Low Speed Settings Research Articles

Rotor Speed Analysis of SMC-based IFOC for Low-Speed Induction Motor Control

The control of electric motors, particularly three-phase induction motors, has developed rapidly due to their application in industry. Indirect Field Oriented Control (IFOC) is one of the most widely used control systems due to its ease of application. IFOC controls a three-phase induction motor in the same way as a DC motor. However, IFOC requires a Sliding Mode Control (SMC) controller with Lyapunov stability theory to ensure robustness and stability. In exceptional conditions, such as low-speed settings, the SMC-based IFOC requires unique sets to operate with a steady-state error (Ess) at a speed response of less than 2%. Other parameters to be considered are rise time and electromagnetic torque response at low speeds. The addition of the boundary layer of the hyperbolic tangent function to a first-order SMC can increase induction motor (IM) control up to 175 rpm with a value of Ess = 1.96% compared to the saturation and signum functions, which are only capable of a reference speed of 300 rpm in no-load conditions with a value of Ess = 2% for the saturation function and 1.94% for the signum function. SMC with the hyperbolic tangent function boundary layer performs best under load conditions. The rising time value does not significantly differ under no-load or torque-load conditions between the SMC with the saturation, hyperbolic tangent function boundary layers and without the boundary layer. Adding a boundary layer with the hyperbolic tangent function can reduce ripple significantly compared to the saturation function under no-load or load conditions.

How do the type and duration of distraction affect speed selection and crash risk? An evaluation using naturalistic driving data

Distracted driving is among the leading causes of roadway crashes worldwide. However, due to limitations of police-reported crash data, it is often challenging to understand the nature and magnitude of this problem. Distraction has also been shown to affect driver speed selection, which is important as both mean speed and speed variance have substantive impacts on crash risk. This study utilizes naturalistic driving data to investigate the relationship between the engagement in various secondary (non-driving) tasks and driver speed selection under different driving contexts. Separate analyses were conducted for low-speed and high-speed driving environments. Two-way random effects linear regression models were estimated for both speed regimes, while controlling for driver, roadway, and traffic characteristics. The differences were assessed based upon ten types of secondary tasks. In general, engagement in all tasks was found to decrease speeds in high-speed environments while the effects were mixed in low-speed settings. The changes in speeds were much pronounced for secondary tasks that include a combination of visual, manual, and cognitive distractions, such as cell phone use. Among all secondary tasks, an average episode of a driver talking on a handheld cellphone was associated with a 6-mph speed reduction in high-speed environments, but a 3.5-mph increase in low-speed settings. In addition to examining impacts on speed selection, the risk of involvement in crash and near-crash events was also evaluated in consideration of the type and duration of distraction. Interestingly, distractions tended to show similar relationships, in both direction and magnitude, with the risk of involvement in both crash and near-crash events. From a policy standpoint, this study provides further motivation for legislation and other programs aimed at curbing distracted driving.

Chattering Reduction Using Boundary-SMC on Low-Speed Setting of 3-Phase Induction Motor with IFOC Method

Vector control has been widely used in induction motor speed settings due to its high performance and ability to be separately controlled as DC motors. Indirect Field Oriented Control (IFOC) is a vector control method applicable to induction motors due to the ease of design and implementation. However, its performance decreases due to changes in motor parameter variations and load disturbances, which led to the use of Sliding Mode Control (SMC), capable of resisting and stabilizing parameter changes and load disturbances. In the First Order Sliding Mode Control (FOSMC), a dangerous chattering phenomenon occurs and results in the stability of the control system. Therefore, this research designed a Boundary-SMC controller to control the speed of a 3-phase induction based on IFOC with a change in load disturbance to reduce the chattering phenomenon at low speeds, where the largest percentage occurs. Furthermore, this research used Lyapunov's stability theory to ensure stability with the performance of these controls monitored and analyzed in LabView. The results showed that FOSMC has better resilience and stability than PID, with a steady error rate of 0.001% and a chattering percentage of 0.12%. With Boundary-SMC, the chattering percentage and stiffness are reduced to 0.005% and 0.284%, respectively.

