Using the Predictive Time-Frequency Analysis, several different pulse width modulation (PWM) techniques are studied with naturally and regular sampled PWM. This study observes a dynamic trajectory modelling an electric drive chain with a constant acceleration of the machine to its nominal speed. This global method allows to observe different phenomena at the same time (resonance, sub-harmonics, and harmonic distortion) specific to the trajectory. The Predictive Time-Frequency Analysis applied to Electric Drive Systems (PreTiFEDS) highlights the reasons why a naturally sampled PWM is not necessarily the most appropriate when it comes to using other PWM strategies for high-speed applications.
Increasing the knowledge about components used to assemble an electric drive becomes more and more crucial. Especially for efficient electrical drives, that are produced in large volumes, it becomes necessary to know, how build in components like electrical steel stacks of stator and rotor perform. For the latter, their magnetic behavior is primarily responsible for an electric drive's overall performance. Hence, a magnetic measurement device has been designed and built to further investigate net shape parts regarding production-related magnetic property variations. Within this paper, a detailed insight in the design of a net shape part measuring setup for segmented stator teeth is given. The measurement system is validated concerning its ability to perform repeatable measurements of the same part geometry. The small measurement deviation allows to further investigate variations in testing conditions like the applied mounting pressure. To give an outlook on the future field of application of such measurement systems in large volume production lines, an investigation of parts produced from different batches indicates the range in which magnetic properties of final parts vary.
With the development of modern electric drive train systems, an effective cooling strategy is becoming a critical issue. Among various cooling methods, direct oil cooling is becoming more popular since it enables it to remove the heat directly from the heat source and subsequently improves the cooling performance. Aside from the cooling performance with direct cooling, the material compatibility of the coolant with machine components, particularly the electrical insulation system, is currently getting more attention. However, practical work regarding this issue is rare. Importantly, there still need to be widely recognised standards or instructions for compatibility evaluation. In the present work, the feasibility of conventional diagnostic approaches of insulation systems for compatibility evaluation is discussed. Particularly, a method to estimate the lifetime of the insulation system considering the compatibility issue is provided, and the role of mechanical stress during the compatibility study is analysed.
Refurbishment of hydro-generators promises an increased lifespan and improved efficiency. Old generators are not only less efficient but also less reliable; their fault occurrence is more common. The economic impact of out-service time can be astronomical. Thus, refurbishment is a critical task; but it is challenging too. Most of the conducted works focus on the material update, enhancing the cooling network, and obtaining better efficiencies. Modifying winding type, i.e. conversion from lap winding to wave winding is rare since it often requires a change in the slot number. Such a move can be laborious, size change can become mandatory. In this study, a refurbishment design strategy is proposed which includes a winding type conversion. The task is to implement a wave winding since it has less out-service time and is easily replaced by field workers. In this paper, an old generator that started operation in 1956 is used for a refurbishment. This study promises a guideline to hydro-generator designers who work on a refurbishment study on old hydro-generators that have diamond coils.
This article presents a MATLAB-based iterative design strategy, aimed at the investigation of axially asymmetric design possibilities for electrical machines. The developed tool for this strategy has modifiable individual portions and the capability of selecting various design criteria. The current study showcases the interdependence of various design parameters on the output performance parameters of a synchronous reluctance machine, for a selected set of design constraints. A brief analysis of the interrelated variables is presented and an approach to study and establish better control over compromising parameters is proposed for future work.
