Assignment Task

Introduction:

The selection of an electric motor is a crucial factor in enhancing the driving range, performance, and efficiency of electric cars. Features including easy controllability, high power density, low maintenance costs, and simple design are prioritised when choosing motors for electric cars.

Better materials and more effective design techniques could lead to an increase in the motor`s efficiency while reducing its size, weight, and cost. Electric motor performance and use in traction, wind, aviation, and transportation are greatly enhanced by the design of an effective cooling system. Overcoming the difficulties with the power to weight ratio and fitting everything into the restricted amount of space available is the main task for designers of electric motors. (Jaeger et al., 2018)

The primary problem with induction motors is that they can become less efficient at high speeds due to eddy-current losses. These losses happen as a result of circulating currents developing in the conductive parts of the motor, which dissipate energy as heat. The limited transient overload capability of induction motors prevents them from meeting prolonged periods of rapid, high torque demands. In EVs, where quick acceleration is occasionally necessary. (Ravindra Jape & Thosar, 2017)

A Permanent Magnet Synchronous Motor (PMSM) with a rotor weight of 8.7 kg and a continuous power output of 75 kW is composed of the following parts: the rotor shaft makes up 30%, the permanent magnets comprise 16%, the magnet carrier makes up 61%, and other parts make up 2% (Peter et al., 2013). The steel and aluminium components` hefty weight is mostly due to their utilisation. Achieving great energy efficiency while substituting contemporary materials for conventional ones is a challenging task. Worldwide, 10 lakh electric motors are produced year (Solomon et al., 2020).

The three main losses in PMSM are copper, iron, and mechanical losses. In a stator, iron losses like hysteresis loss and eddy current loss might happen. High current flow in the armature winding is the cause of copper losses. Mechanical losses are caused by bearing friction losses and windage loss. Winding insulation failure is caused by temperature changes that occur while the motor is operating. This could lead to winding short circuits. The permanent magnets in the PMSM may demagnetize due to high temperatures that are created in rotor hot spots exceeding critical ranges. Therefore, the motor`s produced heat needs to be dissipated in order for it to operate safely (Dilshad et al., 2016). The actual difficulties faced by a high-speed electric motor are minimising weight with increase efficiency.

Aims

• Low weight of electric motor and high efficiency
• Reduce the weight of electric motors by using rotor and stator redesigns that provide efficient cooling and reducing the motor`s overall size to increase power and torque.

Objectives

• In the rotor the rotating back iron of the double airgap motor design is made from a soft magnetic compound, produced with an injection moulding process. enable highest lightweight potential, the back iron is designed as a 2-component-part with soft magnetic material in the magnetic active areas and PA6-GF30 for the structural integrity.
• In the stator the patented Fiber Printing technology is presented, which is based on a weaving process with the help of a tailor-made machinery, followed by moulding process.
• In oil cooling method high output power to volume ratio was achieved using oil circulation system to cool the electric motor and its shaft bearing. Here the circulated oil is cooled by the water externally.

Programme of work (Activities)

1. Literature review

In the past, magnetic losses and power losses provided the only primary architecture parameter. The losses in electric motor are distributed into various components, in three-phase motors, resistance losses in stator windings and rotor bars will result in an output loss of up to 15 percent. In single phase fractional horsepower motors the losses could be up to 30 percent.

2.Material Selection (end of 3 weeks)

Examine materials that are lightweight, such as glass fibre reinforced polymers (GFRP) for the rotor shaft, carbon fibre reinforced polymers (CFRP) for the torque gearbox, and soft magnetic compounds (SMCs) for the magnetic field motor components flow.

Perform trade-off analyses considering elements such as manufacturing feasibility, thermal properties, electromagnetic characteristics, and strength-to-weight ratio.

3. Design of rotor

SMC material carrier is pushed onto a CFRP and steel hybrid shaft. The goals of both technologies are to reduce weight and enable scalable and flexible manufacturing.

The following explains the fundamental design of a rotor that incorporates both technologies, as seen in Fig. 2.

On both ends of the hybrid rotor, steel components are installed to support the ball bearings, shaft encoder, and coupling connection. The CFRP shaft and both steel parts are positively connected by a polygonal connection with rounded edges. The entire length of the rotor`s electro-magnetic active section is covered by the CFRP shaft.

Figure 2 shows an injection-moulded magnetic carrier with magnets installed on a rotor disc. The torque gearbox and magnetically active portion are the two functional needs that this structure combines. Torque gearbox is accomplished through the use of GFRP (glass fibre reinforced plastics), and magnetic field flow is accomplished by SMC. The magnet`s length and the magnet carrier`s length were balanced. The necessary number of magnets can be accommodated by assembling multiple magnet carriers. According to Koch et al. (2017), splines are utilised to facilitate assembly on the rotor shaft and to transmit torque positively between the shaft and rotor disc.

Figure 3 . Injection moulded magnet carrier a) Soft magnetic composite (inner) and Polyamide (outer) b) Magnets mounted on single rotor disc (Koch et al., 2017)

4. Design of Composite Stator

Better overall KPIs for ironless machines are made possible by compact thin composite stator design, which also results in lower costs because less permanent magnet material is used. Higher CFF and higher allowed current loading are the essential factors that enable thin stator design.

