Unaprijeđeno upravljanje momentom visokobrzinskog pogona s asinkronim motorom bez mjerenja brzine

This paper presents improved torque control scheme for a high speed sensorless induction motor drive. The proposed high speed torque control scheme substitutes the flux oriented control by the voltage angle control in the flux weakening regime. This scheme uses maximum of available inverter voltage, alleviates well known problems of current control schemes in conditions with insufficient voltage margin and avoids the influence of estimated speed error to the achieved flux level. The algorithm uses similar slip control as flux oriented control algorithm, but is applied without an outer flux trajectory reference which is typical for the flux weakening, providing a fast and well damped torque response even if error in estimated speed is present. Experiments confirm the effectiveness of proposed torque control algorithm, smooth transition from the flux oriented control in the base speed region to the voltage angle control in the flux weakening, superior dynamic performance of the voltage angle torque control, and its robustness to an estimated rotor speed error.U radu je predstavljena unaprijeđena shema upravljanja za pogon visokobrzinskog asinkronog motora bez mjerenja brzine. Predloženi postupak zamjenjuje vektorsko upravljanje upravljačkom strukturom s upravljanjem kutom napona u slabljenju polja. Predložena shema koristi maksimalni raspoloživi napon invertora, eliminira dobro poznate probleme strujno reguliranih pogona u uvjetima s nedovoljnom rezervom napona i eliminira utjecaj greške u estimaciji brzine na dostignutu razinu toka. Algoritam koristi sličnu kontrolu klizanja kao i vektorsko upravljanje, ali bez tipičnog vanjskog zadavanja toka u slabljenju polja, pružajući brz i dobro prigušen odziv momenta čak i u slučaju greške u estimaciji brzine. Eksperimenti izvedeni na velikoj brzini vrtnje potvrđuju učinkovitost predložene regulacije momenta, gladak prijelaz iz baznog područja brzine u slabljenje polja, vrhunske dinamičke performanse upravljanja kutom napona i robusnost na pogrešku u estimiranoj brzini vrtnje

Comparison of interior permanent magnet synchronous machines for a high-speed application

Permanent Magnet machines have been increasingly used in high-speed applications due to the advantages they offer such as higher efficiency, output torque and, output power. This dissertation discusses the electrical and magnetic design of permanent magnet machines and the design and analysis of two 10 kW, 30000 rpm Interior Permanent Magnet (IPM) machines. This dissertation consists of two parts: the first part discusses high-speed machine topologies, and in particular the permanent magnet machine. Trends, advantages, disadvantages, recent developments, etc. are discussed and conclusions are made. The second part presents the design, analysis and testing of interior permanent magnet machines for a high-speed application. The machines are designed from first principles and are simulated using Ansys Maxwell software to understand the finite element analysis. In order to obtain a fair comparison between the machines, the required output criteria was used as the judging criteria (10kW, 30000 rpm). As a result, the rotor diameter, stator diameter, airgap length, and stack length were kept the same for both machines. The winding configuration was set as distributed windings, however the number of turns and other details were kept flexible in order to be able to obtain the best design for each machine. Similarly, the magnet volume was kept flexible as this could be used as a comparison criteria relating to the cost of the machines. The two IPM topologies are compared with respect to their torque, magnetic field, airgap flux, core loss, efficiency, and cost. The radial IPM produces a smoother torque output, with lower torque ripple, and has lower losses compared to the circumferential IPM which produces a higher torque and power output. Furthermore, the circumferential IPM also experiences much higher torque ripple and core losses, both of which are highly undesirable characteristics for high-speed machines. In addition, the circumferential IPM has a much more complex manufacturing process compared to the radial IPM which would significantly increase the cost of prototyping the machine, thus the radial IPM was selected for prototyping and brief experimental analysis. The radial IPM has been experimentally tested under no-load conditions. These results were successfully compared to the simulated and analytical results to show correlation between the design and experimental process. Potential areas of further work may include conducting detailed loss analysis to understand the effects that changing various design parameters has on the core loss and overall performance. Detailed thermal and mechanical analysis of the machines may also result in interesting conclusions that would alter the design of the machine to make it more efficient

High speed high power electrical machines

DEng ThesisHigh Speed High Power (HSHP) electrical machines push the limits of electromagnetics, material capabilities and construction techniques. In doing so they are able to match the power performance of high speed turbomachinery such as gas turbines, compressors and expanders. This makes them attractive options for direct coupling to such machinery as either a power source or as a generator; eliminating the need for gearboxes and achieving a smaller system size and greater reliability. The design of HSHP machines is a challenging, iterative process. Mechanical, electromagnetic and thermal constraints are all placed on the machine shape, topology, operating point and materials. The designer must balance all of these constraints to find a workable solution that is mechanically stable, can work within the available electrical supply and will not overheat. This thesis researches the fundamental origins and interaction of the mechanical, electromagnetic and thermal constraints on electrical machines. Particular attention was paid to improving the accuracy of traditional mechanical rotor design processes, and improving loss estimation in inverter fed machines. The issues of selecting an appropriate electric loading for low voltage machines and choosing effective, economic cooling strategies were explored in detail. An analytical iterative design process that combines mechanical, electromagnetic and thermal design is proposed; this process balances the need for speed versus accuracy for the initial design of a machine, with Finite Element Analysis used only for final validation of performance and losses. The design process was tested on the design and manufacture of a 1.1MW 30,000rpm PM dynamometer used in an industrial test stand. The machine operating point was chosen to meet a gap in the industrial machines market and exceed the capabilities of other commercially available machines of the same speed. The resulting machine was successfully tested and comfortably meets the performance criteria used in the design process