Atsushi Yao

PWM inverter-excited iron loss characteristics of a reactor core

In this paper, we focus on an evaluation of iron losses in a reactor core under pulse width modulation (PWM) inverter excitation. We examine the inverter- and sinusoidal-fed iron losses of the reactor core through both experiments and numerical simulations. The proposed measurement includes operation at a higher frequency than is used commercially. We discuss the building factor (BF) of reactor losses under PWM inverter and sinusoidal excitations based on material iron losses measured in a ring specimen. The BF calculation based on inverter-fed tests is an almost constant value because the magnetic flux density distributions related to the carrier frequency mostly do not depend on the reactor gaps.

Core losses of a permanent magnet synchronous motor with an amorphous stator core under inverter and sinusoidal excitations

We report core loss properties of permanent magnet synchronous motors (PMSM) with amorphous magnetic materials (AMM) core under inverter and sinusoidal excitations. To discuss the core loss properties of AMM core, a comparison with non-oriented (NO) core is also performed. In addition, based on both experiments and numerical simulations, we estimate higher (time and space) harmonic components of the core losses under inverter and sinusoidal excitations. The core losses of PMSM are reduced by about 59% using AMM stator core instead of NO core under sinusoidal excitation. We show that the average decrease obtained by using AMM instead of NO in the stator core is about 94% in time harmonic components.

Soft magnetic characteristics of laminated magnetic block cores assembled with a high Bs nanocrystalline alloy

This paper focuses on an evaluation of core losses in laminated magnetic block cores assembled with a high Bs nanocrystalline alloy in high magnetic flux density region. To discuss the soft magnetic properties of the high Bs block cores, the comparison with amorphous (SA1) block cores is also performed. In the high Bs block core, both low core losses and high saturation flux densities Bs are satisfied in the low frequency region. Furthermore, in the laminated block core made of the high Bs alloy, the rate of increase of iron losses as a function of the magnetic flux density remains small up to around 1.6 T, which cannot be realized in conventional laminated block cores based on amorphous alloy. The block core made of the high Bs alloy exhibits comparable core loss with that of amorphous alloy core in the high-frequency region. Thus, it is expected that this laminated high Bs block core can achieve low core losses and high saturation flux densities in the high-frequency region.

Iron loss characteristics of electric motor in high-temperature environment

In this paper, we focus on an evaluation of iron losses of an electric motor under a wide range of ambient temperatures. We experimentally and numerically examine the inverter- and sinusoidal-fed core losses of an induction motor core. The core losses under sinusoidal and inverter excitations decrease with increasing temperatures. In addition, we discuss the building factor (BF) of teeth part of the induction motor at room temperature and 300 °C based on material iron losses. To our surprise, the calculated BF in the teeth part is an almost constant value, which corresponds to about 1.4, under sinusoidal and inverter excitations. It is considered that the BF value of 1.4 depends on the iron losses caused by factors such as the manufacturing process and the core geometrical configuration. In addition, it is expected that we can estimate the iron losses, which depend on the manufacturing process and the core geometrical configuration, of the high-temperature motor by using the BF.

Magnetic Multiscale Model for Local Eddy Current Flow in Complex Materials With Insulated Conductive Particles

This paper proposes an equivalent magnetic hysteresis (B–H) curve for magnetic multiscale problems of complex materials composed of electrical conductors separated by insulating material. The conventional method, which assigns equivalent material constants to each material, cannot properly express the local eddy current loss and the extra magnetic field derived from the local eddy current. To solve this problem, we derive the magnetic hysteresis curve from the volume-averaged magnetic flux density and the surface magnetic field in the micro-model, and apply this curve to the macro-model. The mesh number of the novel macro-model is reduced to around one-tenth that of the micro-model. Magnetic hysteresis is treated by a free energy magnetic hysteresis model, and the macro-model ignores electrical conductivity. The magnetic hysteresis curve and the numerically calculated losses are consistent in the micro- and macro-models. The proposed method well expresses the local eddy current phenomena.

Experimental study on iron loss properties of an amorphous ring under different inverter excitations

This study focuses on an evaluation of iron losses of an amorphous ring under different inverter excitations. We examine the iron loss characteristics as a function of carrier frequency under Si-IGBT- and GaN-FET-inverter excitations. The ring test under GaN-FET-inverter excitation at high carrier frequency shows drastically large iron loss compared with that excited by Si-IGBT-inverter because of the ringing derived from the high speed switching.

Iron loss characteristics under PWM inverter excitation at high ambient temperatures

This study addresses magnetic properties of the inverter-fed electrical steel sheet under a wide range of ambient temperatures. We examine the iron loss characteristic under sinusoidal and inverter excitations at room temperature and 300 °C. The iron losses under sinusoidal and inverter excitations decrease with increasing temperatures because the electrical resistivity of electrical steel sheet increases. The temperature dependency of iron loss properties is related not only to major loops but also to minor loops in the B-H curve under inverter excitation.

Evaluation system of reactor iron loss under PWM inverter excitation

Reactor iron loss was evaluated under inverter excitation using LC parallel resonance circuit. LC parallel resonance was used to supply a higher current than the limitation of the power source. Experimental results showed that there was a difference in ring iron loss, but there was no difference in reactor iron loss between sinusoidal excitation and inverter excitation. The reason why there is no difference in loss in the reactor is that the carrier harmonic component becomes relatively small. This means that the influence of the harmonic component on the core loss is small.

Magnetic multi-scale problem of equivalent electromagnetic material constants for local eddy current flow

Equivalent magnetic hysteresis (B-H) curve is proposed here for magnetic multi-scale problem of complex material with insulated electrical conductive material. The conventional method to introduce the equivalent material constants is difficult to express local eddy current loss and extra magnetic field derived from the local eddy current. To solve the problem, magnetic hysteresis curve, which is derived from the volume-averaged magnetic flux density and the surface magnetic field in micro-model, is used for the macro-model. Mesh number reduction is realized less than one-tenth by this method. Free energy magnetic hysteresis model is used for magnetic hysteresis modelling, and electrical conductivity is ignored in macro model. The magnetic hysteresis curve and the loss from the numerical calculation results of macro model agree with the ones of micro-model. The proposed method well expresses the local eddy current phenomena.