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This paper considers the possibilities of using digital feedback for precise anisotropic magneto-resistance (AMR) magnetometers using commercial off-the-shelf (COTS) components. Requiring only a few analog parts, most of the signal processing is done digitally within an STM32 microcontroller. Because most of the precision is made by the feedback circuit, the analog-to-digital converter (ADC) can be a low-cost type. The compensation source is made with a pulsewidth modulation-driven H-bridge sourced from a voltage reference, so the cost reduction when compared to a “full-analog” design is large. The demodulation of a flipped-AMR signal is done with software after the AD conversion because it improves the offset stability and brings the reduction of the preamp’s and ADC’s LF noise. This paper presents the full characterization of a real instrument, including its noise, linearity, stability, and power consumption. [ABSTRACT FROM AUTHOR]

In this paper, we propose a high-efficient constrained adaptive 5-binary to 4-ternary (5B4T)-modulation in pulsewidth modulation (PWM)-based ternary perpendicular magnetic recording (PMR). The high-efficient modulation is required to obtain higher user-bit density (UBD) gain in low-resolution channel, in which transition interval and magnetic-grain size are equivalent on media. In our proposed constrained adaptive 5B4T-modulation, one mapping-set is adaptively selected from the prepared two different mapping-sets to satisfy a specific constraint of ternary signal in modulation block-by-block. For the signal detection in the proposed modulation, we provide a practical solution which is a blind-detection method on likelihood vector. The likelihood vector is re-calculated as joint-metric using the likelihood values of adjacent modulation blocks. By using the vector of joint-metric, a likelihood vector is further generated to decode non-binary low-density parity-check (NB-LDPC) codes. Our simulation results demonstrate that the proposed adaptive 5B4T-modulated PWM-based ternary-PMR, combined with NB-LDPC codes over GF(32), shows a significant robustness in ultra-low-resolution channel, which occurs magnetization-missing frequently. [ABSTRACT FROM AUTHOR]

Power losses in soft magnetic materials can be solidly assessed by the statistical theory of losses (STLs), which provides physical foundation to the concept of loss separation. The theory is, however, limited to the conventional case of symmetric hysteresis loops and cannot be straightforwardly applied for a magnetic core operating under a dc bias. We show, in this paper, that such constraint can be released by combining the STL with a simplified approach to the dynamic Preisach model. This approach leads to the more affordable static Preisach model with largely reduced computation time. In this way, the hysteresis and excess loss components, with and without dc bias, are identified and calculated starting from a minimum set of experimental data. We provide a wide-ranging experimental validation of the theory, which is applied to the behavior of the energy loss versus frequency, measured up to $f = 1$ kHz, in non-oriented and grain-oriented iron-silicon sheets and in iron-cobalt alloys, subject to different polarization bias levels. [ABSTRACT FROM AUTHOR]

This paper investigates acoustic noise when an electric motor is fed with three-phase pulsewidth-modulated (PWM) currents with varying modulation indices. The procedure involves using a data-driven process to create a design space for different geometries of an interior permanent magnet synchronous motor. The motor structures are then analyzed using a finite-element analysis package to extract knowledge related to the sound pressure levels from the PWM excitation. It is demonstrated that sampling the air-gap space at a single time instant, which is a routine procedure in acoustic noise calculations, can result in an inaccurate estimation of the sound pressure levels, especially when the noise source is PWM motivated. Multiple-time sampling over the electrical period is proposed as a better approach for analyzing the sound pressure levels, irrespective of the type of supply current quality. [ABSTRACT FROM AUTHOR]

In this paper, we propose a loss calculation method considering minor hysteresis loops for permanent magnet (PM) motors driven by pulsewidth modulated (PWM) inverters. In the governing equation of the proposed method, both the effects of the major and minor hysteresis phenomena are expressed by a reaction magnetic field. This field is determined by iterative calculations of finite-element analysis (FEA) with a simple hysteresis modeling that considers the minor loops. The proposed method is applied to a PM motor, and the experimental verification is carried out. It is clarified that the minor hysteresis loops affect not only the hysteresis loss but also the eddy current loss because the skin depth varies with the differential permeability of the minor loops. [ABSTRACT FROM AUTHOR]

