EPE Journal Volume 16-3 
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EPE Journal Volume 16-3 - Editorial
EPE Journal Volume 16-3 - Papers



 EPE Journal Volume 16-3 - Editorial 

Invitation to EPE 2007  [Details]
By Frede Blaabjerg, Aalborg University
The editorial of EPE Journal volume 16-3, July - September 2006, "Invitation to EPE 2007", written by Prof. Frede Blaabjerg, the EPE 2007 Conference Chairman


 EPE Journal Volume 16-3 - Papers 

A Sensorless Field Oriented Control of Induction Motor Using Ripple Currents in Space Phasor Based PWM Control  [Details]
By K. K. Mohapatra, K. Gopakumar, M. R. Baiju, Balarama. V. Murty

A scheme for sensorless flux estimation for the induction motor drives is presented in this paper, where the flux information is derived from the current ripple. The scheme measures the stator current phasor deviation to determine the back emf vector position during the zero vectors of the inverter. The position of the rotor flux is detected indirectly by computing the position of the motor back emf, which is orthogonal to the rotor flux position. The space vector PWM generates a current ripple pattern in the machine current, which depends upon the ripple voltage and equivalent stator leakage inductance. For high speed operation when the time duration for the zero vector switching states are small, an indirect method for estimation of flux position is proposed, where the effect of active voltage vectors on the stator ripple current is eliminated by creating a virtual short circuit at the motor terminals. This is achieved by linear transformation of the fundamental components of two immediate current space phasor deviations within a switching period. The whole scheme is implemented in a space phasor based PWM drive with constant inverter switching frequency. The position of the back emf is estimated for both high speed and low speed by implementing the proposed method in a TMS320LF2407 DSP based board.

Control of Single-Stage Single-Phase PV Inverter  [Details]
By M. Ciobotaru; R. Teodorescu; F. Blaabjerg

In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers (the classical proportional-integral (PI) and the novel proportional-resonant (PR) controllers) have been implemented and an experimental comparison between them has been made. A complete control structure for the singlephase PV system is also presented. The superiority of the PR controller is demonstrated with respect to the PI controller in terms of harmonic current rejection and the capability to remove the steady-state error without using the voltage feedforward (VFF). The control strategy was successfully tested on a real 1.5 kW PV inverter.

Comparison of Direct Multiobjective Optimization Methods for the Design of Electric Vehicles  [Details]
By X. Roboam; J. Régnier; B. Sareni; Y. Ferfermann

"System design oriented methodologies" are discussed in this paper through the comparison of multiobjective optimization methods applied to heterogeneous devices in electrical engineering. Avoiding criteria function derivatives, direct optimization algorithms are used. In particular, deterministic geometric methods such as the Hooke & Jeeves heuristic approach are compared with stochastic evolutionary algorithms (Pareto genetic algorithms). Different issues relative to convergence rapidity and robustness on mixed (continuous/discrete), constrained and multiobjective problems are discussed. A typical electrical engineering heterogeneous and multidisciplinary system is considered as a case study: the motor drive of an electric vehicle. Some results emphasize the capacity of each approach to facilitate system analysis and particularly to display couplings between optimization parameters, constraints, objectives and the driving mission.

Dynamic Performance Comparison of IRFO and SFO–SM Controlled Drives in Field-Weakening Region using Variable-Saturation Regulators  [Details]
By F. Cupertino; N. Salvatore; G. L. Cascella

This paper proposes to use variable-saturation regulators for Induction Motor (IM) drives operating in field-weakening region, and presents a comparative dynamic-performance analysis between the traditional Indirect Rotor Field Oriented (IRFO) control scheme and a new Stator Flux Oriented – Sliding Mode (SFO-SM) control scheme. The traditional IRFO control scheme has the d-axis current component, torque, rotor flux, and speed loops with four PI-type controllers. The SFOSM control system is a Direct Torque Control – Space Vector Modulation (DTC-SVM) scheme with closed loops of torque and stator flux without current PI-type controllers. Both control schemes use regulators with variable-saturation in such a way that maximum dc-bus voltage utilization is reached and overcurrent problems are prevented. The experiments are carried out using dSPACE digital controllers and comparative results show that the SFO-SM controlled IM drive and IRFO one are characterized by similar dynamic responses in spite of structural simplicity of the SFO-SM control scheme.

Characteristic Measurement System for Automotive Class Switched Reluctance Machines  [Details]
By N. H. Fuengwarodsakul; S. E. Bauer; R. W. De Doncker

Flux-linkage characteristics and torque characteristics (versus current and rotor position) of switched reluctance machines (SRM) can be regarded as the fingerprint of SRMs because they are indispensable fundamental data to model machine behavior for both simulation and control proposes. In contrast to other types of electrical machines, e.g. induction machines and synchronous machines, SRMs are basically characterized by a strongly nonlinear behavior due to typical operation in the magnetic saturation region. Hence, no analytical functions can be applied to describe the characteristics of SRMs precisely. An accurate SRM model inevitably needs the complete machine characteristics in form of data-intensive look-up tables to represent the machine behavior. Basically, the SRM characteristics can be calculated by Finite Element (FE) simulation. However, real SRM characteristics can be different from the simulation model due to secondary effects, e.g. non-uniform material and manufacturing tolerances, which are normally not considered in the FEsimulation model. Therefore, the experimental measurement is preferred. Measuring and preparing the SRM characteristics is a complicated and time-consuming task. The time-expense as well as possible human errors in determining the SRM characteristics can be greatly minimized, if the measurement procedures are automated.

This paper presents an automated characteristic measurement system for determining SRM characteristics experimentally. The measurement system was designed for automotive class SRMs, e.g. starter-generators, hybrid or main propulsion motors. The applied measurement methods, the system design and construction are described in the paper. Furthermore, constraints and discussions concerning the measurement accuracy are treated.

Polyphase Boost Converter with Digital Control  [Details]
By R. Mirzaei; V. Ramanarayanan

Boost d.c.-d.c. converters have very good source interface properties. The input inductor makes the source current smooth and hence these converters provide very good EMI performance. On account of this good property, the boost converter is also the preferred converter for off-line UPF rectifiers. One of the issues of concern in these converters is the large size of the storage capacitor on the dc link. The boost converter suffers from the disadvantage of discontinuous current injected to the load. The size of the capacitor is large. Further, the ripple current in the capacitor is as much as the load current; hence the ESR specification of the tank capacitor is demanding. This paper presents the polyphase boost converter, which overcomes the problem of high ripple current in the tank capacitor, which has not been discussed earlier. Comparison between the specifications of single stage and multistage is thoroughly examined. Digital control is more convenient for such a topology on account of the requirement of synchronization, phase shifted operation and current balancing. The control method is simpler and faster than its original form [10]. It does not depend on the previous duty ratio and it has been tested on four boost converters in parallel. Each is a 35W unit switched at 200 kHz. Experimental results in digital control, synchronization operation and current sharing are presented. The control method is implemented using a TI’s general purpose Digital Signal Processor eZdspF2812. This control scheme is applicable for PFC rectifiers as well.