This paper presents a maximum torque per ampere (MTPA) control method for interior permanent-magnet synchronous motor drives. The proposed method employs a variable-equivalent-parameter MTPA control ...law to calculate the MTPA current references. Different from conventional MTPA control laws, this novel MTPA control law equivalently considers both the influence of the motor parameter values as well as the influence of the derivatives of motor parameters with respect to d - and q -axis currents on the MTPA control. Therefore, the proposed method can achieve the accurate MTPA control under different load conditions. In addition, this novel MTPA control law avoids the computation of derivatives of motor parameters and the complicated computations that exist in conventional MTPA control laws. Thus, the proposed method can provide the MTPA current references easily and in real time, allowing for fast MTPA control to be achieved. Both simulation and experimental results confirm the effectiveness of the proposed MTPA method.
For accurate position tracking and robust control of permanent magnet linear synchronous motor (PMLSM) servo systems against various uncertainties, such as parameter change, load disturbance, ...friction force, and so on, this article proposes a novel super-twisting nonsingular terminal sliding mode control method based on a high-order sliding mode observer. First, a dynamic model of PMLSM with uncertainties is established. A novel nonsingular terminal sliding mode function combined with the super-twisting algorithm is then proposed to design a robust super-twisting nonsingular terminal sliding mode controller, which ensures the system convergence to the equilibrium state within a finite time, effectively eliminating the chattering phenomenon and improving the system robustness. To further improve the system tracking performance and anti-interference ability, a high-order sliding mode observer is used to estimate the system uncertainties. The effective tracking performance and robustness of the proposed control method are validated by the experimental results.
Contemporary dentistry literally cannot be performed without use of resin-based restorative materials. With the success of bonding resin materials to tooth structures, an even wider scope of clinical ...applications has arisen for these lines of products. Understanding of the basic events occurring in any dental polymerization mechanism, regardless of the mode of activating the process, will allow clinicians to both better appreciate the tremendous improvements that have been made over the years, and will also provide valuable information on differences among strategies manufacturers use to optimize product performance, as well as factors under the control of the clinician, whereby they can influence the long-term outcome of their restorative procedures.
A new super-twisting-like fractional (STLF) controller is proposed in this article to improve the control performance for surface-mounted permanent magnet synchronous motor (SPMSM) system. Compared ...with the conventional super-twisting sliding mode (STSM) algorithm, the most distinctive characteristic of the proposed strategy is to replace the discontinuous switching function hidden under the integration with a nonsmooth term, which can significantly optimize the performance of SPMSM system. Meanwhile, the introduction of nonsmooth term can provide stronger anti-disturbance capability than the widely used smooth controller. In addition, the desired control performance can be achieved by adjusting the parameters of the proposed STLF controller according to the specific situations. Comparative experiments among the proposed STLF, conventional STSM and proportional integral controllers are carried out to demonstrate the feasibility and effectiveness of the proposed STLF technique.
This paper compares two flux-switching machines, namely, one stator permanent magnet flux-switching machine and one rotor permanent magnet flux-switching (RPM-FS) machine, with the same overall ...dimensions, main material properties, and current density. The comparison of characteristics is conducted from two perspectives, i.e., the electromagnetic torque production mechanism and torque (power)-sizing equation. The contribution of harmonics to average electromagnetic torque is analyzed based on the modulation principle and gearing effect, which reflects the similarities and differences between two FS machines in torque production mechanism. Moreover, torque performances are investigated from the viewpoints of magnetic parameters and electrical parameters. Then, electromagnetic performances including overload capability, flux-weakening capacity, and efficiency are analyzed and compared further. The predicted results indicate the RPM-FS machine exhibits a larger torque capability, a lower torque ripple, and improved flux-weakening capacity. The finite-element analysis predicted results are validated by experiments on two prototype machines.
This paper presents a new asymmetrical rotor hybrid permanent-magnet (AR-HPM) motor with good torque performances. Different from the traditional symmetrical rotor structure, the asymmetrical rotor ...structure is employed to improve the torque production. This makes the reluctance torque and the magnetic torque reach the maximum at the same current phase angle. Based on the concepts, the motor is investigated by the finite-element method (FEM). The frozen permeability method (FPM) is applied to divide the torque into the reluctance torque and the magnetic torque. The electromagnetic characteristics and torque performances of the motor are compared with a conventional motor. The results show that the proposed design is efficacious in boosting output torque at the same operating conditions. Moreover, the results also demonstrate that the topology of the proposed AR-HPM motor features the advantage of avoiding the risk of demagnetization.
