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... design used hairpins made from nested pairs of 8x4mm copper conductor (Fig. 10) to maximise slot fill and to have the minimum number of connections, which was deemed essential for a production design. 2mm copper plates were used to form the complex connections without extending the end windings any more than the absolute minimum of about 24mm (Fig. 11). This is similar to an existing concept [15] except that axial gaps were left between the plates so that the ATF could flow over the surfaces; the conductors protruded from the slots as far as possible; and tabs were added where possible to maximise the cooling surface area (Fig. 12). The plates were coated with epoxy, and were painted ...
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... That is, only a limited number of studies considered the real application of such methods as direct coil cooling method [11], [14]. In some recent studies [9] some concrete power density gains were worked out against the more standard indirect jacket cooling methods, but the robustness with respect to the oilmaterial compatibility has only been studied recently in real applications [15], [16]. However, a fundamental guide on how to make a direct cooling approach robust towards the final prototyping phase has not yet been established yet. ...
The development of the next generation electrical vehicles requires drive-trains to become more compact, high-performant, and robust at the lowest possible cost. These more compact drive-trains operate at the same power ratings as their bigger sized equivalent and do need to dissipate their heat in a smaller volume. Therefore, more advanced liquid cooling methods of the drive-train components are needed to enhance the heat removal and increase the compactness, i.e., power density.
Recent studies showed the high potential of direct oil jet cooled
motor windings as one of the most promising cooling solution. However, several challenges need to be tackled to make such a jet
cooling method robust. Therefore, this paper presents a method
on how to achieve a robust oil jet cooled design systematically.
From a pre-selection of an oil matching the lubrication &
cooling conditions of the powertrain, an expert selection of
sub-component materials for the motor design, the best robust
motor design have been determined. This has been achieved
via a degradation validation guide which includes standard oil-material degradation tests, electrical insulation, DC break down
voltage tests, and a final motor testing validation phase.
... Access to maintainable energy has an immediate relationship with work creation, industrialization, well-being, environmental change, nourishment creation, and thusly financial development [10][11][12][13][14]. Be that as it may, more than one billion individuals in various pieces of the world despite everything need fundamental access to current vitality administrations [15]. ...
... Although such combinations show great potential in benefiting the performance-metrics of the machine, there is only a relatively small amount of literature that has been published regarding this topic. Wearing et al. [11] designed and manufactured a frameless permanent magnet motor with hairpin windings cooled by oil which was sprayed from the rotor shaft, however, the estimation procedure of the cooling performance is not reported. Park and Kim [12] numerically simulated the cooling phenomenon of a similar setup where the cooling oil was sprayed onto the end-windings from the rotor shaft, and the results were validated with experiments. ...
... where Ω1 and Ω2 are the solid angles subtended onto the nozzle orifice by the impingement surface and the spray cone as shown in Fig. 1 [26]. Equation (11) can be used to calculate the mean volumetric flux on any object as long as the object's solid angle and surface area can be determined. By way of example, consider the case where the end region of a stator with hairpin windings is being sprayed on from the axial direction as shown in Fig. 2; in such case Ω1 is subtended by the portion of the end-winding's axial projection that is covered by the spray region, indicated by the area shaded in dark blue. ...
... where w is the width of the rectangle, which is equal to the width of the end-winding. Equation (13) can then be used in (11) to determine the mean volumetric flux on the end-winding. The cover angle β can be calculated by [28]: ...
Hairpin windings and spray cooling are becoming an increasingly popular combination in the field of high-performance electrical machine design. Machines adopting hairpin windings can achieve higher torque and power densities while enabling them to be manufactured automatically on a large scale to meet the rapid market growth of electric transport. Spray cooling is an effective way for high heat flux removal, which has shown great potentials in electrical machine applications. Although spray cooling has been studied for decades in different engineering applications, the focus had been on investigating its performance on regular surfaces using low-viscosity liquids, such as water. Additionally, many existing models for spray cooling heat transfer were built on spray parameters that are difficult to obtain without specialist equipment. Thus, most results from previous studies are difficult to be interpreted and directly applied to electrical machine applications. Practical and economical approaches for estimating the heat transfer coefficients of spray cooling on hairpin windings are needed. This paper proposes and validates an experimental approach based on reduced-parameter models which can be applied to predict the heat transfer coefficient of spray cooling setups on hairpin windings.
... The electric and thermal behaviour are significantly more challenging to model due to the increased level of kinetic energy regeneration, increased function of providing vehicle propulsion in fully electric drive and the migration to higher voltage levels to provide the necessary power required for vehicle propulsion [8]. The control system modelling of this type of propulsion system is also increasingly challenging due to the increased level of complexity of providing power to wheel in internal combustion engine only, combination of internal combustion & electric and electric only energy source [83,[87][88][89][90]. ...
Thermal management plays a vital role in the modern vehicle design and delivery. It enables the thermal analysis and optimisation of energy distribution to improve performance, increase efficiency and reduce emissions. Due to the complexity of the overall vehicle system, it is necessary to use a combination of simulation tools. Therefore, the co-simulation is at the centre of the design and analysis of electric, hybrid vehicles. For a holistic vehicle simulation to be realized, the simulation environment must support many physical domains. In this paper, a wide variety of system designs for modelling vehicle thermal performance are reviewed, providing an overview of necessary considerations for developing a cost-effective tool to evaluate fuel consumption and emissions across dynamic drive-cycles and under a range of weather conditions. The virtual models reviewed in this paper provide tools for component-level, system-level and control design, analysis, and optimisation. This paper concerns the latest techniques for an overall vehicle model development and software integration of multi-domain subsystems from a thermal management view and discusses the challenges presented for future studies.
