Analysis of self-excitation and performance characteristics of a single-phase self-excited induction generator by field-circuit method

Abstract

Purpose – The purpose of this paper is to present analysis of an influence of rotor slots opening on self-excitation process, terminal voltage and performance characteristics of the single-phase self-excited induction generator (SPSEIG). Design/methodology/approach – The paper presents field analysis of the self-excitation problem in the SPSEIG and performance characteristics on the base of two-dimensional field-circuit model of the generator. Findings – The carried out field computations of the tested SPSEIG with closed rotor slots showed that only an initial voltage across the excitation capacitor of about nominal value (230 V) causes successful self-excitation of the generator. It was also proved that the suitable opening of the rotor slots, beside remnant flux density in the rotor core, facilitates self-excitation in the generator. Since in working applications initially charging of the capacitor to almost nominal voltage may cause a problem, therefore employment of semi-closed rotor slots in the SPSEIG would be proper solution. Originality/value – The conducted simulations, validated by laboratory tests showed that not only suitable excitation capacitor capacitance and rotor speed are needed to obtain desired terminal voltage of the generator, but also suitable initial voltage across the capacitor in auxiliary stator winding is very important and necessary for reliable self-excitation of the single-phase induction generator with closed rotor slots. The employment of semi-closed rotor slots in the SPSEIG makes the self-excitation more effective.

Pengaruh Pembebanan Terhadap Tegangan dan Frekuensi Pada Generator 3 Fasa

“…Penggunaan generator sebagai sumber daya listrik sudah merupakan hal yang umum, [2] mengungkapkan generator induksi dapat dioperasikan menggunakan motor induksi 3 fasa, disamping harga yang lebih murah, konstruksi sederhana juga kemudahan dalam mengoprasikannya [3]. Namun tetap saja penggunaan generator jenis ini tidak lepas dari masalah, [4] menjelaskan bahwa generator 3 fasa yang tereksitasi diri dapat menghasilkan harmonic, dimana harmonic merupakan deretan gelombang arus atau tegangan yang frekuensinya merupakan kelipatan bilangan bulat dari frekuensi dasar arus atau tegangan itu sendiri. Adanya harmonik ini dapat mempengaruhi faktor daya dan kinerja dari peralatan-peralatan listrik yang terpasang pada sistem, terutama pada sumber penghasil energi listrik itu sendiri yaitu generator [5].…”

Comparative analysis of single-phase self-excited induction generators of various rotor cages

“…For production of low-power single-phase electrical energy, self-excited induction generators (SP-SEIGs) driven by a micro-hydro or micro-wind turbine may be applied. Usually, for single-phase power generation as an auxiliary energy source at household, single phase of two separate stator windings' induction machines of power up to 3 kW will be sufficient operating as an autonomous single-phase selfexcited induction generator [1][2][3][4][5][6]. When larger electrical power is needed, a three-phase stator winding self-excited induction generator with single-phase output should be employed for feeding single-phase loads [7][8][9].…”

Field-circuit analysis and measurements of a single-phase self-excited induction generator

“…The field-circuit model of the generator was described in detail in [5]. Self-excitation transients of voltages and currents of stator windings obtained by measurements at no-load and speed n = 1620 rpm for N A = 444 and 424 turns, and excitation capacitor Cex = 40 µF with capacitor C sh = 20 µF connected in parallel to terminals, are presented in Figures 3-6.…”

“…The finite element mesh of ,t)] -the current density in the rotor bars, ν -reluctivity of magnetic material, σ -electric conductivity. Two-dimensional field equations coupled with voltage equations of stator and rotor windings [5] were solved simultaneously to obtain voltages and currents induced in the stator and rotor. Having the variables A and J computed, the other quantities of electromagnetic field as magnetic flux, magnetic induction, etc.…”

“…A comprehensive simulation model valid both for steady-state and transients may be obtained only by field-circuit modeling of the induction generators. Such field-circuit models can be found in recent papers [5][6][7][8][9]. They allow to analyze all relevant electromagnetic phenomena in induction machines and usually yield more accurate results but are more expensive in terms of computing time.…”