Study on segmented-rotor switched reluctance motors with different rotor pole numbers for bsg system of hybrid electric vehicles

© 1967-2012 IEEE. This paper investigates the design principles and performance optimization for segmented-rotor switched reluctance motors (SRSRMs) with different rotor pole numbers for belt-driven starter generators of hybrid electric vehicles. For the design principles, several constraints are derived for the numbers of stator and rotor poles, the dimensions, and the number of winding turns. Two SRSRMs with 16/10 and 16/14 stator/rotor poles are presented according to these principles. For the performance optimization, the two motors are optimized individually for maximizing the torque. To evaluate the effect of different segmented-rotor numbers, the overall performances of the two SRSRMs are investigated and compared. It is found that the 16/14 SRSRM has higher flux linkage and static torque. The 16/14 SRSRM exhibits higher torque and lower torque ripple at low speed operation, whereas at high speed, the 16/10 SRSRM performs better in terms of torque and power densities. Compared with the 16/14 SRSRM, the 16/10 SRSRM has higher final steady speed under the same startup condition. The 16/10 SRSRM can achieve higher steady speed under starter mode and provide higher generated power under braking mode. Moreover, the 16/10 SRSRM exhibits higher efficiency in the most feasible speed range, especially in high speed range, and it has wider high-efficiency area. Finally, a 16/10 SRSRM is prototyped and tested to validate the simulation results

Design and performance analysis of a novel PM assisted synchronous reluctance machine

This paper proposes a novel permanent magnet assisted synchronous reluctance (PMAREL) machine, the main structure of this machine is quite similar to that of traditional PMAREL machine, and the main difference is that the grain-oriented silicon steel is used to replace some part of the stator teeth. The rolling direction of the grain-oriented silicon steel is along the radial direction of the machine, thus the advantage of higher permeability and higher kneel point in this material can be used to release the flux saturation problem of the traditional non-grain-oriented steel used in the PMAREL machine when the applied current density is high. Firstly, the structure of both proposed novel and traditional PMAREL machines are optimized and the design parameters are determined. Secondly the electromagnetic and mechanical performance are compared in these two machines which includes the demagnetization analysis, mechanical stress analysis when the rotor at the maximum speed, torque ability, efficiency by using the finite element method (FEM). It can be seen that the problem of stator teeth saturation in the novel PMAREL has been alleviated, and compared with the traditional PMAREL machine, the novel PMAREL has higher efficiency, wider speed range and 7% higher torque ability

Power density improvement due to rotor flux screens in an SRM with a higher number of rotor poles than stator poles

This paper studies the performance of screened switched reluctance motors (SRMs) with a number of rotor poles higher than the number of stator poles. Flux (conducting) screens are electrically conducting, non-magnetic materials like aluminum or copper. These screens fill the interpolar rotor air gaps decreasing the unaligned inductance, and thereby increasing the output torque. In addition, flux screens result in a cylindrical rotor structure which minimizes windage losses especially at high speeds. The paper investigates the effect of the flux screens thickness and material on the SRM performance including output torque, power and phase current. A modified flux tube approach for estimating the unaligned inductance of screened SRM is proposed. Finite element analysis results for different screen cases confirm the effectiveness of conducting screens in improving the torque, hence power capability, of switched reluctance motors

High-performance control for a permanent-magnet linear synchronous generator using state feedback control scheme plus grey wolf optimisation

© 2020 The Institution of Engineering and Technology. This study proposes an optimal control scheme for a permanent-magnet linear synchronous generator (PMLSG) using the state feedback control (SFC) method plus the grey wolf optimisation (GWO) algorithm. First, A novel state-space model of linear PMLSG is established in order to obtain desired dynamics and enough power when used for the smooth wave energy. Second, the GWO algorithm is adopted to acquire weighting matrices Q and R in the process of optimising linear quadratic regulator (LQR). What is more, a penalty term is brought into the fitness index to reduce the overstrike of output voltage and keep the rate of work more stable. Finally, optimal LQR-based SFC with and without penalty term and proportional-integral (PI) controllers are compared both in simulations and in experiments. Results clearly prove that the proposed optimal control strategy performs a better response when compared to other strategies

An Improved Model Predictive Current Control for PMSM Drives Based on Current Track Circle

Model predictive current control (MPCC) is a high-performance control strategy for permanent-magnet synchronous motor (PMSM) drives, with the features of quick response and simple computation. However, the conventional MPCC results in high torque and current ripples. This article proposes an improved MPCC scheme for PMSM drives. In the proposed scheme, the back electromotive force is estimated from the previous stator voltage and current, and it is used to predict the stator current for the next period. To further improve the steady state and dynamic performance, the proposed MPCC selects the optimal voltage vector based on a current track circle instead of a cost function. Compared with the calculation of cost function, the prediction of the current track circle is simple and quick. The proposed MPCC is compared with conventional MPCC and a duty-circle based MPCC by simulation and experiment in the aspect of converter output voltage and sensitivity analysis. Results prove the superiority of the proposed MPCC and its effectiveness in reducing the torque and current ripples of PMSM drives

Speed Sensorless Control of SPMSM Drives for EVs with a Binary Search Algorithm-Based Phase-Locked Loop

© 1967-2012 IEEE. This article presents a new method to extract accurate rotor position for the speed sensorless control of surface-mounted permanent-magnet synchronous motors (SPMSMs), based on the back electromotive force (EMF) information. The concept of finite control set-model predictive control is employed, and its cost function is related to the back EMF. An optimal voltage vector is selected from several given voltage vectors by comparing their fitness values. Moreover, the position space is divided into four sectors, and the fitness of each sector boundary is calculated and compared. The rotor position is first located in the sector surrounded by two boundaries that minimize the cost function. Then the selected sector is split into two parts, and the binary search algorithm is applied to reduce the sector area to improve the accuracy of position estimation. To overcome the drawback of the back EMF-based sensorless scheme, an I-f startup method is employed to accelerate the motor to the desired speed. An experiment has been carried out to compare the performance of the proposed method and the conventional phase-locked loop (PLL) in terms of steady-state and transient conditions

Torque Ripple Reduction of SRM Drive Using Improved Direct Torque Control with Sliding Mode Controller and Observer

The industrial application of the switched reluctance motor (SRM) is limited by its high torque ripples caused by the doubly salient structure. In this article, an improved direct torque control (DTC) with sliding mode controller and observer is developed to reduce the torque ripples of a four-phase SRM. First, a sliding mode controller based on a new reaching law is developed for designing a sliding mode speed controller (SMSC) for the DTC system. An antidisturbance sliding mode observer (ADSMO) is then proposed and combined with the SMSC to build a composite antidisturbance speed control strategy. Moreover, detailed simulation validations are carried out to reveal the effectiveness of the new reaching law, SMSC and ADSMO. Finally, experiments are conducted to verify the performance of the proposed SMSC-ADSMO in a DTC system with a four-phase SRM prototype