Performance Improvement of Turbofans by Electric Power Transfer

Abstract With design trends toward the more electric engine (MEE) for the more electric aircraft (MEA), novel technologies can be pinpointed for multi-spool engines. Provided that a multi-spool MEE is equipped with electrical machines connected to each of its shafts, using power electronic converters (PECs) within a common high-voltage DC bus configuration, it is possible to redistribute a desired amount of power between the engine shafts independent of their speeds. This paper presents the impact of electric power transfer (EPT) on engine performance by using a developed 0-dimensional engine model based on the inter-component volume (ICV) method and engine component maps. Generic component maps are scaled to match the design point of the CFM56-3 engine. Validating the simulation results with engine performance data from literature shows that the steady-state error of the speed and fuel consumption is within 1% and 3.5% for the high- and low-speed settings, respectively, which is acceptable for the purpose of power transfer studies. It is shown that a 400 kW EPT system is the best performing for the cases run for the CFM56-3 engine, which can halve the amount of bleed air from variable bleed valves (VBVs). Results show that EPT with the rescheduled VBVs opening improves the engine performance significantly at low-speed settings by decreasing fuel consumption and increasing surge margins. Detailed simulation results from the engine model and EPT weight penalty analysis show that fuel consumption for short- and medium-haul flights reduces by up to 0.46% and 0.79% with state-of-the-art, and 0.60% and 1.0% with future technologies, respectively. Furthermore, results show that electric power transfer can recover the surge margins of degraded engines at high-speed settings.

A Dual-Channel-Enhanced Power Generation Architecture With Back-to-Back Converter for MEA Application

This article proposes an improved power generation architecture (PGA) for future more electric aircraft applications. In the proposed architecture, a starter/generator is connected to the high-pressure (HP) shaft, and a generator is connected to the low-pressure (LP) shaft. Their outputs supply a common dc bus via active power converters. A back-to-back (B2B) converter is deployed to link the ac terminals of the two generators. The proposed topology embraces three main advantages. First, with the B2B converter, the HP generator can operate at a high speed without flux weakening; thus, the magnitude of stator current will be decreased when output same active power. This will lead to the reduction of power losses on the generators and the active rectifiers. Second, the proposed PGA allows power transfer from the LP and to the HP shafts. This can potentially reduce the fuel consumption and increase aircraft engine compressor surge margins when the engine is at low-speed setting. Third, the B2B converter provides an additional power flow path to the generators under converter fault scenarios, hence improving the postfault operation ability. For the proposed PGA, engine benefits, modeling, control design, and efficiency improvements are illustrated in detail. The control performances of the proposed PGA, engine performance improvement by transferring power from the LP to HP shaft, and power loss reduction are verified via simulations and experimental results collected from a twin-shaft aircraft power generation test rig.

Effect of ice mass fraction on ice slurry flow for cold energy storage application

The characteristics of ice slurry flows in a pipe are critical due to the potential consequence of pressure drops. This work attempted to conduct an experimental study on ice slurry flow in a horizontally posited circular pipe. This study was conducted on glycol-added (20%) ice slurry with varied ice mass fractions (10%, 15% 20%, 25%, 30%). During experiments, the flow tests were conducted by covering both laminar and turbulent flows. Results of the investigation discovered ice slurry to behave as a Newtonian fluid at mass fraction below 10%, while it also behaved as a non-Newtonian fluid at mass fraction up to 15%. Then, pressure drop was revealed to increase significantly at low-speed settings and high ice mass fractions. To maximize the use of ice slurry as a cold energy storage, therefore, ice mass fraction must be kept at below 20% in a laminar flow.

