Papers by Michael Lampérth
World Electric Vehicle Journal
Axial flux (AF) motors and generators have been used in niche automotive applications for many ye... more Axial flux (AF) motors and generators have been used in niche automotive applications for many years. Given their disk like shape they offer distinct advantages for integration into hybrid powertrains where available length is limited. An overview of axial machine topologies is given and the design and performance laws that govern the sizing of axial flux permanent magnet machines are presented. Based on the analytical laws described it is shown that an axial machine can achieve significantly more torque than a size comparable radial machine. 3D finite element analysis is used to fine-tune designs and to investigate loss mechanisms. A P2 hybrid module case study is used to show the benefits and challenges of the axial topology when compared to the radial one. The cooling system of the machine is presented in order to show how the integration of coolant passages could be achieved. The possibility of introducing heat barriers into a hybrid powertrain, decoupling the hybrid module from the rest of the powertrain, is also presented. The predicted performance of the machine is presented and compared to the initial test results.
World Electric Vehicle Journal, Jun 26, 2015
Axial flux (AF) motors and generators have been used in niche automotive applications for many ye... more Axial flux (AF) motors and generators have been used in niche automotive applications for many years. Given their disk like shape they offer distinct advantages for integration into hybrid powertrains where available length is limited. An overview of axial machine topologies is given and the design and performance laws that govern the sizing of axial flux permanent magnet machines are presented. Based on the analytical laws described it is shown that an axial machine can achieve significantly more torque than a size comparable radial machine. 3D finite element analysis is used to fine-tune designs and to investigate loss mechanisms. A P2 hybrid module case study is used to show the benefits and challenges of the axial topology when compared to the radial one. The cooling system of the machine is presented in order to show how the integration of coolant passages could be achieved. The possibility of introducing heat barriers into a hybrid powertrain, decoupling the hybrid module from the rest of the powertrain, is also presented. The predicted performance of the machine is presented and compared to the initial test results.
The use of computer aided design tools has now proliferated to many areas of engineering and the ... more The use of computer aided design tools has now proliferated to many areas of engineering and the use of robust and flexible design tools is paramount to modeling complex systems. Hybrid powertrains present often complex systems where simulation and modeling are important issues. This paper presents the development of a simulation tool for the modeling of hybrid powertrains for vehicular
Designing a heavy duty hybrid electric delivery vehicle requires careful selection of batteries, ... more Designing a heavy duty hybrid electric delivery vehicle requires careful selection of batteries, considering chemistry and size, to accommodate the vehicle’s energy requirements from driving demands. This paper presents an assessment of traction batteries suitable for Hybrid Electric Vehicles, examining the impact on performance and battery pack size of the vehicle’s duty capability. The effect of the battery capacity on cargo carrying capacity is explored for different control strategies, evaluating EV range, depth of discharge (DOD) and predicting battery pack life.
The thermal behaviour and cooling system efficacy of an axial flux stator has been modelled and i... more The thermal behaviour and cooling system efficacy of an axial flux stator has been modelled and investigated. This stator has been designed as part of a generator for a hybrid electric heavy goods vehicle. From the stator cooling system's heat removal capability, an indication of the maximum allowable current and hence corresponding torque and power could be obtained. The thermal model is a lumped circuit model. The model divided the geometry into rectangular pieces in the axial cross section and in different layers in the axial direction. This gives a model that includes both radial and axial heat flow in the machine.
Regenerative braking is an established feature of rail vehicles. The subject is under development... more Regenerative braking is an established feature of rail vehicles. The subject is under development in the road vehicle industry through recent developments in Hybrid Electric (HEV) and pure Electric Vehicles (EV). Up to 30% of the overall energy demand can be satisfied by energy saved through regenerative braking, significantly improving a vehicle's overall efficiency. In addition, the brake force requirement on friction brake modules is reduced and, in-turn, their size can be reduced. The paper discusses an overall approach to brake system, powertrain and energy storage system components. Computer codes have been developed to simulate component performance and examine control strategies, which demonstrate significant reduction in friction brake use. A notable finding has been the improved energy retention by the incorporation of ultracapacitors.
