Operation Characteristics of Adjustable Field IPMSM Utilizing Magnetic Saturation

This paper describes an interior permanent magnet synchronous motor (IPMSM) based on a new adjustable field method. The proposed PM motor achieved magnetic field control utilizing magnetic saturation. In this paper, a back electromotive force (e.m.f.) measurement test and a load test using the prototype motor were conducted to clarify if the proposed motor had a wide operation range. In the back e.m.f. measurement test, it was confirmed that the proposed motor had a wide magnetic field controllable range of 51.7%. In addition, it was revealed, through the load test, that the proposed motor had a wide operating range, including both low-speed high-torque and high-speed low-torque driving conditions. Moreover, based on electromagnetic field analysis, the magnetic field control performance of the proposed adjustable field method was compared with the conventional field weakening control and other adjustable field methods. As a comparison result, it was verified that the proposed motor had less copper loss for the magnetic field control and fewer losses in the high-speed operating range.

Strategies to Form Homogeneous Mixture and Methods to Control Auto-Ignition of HCCI Engine

Homogeneous charge compression ignition (HCCI) engine has emerged as a promising combustion technology. Theoretically, an HCCI engine can reduce both NOx and soot emissions significantly down to almost zero levels. This is possible as a result of two fundamental processes that occur in the HCCI engine, i.e. the homogeneous mixture and its autoignition characteristics. Neither spark plug nor injector is used in the HCCI engine. The autoignition of the homogeneous mixture is solely influenced by its chemical reactions inside the combustion chamber. However, this is where the problems start to occur. At low loads or too lean mixtures, misfire may occur, thus increasing the HC and CO emissions. At high loads or too rich mixtures, soot emissions and knocking tendency may increase. Moreover, an undesirable pressure rise due to knocking will increase the combustion temperature and potentially increase the probability of NOx formation. Therefore, the operating range of HCCI engine is very limited only to part loads. Controlling its combustion phasing play an important role to extend the narrow operating range of the HCCI engine. Despite numerous review articles have been published, classification of the approaches to achieve HCCI combustion in diesel engines were rarely presented clearly. Therefore, this review article aims to provide a concise and comprehensive classification of HCCI combustion so that the role and position of each strategy found in the literature could be understood distinctively. In short, two important questions must be solved to have successful HCCI combustion; (1) how to form a homogeneous mixture? and (2) how to control its auto-ignition?

Stochastic Model For Setpoint of a Rolling Mill: An Application In The Soybean Oil Production

A scientific challenge on industrial production is to mathematically represent a production process, and this challenge increases when describing production processes with stochastic behavior. The present paper will be approaching a specific part of the production process of soybean oil, where the main objective is to maximize the oil extraction by keeping the thicknesses of the soybean flakes within an operating range. We propose a method, based on a mathematical stochastic model, to obtain pressure setpoints that produce flakes as ideal as possible for oil extraction. The results reported are achieved by applying the proposed method in the industry with improvements within the process in terms of time and quality.

Numerical Analysis of a Novel Twin-Impeller Centrifugal Compressor

Centrifugal compressors are widely used in many industrial fields such as automotive, aviation, aerospace. However, these turbomachines suffer instability phenomenon when the flow rate is too high or too low, called rotating stall and surge. These phenomena cause the operation failure, pressure fluctuations and vibrations of the thorough system. Numerous mechanical solutions have been presented to minimize these instabilities and expand the operating range towards low-flow rates like active control of the flow path, variable inlet guide vane and casing treatment. Currently, our team has developed a novel compressor composed of a twin-impeller powered by autonomous systems. We notice the performance improvement and instabilities suppression of this compressor experimentally. In this paper, an active control method is introduced by controlling the speed and rotation direction of the impellers to expand the operating range. A CFD study is then conducted to analysis flow morphology and thermodynamic characteristics based on the experimental observations at three special points. Numerical results and experimental measurements of compressor maps are consistent.

Experimentally Validated Extension of the Operating Range of an Electrically Driven Turbocharger for Fuel Cell Applications

From an aerodynamic point of view, the electric turbocharger for the air supply of an automotive fuel cell faces difficult requirements: it must not only control the pressure level of the fuel cell, but it also has to operate with very high efficiency over a wide range. This paper explores features for the compressor and the turbine of an existing electric turbocharger, which are intended to meet the specific requirements of a fuel cell in an experimentally validated numerical study. Adjustable diffuser or nozzle vanes in the compressor and turbine achieve wider operating ranges but compromise efficiency, especially because of the necessary gaps between vanes and end walls. For the turbine, there are additional efficiency losses since the pivoting of the nozzle vanes leads to incidence and thus to flow separation at the leading edge of the nozzle vanes and the rotor blades. An increase in the mass flow and a slight efficiency improvement of the turbine with the low solidity nozzle vanes counteracts these losses. For the compressor, a reduction in the diffuser height and its influence over the operating range and power consumption yields an increase in surge margin as well as in maximum efficiency.

A Gyroless Algorithm with Multi-Hypothesis Initialization for Projectile Navigation

Projectiles are subjected to a high acceleration shock at launch (20,000 g and higher) and can spin very fast. Thus, the components of onboard navigation units must therefore withstand such constraints in addition to being inexpensive. This makes only a few inertial sensors suitable for projectiles navigation. Particularly, rate gyroscopes which are gun-hardened and have an appropriate operating range are not widely available. On the other hand, magneto-resistive sensors are inexpensive and can satisfy both gun-hardening and operating range requirements, making them an alternative for angular estimation in guided projectiles. This paper presents a gyroless navigation algorithm for projectiles. The lack of gyroscope is handled by the usage of attitude kinematics computed over past attitude estimates of the filter, coupled with a measurement model based on magnetometer and GPS observations of the attitude. The observability of the attitude when considering non-calibrated magnetometers and its dependency on the initialization is addressed. Then, to cope with the initialization dependency of the filter, we proposed a multi-hypothesis initialization algorithm. In terms of performance, the algorithm is shown to provide a high-rate navigation solution with an interesting performance.