James W. Jiang

Design optimization of switched reluctance machine using genetic algorithm

This paper studies a design optimization procedure for switched reluctance motors (SRMs) using a Genetic Algorithm (GA). A multi-objective optimization method has been employed in the optimization of current commutation angles for priority operating points and over the entire operating range of the machine. Criteria of optimal control, which are maximizing output average torque and minimizing the root mean square value of net torque ripple, have been used in the optimization problem. A decision-making algorithm has been investigated to choose a solution from the optimal Pareto-front with finite optimal points. Five SRM design candidates have been selected and studied. The optimized motor performance at the priority operating points has been used to compare between different designs. Finally, a motor design that satisfies all design requirements has been characterized over its entire operating envelope based on turn-on and turn-off angles.

Three-Phase 24/16 Switched Reluctance Machine for a Hybrid Electric Powertrain

This paper presents the design process of a 60-kW switched reluctance motor for traction application in a hybrid electric vehicle. The motor has 24 stator poles and 16 rotor poles. A multiobjective optimization method has been employed in the optimization of conduction angles for priority operating points and over the entire operating range. Two objectives, maximizing output torque and minimizing torque ripple, are used in the optimization problem. A comprehensive comparative performance analysis with varying stator pole height, stator taper angle, rotor pole arc angle, and pole shoe shape is also presented. The performance of the proposed motor over the entire operating range has been characterized based on the optimized conduction angles. The finite element analysis results of the machine demonstrate the potential of the proposed motor in hybrid powertrains in terms of output torque, torque quality, and efficiency.

Hybrid Acoustic Noise Analysis Approach of Conventional and Mutually Coupled Switched Reluctance Motors

This paper presents a method to calculate the acoustic noise of conventional switched reluctance motor (CSRM) and mutually coupled switched reluctance motor (MCSRM). This method is based on dynamic electromagnetic models, combined with analytical estimation of the stator eigenmodes and radiation efficiency, considering the switching effects and frame effects. The proposed method is applied to predict and compare the acoustic noise performances of a CSRM and an MCSRM in a wide speed range. The results are validated using commercial finite element analysis software, JMAG for electromagnetics and ACTRAN for acoustics. An acceleration test based on a setup with a 12/8 CSRM is used for experimental validation. Results show that the proposed method can provide reliable prediction of main acoustic noises during acceleration.

Noise and vibration reduction for IPMSM by using rotor circumferential slits

In this paper, rotor slits on the rotors outer circumference is adopted to reduce certain harmonic components of radial forces and, hence, acoustic noise and vibration in an interior permanent magnet synchronous machine (IPMSM). The 48th order of harmonic component for the radial force is found to be responsible for the noise and vibration problem in the studied motor. For this purpose, the influential natural frequencies, speed range, and order of harmonic components for radial force are analyzed in a systematic way. A set of design procedures is formulated to find the proper locations for the slits circumferentially. Two base designs have been identified in electromagnetic analysis to reduce the radial force component and, hence, vibration. The features for both base models are combined to create a hybridized model. Then, the operating conditions, such as speed, current, and excitation angle are investigated on the hybridized model, in the high-dimensional analysis. At influential speed region, the hybridized model achieved up to 70% drop of 48th order harmonic for radial force in a wide operating range, and the highest drop goes up to 82.5%. Torque drop in the influential speed ranges from 2.5% to 5%.

An investigation of slot-pole combinations for interior permanent magnet synchronous machines with different magnet topologies

In this paper three different magnet configurations, e.g. single V-shape, double V-shape and delta-shape are investigated in the integer-slot 48/8 and fractional slot 36/8 interior permanent magnet synchronous machines (IPMSM). An optimization procedure for maximizing torque per ampere is used to compare these six motor models under the same output torque levels. The torque qualities at both low- and high-speed points for these six motor models are studied first. Fast Fourier Transform (FFT) analysis is also performed on the torque waveforms. Harmonics of magnetomotive force of the rotors and stators are analyzed. Radial force waveforms are also compared for these motor models. 36/8 winding configuration improves torque quality at both low- and high-speed points.

Thermal analysis of a three-phase 24/16 switched reluctance machine used in HEVs

This paper presents the thermal analysis of a 60 kW switched reluctance motor (SRM) under peak operating conditions for traction application in a hybrid electric vehicle (HEV). The SRM has 24 stator poles and 16 rotor poles, and three-phases. Heat generation losses are determined using finite element analysis (FEA) electromagnetic simulations and these losses are input into a lumped parameter thermal network (LPTN) simulation representing the thermal circuit of the electric machine. A range of coolant inlet temperatures are input and the testing of various priority operating speed points leads to the analysis of the rise in temperature of different components within the machine. By applying temperature limiting constraints of the copper windings and the rotor lamination surface, the operating times with varying coolant inlet temperatures and operating speeds can be determined.

A Review of Shaft Voltages and Bearing Currents in EV and HEV Motors

In most mechanical and electrical systems, reliability is paramount. Consumers, users and operators trust that their product will perform properly over its expected lifetime. Electric Vehicles (EVs) and Hybrid-Electric Vehicles (HEVs) are no exception to this statement. One of the most important components to consider when determining the reliability of EVs and HEVs is the electric motor. Within electric motors, many things can cause reduced reliability. This paper will focus on the most important component: the bearings. In this review paper, a general summary of bearing failure methods is provided along with an in-depth analysis of all facets relating to the shaft voltage and bearing current phenomenon with specific discussion relating to EV and HEV motors. Subsequently, this paper will provide a review of several mitigation techniques to render the bearing current failure mode obsolete.