Dynamic control of the permanent magnet-assisted reluctance synchronous machine

A digital signal processor-based control system for the permanent magnet-assisted reluctance synchronous machine, with the emphasis on dynamic performance, is proposed. A classical design approach is used to design the current and speed controllers for the machine. The stator current of the machine is controlled in such a way that the current angle in the dq synchronous reference frame is constant. The load-torque is estimated using a state space observer and compensation current based on the estimated load is used to improve the dynamic performance of the drive. The control system design is machine specific as it relies on data from finite-element analysis. Simulated and measured results on a 110-kW power level show that the resulting control system is stable and robust with good dynamic performance     

Direct finite element design optimisation of the cagelessreluctance synchronous machine

The finite element analysis method is used directly in optimisation algorithms to optimise in multidimensions the design of the cageless reluctance synchronous machine. Two optimisation methods are evaluated to minimise or maximise the function value. These are the direction set method of Powell and the quasi-Newton algorithm. Both methods proved to be successful, with some advantages and disadvantages. Using these methods at a power level below 10 kW, results are given of structures of the reluctance synchronous machine which have been optimised according to specific criteria. Calculated and measured results show that the maximum torque optimum designed reluctance synchronous machine has the advantages of high power density and high efficiency     

Digital implementation of bus clamped space vector modulation

Space vector modulation has recently become a popular PWM method of supplying a high performance drive. An adaptation of SVM modulation is presented here. This system is called bus clamped space vector modulation. This method has some practical advantages when compared to normal SVM. These include a reduced average switching frequency, easy digital implementation and asynchronous control and switching frequencies     

The influence of angiotensin-converting enzyme inhibition on renal tubular function in progressive chronic nephropathy

The influence of angiotensin-converting enzyme (ACE) inhibition on renal tubular function in progressive chronic nephropathy was investigated in 69 patients by the lithium clearance (C(Li)) method. Studies were done repeatedly for up to 2 years during a controlled trial on the effect of enalapril on progression of renal failure. The pattern of proteinuria was followed over the first 9 months. At baseline, the glomerular filtration rate (GFR) was 5 to 68 mL/min. Absolute proximal tubular reabsorption rate of fluid (APR), estimated as the difference between GFR and C(Li), was 1 to 54 mL/min. Calculated fractional proximal reabsorption (FPR) was moderately subnormal. During the study, GFR decreased and sodium clearance was unchanged; fractional excretion of sodium therefore increased. In the group of patients randomized to treatment with enalapril (n = 34), GFR at 1 month was 83% (P < 0.001) and C(Li) was 88% (P < 0.01) of the baseline values, APR and FPR had not changed significantly, and potassium clearance was significantly decreased. Through the rest of the study period, APR remained nearly unchanged and FPR even increased in the enalapril group. In the group of patients randomized to treatment with conventional antihypertensive drugs (n = 35), C(Li) was unchanged until severe reduction in GFR, APR and FPR decreased gradually, and potassium clearance was almost unchanged. These differences in tubular function between the two treatment regimens were significant (P < 0.05). An unchanged or increased APR in either treatment regimen was associated with a long-term slower progression of renal failure. Over 9 months, the 24-hour fractional clearance of albumin decreased in the ACE inhibitor group (P < 0.01), whereas the clearances of immunoglobulin G and retinol-binding protein were unchanged in this group. In the conventional group, the fractional clearances of these three plasma proteins all increased. It is concluded that in progressive chronic nephropathy ACE-inhibitor treatment was associated with different adaptive tubular changes in the handling of sodium, water, and protein compared with conventional antihypertensive therapy. During ACE inhibition, the reabsorptive capacity of the proximal tubule appeared to be better preserved, which might be of importance for the beneficial effect of this treatment in chronic renal disease.     

Review of superconducting electronics

This review will sketch the present state of affairs in applications of Josephson junctions and SQUIDs to: magnetometry, DC and RF metrology, detection and amplification of electromagnetic signals, frequency metrology, noise thermometry and computers. It will also mention recent progress in super-stable oscillators using superconducting resonant circuits, pulse transmission lines, and thin-film deviees to detect radiation or charged particles. Many of these topics are maturing nicely.     

六相感应电机直接转矩驱动系统的建模和仿真研究

研究了六相感应电机直接转矩控制的新策略.根据直接转矩控制技术,一个小型(2kW)两极六相感应电机驱动系统在电流数字滞环控制下通过Matlab仿真和实验实测得到证实,理论计算结果与实验结果基本一致.仿真和实验结果表明,电磁转矩和转矩电流在MMF平衡条件下呈线性关系而与负载的大小无关,这种转矩控制策略可使系统具有良好的动态性能.     

IPM Traction Machine With Single Layer Non-Overlapping Concentrated Windings

In this paper, an interior permanent-magnet traction drive machine with single layer non-overlapping concentrated stator winding is analyzed. In the single layer winding design, the number of stator slots and a winding factor are specifically considered. Moreover, the effect of varying the coil pitch on the winding factor and torque pulsations is investigated. A new calculation method is proposed, whereby the constant torque and field-weakening speed characteristics of the machine drive can be predicted using torque and flux linkage functions. The measured and predicted field-weakening performance of a 150-kW direct traction drive machine is presented.     

Advanced load application on deformable ring gears in planetary gearboxes

This paper discusses the implementation of deformable ring gears in Multi-Body-Simulation-Models (MBS-Models) of planetary gearboxes using the example of a Wind Turbine (WT). For this purpose an add-on to the MBS-Software Simpack was developed and tested by the project partners Bosch Rexroth and the Institute for Machine Elements and Machine Design at Rwth-Aachen University (Ime).The presented research includes a measurement campaign on a test rig owned by Bosch Rexroth to obtain data for a validation of the newly developed add-on.     

Time course of cardiac conditioned responses in restrained rats as a function of the trace CS–US interval.

Two experiments aimed at understanding the temporal characteristics of trace-conditioned heart-rate responses to a 0.5-s tone (conditioned stimulus [CS]) in restrained rats. A CS paired with a tail-shock (unconditioned stimulus [UCS]) elicited lasting bradycardiac responses. The magnitude and extinction rate of conditioned responses (CR) were independent of the CS–US interval (interstimulus interval [ISI], 3 s to 20 s). Unreinforced test trials were analyzed for CR topography. Responding was delayed in groups with longer ISIs, but CR latencies, peak and decay times were not proportional to the ISI Response peaks tended to cluster either about 6 s after CS onset, or about 10 s with a slow decay, depending on the ISI. The authors postulated 2 components of auditory stimulus traces involved in cardiac conditioning, maximally active 6 s and 10 s respectively after CS onset. The topography of the CR could be constrained to combinations of associative strength and instantaneous activity of these 2 components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)