This paper presents a high efficiency high power-density LLC DC-DC converter for Electric Vehicles (EVs) on-board low voltage DC-DC converter (LDC) application. In the proposed LDC, primary switches ...achieve ZVS turn-on and secondary synchronous rectifier switches achieve ZVS turn-on and ZCS turn-off. To reduce current stress and improve efficiency, three phase interleaved LLC DC-DC converters are paralleled to provide more than 200A load current. Switch-Controlled Capacitor (SCC) technology is used to achieve the load current sharing of the three phase LLC DC-DC converter. In addition, GaN HEMTs are used in the transformer primary to improve the switching frequency and power-density. To verify the analysis, a 3.8kW(14V/270A) LLC DC-DC converter prototype is designed. The experimental results show that full load efficiency is 95.8% at 270A load current and 3kW/L power-density is achieved.
Understanding the importance of saturation of parameters in line-start permanent magnet synchronous machine (LSPMSM) and the scanty available research literature on simplistic methods of determining ...the magnetizing characteristics of LSPMSM, this paper proposes a novel and yet simplistic approach towards its determination. Experimental investigations have been performed on a laboratory LSPMSM based on the proposed dq axis (two-axis)-based methodology and the measured magnetization characteristics of the machine has been incorporated into the machine model. The measured characteristics have hence been validated through dynamic and steady state performance analyses of the machine under direct online (DOL) starting. Furthermore, performance analysis of the machine has also been performed through the developed machine model with and without incorporating the magnetization characteristics of the machine to elicit the effects of parameter saturation during startup and synchronization of the machine.
Understanding the need for improvement in monitoring and protection in high performance charging technology for a growing demand of EVs/PHEVs, this research manuscript presents a part of an ongoing ...project and proposes a novel low cost dual purpose triangular neural network based module for power quality monitoring and protection (M&P) and elicits its performance in times of abnormalities or malfunction in a high performance off-board level 3 bi-directional charger for electric vehicles. Firstly, design and implementation of the low cost dual purpose triangular neural network based device for monitoring the power quality and hence, protecting the grid has been explained and its performance has been presented through numerical investigations. Going a step further, the device has also been experimentally tested using an in-house electric vehicle containing a commercially available battery charger and the measured results are analyzed. Secondly, a high-performance vector-controlled bi-directional off-board level-3 charger for faster and efficient charging has been developed and investigations have been performed on the healthy charger to analyze its performance. The primary aim of developing this charger was to elicit the usage and performance of the previously developed M&P device to protect the grid in case of some typical charger malfunction problem in such a charger, which is not detectable by conventional low cost sensors employed with such chargers. Once the module detects any abnormalities in the charger's operation, information gathered can be used to tune the controller in the charger to obtain a constant improved performance of the charger or the power transfer can be terminated.
Centralized generation is being supplemented or replaced fast by distributed generation, a new way of thinking about electricity generation, transmission and distribution. Understanding the ...significance and prospects of self-excited induction generators (SEIGs) in distributed wind power generation (DWPG), this paper firstly presents a comprehensive suitability analysis of commercially available niche copper-rotor induction motor (CRIM) and conventional aluminum-rotor induction motor (ARIM) to be used as induction generators in the above application, through experimental investigations performed on two industrial 7.5 hp CRIM and ARIM. The results of the performance analyses on the two machines provide data for development of a novel control scheme comprising of wavelet transforms and particle swarm optimization technique, proposed next, to alleviate the problem of voltage regulation (VR) associated with the SEIGs. The developed controller for VR is implemented on a low cost embedded system, hence making it economical and flexible for patenting. The developed embedded system is validated initially through an actuator performing mechanical switching of requisite capacitances and finally by integrating it with another actuator, namely, the static synchronous compensator (STATCOM), for efficient voltage regulation. Finally, the tested results are presented.
The traditional higher order sliding mode observer (HSMO) based sensorless control strategy uses a constant gain. However, very large gain value can decrease the output accuracy, while very small ...gain value will degrade the sliding mode observer's stability. Therefore, under uncertain disturbances, an adaptive gain should be set for the higher order sliding mode observer. This paper proposes a variable universe fuzzy adaptive high order sliding mode observer based sensorless control (VUF-HSMO) strategy for permanent magnet synchronous machines (PMSMs) to achieve high precision sensorless control. Firstly, fuzzy logic control technique is used to get an adaptive gain in the HSMO. Then, variable universe theory is employed to self-tune the universe of discourse according to the change of inputs, and this results in the improvement in position estimation accuracy. Experiment results under different conditions demonstrate the effectiveness and the superiority of the proposed VUF-HSMO based sensorless control compared with the traditional HSMO and fuzzy logic based HSMO.
This paper presents an unscented Kalman filter (UKF) based method to estimate the severity level of stator interturn short circuit fault in permanent magnet synchronous machines (PMSMs). A ...mathematical model is firstly built for PMSMs to represent the machine dynamic with inter-turn faults (ISF). The voltage imbalance, inherent asymmetry, and ISF effects are all differentiated analytically by the model. To quantify the fault severity in the presence of unmeasurable fault parameters, the UKF is employed to estimate the nonlinear fault-related quantities in PMSMs, such as the short circuit current, the percentage of shorted turns, and fault loop resistance. The effectiveness and reliability of the proposed method have been validated by extensive simulations.
As Canada and the world move rapidly toward increased reliance on wind power generation, self-excited induction generators (SEIGs) will play an important role in distributed wind power generation ...(DWPG). Understanding the significance and prospects of SEIGs in DWPG, first, this paper elucidates the significance of fault detection (FD) and voltage regulation (VR) in the aforementioned application. A comprehensive analysis of VR and faults on niche industrial 7.5-hp copper-rotor SEIG and conventional 7.5-hp aluminum-rotor SEIG is performed through numerical simulations, and the calculated results are validated through experimental investigations. Second, a twofold Daubechies-wavelet-transform-based module is designed for the following: 1) FD and 2) VR, respectively. A discrete-wavelet-transform-based algorithm is proposed and implemented on a low-cost embedded system to provide an economical solution for the aforementioned issues. Thereafter, the aforementioned schemes are tested, and results are investigated.
The reliability analysis of traction inverters is of great interest due to the use of new semi-conductor devices and inverter topologies in electric vehicles (EVs). Switching devices in the inverter ...are the most vulnerable component due to the electrical, thermal and mechanical stresses based on various driving conditions. Accurate stress analysis of power module is imperative for development of compact high-performance inverter designs with enhanced reliability. Therefore, this paper presents an inverter reliability estimation approach using an enhanced power loss model developed considering dynamic and transient influence of power semi-conductors. The temperature variation tracking has been improved by incorporating power module component parameters in an LPTN model of the inverter. A 100 kW EV grade traction inverter is used to validate the developed mathematical models towards estimating the inverter performance and subsequently, predicting the remaining useful lifetime of the inverter against two commonly used drive cycles.
In this era of electrified transportation, inadequate fast-charging infrastructure and limited driving ranges in vehicles due to current energy storage technology remain bottlenecks in motivating ...consumers to rapidly shift to these electrified vehicles. Mass integration of these vehicles into the grid in the future would result in huge stress on the existing grid in terms of quantity and quality of power consumed. Understanding these issues in detail, this article exclusively discusses the design, development, and comprehensive testing of a multi-port sustainable fast-charging station involving solar photovoltaic, an in-house battery electric vehicle, the utility grid, multiple power electronic converters, and proper control under various modes of operation of the charging station. Such a charging station would enable quick and conventional charging with a lower power level through sustainable power, if available, hence reducing the impact on the grid and the energy cost of system operation.
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