Sensors and Actuators A 106 (2003) 286–291 Permanent magnet machine operation with static converter: modeling and experimental verification of space harmonics effects A. Haniotis, A. Kladas * Laboratory of Electrical Machines, Electric Power Division, Department of Electrical and Computer Engineering, National Technical University of Athens, 9 Heroon Polytechneiou Str., Athens 15780, Greece Abstract An analysis of the higher space harmonics’ impact on permanent magnet actuator performance when supplied by static converters is presented. Alternative models using only the fundamental field component and including higher harmonics are compared to measurements. Inaccuracies of fundamental component models greatly depend on machine loading. A new modeling technique is proposed providing good accuracy in all cases. © 2003 Elsevier B.V. All rights reserved. Keywords: Permanent magnet actuators; Higher harmonics; Static converters; Voltage waveforms 1. Introduction The paper compares alternative modeling techniques for simulation of permanent magnet machines operating with static converters [1]. The model representing only the fun- damental component of the air-gap magnetic field based on d–q-axes analysis, frequently used in the literature [2], is compared with a new one incorporating all magnetic field space harmonics. The case of a “peripheral structure” permanent magnet machine has been used in association with a converter comprising a rectifier and an inverter stage. Permanent magnet machines present important space harmonics in the air-gap field distribution, due to their structure, which may interact with the converter time har- monics and result in important inaccuracies when modeled by the standard fundamental field representation, adopted by d–q-axes transformation techniques [3,4]. An alterna- tive model is proposed for the machine analysis, including space harmonics through convenient description of the ma- chine electromotive force, which can be obtained through field calculations by finite-element techniques. The pro- posed model provides good accuracy in all system loading conditions. * Corresponding author. E-mail addresses: achan@cc.ece.ntua.gr (A. Haniotis), kladasel@central.ntua.gr (A. Kladas). 2. Permanent magnet actuators Permanent magnets have been extensively used to replace the excitation winding in synchronous machines with the well-known advantages of simple rotor design without field windings, slip rings and exciter generator, avoiding heat dis- sipation in the rotor and providing higher overall efficiency. The rotor design can be distinguished into three main types according to the magnet position, namely the interior [3], the peripheral [7], and the claw-pole type. Recent advances in power electronics enabling energy-efficient drives have aroused interest in using permanent magnet machines in small and medium systems [5,6]. In small-scale systems the ferromagnetic material opti- mization in conjunction with standard-shape low-cost per- manent magnets can provide attractive rivals to the common asynchronous machine actuators. New magnetic materials exhibiting greater magnetization, such as neodymium alloys, enable advances in machine performance [7]. 3. Fundamental component and higher harmonic models In order to predict the behavior of such a permanent mag- net actuator accurately, different types of simulation models need to be combined. What is very important is the time variation determination of electromotive force produced by 0924-4247/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0924-4247(03)00186-9