This work investigates three-dimensional power loop layout for application to a SiC based matrix converter, providing a symmetric, low-inductance solution. The thesis presents various layout types to achieve this design target, and details the implementation of a hybrid layout to the matrix converter phase-leg. This layout is more easily achievable with a surface-mount device package, which also offers benefits such as ease in manufacturing, and a compact package. In order to implement a surface-mount device, a PCB thermal management strategy should be utilized. An evaluation of these methods is also presented in the work. The final power loop solution that implements an aluminum nitride inlay is evaluated through simulated parasitic extraction and experimental double pulse tests. The layout achieves small, symmetric loop inductances. Finally, the full power, three-phase matrix converter demonstrates the successful implementation of this power loop layout. / Master of Science / In the United States, 40% primary energy consumption comes from electricity generation, which is the fastest growing form of end-use energy. Industries such as commercial airlines are increasing their use of electric energy, while phasing out the mechanical and pneumatic aircraft components, as they offer better performance and lower cost. Thus, implementation of high efficiency, electrical system can reduce energy consumption, fuel consumption and carbon emissions [1]. As more systems rely on this electric power, the conversion from one level of power (voltage and current) to another, is critical. In the quest to develop high efficiency power converters, wide bandgap semiconductor devices are being turned to. These devices, specifically Silicon Carbide (SiC) devices, offer high temperature and high voltage operation that a traditional Silicon (Si) device cannot. Coupled with fast switching transients, these metal oxide semiconductors field effect transistors (MOSFETs), could provide higher levels of efficiency and power density. This work investigates the benefits of a three-dimensional (3D) printed circuit board (PCB) layout. With this type of layout, a critical parasitic – inductance – can be minimized. As the SiC device can operate at high switching speeds, they incur higher di/dt, and dv/dt slew rates. If trace inductance is not minimal, overshoots and ringing will occur. This can be addressed by stacking PCB traces on top of one another, the induced magnetic field can be reduced. In turn, the system inductance is lowered as well. The reduction of this parameter in the system, reduces the overshoot and ringing. This particular work applies this technique to a 15kW matrix converter. This converter poses a particular design challenge as there are a large number of devices, which can lead to longer, higher inductance PCB traces. The goal of this work is to minimize the parasitic inductance in this converter for high efficiency, high power density operation.

This thesis proposes a new bidirectional three-phase AC-DC power converter using matrix converter and Z-source inverter topologies. Advantages of the AC-DC matrix converter are the inherently controllable power factor, the tight DC voltage regulation, the wide bandwidth with quick response to load variation, the single-stage buck-voltage AC-to-DC power conversion; advantages of the z-source inverter are the increased reliability by allowing the shoot-through between upper and lower power switches of one inverter leg, insensitivity to DC bus voltage due to the extra freedom of controlling DC-link voltage. The proposed Matrix-Z-source converter (MZC) marries up both advantages of AC-DC matrix converter and Z-source inverter. It can achieve voltage-boost DC-AC inversion capable of variable voltage variable frequency (VVVF) AC output; it can achieve voltage-buck AC-DC rectification capable of inherent control over AC current phase angle and DC output regulation with a (VVVF) AC source supply. Both foresaid performance in DC-AC inversion and AC-DC rectification can be implemented in a simple open-loop control manner. Three constraints of VSI, in the bidirectional AC-DC power conversion, are the peak AC voltages are always less than DC-link voltage, closed-loop control has to be employed when DC regulation and/or AC current phase angle control are required, and AC voltage is sensitive to the variation of the DC-link voltage in DC-AC inversion. The voltage-boost inversion and/or voltage-buck rectification of MZC overcomes the first constraint; thus MZC enables the AC machine voltage increased higher than DC-link voltage hence advantages of running AC machine at relatively high voltages are enabled. The direct DC voltage regulation and inherent AC-current-phase-angle control of MZC overcomes the second constraint in an open-loop manner; hence a simplified system design is obtained with sufficient room for the further improvement by closed-loop control schemes. The extra freedom in controlling DC-link voltage of MZC overcomes the third constraint hence a DC source voltage adaptable inverter is obtained. This thesis focuses on the study of the feasibility of the proposed MZC through theoretical analysis and experimental verification. At first, the proposed MZC is conceptually constructed by examining the quadrant operation of AC-DC matrix converter and Z-source inverter. After the examination of the operating principles of both AC-DC matrix converter and Z-source inverter, the configuration of MZC is then proposed. The MZC has two operating modes: DC-AC inversion and AC-DC rectification. Circuit analysis for both operating modes shows that the new topology does not impose critical conflict in circuit design or extra restriction in parameterization. On the contrary, one version of the proposed MZC can make full advantage of Z-source network components in both operating modes, i.e. a pair of Z-source inductor and capacitor can be used as low-pass filter in AC-DC rectification. The modulation strategy, average modeling of system, and features of critical variables for circuit design of the proposed MZC were examined for each operating mode. Simulations of the proposed MZC and its experimental verification have been presented. Analytical models of conduction and switching losses of the power-switch network in different operating mode have shown that the losses in the MZC compare favorably with conventional VSI for a range of power factor and modulation indices.