The performance of ironless machines was revolutionised by the proprietary Fibre Printing technique. Although it needs specialised production equipment, its flexible nature allows for a variety of winding arrangement patterns (Fig. 4). Litz wires are used to create the weft threads in the weaving process, which forms the basis of the overall production process. The resulting mats are then rolled, placed in a mould, and resin-cast.

In order to dissipate the heat produced by an electric motor, Zadeh et al. studied the effectiveness of indirect cooling using cutting-edge nanofluid coolants. To increase the rate of heat transfer, aluminium oxide nanoparticles are added to the base fluid. According to the results, a remarkable 40% increase in heat transfer rate was achieved with a 4% increase in flow rate and a higher fraction of nanoparticles (Deriszadeh & de Monte, 2020).

5. Simulation and Optimization

• Use computational tools to realistically prototype and optimise the lightweight motor design, such as ANSYS, Motor-CAD, and multi-physics simulation.

6. Manufacturing and Results analysis

• Create manufacturing procedures that incorporate methods such as injection moulding, compression moulding, or resin transfer moulding to produce lightweight motor components in substantial quantities.

7. Report compilation

• Research Methodology: Describe all the information for the report was gathered.this might involve literature review, data analysis, and combination of these methods.

Resources:

1. Materials

• Parts of electric motors can be replaced with fibre reinforced polymers (FRP) to lower the total weight. Electrical conductivity and mechanical qualities are improved by FRP materials. FRP materials that thermoset provides excellent resistance to heat and chemical corrosion. High power to weight ratios can be achieved at lower production costs by using soft magnetic composites (SMC). Phenolic composite materials (PCM) are helpful for replacing numerous metallic pieces with one cohesive piece. Assembling tasks could take less time, and maintenance could be completed more quickly as well.

• A motor`s overall efficiency is determined by its mechanical, electrical, and building materials. High-quality parts and engineered architecture are used by power-sensitive motors to get greater efficiency. Minimising motor resistance losses is achieved by using larger copper wire diameters in the stator and more aluminium in the rotor. Reduction of stray loss is achieved by improved rotor configuration and optimal air gap between stator and rotor. The energy-efficient motor may operate with reduced magnetization losses thanks to thinner and better-quality rotor and stator core steel laminations. Friction losses are decreased by high-quality bearings (Kuehl et al., 2018).

• The design of electric motors facilitates not just to reduce the cost but also to enhance the performance and the pursuit of the full potential. There are many facets of attaining the maximum performance of an electric motor. The choice of core materials, too, is among them. A task that also includes the components that makes up the core of electrical motors, from magnetic lamination to the stator case.

 2. Simulation and Optimization

• Use computational tools to realistically prototype and optimise the lightweight motor design, such as ANSYS, Motor-CAD, and multi-physics simulation.
• Conduct combined thermal, structural, vibroacoustic, and electromagnetic evaluations to iteratively improve the design.

It seems that working with very thin materials is the current trend, everything from mechanical components to laser-based methods that are less affected by thickness and cause a minor decline in magnetic activity in the areas being cut. Meanwhile, we ought to envision creating ultra-thin laminations using a multilayer technology that can lessen magnetic loss and make them easier to utilise.

3. Financial cost over all electric motor

Outcomes:

In past research the steel metal rotor shaft (which makes up about 30% of the overall weight of the rotor) and the laminated magnet carrier (which makes up approximately 61% of the entire weight of the rotor) are the two components in the traction drive with the largest mass. This information may be obtained by looking at the mass distribution of the individual components. Manufacturers of automobiles have asked that parts with improved weight and inertia should have benefits in terms of overall motor mass and dynamic. It is looked into replacing both components with ones that have less bulk, inertia, and better electro-magnetic characteristics. The replacement for the rotor shaft is a hybrid carbon Fiber reinforced plastic shaft.

The replacement for the rotor shaft is a hybrid carbon Fiber reinforced plastic shaft.  The combined dry filament winding process for preforming and the impregnation by a rotational molding process can produce 18,000 parts per year. The replacement for the magnet carrier is an injection moulded SMC part with a functional separation of the torque transmission and the magnetically active part. A standard injection molding machine with two injection units and a special Mold are sufficient. This simple setup already allows the production of 127,000 magnet carriers per year.

Conclusion:

The development of lightweight components comprised of Fiber-reinforced polymers and composites to replace aluminium and steel metal parts is discussed. The specifics of what materials must have to resist a turning moment and well they conduct magnetic fields are covered. The intricate details of designing composite parts that meet the specifications are displayed. A new indirect cooling technique using nanofluids as coolants is demonstrated. The rate of heat transmission is observed to increase to 40% when base fluid water is mixed with nanoparticles of aluminium oxide. It has been discovered that high temperature superconducting (HTS) cables boost power density while lowering weight. Energy-efficient motors use high-quality materials and optimised designs to achieve high efficiencies.