6th IET International Conference on Power Electronics, Machines and Drives (PEMD 2012), 2012
ABSTRACT This paper presents an experimental method for measuring heat generation rate in the per... more ABSTRACT This paper presents an experimental method for measuring heat generation rate in the permanent magnets of rotating electrical machines. The results obtained from the experimental work are used to derive an empirical correlation which is subsequently used to predict the total thermal energy stored in a magnet after a speed varying torque load. The results of an uncertainty analysis are offered in order to show the usefulness of the technique. An axial flux permanent magnet machine has been used as a case study in this work, though the methodology could certainly be applied to other topologies.
Energy Conversion and Management, 2015
ABSTRACT Energy conversion devices undergo thermal loading during their operation as a result of ... more ABSTRACT Energy conversion devices undergo thermal loading during their operation as a result of inefficiencies in the energy conversion process. This will eventually lead to degradation and possible failure of the device if the heat generated is not properly managed. The ability to accurately predict the thermal behavior of such a device during the initial developmental stage is an important requirement. However, accurate predictions of critical temperature is challenging due to the variation of heat transfer parameters from one device to another. The ability to determine the model parameters is key to accurately representing the heat transfer in such a device. This paper presents the use of an inverse identification technique to estimate the model parameters of an energy conversion device designed for vehicular applications. To simulate the imperfect contact and the presence of insulating materials in the permanent magnet electric machine, thin material are introduced at the component interface of the numerical model. The proposed inverse identification method is used to estimate the equivalent thermal conductance of the thin material. In addition, the electromagnetic losses generated in the permanent magnet is also derived indirectly from the temperature measurement using the same method. With the thermal properties and input parameters of the numerical model obtained from the inverse identification method, the critical temperature of the device can be predicted more accurately. The deviation between the maximum measured and predicted winding temperature is less than 2.4%.
Proceedings of the 15th International Heat Transfer Conference, 2014
Energy conversion device suffer from thermal loading as a result of inefficiencies during their o... more Energy conversion device suffer from thermal loading as a result of inefficiencies during their operation which may lead to device degradation and possible failure. It is of interest to monitor the internal temperature of the device to ensure its safe operation. Mathematical models of different complexities have been developed for the purpose of real time temperature monitoring. Temperature estimation accuracy is dependent on the thermal parameters such as the material conductivities and convective heat transfer coefficients. The complex construction of such devices means that the exact value of the thermal parameters is often not known. This paper presents the use of an inverse identification technique for the estimation of thermal parameters of an axial flux permanent magnet device designed for vehicular applications. The proposed method provides a practical approach to determine the thermal parameters indirectly from temperature measurements. A constraint least square method coupled to an analytical solution of the one step ahead predictor of temperature is used for parameter estimation. A parametric study is performed and it has shown that some of these parameters vary as a function of the operating point of the device. The estimated parameters are then used in an analytical thermal model for real time temperature monitoring during a drive cycle. A maximum time averaged error of 1.8 • C or an equivalent error of about 3% of the measurement range is observed for the estimated winding temperature.
SAE Technical Paper Series, 1999
2006 IEEE Vehicle Power and Propulsion Conference, 2006
This paper presents an overview of the research project and analysis of a mnulti-stack axial flux... more This paper presents an overview of the research project and analysis of a mnulti-stack axial flux generator. The Diesel research project focuses on developing a series hybrid drive Engine system, based on a diesel engine driven prime mover unit and G flywheel technology as energy storage, for light rail vehicles. A
Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine, 2012
Minimally invasive surgery is a widely used medical technique, one of the drawbacks of which is t... more Minimally invasive surgery is a widely used medical technique, one of the drawbacks of which is the loss of direct sense of touch during the operation. Palpation is the use of fingertips to explore and make fast assessments of tissue morphology. Although technologies are developed to equip minimally invasive surgery tools with haptic feedback capabilities, the majority focus on tissue stiffness profiling and tool-tissue interaction force measurement. For greatly increased diagnostic capability, a magnetic resonance imaging-compatible tactile sensor design is proposed, which allows minimally invasive surgery to be performed under image guidance, combining the strong capability of magnetic resonance imaging soft tissue and intuitive palpation. The sensing unit is based on a piezoelectric sensor methodology, which conforms to the stringent mechanical and electrical design requirements imposed by the magnetic resonance environment The sensor mechanical design and the device integration ...
Uploads
Papers by Michael Lampérth