Kazumi Kurihara

High-efficiency line-start interior permanent-magnet synchronous motors

This paper presents a successful design of a high-efficiency small but novel interior permanent-magnet motor using NdBFe magnets. It is designed to operate both at line and variable frequencies. Line start with high inertia load was a special consideration. Time-stepping finite-element analysis has been used to successfully predict the dynamic and transient performances of the prototype motors. It has been found that the proposed design has yielded successful simulation and experimental results. The maximum load inertia corresponding to the rotor-bar depth has been determined from the simulation results.

High efficiency line-start interior permanent magnet synchronous motors

This paper presents a successful design of high efficiency small but novel interior permanent magnet motor using NdBFe magnets. It is designed to operate both at line and variable frequencies. Line-start with high inertia load was a special consideration. Time stepping finite element analysis has been used to successfully predict the dynamic and transient performances of the prototype motors. It has been found that the proposed design has yielded successful simulation and experimental results. The maximum load inertia corresponding to the rotor-bar depth has been determined from the simulation results.

Steady-state performance analysis of permanent magnet synchronous motors including space harmonics

This paper describes the method for the analysis to obtain steady-state currents and torques of permanent magnet synchronous motors including space harmonics. A time-stepping finite element technique including the rotor movement is proposed, where both terminal voltage and load angle are given as the known values. In simulating the rotor movement, the suitable rotation step to take account of the effects of space harmonics, is determined. The agreement between calculated and measured results of the synchronous performance in an experimental motor is good. >

Advances on Single-Phase Line-Start High Efficiency Interior Permanent Magnet Motors

The past 25 years have been a significant period with advances in the development of interior permanent magnet (IPM) machines. Line-start small IPM synchronous motors have expanded their presence in the domestic marketplace from few specialized niche markets in high efficiency machine tools, household appliances, small utility motors, and servo drives to mass-produced applications. A closer examination reveals that several different knowledge-based technological advancements and market forces as well as consumer demand for high efficiency requirements have combined, sometimes in fortuitous ways, to accelerate the development of the improved new small energy efficient motors. This paper provides a broad explanation of the various factors that lead to the current state of the art of the single-phase interior permanent motor drive technology. A unified analysis of single-phase IPM motor that permits the determination of the steady-state, dynamic, and transient performances is presented. The mathematical model is based on both d-q axis theory and finite-element analysis. It leads to more accurate numerical results and meets the engineering requirements more satisfactorily than any other methods. Finally, some concluding comments and remarks are provided for efficiency improvement, manufacturing, and future research trends of line-start energy efficient permanent magnet synchronous motors.

Steady-State and Transient Performance Analysis for a Single-Phase Capacitor-Run Permanent-Magnet Motor With Skewed Rotor Slots

This paper presents a numerical analysis method to accurately predict the steady-state and transient performance of a single-phase capacitor-run permanent-magnet motor with skewed rotor slots. Two-dimensional time-stepping finite-element analysis has been used to successfully predict the steady-state and dynamic transient performance of the prototype motor by using a multislice model. The agreement between computed and measured results of the prototype motor validates the proposed analysis method. The maximum efficiency and minimum torque ripple versus the value of capacitance have been determined from the results of the steady-state synchronous performance analysis. The run-up response corresponding to skew pitch has been obtained from the results of the starting performance analysis.

Transient performance analysis for permanent-magnet hysteresis synchronous motor

The combination of hysteresis and permanent-magnet materials in the rotor of a self-starting synchronous motor makes the motor analysis very difficult due to its inherent nonlinearity. This paper presents the simulation results of the transient performance of permanent magnet hysteresis synchronous (PMHS) motors. The major feature in this study is to combine the time-stepping finite-element technique with the model for B-H hysteresis loop in order to take the nonlinear magnetic hysteresis into account. The good agreement between computed and measured performance in a laboratory PMHS motor validates the proposed analysis.

Radial flux type hysteresis motor with reaction torque--Numerical analysis of hysteresis motor using finite element method

This paper describes a new form of the radial flux type hysteresis motor having large output, high efficiency, and high power factor. The rotor ring of the machine is made of Fe-Cr-Co magnet steel and has magnetic anisotropy and slits. In order to analyze motor performance at synchronous speed and starting, the finite-element method is used. In this paper, magnetic hysteresis is considered by Using complex permeability. Predicted and measured values of motor performance characteristics agree well. Finally, the relation between dimensional ratio of slits and motor performance is described quantitatively.

Effects of Damper Bars on Steady-State and Transient Performance of Interior Permanent-Magnet Synchronous Generators

This paper addresses the small but high-efficiency interior permanent-magnet (IPM) synchronous generators with damper bars. The effects of the damper bars on stability during load change, maximum output, and efficiency are investigated. Two generators with and without damper bars were designed, built, and used for steady-state and dynamic load test. In addition, a typical IPM synchronous generator without damper bars is used for comparison. Time-stepping finite-element analysis has been used to successfully predict the steady-state and transient performances of the prototype generators. It has been found that the damper bars have contributed the stability effectively and increased the maximum output and efficiency. It is clear from simulation results that there were little higher harmonics in the flux density of the PMs because the damper bars reduced the space harmonics by the slot ripples effectively.

Starting performance analysis for a single-phase capacitor-run permanent magnet motor with skewed rotor slots

This paper presents the novel starting performance analysis for a single-phase capacitor-run permanent magnet motor with skewed rotor slots. 2-D time-stepping finite element analysis has been used to successfully predict the starting performance of the prototype motor by using a multislice model. The agreement between computed and measured results of the prototype motor validates the proposed analysis. The run-up response corresponding to skew pitch has been given from the simulation results.

High-Efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation

This paper presents the new scheme for high-efficiency operation of PWM inverter-driven hysteresis motor with short-duration overexcitation. When the terminal voltage Vi of the hysteresis motor running at synchronous speed is continuously increased up to nVi (n≪1) and then continuously decreased to Vi, input currents are reduced and output power is increased at the same time. Because of this, the efficiency becomes high. In this paper, the terminal voltage is controlled by changing the modulation degree of PWM inverter continuously.