In this thesis, an optimal multivariable current control method is presented for the highspeed permanent magnet synchronous motor (HS-PMSM). The HS-PMSMs have growing applications in the industry. One of their major challenges is the low switching to fundamental frequency ratio (SFR). At high speed and low SFR, the control time delays including the digital, the PWM, and sensor delays become more pronounced and lead to oscillations and even instabilities. A well-known method for delay compensation is to advance the phase angle of control input for a known amount. In practice, the exact delay is unknown, and mismatch in the compensating angle causes deteriorating effect on the system. In the proposed method, the digital and PWM delays are modelled and integrated with an optimal multivariable controller. This method improves the stability margin and achievable speed margin compared to the traditional phase advancing delay compensation (PADC) method. Combining the proposed delay modeling and the PADC method further improves the response, as the uncertain sensor delays can be compensated greatly. Besides the delay, the cross-coupling between ���� axis affects the dynamic performance of the machine. The proposed multivariable approach considers and directly addresses the coupling. Dynamic performance of the PMSM with the proposed method is thoroughly compared with the conventional delay compensation method. The proposed method is validated through extensive simulation studies on a 2 kW high-speed machine.

Dizertační práce se zabývá modelováním a řízením elektrických pohonů během poruchových stavů. Práce se obzvláště zaměřuje na více-fázové motory. První část práce se zabývá matematickými rovnicemi obecného více-fázového motoru a následným odvozením n-krát troj-fázového zapojení motoru. Modely v dq souřadnicovém systému a modely ve statorových souřadnicích jsou navrženy pro simulaci chování motoru během poruchových stavů. Další část práce se zabývá analýzou poruch ve více-fázových motorech s využitím matematických modelů. Různé vnitřní struktury vinutí motoru jsou analyzovány z pohledu možného řízení během poruchového stavu. Taktéž je prezentováno chování těchto různých struktur motoru během poruchových stavů. Předmětem analýzy jsou elektrické poruchy vinutí motoru a elektrické poruchy výkonové elektroniky. Poslední část práce se zabývá testováním navrženého řídícího algoritmu a navržených kompenzačních strategií pro poruchy na reálných motorech. Pro testování byl použit segregovaný dvakrát troj-fázový motor a experimentální motor s odbočkami pro emulaci poruch vinutí. Provedené testy prokázaly, že vhodně navrhnutý motor v kombinaci se správným řídícím algoritmem a výkonovou elektronikou dokáže zaručit kontinuální běh pohonu i během poruchy.

Characteristics of synchronous machines with permanent magnets depend among others on geometric layout of the machine section. Unlike EC motors, where rectangular arrangement of quantities is suitable, these machines require sinusoidal behaviour. Specific forming of individual machine parts is partially derived from this requirement. This thesis deals with design of such machines, including various geometrical modifications of their sections and examination of influence of those modifications. The thesis includes also analytical calculation procedure of machine parameters as well as verification of final characteristics using the finite element method. It results in a combination of various design methods. FEMM, Maxwell RMxprt and Maxwell 2D Transient Analysis programs were used for verification. Individual modifications of machine geometries are applied to machines with concentrated windings with different ratio of number of slots and poles, and differences between machines and results of individual methods are compared.

<div>The numerical calculation of the electromagnetic fields within electric machines is sensitive to the magnetic characteristic of steel. However, the magnetic characteristic of steel is uncertain due to fluctuations in alloy composition, possible contamination, and other manufacturing process variations including punching. Previous attempts to quantify magnetic uncertainty due to punching are based on parametric analytical models of <i>B-H</i> curves, where the uncertainty is reflected by model parameters. In this work, we set forth a data-driven approach for quantifying the uncertainty due to punching in <i>B-H</i> curves. In addition to the magnetic characteristics of steel lamination, the remanent flux density (<i>B_r</i>) exhibited by the permanent magnets in a permanent magnet synchronous machine (PMSM) is also uncertain due to unpredictable variations in the manufacturing process. Previous studies consider the impact of uncertainties in <i>B-H</i> curves and <i>B_r</i> of the permanent magnets on the average torque, cogging torque, torque ripple and losses of a PMSM. However, studies pertaining to the impact of these uncertainties on the combined machine/drive system of a PMSM is scarce in the literature. Hence, the objective of this work is to study the effect of <i>B-H</i> and <i>B_r</i> uncertainties on the performance of a PMSM machine/drive system using a validated finite element simulator. </div><div>Our approach is as follows. First, we use principal component analysis to build a reduced-order stochastic model of <i>B-H</i> curves from a synthetic dataset containing <i>B-H</i> curves affected by punching. Second, we model the the uncertainty in <i>B_r</i> and other uncertainties in <i>B-H</i> characteristics e.g., due to unknown state of the material composition and unavailability of accurate data in deep saturation region. Third, to overcome the computational limitations of the finite element simulator, we replace it with surrogate models based on Gaussian process regression. Fourth, we perform propagation studies to assess the effect of <i>B-H</i> and <i>B_r</i> uncertainties on the average torque, torque ripple and the PMSM machine/drive system using the constructed surrogate models.</div>