... In recent years, the use of low-voltage (48V) induction motor (IM) drive systems has become a trend for both pure electrical vehicles (EVs) and hybrid EVs due to their safety and lack of need of a high-voltage protection device [1]. In such a situation, the high-power battery pack with low-voltage outputs a large current, i.e., several hundred amperes. ...
This paper proposes a scheme that can compensate for the nonlinear characteristics of voltage source inverters (VSIs) for low-voltage delta-connected induction motors (IMs). Due to the nonlinearity introduced by the dead-time, the on/off delay, and the voltage drop across the power device, the output voltage of VSIs is seriously distorted, causing distortion in the phase current of the IM, which will lead to output torque ripple. However, the existing compensation methods for three-phase VSIs are derived from star-connected loads, or ignore the conducting properties of power devices. Moreover, the current polarity detection near the current zero is quite complex. In this paper, by taking such nonlinear characteristics into consideration, especially the conducting property of metal-oxide-semiconductor field effect transistors (MOSFETs), an output voltage model of VSIs for low-voltage delta-connected induction motors is presented. After that, in view of the difficulty in detecting the line current polarity near the current zero which might lead to the wrong compensation, an advancing current crossing zero (ACCZ) compensation is proposed. Subsequently, a compensation scheme which combines the compensation based on the VSI output voltage model and ACCZ compensation is proposed. Finally, the proposed compensation scheme is implemented based on a digital signal processor (DSP) drive system. The experimental results show that the proposed scheme has better performance than the common method in terms of suppressing the effect of the nonlinear characteristics of VSI, which demonstrates that the proposed compensation scheme is feasible and effective for the compensation of the nonlinear characteristics of VSI for low-voltage delta-connected IMs.
... The mild hybrid systems can use ultracapacitors or batteries based on lithium. As well in the micro hybrid systems on the mild hybrid the EM can be a permanent magnet synchronous motor, induction motor or switched reluctance motor (SRM), but due the combination of efficiency, robustness and the ability to be controlled make the SRM the most used motor in the under development and recently developed systems [30][31][32] (see Fig. 3). ...
The CO2 legislation has become more restrictive over time, and to reach the goals imposed by this legislation the automotive industry saw in the hybrid vehicles a solution. Technologies like micro, mild, full and plug in hybrids emerged in order to achieve the imposed goals. This article will provide an overview of the status of micro and mild hybrid technology and is intended to show that this type of technologies is a necessary step until the barriers are not exceeded and purely electric vehicles become the mainstream.
... On numerical control machine, frameless motor is usually applied as motorized spindle drive for high speed and torque [7]- [8]. For frameless motor with high power, it can be used in a dual clutch transmission of mild hybrid light duty vehicle with power of 20-25kW [9]. This paper focused on a kind of frameless PMSM with 39 slots and 12 poles. ...
In applications like robot joint and medical instruments with limitations for space and mass, frameless motor is an ideal choice as it doesn't contain shell, bearing, etc. In view of frameless PMSM with 39 slots and 12 poles, a method adopting 6 sets of three-phase winding for phase division and arranging coils in wave winding is proposed in this paper. Specifically, three-phase winding in every set is differently divided by approximate 60° phase belt, so that composite electromotive forces (EMFs) attached to same phase in different sets are not coincide but adjacent. Then embed double-layer short-pitch distributed wave winding of each set of three-phase winding according to this phase division and successively connect coils belonging to same phase in series. In this way, not only deviations in amplitude and phase among three-phase fundamental EMF caused by single set of winding can be reduced, but also higher winding factor can be obtained. Additionally, it can also save the copper wire and make the winding end shorter to achieve lighter weight and higher efficiency. Theoretical analysis about EMF and magnetomotive force (MMF) in this paper showed the validity of this design, while simulation results proved that the frameless PMSM has excellent electromagnetic performance. Prototype machine also shows that the arrangement of copper wires is very uniform and there is no more additional winding end.
... The vehicle's speed and braking power over NEDC and WLTC are shown in Figure 2 and Figure 3 respectively. The full details of the modelling approach and simulations run are presented in [9]. eMachine power rating of between 10 kW and 30 kW were considered; 10 kW is the "status quo" and beyond 30 kW the amount of recovered energy does not significantly increase as there are no braking events over the drive cycle where the recoverable power exceeds 30 kW [9]. ...
... The full details of the modelling approach and simulations run are presented in [9]. eMachine power rating of between 10 kW and 30 kW were considered; 10 kW is the "status quo" and beyond 30 kW the amount of recovered energy does not significantly increase as there are no braking events over the drive cycle where the recoverable power exceeds 30 kW [9]. Further consideration of eMachine cost and speed, in addition to packaging volume, lead to the selection of a 25 kW peak power design. ...
... The following sections of this paper present a high-level approach to the electric machine, the detail of which is shown in [9], and the approach to the control of the selected machine topology. Finally, the paper presents test results showing the performance of the eMachine. ...
div class="section abstract"> A duplex 3-phase (6-phase with 2 star-points) eMachine and associated inverter, including the development of the control algorithm, for a P2 hybrid vehicle was developed. The requirements, relating to power and duty cycle, flow down from the vehicle to the eMachine: these are shown and design issues relating to the use of a 48V system presented. The focus on low cost, compact solutions runs through the work. The inverter is rated at 25 kW to drive an interior permanent magnet eMachine, supplied by a 48V dc-link. The focus of the work presented in this paper is the inverter controller development and powertrain sizing. The test results of the eMachine with the inverter are presented to show the drive system operating the 6-phase current controller and inverter.
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