The on-state resistance Rds,on is a key characteristic of unipolar power semiconductors and its value depends on the operating conditions, e.g. junction temperature, conducted current and applied gate voltage. Hence, the exact determination of the Rds,on value cannot rely on datasheet information and requires the measurement of current and on-state voltage during operation. Besides the determination of the conduction losses, the on-state voltage measurement enables dynamic Rds,on analysis, device temperature estimation, condition monitoring and consequently time-to-failure prediction. However, in contrast to a switch current measurement, several challenges arise in the design of an on-state voltage measurement circuit(OVMC), i.e. high measurement accuracy(mV-range) during on-state, high blocking voltage capability(kV-range) during off-state and fast dynamic response(ns-range) during switching transitions are demanded. Different OVMC concepts are known from IGBT applications, however, the more severe requirements introduced from the high switching frequency and low OV characterizing the operation of fast switching power semiconductors, prevent their usage. Off-the-shelf products hardly satisfy the mentioned specifications, whereas the performance of state-of-the-art OVM research prototypes require further investigations and/or improvements. With this aim, an innovative OVMC concept is designed, analyzed, calibrated and tested in this paper. Furthermore, the conduction losses of different power semiconductors are measured as function of their operating conditions to validate the performance and highlight the potential of the proposed OVMC.

The power quality problem in the power system is increased with the use of non-linear devices. Due to the use of non-linear devices like power electronic converters, there is an increase in harmonic content in the source current. Due to this there is an increase in the losses, instability and poor voltage waveform. To mitigate the harmonics and provide the reactive power compensation, we use filters. There are different filters used in the power system. Passive filters provide limited compensation, so active filters can be used for variable compensation. In this paper, a shunt active filter has been made adaptive using a Variable Leaky Least Mean Square(VLLMS) based controller. Proposed adaptive controller can be able to compensate for harmonic currents, power factor and nonlinear load unbalance. DC capacitor voltage has been regulated at a desired level using a PI controller and a self-charging circuit technique. The design concept of proposed adaptive controller for shunt active filter has been verified through simulation and experimentation.

A large number of photovoltaic(PV) systems are decentralized and connected to distribution networks, leading to challenges in model simulation. This paper presents an equivalent modeling method for regional decentralized PV clusters based on cluster analysis. The proposed method is based on the grouping principle that PV systems have similar dynamic response characteristics, and grouping results are obtained using a fuzzy C-mean (FCM) clustering algorithm. Based on the clustering evaluation index, the optimal grouping number can then be determined and PV systems in the same group are combined into an equivalent PV system. The method to acquire equivalent parameters for PV arrays, transformers, and lines is also presented. A multi-machine equivalent model of regional decentralized PV clusters is established, and the precision and efficiency of the proposed method is demonstrated using an actual distribution network.

This paper presents two typical modulations to reduce conducted electromagnetic interference(EMI) for three-level voltage-source inverters. The first modulation called variable switching frequency pulse-width modulation(VSFPWM) based on real-time current ripple prediction is used to reduce differential-mode(DM) EMI noise. This technique can make conducted EMI between kHz and MHz achieve great attenuation. The other method named zero common-mode(CM) PWM is used to decrease CM voltage and current. A comprehensive analysis and comparison between normal SVPWM and zero-CM PWM state that zero-CM PWM pays the prices of higher Total Harmonic Distortion(THD), serious neutral voltage unbalance, more switching loss and lower modulation index to achieve theoretical elimination of CM voltage. Then, combination of VSFPWM and zero-CM modulation is designed to avoid the disadvantages such as large switching loss produced by zero-CM PWM, and the new method has obvious predominance of reducing conducted EMI noise. Relevant experimental results validate the advantages of these modulations.

