A holistic DC link architecture design method for multiphase Integrated Modular Motor Drives

This article describes a holistic DC link architecture design method that considers the end-application of the drive and its corresponding constraints e.g. the maximum battery ripple current for a battery-supplied inverter. Also, the levers that are available to comply with the design criteria are presented e.g. the use of interleaved carrier waves. This holistic approach will result in a feasible and performant Integrated Modular Motor Drive from an application point of view. Finally, a platform is presented that was developed for feasibility and performance assessment of various DC link architectures obtained from the holistic design approach. The platform comprises a fifteen phase integrable modular motor drive for an Axial Flux Permanent Magnet Synchronous Machine. It allows non-intrusive reconfiguration of the DC link architecture and implementation of various control strategies and interleaved PWM schemes

Modeling and simulation enabled UAV electrical power system design

With the diversity of mission capability and the associated requirement for more advanced technologies, designing modern unmanned aerial vehicle (UAV) systems is an especially challenging task. In particular, the increasing reliance on the electrical power system for delivering key aircraft functions, both electrical and mechanical, requires that a systems-approach be employed in their development. A key factor in this process is the use of modeling and simulation to inform upon critical design choices made. However, effective systems-level simulation of complex UAV power systems presents many challenges, which must be addressed to maximize the value of such methods. This paper presents the initial stages of a power system design process for a medium altitude long endurance (MALE) UAV focusing particularly on the development of three full candidate architecture models and associated technologies. The unique challenges faced in developing such a suite of models and their ultimate role in the design process is explored, with case studies presented to reinforce key points. The role of the developed models in supporting the design process is then discussed

Flux Weakening Strategy Optimization for Five-Phase PM Machine with Concentrated Windings

The paper applies an Efficient Global Optimization method (EGO) to improve the efficiency, in flux weakening region, of a given 5-phase Permanent Magnet (PM) machine. An optimal control for the four independent currents is thus defined. Moreover, a modification proposal of the machine geometry is added to the optimization process of the global drive. The effectiveness of the method allows solving the challenge which consists in taking into account inside the control strategy the eddy-current losses in magnets and iron. In fact, magnet losses are a critical point to protect the machine from demagnetization in flux-weakening region. But these losses, which highly depend on magnetic state of the machine, must be calculated by Finite Element Method (FEM) to be accurate. The FEM has the drawback to be time consuming. It is why a direct optimization using FEM is critical. EGO method, using sparingly FEM, allows to find a feasible solution to this hard optimization problem of control and design of multi-phase drive

A SyR and IPM machine design methodology assisted by optimization algorithms

The design optimization of synchronous reluctance (SyR) machine and its extension to internal permanent magnet (IPM) motors for wide speed ranges is considered in this paper by means of a Finite Element Analysis-based multi-objective genetic algorithm (MOGA). The paper is focused on the rotor design, that is controversial key aspect of the design of high saliency SyR and IPM machines, due to the difficult modeling dominated by magnetic saturation. A three step procedure is presented, to obtain a starting SyR design with the optimal torque versus torque ripple compromise and then properly include PMs into the SyR geometry, given the desired constant power speed range of the final IPM machine. The designed rotors have been extensively analyzed by computer simulations and two SyR prototypes have been realized to demonstrate the feasibility of the design procedur

Exploiting CAFS-ISP

In the summer of 1982, the ICLCUA CAFS Special Interest Group defined three subject areas for working party activity. These were: 1) interfaces with compilers and databases, 2) end-user language facilities and display methods, and 3) text-handling and office automation. The CAFS SIG convened one working party to address the first subject with the following terms of reference: 1) review facilities and map requirements onto them, 2) "Database or CAFS" or "Database on CAFS", 3) training needs for users to bridge to new techniques, and 4) repair specifications to cover gaps in software. The working party interpreted the topic broadly as the data processing professional's, rather than the end-user's, view of and relationship with CAFS. This report is the result of the working party's activities. The report content for good reasons exceeds the terms of reference in their strictest sense. For example, we examine QUERYMASTER, which is deemed to be an end-user tool by ICL, from both the DP and end-user perspectives. First, this is the only interface to CAFS in the current SV201. Secondly, it is necessary for the DP department to understand the end-user's interface to CAFS. Thirdly, the other subjects have not yet been addressed by other active working parties