<p>U ovoj doktorskoj disertaciji optimizacioni algoritam zasnovan na roju čestica primenjen je na problem optimalnog upravljanja pogonom sa sinhronim motorom sa stalnim magnetima pri velikim brzinama obrtanja. Kako bi se smaljili ukupni kontrolabilni gubici električne energije i povećala efikasnost generisan je optimalni referentni vektor statorske struje za širok opseg brzina i za različita opterećenja. Prilikom optimizacije uvažena su naponska i strujna ograničenja invertora, kao i promena induktivnosti statora. Sačuvani generisani vektor struje statora se koristi prilikom upravljanja pogonom u realnom vremenu, a predloženi algoritam se poredi sa standarnim upravljanjem.</p> / <p>In this PhD thesis, a particle swarm optimization algorithm was applied to the problems of optimal control of high speed permanent magnet motor drives. In order to minimize the total controllable electrical losses and to increase the efficiency, the optimum current vector references are calculated offline for the wide speed range and for different load conditions. The voltage and current limits of the drive system and the variation of stator inductances are all included in the optimization method. The stored optimal current vector references are used during the real time control and the proposed algorithm is compared with the conventional control algorithm.</p>

This thesis focuses on the development of a novel Direct Torque Control (DTC) scheme for permanent magnet (PM) synchronous motors (surface and interior types) in the constant torque region with the help of cost-effective hall-effect sensors. This method requires no DC-link sensing, which is a mandatory matter in the conventional DTC drives, therefore it reduces the cost of a conventional DTC of a permanent magnet (PM) synchronous motor and also removes common problems including; resistance change effect, low speed and integration drift. Conventional DTC drives require at least one DC-link voltage sensor (or two on the motor terminals) and two current sensors because of the necessary estimation of position, speed, torque, and stator flux in the stationary reference frame. Unlike the conventional DTC drive, the proposed method uses the rotor reference frame because the rotor position is provided by the three hall-effect sensors and does not require expensive voltage sensors. Moreover, the proposed algorithm takes the acceleration and deceleration of the motor and torque disturbances into account to improve the speed and torque responses. The basic theory of operation for the proposed topology is presented. A mathematical model for the proposed DTC of the PMSM topology is developed. A simulation program written in MATLAB/SIMULINK® is used to verify the basic operation (performance) of the proposed topology. The mathematical model is capable of simulating the steady-state, as well as dynamic response even under heavy load conditions (e.g. transient load torque at ramp up). It is believed that the proposed system offers a reliable and low-cost solution for the emerging market of DTC for PMSM drives. Finally the proposed drive, considering the constant torque region operation, is applied to the agitation part of a laundry washing machine (operating in constant torque region) for speed performance comparison with the current low-cost agitation cycle speed control technique used by washing machine companies around the world.

