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Gallium nitride (GaN) based high-electron-mobility transistor (HEMT) is getting popular in power electronics applications due to its low on-state resistance and superior switching characteristics. The on-state resistance of the switch is an important factor in the efficiency of the GaN switch based power converter. Firstly, the basic principle of operation of a normally-on GaN/AlGaN HEMT is reviewed...
Asymmetric H-bridge converter is widely used for feeding a switched reluctance machine (SRM). This paper discusses a method to estimate the losses in the power devices in such type of converters, where average torque control or square current injection is employed. This paper presents the cooling system design for a silicon carbide (SiC) based asymmetric H-bridge converter. The SiC MOSFETs and the...
Silicon Carbide (SiC) is a compound semiconductor has ten times the dielectric breakdown field strength, three times the band-gap, and three times the thermal conductivity of silicon (Si). SiC MOSFETs can be operated at higher switching frequencies and higher ambient temperatures than Si MOSFETs. This paper deals with design, fabrication and testing of a gate driver circuit for driving SiC power MOSFETs...
Isolated DC-DC conversion with high power density is widely achieved by DC to high-frequency AC conversion, followed by isolation and high frequency rectification. Selection of high-performance diodes for such high-frequency rectification is challenging as a trade-off is often required among numerous conflicting parameters. Three high performance diodes, namely, an ultra-fast silicon diode, a super...
Position sensorless vector control drives in the rotor-flux-oriented reference frame require precise estimation of rotor flux. A few open-loop rotor flux estimation methods are quite popular. However, the performance of these estimators is quite poor when the inverter switching frequency is quite low as in case of high power drives or when the ratio of switching frequency to maximum fundamental frequency...
Inverter dead-time is known to make open-loop induction motor drives oscillatory, while operating at light-loads in particular. While dead-time compensation schemes exist, precise compensation of the same is often challenging as it involves factors such as device and driver delays and switching transition times, which are difficult to be quantified accurately. Hence, the effect of dead-time could...
Offline pulse width modulation (PWM) techniques are employed to reduce the line current distortion in induction motor (IM) drives where the switching frequency is highly constrained. An optimal PWM technique is proposed here for a neutral point clamped (NPC) inverter fed IM drive to minimize the motor current distortion, subject to constraints on number of switching instants per quarter cycle. Two...
A novel current controller for constant current injection based characterization of switched reluctance machine (SRM) is proposed here. Unlike conventional characterization methods, where the rotor is locked at a fixed position, the current injection based method maintains the phase current constant while the machine is run at constant speed. The proposed constant current injection scheme yields the...
Switched reluctance machine drive requires knowledge of flux linkage characteristics and its partial derivatives for high performance controller design and implementation. A mathematical model, which accurately describes the flux linkage characteristics as well as easily provides its partial derivatives, is proposed in this paper. The proposed model, even though accurate, has fewer parameters than...
Miniature Full Spectrum Simulator (mini-FSS) is a real-time simulator for power electronics and power systems applications, meant for educational purposes. It has been indigenously developed under the National Mission on Power Electronics Technology (NaMPET) Phase II, funded by Government of India. This paper presents the real-time simulation of an islanded microgrid on the mini-FSS. As a first test...
In this paper focus is to study various transition sub-intervals of an IGBT during switching events. The relationship of these transition duration with the switching voltage, device current and junction temperature is studied experimentally. This study is further extended to understand the effect of these time duration deciding the dead time between the switching of positive and negative devices in...
In this paper the focus is to study the switching characteristic of antiparallel diode in an IGBT module. The switching characteristic parameters reverse recovery time, peak reverse recovery current and corresponding energy loss during the diode turn-off transition are studied experimentally. The relationship of these characteristic parameters with the operating conditions, namely, switching voltage,...
High speed generation derives its motivation from a variety of applications such as concentrated solar power (CSP) generation, hybrid automotive power generation and aerospace. Research is actively been pursued in the field of power generation using solar heat, where novel thermodynamic cycles like supercritical carbon dioxide (sCO2) Brayton and Organic Rankine Cycles are considered as superior options...
Impact of integration of distributed generation (DG) sources on large power networks cannot be studied accurately using computer simulations since building of accurate models of a variety of DG sources and their controls is challenging. Power hardware in the loop (PHIL) simulations help realistic integration studies as they allow interfacing of physical DG systems with well-established power grid...
In sine-triangle (ST) pulse width modulation (PWM), the carrier frequency is chosen to be an odd-triplen multiple (e.g., 3, 9, 15… etc.) of the modulating signal frequency in order to maintain the three-phase symmetry among the three pole voltages. However, for ST PWM with non-triplen pulse numbers (e.g., 5, 7, 11… etc.), the three-phase symmetry is not maintained. This paper studies the influence...
For safe operation of voltage source converters, dead-time is provided to the IGBTs that belong to a single leg. While a large value of dead-time prevents dc-bus shoot-through, it also causes error in the output voltage of the power converter, leading to distortion of line currents and increased harmonic content in them. The problem is more severe in case of high switching frequency operation of the...
This paper describes mechanical and thermal design aspects of a 5 kW Switched Reluctance Motor. In Switched Reluctance Motor (SRM), the rotor neither has winding nor any permanent magnet in contrast to conventional Induction or permanent magnet machines. Although, this considerably simplifies the mechanical design, high current densities in the stator generate a substantial amount of heat. It is,...
In this paper a systematic procedure for designing a switched reluctance machine (SRM) is given. The process starts with specified torque, speed and DC bus voltage and ends with stator dimensions, rotor dimensions and stator winding details. It is divided into three parts - machine configuration where number of phases, stator and rotor poles are chosen, magnetic design where the machine dimensions...
The effect of inverter dead-time on the inverter output voltage is well studied in literature. This paper studies the effect of the dead-time on the inverter input current, and includes this effect in the dc link dynamic model of a diode-bridge-rectifier (DBR) fed voltage source inverter (VSI). Based on this study, this paper proposes a dynamic model of a rectifier-inverter-fed induction motor, that...
Neutral point clamped (NPC) multilevel inverter fed high power drives, operating at low switching frequency, are prone to low-order torque pulsations. This paper considers a specific case of four switching angles per quarter cycle of the pole voltage. For such cases, apart from maintaining the fundamental component, three voltage harmonics can be eliminated. Consequently, only one torque harmonic...
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