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This paper presents an asymmetric magnetic pole structure interior permanent magnet synchronous motor (IPMSM) with a simplified magnet shape that uses bonded rare-earth magnets. By adopting the asymmetrical magnet arrangement, the current phase angle, where the magnetic torque is maximized, can be set to almost the same phase while maximizing the reluctance torque. It was shown that the proposed motor can achieve larger torque compared with conventional IPMSMs that use sintered neodymium magnets.

This paper presents an operating analysis of a ferrite orthogonal core for high-frequency power control and power conversion. The analysis is based on the three-dimensional nonlinear magnetic circuit of the orthogonal core, and is called Reluctance Network Analysis. The magnetization characteristics of the ferrite orthogonal core are calculated accurately by using Reluctance Network Analysis. On the basis of the obtained magnetization curves, we can analyze the operating characteristics of the various application circuits of the orthogonal core. For an example, the control characteristics of a high-frequency variable inductor using the ferrite orthogonal core are calculated in this paper. © 2001 Scripta Technica, Electr Eng Jpn, 137(4): 10–17, 2001

The operating characteristics of parametric transformers and dc-ac converters with an orthogonal core depend heavily on the core shape. Accordingly, to obtain the optimal design for such devices, the quantitative relationship between the orthogonal core shape and the operating characteristics of the application device are determined. In this paper, the application characteristics are discussed analytically in terms of the orthogonal core shape, with reference to a magnetic circuit model of the core.

This paper describes a push-pull parametric transformer constructed using a pair of orthogonal-cores. The operating characteristics of the parametric transformer with a rectifier load were analyzed based on SPICE simulations. The analysis results show good agreement with experiment. It was found that the input surge current of the full-wave rectifier circuit with a smoothing capacitor can be compensated by the parametric transformer. Use of the parametric transformer as a power stabilizer is anticipated owing to its various functions, such as for voltage regulation and overload protection.

In a previous paper, the authors proposed an orthogonal-core type dc-ac converter for use in photovoltaic power systems. The dc-ac converter has such desirable features as a simple construction, high degree of safety, and, ease of maintenance. The operating characteristics of a single-phase converter for residential photovoltaic power systems have also been reported. In this paper, we discuss the basic operation of an orthogonal-core type dc-ac converter for a three-phase power system based on simulations and experiments. An optimal construction of the orthogonal-core type three-phase dc-ac converter has been developed.

The orthogonal-core has various applications such as a parametric transformer and a DC-AC converter. The operating characteristics of the application devices can be calculated based on the measured flux-MMF relationship of the orthogonal-core. For the optimum design of the applications, we have to predict the flux-MMF relationship. However, in order to calculate the relationship, we need to solve the three-dimensional nonlinear problem. In this paper, we calculate the flux-MMF relationship based on the magnetic circuit model of the orthogonal-core. The computed results agree well with the experimental ones. It is obvious that the method on this study is valid for the calculation and useful for the optimum design of the applications.

This paper describes an analysis of the behavior of orthogonal-core type push-pull parametric transformers, taking the iron loss of the orthogonal-cores and the copper loss of the windings into consideration. The analysis was performed for the magnetic circuit of the orthogonal-core under magnetic saturation and with hysteresis. To improve the accuracy of calculations, the saturation characteristic was approximated by a series which includes terms of up to 21st order in the flux, and the hysteresis curve by a series including terms of up to 5th order in the exciting voltage. The calculated results show good agreement with experimental data. The analytical method presented here is useful for optimizing the design of push-pull parametric transformers.

In this study, the capacitance of capacitors connected in series with the auxiliary winding of a capacitor motor was changed by switching the firing angle of the triac, and ferrite magnetic wedges were inserted into the stator slots to reduce the flux density distortion in the air gap.

The characteristics of the capacitor motor under voltage control are highly applicable to home electric appliances. In this study, the supply voltage controlled by a triac has been applied to a split-phase capacitor motor. The capacitor motor usually produces an oscillative torque with a double supply frequency. When asymmetrical voltages controlled by the triacs are applied to the motor, the voltage and current behaviors are distorted. The authors have proposed a countermeasure of the insertion of ferrite magnetic wedges into the motor slot openings to smooth the flux density pulsation across the air gap. As a result, some significant relationships have been obtained.

The authors have inserted ferrite magnetic wedges into the stator slot openings of the capacitor motor to decrease the pulsation of flux density distribution in the air gap. As a result, the iron loss was reduced greatly to increase the motor efficiency and to improve other running characteristics.

The split-phase condenser motor is very useful for driving home electric appliances, but it has low efficiency. In other words, since the condenser motor is operated by two magnetic fields constituting positive phase and negative phase sequences, large electric power losses in light loads and oscillative torque are usually produced. In addition to this, the presence of the slot embedding electric conductors disturbs the flux density distribution in the air gap, producing tooth pulsation and higher harmonic losses. In this study, ferrite magnetic materials have been wedged into the stator slot openings of the condenser motor to smooth the pulsative distribution of the flux density in the air gap, and some experiments have been carried out to discuss the effect of the ferrite wedges on the motor characteristics with various running condenser capacities. As a result, the usefulness of the ferrite magnetic wedge has been verified.

Split-phase capacitor motors are commonly used to drive household electric appliances. The motor has some slots and teeth to embed electric conductors or coils. The presence of the slots and teeth induces the variation of magnetic reluctance through the magnetic circuit to introduce heavy pulsation of the air gap flux. Thus, the voltage, current and torque of the motor become oscillative to increase the electric power loss and finally to reduce the motor efficiency. First, the authors discuss the characteristics of a 3-phase cage-type induction motor in which the ferrite magnetic wedges have been installed into the stator slot openings of the motor to smooth the air gap flux pulsation and to decrease the electric power loss, resulting in improved motor efficiency. If the motor is driven by the voltage source in accordance with the loading condition, more economical operation will be achieved. In this study, a nonsinusoidal voltage controlled by the switching element of a triac has been applied to a capacitor motor with wedges of ferrite magnetic materials. This paper reports on the interesting results obtained.

Low-loss polarisation-maintaining fibres, with the zero dispersion wavelength shifted to 1.56 ?m, have been fabricated. A minimum transmission loss of 0.27 dB/km and crosstalk of ?22dB over a length of 4.1km, corresponding to h = 1.53 × 10-6m-1, are achieved at the same wavelength.