The aim of this thesis is to determine the size of overshoot produced at the output of a linear continuous second order system controlled by pulse width modulation depending on the period and duty cycle of the modulation and system parameters. This thesis contains analytic calculation of the size of overshoot produced at the output of the second order system with damping ratio > 0, except the damping ratio equals to 1 (i.e. both underdamped and damped system) depending on period and duty cycle of the modulation. This thesis also includes a comparison of partial analytic results to numerical simulation in Matlab program and also with measurement at second order system model.

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The modulation methods Space Vector PWM (SVPWM), Discontinuous PWM (DPWM1, DPWMMAX) and six-step mode are investigated in the overmodulation range of a voltage-fed induction motor drive. This area enables an increase of inverter output voltage so that drive performance can be enhanced. Though, pulse dropping occurs which results in increased iron losses and current waveform quality degradation. Due to differences in harmonic distortion the modulation methods cause various torque oscillations and power losses in induction motors and inverter drives. To quantify these effects in a squirrel cage induction motor drive a simulation model containing a finite element machine model and an analytic inverter model is developed, in order to find the PWM scheme offering maximum torque and minimal power losses. Additionally, the holistic investigation of machine and inverter losses allows for making statements concerning total losses of drive systems and the most suitable overmodulation scheme for the application.

Modern aircraft, military and commercial, rely extensively on hydraulic systems. However, there is great interest in the avionics community to replace hydraulic systems with electric systems. There are physical challenges to replacing hydraulic actuators with electromechanical actuators (EMAs), especially for flight control surface actuation. These include dynamic heat generation and power management. Simulation is seen as a powerful tool in making the transition to all-electric aircraft by predicting the dynamic heat generated and the power flow in the EMA. Chapter 2 of this dissertation describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. This model is capable of representing transient dynamics of an EMA, mechanically, electrically, and thermally. Inductance is a primary parameter that links the electrical and mechanical domains and, therefore, is of critical importance to the modeling of the whole EMA. In the dynamic mode of operation of an EMA, the inductances are quite nonlinear. Chapter 3 details the careful analysis of the inductances from finite element software and the mathematical modeling of these inductances for use in the overall EMA model. Chapter 4 covers the design and verification of a nonlinear, transient simulation model of a two-step synchronous generator with three-phase rectifiers. Simulation results are shown

An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved self-oscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.

This report covers the construction of a prototype inverter system designed to power the rail of a maglev train, from component selection through simulations and power demands to mounting and wiring the components into a cabinet. The inverter is made with insulated gate bipolar transistors controlled with pulse-width modulated signals provided by a custom microcontroller. The output of the inverter is a controllable three-phase square wave. The prototype was tested with a microcontroller designed for a different gate driver, making it necessary to design and create an adapter to be able to test it. The results showed that an inverter of two-level topology, together with capacitors, is a viable option for a 10 kHz switching frequency. / Denna rapporten täcker konstruktionen av en prototyp till en inverter topologi designad för att driva rälsen till ett maglevtåg. Från komponentval genom simulering och kapacitetskrav, till montering och sladdragning av komponenterna in i ett skåp. Invertern är gjort med bipolär-transistorer med isolerat syre (IGBTer) som styrs med en pulsbreddsmodulerad signal försedd av en egendesignad mikrokontroller. Utsignalen från invertern är en styrbar trefas fyrkantsvåg. Prototypen skulle testas med en mikrokontroller designad för en annan gate driver, därför var det nödvändigt att designa och producera ett adapterkort för att kunna köra testerna. Resultated visade att en två-level inverter, tillsammans med kondensatorer, är en genomförbar lösning för 10 kHz switchingfrekvens.

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