Structural and Thermal Insulation Materials Based on High-Strength Anhydrite Binder

The properties of a structural and thermal insulation composition based on a high-strength anhydrite binder based on fluoroanhydrite and expanded perlite sand have been studied. Fluoroanhydrite is a waste product of hydrofluoric acid and it is an eco-friendly material. Due to the processing of man-made anhydrite, it is possible to reduce the harm caused to nature in places of raw materials dumps, as well as significantly reduce the cost of producing new construction materials. The use of anhydrite compounds in the manufacture of products is limited with low speed setting and hardening. To activate the structure formation of the anhydrite binder, 3% aqueous solution of sodium phosphate Na3PO4 was used. Expanded perlite sand was used as an ultralight aggregate. As a result of the experiments, it was possible to obtain a lightweight composition possessing high strength. Studies of the microstructure and X-ray microanalysis showed new formations appearing in the interfacial zone at the border of the anhydrite binder and expanded perlite, which is confirmed by the results of the infrared spectroscopy. Also there has been noted the consolidation of the anhydrite binder structure by nanodispersed structures formed in the intercrystallite pores of the anhydrite binder. The developed composition can serve as a cheap substitute for gypsum in the production of warm plaster, gypsum boards, architectural elements by molding, tongue-and-groove slabs, wall blocks, as well as wall thermal insulation during frame construction, including for filling hollow masonry.

Dynamic ride-sharing and fleet sizing for a system of shared autonomous vehicles in Austin, Texas

Shared autonomous (fully-automated) vehicles (SAVs) represent an emerging transportation mode for driverless and on-demand transport. Early actors include Google and Europe’s CityMobil2, who seek pilot deployments in low-speed settings. This work investigates SAVs’ potential for U.S. urban areas via multiple applications across the Austin, Texas, network. This work describes advances to existing agent- and network-based SAV simulations by enabling dynamic ride-sharing (DRS, which pools multiple travelers with similar origins, destinations and departure times in the same vehicle), optimizing fleet sizing, and anticipating profitability for operators in settings with no speed limitations on the vehicles and at adoption levels below 10 % of all personal trip-making in the region. Results suggest that DRS reduces average service times (wait times plus in-vehicle travel times) and travel costs for SAV users, even after accounting for extra passenger pick-ups, drop-offs and non-direct routings. While the base-case scenario (serving 56,324 person-trips per day, on average) suggest that a fleet of SAVs allowing for DRS may result in vehicle-miles traveled (VMT) that exceed person-trip miles demanded (due to anticipatory relocations of empty vehicles, between trip calls), it is possible to reduce overall VMT as trip-making intensity (SAV membership) rises and/or DRS users become more flexible in their trip timing and routing. Indeed, DRS appears critical to avoiding new congestion problems, since VMT may increase by over 8 % without any ride-sharing. Finally, these simulation results suggest that a private fleet operator paying $70,000 per new SAV could earn a 19 % annual (long-term) return on investment while offering SAV services at $1.00 per mile for a non-shared trip (which is less than a third of Austin’s average taxi cab fare).

Evaluation of automated speed enforcement on Loop 101 freeway in Scottsdale, Arizona

Speed cameras can reduce speeding and injury crashes, but in many communities they are confined to low-speed settings such as residential streets and school zones. In 2006 the city of Scottsdale, Arizona, implemented a 9-month pilot program to evaluate the feasibility and effects of highly visible speed camera enforcement on a busy urban freeway. This was the first use of fixed speed cameras on a major US highway. Deployment of six cameras along an 8-mile corridor was associated with large declines in mean speeds and an 88% decrease in the odds of vehicles traveling 11 mph or more above the 65 mph limit. Traffic speeds increased soon after the pilot program was suspended. In addition to reducing speeding along the enforcement corridor, speed cameras were associated with large reductions in speeding on the same highway but 25 miles away from the camera installations. However, traffic speeds were fairly stable on urban freeways in Scottsdale that were not part of the study road. Public opinion surveys found widespread concerns about speeding on the Loop 101 freeway and high levels of support for speed camera enforcement on this road.