This thesis deals with the integral motor of tomorrow, and particularly with a variable speed, sensorless permanent magnet synchronous motor with an integrated converter. The rated power is 15 kW at 1500 r/min. The outer dimensions are approximately the same as for the equivalent standard induction motor. Control strategies for pumps and fans, i.e. suitable loads for variable speed motors, are briefly described. The huge energy savings that can be made by reducing the speed instead of throttling/choking the flow are pointed out. Compared to installing an induction motor with a separate converter, a PM integral motor will probably pay-off in less than a year. A totally analytical expression for calculating the airgap flux density of permanent magnet motors with buried magnets is derived. The analytical expression includes axial leakage, and iron saturation of the most narrow part of the magnetic circuit of the machine. A computer program for optimization of PM motors with buried magnets has been developed. It was used to design the manufactured prototype PM integral motor, and the parameters are investigated with analytical and/or FEM calculations. The optimization program is also used to suggest nearoptimum pole numbers for desired powers (4-37 kW) and speeds (750- 3000 r/min) of inverter-fed PM motors. Results show that compact buried PM motors should have relatively large airgaps and high NdFeB-magnet masses to improve the efficiency. Ferrite magnets are unsuitable. Measurements on the manufactured PM motor, the novel concept of stator integrated filter coils, and the complete PM integral motor are presented. Special attention was given to temperature and overall efficiency measurements. The rotor cage losses were investigated by time-stepping FEM. Four short circuit fault conditions were also examined in order to evaluate the risks of demagnetization of the buried magnets.

The objective of this thesis is to design and implement a velocity-stabilizing driver for permanent magnet synchronous motor. The research presents how to achieve high efficiency in stabilizing overall velocity for a permanent magnet synchronous motor. In order to drive the integral system, there are six steps square-wave starting device, sine-wave driver, estimation of magnetic angle, velocity feedback and current feedback control circuits designed. A test platform is built by Microchip-made dsPIC33FJ128MC804 digital signal processor used as a control core. ¡§Simulink¡¨ simulator is used during the laboratory test. The simulation results are compared with those of experiments in order to verify the achievement of excellent performance of Robust Integral Velocity-stabilizing Controller on Permanent Magnet Synchronous Motor Driver.

In this thesis, high performance torque and speed control for a surface-mounted permanent magnet synchronous machine (PMSM) is designed, simulated and implemented. A three-phase two-level pulse width modulation voltage-source inverter (PWM-VSI) with power MOSFETs is used to feed the PMSM. The study has three objectives. The first is to compensate the voltage disturbance caused by nonideal characteristics of the voltage-source inverter (VSI). The second is to decouple the coupled variables in the synchronous reference frame model of the PMSM. The last is to design a load torque estimator in order to increase the disturbance rejection capability of the speed control. The angular acceleration required for load torque estimation is extracted through a Kalman filter from noisy velocity measurements. Proposed methods for improved torque and speed control performance are verified through simulations and experimental tests. The drive system is modeled in Matlab/Simulink, and control algorithms are developed based on this model. The experimental drive system comprises a three-phase VSI and a 385 W surface-mounted PMSM. Control algorithms developed in the study have been implemented in a digital signal processor (DSP) board and tested comprehensively. With the use of the proposed methods, a considerable improvement of torque and speed control performance has been achieved.

This thesis focuses on the development of a novel Direct Torque Control (DTC) scheme for permanent magnet (PM) synchronous motors (surface and interior types) in the constant torque region with the help of cost-effective hall-effect sensors. This method requires no DC-link sensing, which is a mandatory matter in the conventional DTC drives, therefore it reduces the cost of a conventional DTC of a permanent magnet (PM) synchronous motor and also removes common problems including; resistance change effect, low speed and integration drift. Conventional DTC drives require at least one DC-link voltage sensor (or two on the motor terminals) and two current sensors because of the necessary estimation of position, speed, torque, and stator flux in the stationary reference frame. Unlike the conventional DTC drive, the proposed method uses the rotor reference frame because the rotor position is provided by the three hall-effect sensors and does not require expensive voltage sensors. Moreover, the proposed algorithm takes the acceleration and deceleration of the motor and torque disturbances into account to improve the speed and torque responses. The basic theory of operation for the proposed topology is presented. A mathematical model for the proposed DTC of the PMSM topology is developed. A simulation program written in MATLAB/SIMULINK® is used to verify the basic operation (performance) of the proposed topology. The mathematical model is capable of simulating the steady-state, as well as dynamic response even under heavy load conditions (e.g. transient load torque at ramp up). It is believed that the proposed system offers a reliable and low-cost solution for the emerging market of DTC for PMSM drives. Finally the proposed drive, considering the constant torque region operation, is applied to the agitation part of a laundry washing machine (operating in constant torque region) for speed performance comparison with the current low-cost agitation cycle speed control technique used by washing machine companies around the world.