A new method for fast calculating the permanent magnet (PM) eddy current losses (ECLs) in interior PM synchronous machine caused by the high-frequency harmonic voltages (HFHVs) under pulsewidth modulation (PWM) voltage source inverter supply is proposed, by which time-consuming transient finite element analysis (FEA) is eliminated and the influence of the axial segmentation on the PM ECLs can be taken into consideration. The combination of the fixed differential permeability method and the linear frequency FEA is proposed to investigate the relationship between arbitrary HFHV and the corresponding PM ECL at different load conditions. The analytical model proposed in the previous published paper is used to describe this relationship quantitatively. Finally, the total PM ECLs at different load conditions can be calculated based on the fast Fourier transform results of the input PWM voltages. The relative errors between the total losses obtained with the proposed method and those with time-stepping FEA are within 21% at four typical load conditions, and the proposed method can reduce the computation time for one load condition to few minutes considering arbitrary PM axial segmentation. [ABSTRACT FROM AUTHOR]

This paper studies the effect of common-mode voltage elimination (CMVE) on the iron loss of electrical machine core laminations under multilevel converter supply. Three identical magnetic ring cores are excited by either a three-level converter or a five-level voltage source converter to study the behavior of CMVE on a three-phase system. Both multilevel converters are controlled by using a space vector pulsewidth modulation as it is one of the most often used techniques for CMVE. These experimental results are confirmed numerically with a dynamic iron loss model. In addition, the effect of CMVE, at different switching frequencies, on the core loss of a synchronous machine is numerically studied. The results presented in this paper show that the core loss is considerably increased when the CMVE is implemented. However, this iron loss increase in the five-level drive systems is lower compared with the three-level ones. Therefore, it is important that the designers of drive systems take such effects into consideration. [ABSTRACT FROM AUTHOR]

High-speed permanent magnet machines, supplied by pulsewidth modulation (PWM) voltage source inverters, operate with distorted stator currents. Harmonics present in these stator currents deteriorate the machine performance by generating losses. Mostly, these losses are following the machine design using a transient finite-element model. The precise measurement of these rotor eddy-current losses is extremely difficult, hence, only a few papers provide convincing comparisons between predictions and measurements. This paper presents a fast and precise analytical approach, verified with measurements, to consider rotor losses of machines, supplied by PWM voltages, already during the design procedure. [ABSTRACT FROM AUTHOR]

Large amounts of harmonics are contained in the current as the motor is driven by pulse width modulation (PWM). Significant amounts of computing time are required to compute local flux density variation considering such current harmonics. Since the amplitudes of higher harmonics are significantly smaller than that of fundamental harmonic, flux density variations due to the higher harmonics are small, and the relationship between the field strength and flux density can be assumed to be linear. When the operating point of each element is known, flux density variations for the higher harmonics can be analyzed by linear finite-element analysis (FEA). This paper suggests a method to calculate flux density variations in the iron core while taking into considering PWM current harmonics. First, the operating point solution is obtained by nonlinear FEA, second each element is linearized. Then, the flux density for the PWM current is obtained through linear FEA. Finally, the obtained results are presented and compared with nonlinear FEA results for verification. [ABSTRACT FROM AUTHOR]

In this paper, the concept of multirate partial differential equations (MPDEs) is applied to obtain an efficient solution for nonlinear low-frequency electrical circuits with pulsed excitation. The MPDEs are solved by a Galerkin approach and a conventional time discretization. Nonlinearities are efficiently accounted for by neglecting the high-frequency components (ripples) of the state variables and using only their envelope for the evaluation. It is shown that the impact of this approximation on the solution becomes increasingly negligible for rising frequency and leads to significant performance gains. [ABSTRACT FROM AUTHOR]

