current ripple reduction helps preserve the renewable energy sources since they suffer deterioration when current with considerable ripple is drawn from them. Dynamic and steady-state analysis are performed along with the components sizing. Simulation and experimental results are provided to demonstrate the principle of the proposition.

Modular multilevel converter (MMC) is regarded as one of the most potential topologies for high-voltage direct current transmission system. However, the multi-frequency behaviour and complex control structure of MMC bright great challenges to the stability analysis, identification of factors affecting stability, and controller design. To address this problem, the harmonic state-space (HSS) theory is applied to MMC in this study. First, the small-signal HSS model is established to describe the multi-frequency behaviour of MMC. Capacitor voltage control, circulating current control, and output current control are also taken into account in the modelling. On this basis, the stability analysis is performed by evaluating the eigenvalues of the HSS model, and participation factor is introduced to identify the factors affecting stability. In addition, the proposed approach reveals the influence of different controllers on the system stability, providing guidance for the tuning of multiple controller parameters. Finally, the effectiveness and accuracy of the proposed approach are verified by simulation and experiment results.

Electric vehicle (EV) power system is flammable and explosive when the direct current (DC) arc occurs at elevated temperature. Thus, DC serial arc real-time monitoring is an insurance to keep away from disaster. In this study, the detection algorithm of DC serial arc is proposed. The wavelet entropy algorithm, the classification model based on support vector machine and logistic regression are analysed separately. The above algorithms are combined to identify the DC serial arc faults effectively under different types of loads in EV power system. The results show that the combined algorithm has a good performance of DC serial arc detection with high accuracy and robustness compared with a simple approach. Meanwhile, the false detection rate of the detection algorithm is close to zero, which could ensure the safety and stable operation of the system.

Although compact fluorescent lamps (CFLs) have been in the market for a long time, many of them do not achieve the same power factor as the incandescent lamps do, which appears to be a significant problem for the utility with the current widespread use of CFLs for household lightings. A single-stage single-switch electronic ballast with active power factor correction is presented in this study for CFL applications. Unlike other single-switch ballast circuits, the presented integrated dual-boost converter circuit can produce a symmetric bipolar square-wave voltage, thus generating a near-pure high-frequency sinusoidal voltage on the lamp, which is beneficial to the CFL lifetime. Moreover, its soft-switching variant can achieve the ZVZC turn-on and ZV turn-off for the MOSFET to improve the conversion efficiency. Detailed operating principles and circuit analysis of the proposed circuit have been provided in this study. Simulation and experimental results on a prototype of a 15 W CFL validate the theoretical analysis and highlight the merits of the presented work.

This work presents a three-phase thyristor-controlled reactor (TCR), which makes use of two constituent banks of controlled reactors, with coordinated control of the triggering angle of both the banks. The first reactor bank has a set of ‘delta’ connected back-to-back thyristor switches with a balanced set of reactors in series with each switch, while the second reactor bank also has back-to-back thyristor switches in ‘delta’ connection but with a balanced set of reactors in series with each line. It is demonstrated that this arrangement prevents some major current harmonics in the supply line by proper choice of the maximum kVAr ratio between the two reactor banks. The use of delta connected switches in both banks reduces the current rating of the switches. Hence, without using any phase-shifting isolation transformer or filters, the proposed technique permits control of reactive power over a reasonable range, with a low current total harmonic distortion meeting existing harmonics standards. Simple construction and operation of the proposed TCR make it an attractive and cheaper solution. The modelling, analysis and performance assessment of the new TCR are presented.

Matrix converters can be sensitive to abnormal supply conditions due to the absence of energy storage elements. This sensitivity can get worse when the matrix converters are modulated by a traditional indirect space vector modulation that assumes the input variables are sinusoidal and balanced. Therefore, this study proposes a methodology for the modulation of matrix converters without requiring any assumption of the input voltages. The method uses a geometric representation based on the singular value decomposition of the switch states to synthesise the rotating vectors of the target duty-cycle matrix. Furthermore, this study mathematically highlights the factors that regulate the amplitude of the output voltages and utilise them to compensate the adverse effect of the abnormal input voltages. Experimental results presented in this study validate that the proposed method can provide sinusoidal and balanced output currents in the presence of abnormal supply conditions.