This article presents a novel structure of a bearingless motor with integrated passive axial electrodynamic suspension. The simple initial structure has been improved in three steps. The structure ...was upgraded by including additional rings of permanent magnets and rotating back iron yokes in a double rotor structure that embraces the stator. Electrodynamic force generated in the final model was several times higher than that of the initial one. A prototype machine of the final structure was built. The suspension currents and axial electrodynamic forces were validated through an experiment under quasi-static condition, that is, constant rotational speed and fixed axial displacement. Theoretical equations for the axial electrodynamic force were derived. The force equation was compared to the finite-element analysis and experimental results.
This article proposes a design method of the high-speed multilayer interior permanent magnet synchronous motor (HSML IPMSM) employing the ferrite permanent magnet (PM). Since the maximum speed of the ...traction motor in this article is 15 kr/min, the mechanical stability must be considered. Additionally, in the case of the HSML IPMSM, as the number of the PM layers increases, the thickness of the PMs must be reduced to be mechanically stable. On the other hand, because the ferrite PM has a relatively low coercive force compared with the Nd PM, an irreversible demagnetization of the ferrite PM of the HSML IPMSM is likely to occur. Therefore, the mechanical stability and irreversible demagnetization must be considered at all design steps. As the irreversible demagnetization and mechanical stability can be confirmed only by the finite-element analysis (FEA), the proposed method in this article is a design method that considers the irreversible demagnetization and mechanical characteristics at all design steps using the FEA. After the design of the traction motor is completed using this design method, the designed motor is manufactured. To verify the validity of the design method, experiments are conducted on the manufactured motor, and the test results are compared with FEA results.
This paper proposes a novel permanent magnet vernier synchronous machine with saddle shaped permanent magnets. The torque of permanent magnet vernier synchronous machine with saddle shaped permanent ...magnets is increased of 35.4% and 45.6% compared with the permanent magnet vernier synchronous machine with V shaped permanent magnets and tile shaped permanent magnets respectively. The torque ripple of permanent magnet vernier synchronous machine with saddle shaped permanent magnets is reduced by 0.1% and 1.7% compared with the permanent magnet vernier synchronous machine with V shaped permanent magnets and tile shaped permanent magnets respectively. To facilitate the analysis, the saddle shaped permanent magnets are equivalently transformed to fan shaped permanent magnets, which is ensure that the pole arc angles and air-gap magnetic flux are unchanged. The rotor flux saturation region is modeled to improve the analytical calculation accuracy. The Laplace and Poisson equations are established for each part of the machine, the general solutions of the respective parts are solved, and the boundary conditions and intersection conditions are utilized to solve the factors. Compared with the finite-element method results, the torque difference is 0.32 N ∙ m and the torque ripple difference is 0.2%. The correctness of the analytical calculation is verified by comparing with the finite-element method results. The auxiliary slot angle and slot depth can be optimized resulting in a higher torque and lower torque ripple.
This article investigates the utilization of a consequent-pole (CP) rotor design in the interior permanent magnet (IPM) motor to enhance the permanent magnet (PM) utilization ratio material and ...reduce leakage flux. Compared to the spoke-type IPM motor, the proposed rotor design utilizes a strong flux-focusing effect to improve performance. The evolutionary mechanism of the proposed flux-focusing rotor from flat-type and spoke-type IPM rotors is illustrated, resulting in a higher PM utilization ratio. The multiobjective genetic algorithm is employed to optimize the design of the proposed CP motor, aiming to maximize the PM material utilization while minimizing torque ripple. The optimization process begins with sensitivity analysis, exploring geometric variables of the rotor and determining their respective ranges and step sizes. Furthermore, a set of Pareto front are generated to identify optimal outcome. Finite element analysis is utilized to compare the electromagnetic performance of the two motors. The obtained results indicate that the proposed structure achieves 2.1% increase in output torque and reduction of approximately 40.2% in PM volume compared to the spoke-type motor. Finally, a 3000 r/min 10 kW prototype was manufactured and tested for confirming the effectiveness of the proposed configuration.
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