In order to resolve the starting problem for position sensorless interior permanent magnet synchronous motor, an improved initial rotor position estimation method based on square-wave signal injection is presented in this paper. Instead of the conventional sinusoidal voltage injection, square-wave voltage signals are injected into stator windings to obtain magnet pole position. On the basis of saturation and saliency principle, the voltage pulse injection method was adopted to identify the magnet polarity. Detecting the magnet pole position by using the square-wave voltage injection, the error signal can be calculated without low-pass filters and time delays. The proposed method is verified via a 1.5 kW interior permanent magnet synchronous motor drive platform. [ABSTRACT FROM AUTHOR]

The pulsewidth modulation (PWM) technique is commonly used to supply modern high-speed electrical machines. The fundamental frequency is typically in the kilohertz range, with switching frequencies of several tens of kilohertz, as determined by the new SiC- or GaAs-based power transistors modules. Switching introduces minor loops in the major hysteresis cycle, with durations of the order of 100~\mu \texts or lower, with the resulting magnetization dynamics influenced by strong skin effect. However, since these minor loops have relatively small amplitude, their constitutive equation may be described by an equivalent permeability (real or complex), depending on the mean slope of the minor loop and its static energy loss. By retrieving this permeability, the classical loss is straightforwardly calculated by analytical solution of Maxwell's equations. In this paper, we measure and calculate, according to the quasi-linear approximation for the minor loops, the magnetic energy losses of 0.194 mm thick non-oriented Fe–Si 3.2% sheets subjected to PWM induction waveform. Minor loop peak amplitudes ranging between 50 mT and 0.2 T and frequencies up to 10 kHz are investigated. The results are consistent with the proposed model, to within 5%. [ABSTRACT FROM AUTHOR]

In this paper, the investigation is focused on the iron loss prediction for electrical machines fed by low switching frequency inverter. An improved iron loss model is developed after reviewing various existing iron loss models considering pulse-width modulation (PWM) influence. In order to validate the improved iron loss model, iron loss tests are carried out on an electrical machine. The predicted iron loss results match well with the measured results, which shows that the improved iron loss model is able to predict iron loss in electrical machine fed by an inverter. The comparison between the predicted iron losses with and without considering the PWM influence shows that the iron loss can be significantly increased due to the influence of PWM, especially when the switching frequency is low. [ABSTRACT FROM AUTHOR]

The eddy-current effects in windings, i.e., skin and proximity effects, can be macroscopically modeled via a complex frequency-dependent impedance and reluctivity. In this paper, these two complex quantities are further embedded in a harmonic-balance finite-element model for arriving at the steady-state solution. The proposed approach is validated through a 2-D model of an inductor with pulsewidth modulated voltage supply. Both local and global quantities are shown to agree well with brute-force simulation results. The computational cost of both approaches is compared. [ABSTRACT FROM AUTHOR]

In this paper, a vector-controlled five-phase E-core flux-switching permanent-magnet (FSPM) machine drive system is proposed, in which three different control methods are applied, namely, current-hysteresis control, space-vector pulsewidth modulation (SVPWM) method-1 using only large basic vectors, and SVPWM method-2 using large and medium basic vectors in each section, respectively. The operation principle and simulated results are given. Then, a DSP-based driving system employing an E-core five-phase FSPM prototyped machine is set up to verify the proposed control method. Finally, a comparison among the three control methods is discussed, and it reveals that the SVPWM method-2 shows the best performance both in phase current waveform and in output torque. [ABSTRACT FROM PUBLISHER]

The study of the interaction between an interior permanent magnet (IPM) motor and a pulsewidth modulated (PWM) converter is increasingly becoming important, especially in the case of high-speed drives owing to the losses caused by modulation. Considering the significance of machine–converter interaction, this paper proposes a novel method to calculate magnet eddy current losses in an IPM used in traction applications by incorporating both PWM harmonics as well as rotor geometry and design parameters. The voltage harmonics from the PWM are incorporated into a series of steps in order to calculate the stator magnetomotive force (MMF) using the modified winding function theory. The rotor MMF and, subsequently, the magnet losses are computed using a magnetic circuit model incorporating the harmonics from the stator MMF as well as the flux barrier and the rotor geometry. The results have been demonstrated analytically for various cases of modulation and PWM input parameters to study the dependence of magnet losses on converter properties. The analytical results have been validated by finite-element analysis and experimental investigations. [ABSTRACT FROM PUBLISHER]

