High Torque Conditions Research Articles

Simulation of Pumping Unit Based on Simulink

To study pumping unit of operating state in practical work, permanent magnet synchronous motor of direct torque control was used to model and simulate based on Matlab/Simulink software, and analyzed the waveforms change under normal operation and intermissive pumping. The results indicate that permanent magnet synchronous motor can operate smoothly under low speed and high torque condition, and can transit smoothly with different torque and acceleration. The proposed simulation system can achieve stable control, and its effectiveness is confirmed experimentally. Results of simulation analysis have some certain practical value for pumping unit driven by permanent magnet synchronous motor of direct torque control.

Analysis of PWM Frequency Control to Improve the Lifetime of PWM Inverter

Studies show that the power cycling mean time to failure (MTTF) of the insulated-gate bipolar transistor (IGBT) bond wire in an adjustable speed drive may be very short under some very common conditions. This paper proposes a switching frequency reduction method based on the junction temperature variation (ΔT <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> ) of an inverter IGBT. It has the following advantages. First, it reduces the pulsewidth-modulation frequency under low-speed higher torque condition. Second, the inverter is started more smoothly and safely under higher command switching frequency and high-torque condition. Third, the overall MTTF of the inverter IGBT can be improved. The theory analysis, simulation, and experimental result are provided to show these advantages.

The Challenge of Fuel Path Control at High Load Conditions

AbstractIncreasing emissions standards and fuel economy have forced engine designers to incorporate increasing numbers of degrees of control freedom into the engine. Consequently, calibration is becoming progressively more complex where the issue is most acute with diesel engines. This paper presents a project in which a closed loop controller is used in diesel engine fuel path, where no new calibration is required if any variation occurs. This is an initial investigation into diesel engine fuel path control. In order to prove that such a control technology could be developed over the whole speed and torque operating range, a high speed (2050 rpm) and the high torque (357Nm) point are chosen for investigations into control. This represents a challenging engine conditions for the application of control systems because of the limited time available for air supply and the need to complete combustion quickly. At these conditions the control authority is limited and the ability to detect for example small variations in torque and speed are quite limited owing to the high torque conditions. This paper demonstrates a closed-loop control at a high load condition and presents an architecture of controllable injection for a Caterpillar C6.6 engine using predictive control that includes exhaust temperature, of nitrogen oxides (NOx) and particulate matters (PM) without changing the fuel quantity.

Atomic Force Microscopy of Geroler Motor Wear Debris Ferrograms

Abstract Hydraulic motors convert the flow produced by a hydraulic pump into rotary motion. These motors are often used to propel skid steers, excavators, loaders, feller bunchers, and other heavy equipment. While hydraulic pumps operate under relatively constant high-speed conditions, motors frequently come to a complete stop and reverse direction, particularly when the payload is engaged. As a result, hydraulic motors operate under boundary lubrication conditions which can promote wear-particle generation. In this study we examined wear particles generated by a geroler-type hydraulic motor under high-load conditions using online particle counters, direct-imaging laser particle analysis, ferrography, and atomic force microscopy (AFM). Relatively high quantities of particles were discharged from the hydraulic motor case drain and return-line during the first 30 min of break-in. After 30 min, the particle count decreased to an ISO 17/15/12 level. At the end of the 6-h break-in process case drain samples were approximately four-times cleaner than return-line samples. Under low-speed and high-speed, high-torque conditions, case drain samples were also very clean. Return-line particle counts were five-times higher at 1 rpm than at 450 rpm. Ferrographic analysis revealed that most of the wear particles were less than 15 μm in longest dimension and therefore may be classified as “normal” wear. AFM imaging of ferrograms was performed in contact and tapping mode using a phosphorus doped silicon probe that had a 10 nm tip radius. The largest particles produced during low-speed, high-torque operation tended to be a few hundred nanometers longer and thicker than those produced under milder break-in conditions. Ferrography proved to be a particularly useful method for preparing wear particles for AFM analysis because the ferrogram substrate is flat in the submicron range.

Paper 15: Review of Compressors and Expanders for Air Separation and Liquefaction Plants

This paper deals with the application and operational problems of reciprocating and rotary compressors and expansion turbines within the air separation industry. Suggestions are made regarding the direction in which research, development, and design might be directed. Special problems within the industry are referred to, such as dry lubrication, prevention of gas loss, and special safety considerations applicable to oxygen compression. The high torque conditions on start-up of large rotary compressors, which require careful study in relation to coupling design and shaft stressing, are considered. Design codes are briefly discussed in relation to international requirements for testing and acceptance of machines.

Pulse-Width Modulation DC Motor Control

In order to control the speed of a dc series field motor at different required torque levels, it is necessary to adjust the voltage applied to the motor. For any particular constant voltage the motor speed is determined solely by the torque requirements and top speed is reached under minimum torque conditions. When a series motor is used as a traction drive for vehicles, it is desirable to control the voltage to the motor to fit the various torque requirements of grades, speed, and load. The common method of varying the speed of the motor is by inserting resistance in series with motor to reduce the supplied power. This type of motor speed control is very inefficient and wasteful of battery power due to the I 2 R loss, especially under high current, high torque conditions.