Peripheral Vascular Reactivity in Patients With Pulsatile vs Axial Flow Left Ventricular Assist Device Support

Left ventricular assist devices (LVADs) are either pulsatile or axial flow devices. The latter can be operated at a low-speed setting to allow pulsatility or at a high-speed setting to create continuous flow. The purpose of this study was to compare the effect of continuous flow and pulsatile flow on peripheral vascular reactivity. Twenty consecutive patients were divided into two groups based on the type of LVAD they received. Ten patients had a pulsatile flow LVAD, and 10 had an axial flow LVAD. For the purpose of the study protocol, the axial flow devices were operated at a high speed to ensure continuous flow. The patients' peripheral artery vasoreactivity was assessed with an ultrasound vascular transducer that measured flow-mediated dilation (FMD). The FMD of the patients supported with pulsatile flow (15.6 +/- 5%) was higher than the FMD of the patients supported with temporary continuous flow (1.8 +/- 3%). The difference was statistically significant (p < 0.0001). Pulsatile flow is associated with a better peripheral vascular reactivity than continuous flow. Patients supported by axial flow devices should be kept on the lowest speed setting to allow maximum pulsatility.

New method for speed control of single phase induction motor with improved motor performance

In this paper, a new method of speed control for the single phase induction motor is introduced to overcome the disadvantages of the conventional methods. In this method, the magnitude of the main winding current and its angle are controlled to control the motor speed, as well as to increase the starting torque at all speed settings. In the meanwhile, the voltage applied to the auxiliary winding is kept constant at the rated value. The performance of a 1 hp capacitor run single phase induction motor is experimentally and theoretically investigated, using this method of speed control. The experimental rig is built in the laboratory and a complete set of test results is obtained. On the other hand, a mathematical model for the motor is developed and the motor performance is calculated. Good agreement between the experimental and theoretical results is obtained. These results show that the new method of speed control gives much higher starting torque. This enables the motor to start at low speed settings. Also, a great improvement in motor efficiency and power factor at all speeds is achieved.

New method for speed control of single phase induction motor with improved motor performance

In this paper, a new method of speed control for the single phase induction motor is introduced to overcome the disadvantages of the conventional methods. In this method, the magnitude of the main winding current and its angle are controlled to control the motor speed, as well as to increase the starting torque at all speed settings. In the meanwhile, the voltage applied to the auxiliary winding is kept constant at the rated value. The performance of a 1 hp capacitor run single phase induction motor is experimentally and theoretically investigated, using this method of speed control. The experimental rig is built in the laboratory and a complete set of test results is obtained. On the other hand, a mathematical model for the motor is developed and the motor performance is calculated. Good agreement between the experimental and theoretical results is obtained. These results show that the new method of speed control gives much higher starting torque. This enables the motor to start at low speed settings. Also, a great improvement in motor efficiency and power factor at all speeds is achieved.

REVOLVING-FIELD ANALYSIS OF TWO-SPEED SHUNTED CAPACITOR MOTORS WITH NONQUADRATURE WINDINGS

ABSTRACT The main purpose of this paper is to extend the well-known revolving-field theory for the general development of the so-called analysis equations to predict the performance of two-speed shunted capacitor motors with arbitrary arrangements of their primary windings. It has been found that sometimes by arranging the auxiliary winding at an unconventional location, the motor efficiency can be considerably improved especially at low-speed setting. The accuracy of the present mathematical development has been confirmed by actual measurements on such motors with windings both in quadrature and nonquadrature

Cross-Field Analysis of T- and L-Connected Capacitor Motors with Arbitrarily Displaced Windings

The chief purpose of this paper is to extend the well-known cross-field theory for the general development of the socalled analysis equations to predict the performance of both T- and L-connected tapped-winding capacitor motors with arbitrary arrangements of their primary windings. It has been found that sometimes by arranging the auxiliary and the speed windings at unconventional locations, the motor efficiency can be considerably improved especially at low-speed setting. The typical variations in the line current, input power, net torque output and overall efficiency are tabulated for direct comparisons.

PERFORMANCE EQUATIONS AND CALCULATIONS ON T- AND L-CONNECTED TAPPED-WINDING CAPACITOR MOTORS BY CROSS-FIELD THEORY

ABSTRACT The performance equations and calculations on both T-and L-connected tapped-winding capacitor motors for high and low speed settings are developed in this paper, using the cross-field theory. The necessary steps to employ these equations for performance calculations are suggested. Speed-torque data are calculated, and plotted for the purposes of illustration