Energy storage systems can be utilised to counteract unreliability of renewable energy sources. This study proposes a novel modulation for clamped-three-level inverters when the dc link of inverter contains two series-connected battery banks. By proposed modulator matched with the considered topology, inverter is free from over-modulation even under unbalance neutral-point voltage. In addition, by appropriate zero-sequence common mode voltage injection, neutral-point current is controlled and batteries’ state of charge (SOC) are dealt with so that power generation in discharge mode or power absorption in charge mode is properly shared between batteries. Due to the high capability of the proposed method, output voltage and current of inverter are almost free of low-order harmonic distortion even under severe unbalance condition and/or great asymmetric SOCs. After analysing and rejecting previous modulation-based control strategies for the considered topology, simulation study (charge and discharge modes) and experimental validations (discharge mode) are provided to verify the proposed method in grid-connected and islanded systems under different power factors.

Thermal performance of power converters is a key issue for the power integration. Temperatures inside the active and passive devices can be determined using thermal models. Modelling the temperature distribution of high-frequency magnetic components is quite complex due to the diversity of their geometries and used materials. This study presents a thermal modelling method based on lumped elements thermal network model, applied to planar magnetic components made of double planar E shaped cores (EE) and planar E core combined with plate one (E/PLT). The 3D model is automatically generated from the component's geometry. The computation enables to obtain 3D temperature distribution inside windings and core of planar transformers or inductors, in steady state or in transient case. This study details the proposed modelling method as well as the automated tool including the problem definition and the solving process. The obtained temperature distributions are compared with finite-element simulation results and measurements on different planar transformers.

Rectangular coils are widely used in inductive power transfer (IPT), and the self- and mutual inductances of them are key system parameters. However, the study of the rectangular coil is not enough. In this study, a series of unified analytical formulae for the self- and mutual inductance calculations of a variety of rectangular coils including filamentary coils, pancake coils and thin- or thick-walled solenoids are presented. Various positions of the rectangular coils above are discussed, and the mutual inductance formulae in the case of co-axis, co-plane, misalignment and even overlapping are given. Finally, the experimental measurements are carried out on various types of rectangular coils. The experimental results agree well with the calculated ones, which indicate the effectiveness of the proposed method. Therefore, this study provides an interesting tool for designing the transceiver of rectangular coils in IPT system.

This work describes a comparative study between Kalman filter, a complementary filter and a combination of both, for use in electrical vehicles. Combining the benefits offered by each filter to obtain an optimised filter combination is targeted. Three different combinations: The Kalman-complementary filter (KCF), complementary-Kalman filter (CKF) and 2KCFs are examined here. The filters are used to improve signals obtained via two sensors (gyroscope and accelerometer) integrated into the sensor IMU-MPU6050, with internal DMP. The sensor data are filtered to guarantee the movement quality of electrical vehicles. The KCF combination shows higher performance than the CKF combination. Moreover, the experimental results show that the 2KCF combination yields best performance with minimal noise levels and more accurate angle measurement. The optimal combination is strongly recommended for future electrical vehicle development.

This study proposes a practical passivity-based control (PBC) strategy of the hybrid rectifier based on Vienna and single switch three-phase boost (SSTPB) rectifiers. For medium and high application, the SSTPB rectifier operates at higher output power state with low frequency, the Vienna rectifier operates at power quality improvement state with high frequency, and the hybrid rectifier has the advantages of perfect sinusoidal input currents, unity power factor, high reliability, high efficiency and low cost. PBC is stable globally and has strong robustness to internal and external interference with less parameters and PBC of the hybrid rectifier has the advantages of less parameters, good dynamic characteristic, high current control precision and strong robustness. The detailed mathematical model based on Euler–Lagrange is built, the sixth harmonic current injection strategy is proposed, and the PBC controller is designed by damping injecting method in the study, and simulation results in SIMULINK are also given. At last, a down-sized hybrid rectifier prototype is built and the experimental results verify correctness and effectiveness of the proposed solution and analysis.

A major disadvantage of two-stage topologies of switched capacitors based multilevel inverters is the use of H-bridge switches which endure high peak-inverse-voltage (PIV). In such topologies, the H-bridge stage is preceded by a level-generation stage which synthesises unipolar voltage levels. In this work, a bi-polar module is proposed which can synthesise nine levels at the AC terminals with a single DC input. The proposed module uses power switches with PIV equal to that of the input DC source. Use of switched capacitors in each of the proposed module enables a voltage gain of two. Such bi-polar voltage-doubler modules can be easily connected in a cascaded fashion to increase the number of levels, without involving H-bridge switches. Working modes of the module ensure that the capacitors are self-balanced. A complete analysis of the proposed module is presented. Also, experimental results are presented for validation. In addition, a comparison with other topologies has been presented.