Energy-efficient motors

The use of a copper-squirrel cage in induction motors has been analyzed testing a prototype rated 1.1 kW and comparing the performances with a twin machine with an aluminum cage. The comparison has been made using torque, efficiency, starting torque, and starting current. For the considered machine size, the obtained results show that the simple substitution of the aluminum with copper can improve the efficiency of no more than 1.5% at rated load. Taking into account the copper market cost trend, the use of copper cage increases the break-even time due to the higher cost of copper rotor respect to the aluminum one. For this reason, the discussion about the use of copper cage can be still considered ope

Core Losses and Torque Ripple in IPM Machines: Dedicated Modeling and Design Trade Off

The proper combination of stator and rotor slot numbers is pursued in the design of interior permanent-magnet (IPM) motors with wide constant-power speed range. At high speed, in the flux-weakening region, the arising of stator and rotor iron losses due to magnetomotive-force (MMF) spatial harmonics limits the IPM motor performance. Torque ripple is another problem for this kind of machines, both at low and high speed. The numbers of stator slots and rotor equivalent slots have a major impact on both the loss and ripple aspects. A simplified model is proposed here in order to evaluate both problems with a general approach and point out the possible design tradeoff. With respect to previous models in the literature, both stator and rotor losses are included, and a more comprehensive approach is followed in the description of the rotor MMF harmonics. The model's effectiveness is tested through finite element analysis simulations and some experimental results. The proposed approach is useful for the selection of the IPM machine structure according to the specific requirements of the applicatio

Evaluation of Radiation Thermal Resistances in Industrial Motors

This paper deals with the role of the radiation thermal resistances in industrial motors and describes a test set useful for the resistance evaluation. The test set is based on a vacuum chamber and on a numerical acquisition system, and the resistances are obtained by monitoring motor temperatures during a heating test. An analytical model that describes how the radiation resistance depends on the motor temperature is also provided. Experimental results obtained on a totally enclosed fan-cooled 150-W induction motor are shown and discussed

Energy-Efficient Streaming Using Non-volatile Memory

The disk and the DRAM in a typical mobile system consume a significant fraction (up to 30%) of the total system energy. To save on storage energy, the DRAM should be small and the disk should be spun down for long periods of time. We show that this can be achieved for predominantly streaming workloads by connecting the disk to the DRAM via a large non-volatile memory (NVM). We refer to this as the NVM-based architecture (NVMBA); the conventional architecture with only a DRAM and a disk is referred to as DRAMBA. The NVM in the NVMBA acts as a traffic reshaper from the disk to the DRAM. The total system costs are balanced, since the cost increase due to adding the NVM is compensated by the decrease in DRAM cost. We analyze the energy saving of NVMBA, with NAND flash memory serving as NVM, relative to DRAMBA with respect to (1) the streaming demand, (2) the disk form factor, (3) the best-effort provision, and (4) the stream location on the disk. We present a worst-case analysis of the reliability of the disk drive and the flash memory, and show that a small flash capacity is sufficient to operate the system over a year at negligible cost. Disk lifetime is superior to flash, so that is of no concern

Multipolar SPM machines for direct drive application: a comprehensive design approach

A closed-form, per-unit formulation is proposed, for the design of surface mounted permanent magnet motors with high number of poles. The model evaluates the shear stress, the power factor and the specific Joule loss as the indicators of the machine performance, and demonstrates that this is determined by the correct choice of a very limited set of key-geometrical parameters. The design criteria are described analytically and then applied to example designs, FEA validated. Distributed- and concentrated-winding configurations are considered. The conclusions of the paper are consistent with the literature and aim to give a roadmap for designers of PM machines in modern applications, such as wind power synchronous generator