GOALI: A time-efficient analytical framework for optimal electromagnetic, thermal and structural design of switched reluctance motor

Illinois Institute Of Technology, Chicago IL

Investigators

Abstract

Switched reluctance motors (SRMs) have recently gained attention as a low-cost replacement for permanent magnet (PM) machines, and as a high-efficiency replacement for induction motors. These motors can operate in four quadrants and wide speed-constant power range, which makes them a good candidate for applications ranging from electrical vehicles (EVs) to HVAC systems to domestic appliances. SRMs have concentrated windings on the stator and do not have permanent magnets or windings on the rotor, which makes them an inherently low-cost and good candidate for high-efficiency applications. This motor also has double saliency, high starting torque and low inertia, which can be achieved without large inrush currents. They are also inherently fault tolerant machines since the phase windings are isolated from each other. Despite these advantages, critical problems hindering the wider adoption of SRMs include high acoustic noise, vibration and torque ripple, low efficiency, and power density. In response to these challenges, this research proposes a new modeling paradigm for simultaneous optimization of coupled electromagnetic and structural performance in electric machines. It will also allow modeling of non-homogeneous conditions and 3-D phenomena including acoustic noise and vibration. Successful completion of both these objectives will lead to design techniques that are faster than conventional numerical approaches. This method can be used to implement real-time training of the machine model towards the development of high efficiency, quiet switched reluctance motors, which can easily be extended to other motor types. Conventional approaches for prediction of acoustic noise and vibration in machine design are usually based upon a deterministic approach using finite element analysis (FEA), where the motor is modeled using finite elements solving the partial differential equations (PDEs). Although FEA can be used for problems defined on complicated domains, it requires full discretization of the entire computational domain, which is not numerically efficient. For example, to design a new machine, one must start with a base shape and then tune parameters iteratively to meet the desired performance requirements. Computationally, the domain needs to be discretized several times and PDEs are solved iteratively to identify a relationship between the input parameters and output performance, which makes it computationally intensive. The proposed research will use a kernel free boundary integral method (KF-BIM) approach to develop a comprehensive time and computationally efficient design approach for electric machine design. The kernel-free boundary integral method is a generalization of the classical boundary integral method. It allows the formulation of variable coefficient elliptic PDEs in irregular domain into boundary integrals, without requiring the analytical expression of the Green's function. This approach will be used as a fundamental framework to develop a fast approach to accurately model non-homogenous conditions and 3D phenomena such as noise, vibration and harshness (NVH) and thermal behavior of the machine. This is an inter-disciplinary effort with contributions from Engineering and Applied Mathematics towards a cutting-edge integrated motor drive design framework. Research outcomes will be disseminated through active student engagement in the classroom and research lab, industry collaboration and research presentations. The team will continue to work with undergraduate students from Electrical and Mechanical Engineering in the EDEC laboratory on hands-on tasks and industry-grade benchmarking. Participation by female students and under-represented minority groups will be enhanced through undergraduate Inter-professional Project (IPRO) courses, summer research immersion projects and presentations to the City Colleges of Chicago, Society of Women Engineers and Society of Hispanic Engineers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.