Orientador: Prof. Dr. Marat Rafikov / Tese ( doutorado)- Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2016.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The induction generator has characteristics making it interesting for alternative sources of energy, such as low cost, ruggedness, low maintenance, high availability and good dynamic behavior. So, it is very much applied in alternative energy systems, where low cost, low maintenance and easy availability are essential characteristics. Although this generator is very attractive, its operation presents problems related to a poor voltage regulation, load dependent variable frequency, and the need of large size self-excitation capacitors, for standalone induction generator systems. In order to minimize these problems, this study proposes a sparse matrix converter associated to an induction generator as a way to regulate the generated voltage, fix the frequency and increase the system reliability. Moreover, it allows the reduction of the self-excitation capacitors by draining out of the generator, mostly resistive current thus, reducing capacitor costs and of the whole system size. In this dissertation is presented some simulation and practical results of a sparse matrix converter connected to the induction generator prototype developed in CEEMA laboratories. These results confirm the here presented theory and validate this work. / O Gerador de Indução é atrativo para geração de energia elétrica com fontes alternativas por apresentar baixo custo, robustez, baixo índice de manutenção, grande disponibilidade e bom comportamento dinâmico. Por isso, ele é muito aplicado em sistemas alternativos de geração de energia onde o baixo custo, baixo índice de manutenção, disponibilidade e facilidade de substituição do gerador, são características bastante apreciadas. Particularmente, no caso dos geradores de indução auto-excitados por bancos de capacitores, apesar de também eles serem atrativos, sua operação isolada apresenta problemas relacionados à regulação de tensão insatisfatória e freqüência variável dependentes da carga, e pela necessidade de capacitores de auto-excitação de tamanho e custo elevados. Os custos elevados dos bancos de capacitores ainda limitam o uso isolado do gerador de indução a pequenas unidades apenas, com potência inferior à 50kW. Esta dissertação propõe o uso do Conversor Matricial Esparso como forma de regular a tensão no gerador de indução e fixar a freqüência na carga. Além disso, o uso deste conversor possibilita drenar uma corrente do gerador em fase com sua respectiva tensão, reduzindo assim o custo dos capacitores e do sistema como um todo. São apresentados resultados de simulação e resultados práticos de um protótipo do conversor matricial esparso, desenvolvido nos laboratórios do CEEMA-UFSM para conexão ao gerador de indução. Estes resultados servem de base para a comprovação e validação da teoria desenvolvida para a integração do gerador de indução auto-excitado e do conversor matricial esparso apresentada nesta dissertação.

