Theory and Simulation of the Brushless DC 120° Inverter System

The brushless dc motor- inverter system is becoming increasingly popular in servo and variable speed applications. One type of inverter, the 120° inverter, does not require rotor position sensing hardware. In this thesis, a theory of the brushless dc motor with a 120° inverter is set forth and used to create a fast simulation procedure for steady state operation. This simulation is well suited for evaluation of torque speed curves since the effects of changes of system parameters can be rapidly assessed. Furthermore, it was found that the system operation may be classified into a finite number of distinct operating modes. The properties of these modes and physical reason for their existence is discussed. Classifying the operation into modes provides a powerful tool for understanding system behavior. The theory presented and classification scheme are then used to formulate an approximate analytical method for the steady-state torque, which is quite accurate for normal operating conditions. The approximations presented are suitable for control system design

Thermal Characterization of Magnetic Components

Thermal limits are crucial constraints in the design of power magnetic components. As the power density of magnetic components continues to increase, cooling becomes more critical. Our research focuses on solving for the amount of cooling needed for a particular magnetic component. During the research process, a low-velocity wind tunnel designed and built from the ground up is used to form uniform and controlled conditions for the test components. Thermal Equivalent Circuit (TEC) and parameter identification techniques are used in conjunction to yield temperature distribution results. The expected result is temperature data on various areas of the component under different cooling air flow. Temperature data will aid developers to optimize their component designs. Future work on different types of cooling systems, such as liquid cooled, will be considered

Notional System Report

The objective of this report is to set forth a group of time-domain models for the early-stage design study of shipboard power systems, and to demonstrate their use on various system architectures. The effort stemmed out of an earlier effort in which waveform-level models of three notional architectures – a Medium Voltage AC System, a High-Frequency AC System, and a Medium Voltage DC System were partially developed. Unfortunately, these codes were extremely computationally intense, limiting their usefulness for early design studies in which large numbers of runs, and a degree of user interactiveness, is required.Center for Electromechanic

Notional System Models

The objective of this report is to set forth a group of time-domain models for the early-design stage study of shipboard power systems. These models are highly simplified abstractions of shipboard power system components. The motivation for the simplification is two-fold. First, at an early design stage it is doubtful if the parameters needed for a more detailed system representation would be available. A highly detailed simulation would be based on many assumptions leading to results which are no more indicative of actual performance than a highly simplified simulation. The second reason for the creation of highly simplified model is for the sake of computational speed, so that system simulations based on the component models will run at speeds compatible with the needs imposed by exploring the system behavior under a large variety of conditions.United States Office of Naval ResearchCenter for Electromechanic

Power magnetic devices: a multi-objective design approach

Presents a multi-objective design approach to the many power magnetic devices in use today Power Magnetic Devices: A Multi-Objective Design Approach addresses the design of power magnetic devices-including inductors, transformers, electromagnets, and rotating electric machinery-using a structured design approach based on formal single- and multi-objective optimization. The book opens with a discussion of evolutionary-computing-based optimization. Magnetic analysis techniques useful to the design of all the devices considered in the book are then set forth. This material is then used for in

Analytical modeling of multistack reluctance machines

Although the multistack variable reluctance machine is a synchronous device, Park\u27s transformation does not lead to a machine description with constant coefficients, or constant state variables during steady-state conditions. This complicates the machine analysis and makes linearization of the machine equations impossible. In this work, the method of dynamic multiple reference frames (DMRF) and a companion transformation are introduced which provide a model of the multistack variable reluctance machine in which rotor position dependent terms are not present and in which the state variables are constant in the steady state. The method whereby operating point stability may be determined using the DMRF models is set forth. The models are verified for both steady-state and transient conditions. Also, the DMRF technique is extended to the analysis of the unsymmetrical induction machine

A Common-Mode Shorting Network to Reduce Common-Mode Excitation of Three-Phase Two-Level Electric Drives

Common-mode voltage and current in an electric machine are undesirable. Although the strategic placement of a common-mode inductor and dc input side capacitors may reduce the common-mode current produced by an electric drive system, the effectiveness of this mitigation is a function of machine parasitic capacitance. This engenders the need to insert another electrical component into the system to effectively mitigate the common-mode current. With this purpose, a common-mode shorting network for an inverter-based drive system is proposed in this work. This network, in conjunction with a common-mode inductor and dc input side capacitors, reduces the machine common-mode voltage and current. The proposed approach is experimentally demonstrated