High-voltage supplies for medical X-ray systems require up to 150 kV DC at up to 100 kW to supply the tube. The challenge for the power supply however is not only to deal with the high voltage and high power demand, but also to provide short voltage rise- and fall times in the range of 100μs. A coupled interleaved circuit variant of a single active bridge concept, the coupled interleaved single active bridge converter, is demonstrated in this work providing very fast output voltage control due to its non-resonant structure. The conduction modes of the circuit are analysed in detail and compared to the uncoupled interleaved single active bridge approach, demonstrating the advantages of low inverter RMS current, zero voltage switching(or at least zero current switching) over the full operating range with constant switching frequency. Analytic expressions for the output current-duty cycle relationship are provided. Experiments on a 60 kW(low voltage equivalent) prototype show that rise times as low as five switching cycles are possible, allowing to reach the target of 100μs rise time using a switching frequency of only 50 kHz.

The electromagnetic transient characteristics(ETC) of doubly-fed induction generator(DFIG) under grid voltage dip have been extensively studied theoretically, and various control strategies have been proposed. However, the ETC of DFIG under grid voltage swell are less studied. In order to study the influence on the ETC of DFIG under grid voltage swell and the corresponding control strategy, this paper compares and analyzes the steady-state and transient components of the stator flux linkage, rotor induced voltage and rotor current of DFIG under grid voltage swell and dip. It is deduced that DFIG is less prone to rotor over-current under grid voltage swell so the crowbar protection circuit is not needed, and the grid voltage amplitude changes little, the rotor side inverter is less prone to overmodulation. An experimental setup and simulation model is implemented with high-voltage ride-through of 1.5 MW doubly-fed wind Turbine. Simulation in addition to experimental results verifies the correctness and effectiveness of the theoretical analysis.

Fully electric vehicles are rapidly gaining user and market interest worldwide, due to their zero direct emissions, appealing driving experience and fashionable perception. Unfortunately, cost, range and reliability have not reached the desired targets yet. Since consumers are prone to spend money to have a more reliable system, Design-for-Reliability will be a useful tool for the Design of tomorrow’s EVs, justifying part of the increased cost for these products. In this work, a vertical model-based approach to design-for-Reliability of power converters for EVs is presented, paying special attention to thermally-induced aging. The design starts from various driving cycles, properly assembled to describe the vehicle mission, then load profiles for the converters are found and the resulting thermal stress is quantified. The converter life-time can be estimated, taking into account also parameter dispersion, and requirements for the active thermal control of the parts modeled achieved, thus giving practical information to the system designers.

The increasing integration of Photovoltaic(PV) and Battery Energy Storage Systems(PV-BESS) adds more power control flexibility of the PV systems. This offers an opportunity to improve the PV inverter reliability, where the loading of the PV inverter can be modified through the operation of the battery system(e.g., charge/discharge). In that case, the control strategy of battery systems will affect the PV inverter loading and thereby also the reliability. This paper investigates the potential solution to enhance the PV inverter reliability through the control of battery system, where three self-consumption control strategies are considered. The impact of the battery system control strategies on the PV inverter reliability is analyzed with the mission profile of a 6-kW PV-BESS installed in Germany. The evaluation results indicate that limiting the maximum charging power of the battery system has high potential to enhance the PV inverter reliability, where the damage of power devices in the inverter can be reduced by approximately 50%.

Electric, hybrid and fuel cell vehicles have attracted significant attention in the past decades due to their distinguish advantages to reduce fossil fuel consumption and improve the environment. Electric vehicles use electronic subsystems – in comparison to conventional vehicles, which include electric machines, power electronics, electronic continuously variable transmissions(CVT), on-board chargers, and embedded powertrain controllers. Advanced energy storage systems, such as Li-ion batteries, ultracapacitors, and fuel cells, together with intelligent energy management algorithms, are introduced in the next generation powertrains. In addition to these electrification components or subsystems, conventional internal combustion engines(ICE), mechanical and hydraulic systems may still be present. As a result, the complexity of new powertrain designs and dependence on embedded software is a cause of concern to automotive research and development efforts. This leads to an increasing difficulty in predicting interactions among various vehicle components and systems.