Modular OrCAD simulation approach in teaching power electronics

In this paper the authors present a new technique which can be used in simulating multi power electronic circuits at the same time in a very accurate way without the worries of the circuit analysis being diverted during the simulation. In this technique each circuits is simulated alone and the output current/voltage waveform(s) of this circuit is presented as a 'wave-form' generator. Then the final multi circuit design will be a collection of these 'wave-form' generators. This technique can be used in teaching power electronics system design for undergraduate as well as postgraduate levels and can also be used in the industry. A UPS system is used as an example in demonstrating this technique but this approach could equally be applicable to other multi circuit design configurations

New mathematical model for analysing three-phase controlled rectifier using switching functions

This paper is a postprint of a paper submitted to and accepted for publication in IET Power Electronics and is subject to Institution of Engineering and Technology Copyright. The copy of record is available at IET Digital Library.The aim of this study is to present a set of closed-form analytical equations in order to enable the computation of the three-phase bridge rectifier steady-state performance estimation. The proposed method presented in this study is a fast, accurate and effective mathematical model for analysing three-phase full-wave controlled rectifiers. The steady-state mathematical model is based on the derivation of an appropriate set of switching functions using the general switching matrix circuit (GSMC) techniques. Once the switching functions are derived, the output current, input current and output dc voltage can all be easily derived and generated from the application of this technique. The effect of overlap is accurately modelled and the distortion (notches), frequency content on the input (voltage and current) and output voltage distortion are derived. The proposed mathematical model, unlike conventional analytical methods, can be integrated in the design of active filters. Furthermore, the output voltage reduction, the rms, average and peak values of voltages and currents for the thyristors and any other semiconductor devices used are readily available for the designer by direct substitution into closed-form equations without any need for the waste of time for worst-case scenario simulations. This method can also be applied to other types of converters, specifically to all voltage fed power converters

Variable var compensator circuits

A family of two reactive-power compensator circuit is presented. A general model of some basic linear elements and switching function blocks is developed first. Then the two proposed compensator circuits are derived from the generalised model. The proposed circuits are capable of supplying leading as well as lagging reactive currents in stepless variation without using an inverter configuration. The switching frequency is in the range of 2.5 kHz and the largest capacitor utilised does not exceed 60 muF. The generated reactive current, in either the leading or lagging modes, contains less than 2% total harmonic distortio

Fast functional modelling of diode-bridge rectifier using dynamic phasors

In this paper, a functional model for diode-bridge rectifiers is developed based on the dynamic phasor concept. The developed model is suitable for accelerated simulation studies of the electric power systems under normal, unbalanced and line faulty conditions. The high accuracy and efficiency of the developed model have been demonstrated by comparison against three-phase time-domain model and against the model employing synchronous space-vector representations. The experimental verification of the developed model is also reported. In addition, an error analysis shows that the error of the developed model is less than 10% at the most severe unbalanced conditions. The prime purpose of the model is for the simulation studies of more-electric aircraft power architectures at a system level; however it can be directly applied for simulation study of any other electrical power system interfacing with uncontrolled diode bridge rectifiers

Review of Wireless Charging of EV

Electrified transportation will minimise greenhouse gas emissions while also lowering gasoline prices. To encourage the adoption of electrified transportation, a variety of charging networks must be established in a user-friendly environment. WEVCS (wireless electric vehicle charging systems) could be a viable alternative technology for charging electric vehicles (EVs) without the need for a plug. The work done in the area of wireless power transfer technology for electric vehicles is described in this paper

Power Switching Device Losses - Simulation and Non-Simulation Methods of Calculations

In the design and manufacture of power supplies and converters, commercial factors demand high efficiency figures in the operation and performance of these products. Potential loss areas in the circuits are identified to achieve minimum losses [1] [2]. One of the main component contributing to losses in converters is the switching device.The methods to calculate switching loss [3] are complex and involves several related parameters [4] [5]. Conduction loss, radiation interference [6] and temperature rise, impacts on design efficiency. Depending on the design limitations, a balance between the related parameters is necessary, which can be achieved by optimization processes. The method of linear approximation has useful deductions in the control of turn-on switch loss, choosing switches devices with short switching times, which offers high operating frequencies

Optimisation and Simulation of RC Time Constants in Snubber Circuits

Semiconductor devices are subjected to elevated levels of stresses when used at high voltage high current and temperature applications. This stress is mainly due to hard switching which is proportional to the switching frequency. This paper presents methods used to remove this energy to prevent expensive switch damage due to overheating and high dv/dt oscillations. In confirmation of the research title, the process in the determination of 'RC' in snubber circuits has been proven by OrCAD optimisation and presented

PSPICE Modeling of a Build-in Feedback Automatic –Reactive Power Compensation

Over the last few years, the sudden increase of the use of non-linear loads such as personal computers and TV sets created a Power Factor (PF) problem. Although such loads consume relatively small amount of power, however the large number of these loads resulted on huge distortion in the power quality. This paper proposes an automatic reactive power compensation circuit which can generate a leading as well as lagging reactive current. The proposed circuit consists of a build-in feedback system which automatically controls the amount and the type (leading or lagging) of the reactive power required. The compensator is modeled on PSPICE at the component level to illustrate both the transient and the steady state responses

A solid-state fault current limiting and interrupting device (FCLID) with power factor correction

A Solid-State Fault Current Limiter and interrupting device (FCLID) with power factor correction suitable for low-voltage distribution networks employing the Switched Capacitor (SC) Circuit is presented. Some design parameters are investigated and some optimisation is applied. In this application the Switched Capacitor (SC) is inserted in series with the supply line via an isolating transformer, providing both power factor correction and limitation of the current to a pre-set value in the event of a fault. Interruption of the fault is also possible by setting both semiconductor switches in the off state. The voltage across the load is increased. Optimisation is applied to correct the power factor to an acceptable value of 0.85 and keep the load voltage within acceptable limits. Losses are estimated and rating of components is discussed

Supercapacitor application for PV power smoothing

© 2018 IEEE. The penetration of renewable energy technologies causes grid stability problems and voltage flickering due to fluctuations of the weather conditions, which affect the produced renewable power. The system is first analyzed in order to define the operating point and the controlling parameters, in which the produced power is shared correctly between the load and the grid at a power factor close to unity. The operating point is set by the duty cycle (D) of the DC-DC converter, the depth of modulation (Dm) of the inverter, and the phase angle (δ) between the output voltage of the inverter and the grid voltage. The simulated system is operated in an open-loop mode in order to investigate the effect of each parameter without the corrective action of the closed-loops of the MPPT and the load angle. After that, a preliminary investigation of a supercapacitor controlled storage application is performed in terms of the power flow. All calculated theoretical results are verified by the simulation results. This research forms the basis for an in-depth investigation of supercapacitor and battery storage in grid-connected systems