The generic concept of quasi-single-stage (QSS) power conversion topology for ac-dc rectification and dc-ac inversion is proposed. The topology is reached by direct cascading and synchronized switching of two variety of buck or two variety of boost switching networks. The family of QSS power converters feature single-stage power processing without a dc-link low-pass filter, a unidirectional pulsating dc-link voltage, soft-switching capability with minimal extra commutation circuitry, simple PWM control, and high efficiency and reliability. A new soft-switched single-phase QSS bi-directional inverter/rectifier (charger) topology is derived based on the QSS power conversion concept. A simple active voltage clamp branch is used to clamp the otherwise high transient voltage on the current-fed ac side, and at the same time, to achieve zero-voltage-switching (ZVS) for the switches in the output side bridge. Seamless four-quadrant operation in the inverter mode, and rectifier operation with unity power factor in the charger (rectifier) mode are realized with the proposed uni-polar center-aligned PWM scheme. Single-stage power conversion, standard half-bridge connection of devices, soft-switching for all the power devices, low conduction loss, simple center-aligned PWM control, and high reliability and efficiency are among its salient features. Experimental results on a 3 kVA bi-directional inverter/rectifier prototype validate the reliable operation of the circuit. Other single-phase and three-phase QSS bi-directional inverters/rectifiers can be easily derived as topological extensions of the basic QSS bi-directional inverter/rectifier. A new QSS isolated three-phase zero-voltage/zero-current-switching (ZVZCS) buck PWM rectifier for high-power off-line applications is also proposed. It consists of a three-phase buck bridge switching under zero current and a phase-shift-controlled full-bridge with ZVZCS, while no intermediate dc-link is involved. Input power and displacement factor control, input current shaping, tight output voltage regulation, high-frequency transformer isolation, and soft-switching for all the power devices are realized in a unified single stage. Because of ZVZCS and single-stage power conversion, it can operate at high switching frequency while maintaining reliable operation and achieving higher efficiency than standard two-stage approaches. A family of isolated ZVZCS buck rectifiers are obtained by incorporating various ZVZCS schemes for full-bridge dc-dc converters into the basic QSS isolated buck rectifier topology. Experimental and simulation results substantiate the reliable operation and high efficiency of selected topologies. The concept of charge control (or instantaneous average current control) of three-phase buck PWM rectifiers is introduced. It controls precisely the average input phase currents to track the input phase voltages by sensing and integrating only the dc rail current, realizes six-step PWM, and features simple implementation, fast dynamic response, excellent noise immunity, and is easy to realize with analog circuitry or to integrate. One particular merit of the scheme is its capability to correct any duty-cycle distortion incurred on only one of the two active duty-cycles which often happens in the soft-switched buck rectifiers, another merit is the smooth transition of the input currents between the 60o sectors. Simulation and preliminary experimental results show that smooth operations and high quality sinusoidal input currents in the full line cycle are achieved with the control scheme. / Ph. D.

The study designs and constructs a three-phase to three-phase direct AC&ndash / AC matrix converter based surface mounted permanent magnet synchronous motor (PMSM) drive system. First, the matrix converter topologies are analyzed and the state-space equations describing the system have been derived in terms of the input and output variables. After that, matrix converter commutation and modulation methods are investigated. A four-step commutation technique based on output current direction provides safe commutation between the matrix converter switches. Then, the matrix converter is simulated for both the open-loop and the closed-loop control. For the closed-loop control, a current regulator (PI controller) controls the output currents and their phase angles. Advanced pulse width modulation and control techniques, such as space vector pulse width modulation and field oriented control, have been used for the closed-loop control of the system. Next, a model of diode-rectified two-level voltage source inverter is developed for simulations. A comparative study of indirect space vector modulated direct matrix converter and space vector modulated diode-rectified two-level voltage source inverter is given in terms of input/output waveforms to verify that the matrix converter fulfills the two-level voltage source inverter operation. Following the verification of matrix converter operation comparing with the diode-rectified two-level voltage source inverter, the simulation model of permanent magnet motor drive system is implemented. Also, a direct matrix converter prototype is constructed for experimental verifications of the results. As a first step in experimental works, filter types are investigated and a three-phase input filter is constructed to reduce the harmonic pollution. Then, direct matrix converter power circuitry and gate-driver circuitry are designed and constructed. To control the matrix switches, the control algorithm is implemented using a DSP and a FPGA. This digital control system measures the output currents and the input voltages with the aid of sensors and controls the matrix converter switches to produce the required PWM pattern to synthesize the reference input current and output voltage vectors, as well. Finally, the simulation results are tested and supported by laboratory experiments involving both an R-L load and a permanent magnet synchronous motor load. During the tests, the line-to-line supply voltage is set to 26 V peak value and a 400 V/3.5 kW surface mounted permanent magnet motor is used.