Shunya Odawara

Proposing a Numerical Method for Evaluating the Effects of Both Magnetic Properties and Power Semiconductor Properties Under Inverter Excitation

To evaluate how magnetic properties of magnetic materials are influenced by power semiconductor properties in an inverter circuit, we propose and test a new numerical calculation method. This method combines an electrical circuit analysis for current-voltage properties of power semiconductors with a magnetic analysis based on a magnetic hysteresis model. Previous measurements on an inverter show that magnetic properties, such as B-H curves (B is the magnetic flux density and H is the magnetic field intensity) and iron losses, are affected by ON-voltages of power semiconductors. Those measurements motivate this paper. The magnetic hysteresis model used here is a novel approach that is based on physical thermodynamics theory and can capture the essence of physical magnetic phenomena. Calculations with the proposed method show that measured minor loops in B-H curves are well represented and calculated voltage waveforms properly capture ON-voltage effects.

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.

Impact of Material on the Iron Losses of a Reactor With an Air Gap

The iron losses of a reactor with an air gap are investigated and compared for three different magnetic materials, namely, grain-oriented material (GO230), high performance non-oriented Fe-Si metal (super E ST125), and nanocrystalline soft magnetic material (FINEMET FT-3M). The iron losses of the reactor are measured by the experiments for different voltage supply frequencies and amplitudes. The measured data are compared with the material iron losses that are calculated from the manufacturers material datasheets. It is concluded that the air gap is responsible for a large part of the increase between the reactor and material iron losses and that the FT-3M has sensibly higher building factor compared with the other materials.

Attempt to Evaluate the Building Factor of a Stator Core in Inverter-Fed Permanent Magnet Synchronous Motor

This paper presents an attempt to evaluate the building factor of a stator core made of nonoriented silicon steel laminations. The stator core is used in a synchronous motor with buried permanent magnets driven by a voltage source three-phase inverter with classical pulse-width modulation (PWM) control. The building factor is the ratio between the iron loss density in the stator core and the specific iron loss density of the material. It then gives an evaluation of the impact of the core manufacture and the motor geometrical configuration on the stator iron losses. A first experiment is conducted to measure the iron losses of the inverter-fed motor in no-load condition. The material-specific iron losses are then evaluated by trying to apply similar magnetic flux density conditions in a wound laminated ring. The results show a decrease of the building factor with the PWM carrier frequency.

Magnetic frequency characteristics of permanent magnet for arc-shaped PM motor

Magnetic frequency characteristics of permanent magnet for arc-shaped PM motor are shown, because harmonics components of magnetic flux density is supplied to PM, and the loss increase is expected. Stator core shape of PM motor makes slot harmonics components, and PWM inverter to magnetize the stator core makes time harmonics components. Numerical calculation shows that NdFeB sintered magnet has a large loss because of large eddy current in permanent magnet, though NdFeB bonded magnet has much smaller, because of 100 times smaller electrical conductivity.

Iron-loss characteristics using a 1MHz GaNFET PWM inverter

Next-Generation semiconductor devices like Silicon Carbide (SiC) or Gallium Nitride (GaN) have been introduced for many applications in power electronics due to their outstanding characteristics of high frequency and low loss operation [1].

Sampling frequency influence on magnetic characteristic evaluation under high frequency GaN inverter excitation

Nowadays, there is a great interest on new magnetic materials and their outstanding properties of low iron losses. However, when a magnetic material is experimentally characterized, it is important to select a suitable sampling frequency specially when the inverter is driven at a high carrier frequency. Nevertheless, iron losses of a magnetic material under inverter excitation are usually underestimated when the inverter is driven at an insufficient sampling frequency. This paper introduces the iron losses of a magnetic material at high carrier frequency excitation using a GANFET inverter. In addition, the experimental evaluation of iron losses at several sampling frequencies is presented. As a result of the measurements, at low sampling frequencies, minor loops of BH curves could not be well constructed, because the inverter waveforms are not measured properly. Finally, experimental tests at 100 kHz and 1 MHz of carrier frequency presented an underestimation of 21.4% and 25.1%, respectively. This measurement error is presented when the inverter is driven at a sampling frequency lower than the suitable one.

Iron Loss Characteristics Evaluation Using a High-Frequency GaN Inverter Excitation

Recently, novel magnetic materials have been developed for high-efficiency and high power density electric motors. In addition, next-generation semiconductor devices, like silicon carbide (SiC) or gallium nitride (GaN), have been introduced for power converters due to their high-frequency operation. Therefore, high-frequency operation of new magnetic materials is possible when they are driven by GaN or SiC inverters. Nevertheless, iron loss characterization of magnetic materials when they are excited by high-frequency signals have not been conducted yet. This paper introduces the iron losses characterization of a magnetic material at high carrier frequency excitation using a GANFET inverter. This characterization was carried out by the experimental evaluation of iron losses at carrier frequencies from 5 to 500 kHz at different deadtimes. As a result of the measurements, iron losses seem to have a trend to increase at high carrier frequencies and large deadtimes. In addition, filtering is introduced and it seems to be an effective technique for reducing iron losses.

Trial manufacture of magnetic anisotropic motor and evaluation of drag loss characteristics

A magnetic anisotropic motor, the stator core is made of grain-oriented (GO) steel plates, is manufactured as a trail, and the experimental drug force data show that the iron loss reduction is confirmed. The easy magnetization direction of divided GO steel is arranged so as to follow the main magnetic flux of the stator core in order to realize the low iron loss characteristics in the motor core. A special jig is used in manufacturing it to obtain the sufficient accuracy arrangement of the divided GO piece. The iron loss of the magnetic anisotropic motor is compared with the one of the non-oriented (NO) conventional motor.

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.