To study a multirate system, each subsystem can be solved by a dedicated software with respect to the physical problem and the time constant. Then, the problem is the coupling of the solutions of the subsystems. The waveform relaxation method (WRM) seems to be an interesting solution for the coupling, but until now, it has been mainly applied on academic examples. In this paper, the WRM is applied to perform the coupling of a controlled rectifier and a non-linear finite element model of a transformer. [ABSTRACT FROM AUTHOR]

This paper introduces the periodic carrier frequency modulation (PCFM) for permanent magnet synchronous motor (PMSM) drive systems so as to reduce the low-frequency electromagnetic interference (EMI). PMSMs are widely used in many applications and they are usually fed by pulsewidth modulation (PWM) inverters. The EMI of PMSM, which results from the switch of power device, generates undesirable effects on the control system. Therefore, it is of importance to reduce the EMI of PMSM. The common mode (CM) conducted EMI model of the PMSM drive system is constructed to investigate the CM voltage. The simulations and experiments of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to analyze the CM conducted EMI. The CM EMI spectra of PMSM fed by the FFPWM and PCFM with different spreading frequency widths are compared to explore the influence of PCFM on the CM conducted EMI. The regular patterns on PCFM in reducing the CM conducted EMI of PMSM drive systems are revealed. [ABSTRACT FROM AUTHOR]

This paper investigates a novel estimation method for iron losses considering hysteretic property and skin effect simultaneously. In the proposed method, iron losses considering both hysteretic property and skin effect are estimated by utilizing a 1-D finite element method as a postprocessing of the usual 2-D analyses based on ordinary magnetization curve. To demonstrate the effectiveness of the proposed iron loss estimation method, we compare numerical results with measured ones. Furthermore, the proposed method is applied to iron loss analysis of an interior permanent magnet motor fed by pulsewidth modulation inverter. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel parallel computation technique in the time domain for use in finite-element analyses of time-periodic nonlinear magnetic fields. The proposed method is based on converting problems from single phase to multiple phase and the polyphase time-periodic explicit error correction method. Numerical results that demonstrate its effectiveness are presented. [ABSTRACT FROM PUBLISHER]

This paper focuses on the reduction of eddy-current losses in fractional-slot inset permanent magnet motors. The flux paths of the armature reaction is modified based on pulsewidth modulation technique. Undesirable harmonic contents of the air-gap flux density can be reduced. This improves back electromotive force waveform quality and reduces the amplitude of eddy currents in the solid rotor and magnets. Rotor losses are strongly reduced by this technique. [ABSTRACT FROM PUBLISHER]

Current transformers (CTs) show large errors when they are magnetized by dc current. This error can be reduced after proper demagnetization. One of the methods to demagnetize the CT is to increase the core flux by increasing its burden. The burden should be adjusted according to the measured ac current. In this paper, we show that pulsewidth modulation switchable resistor can be used as variable burden for this application. This method enables to restore the nominal precision of the heavily magnetized CT from 2.5% back to 0.2% without interruption of the CT operation. [ABSTRACT FROM AUTHOR]

In this paper, a comparative study of the effect of different converter topologies on the iron loss of nonoriented electrical steel is presented. Three converter topologies are considered in this investigation; namely: two-, three-, and five-level power converters. Moreover, the effect of the carrier frequency on both the iron loss and converter loss is introduced. The experimental results show a dramatic increase of the iron loss for the two-level converter, especially for low levels of the carrier frequency. Furthermore, the increase of the iron loss is negligible for the multilevel converter topologies. Specifically, the use of the five-level converter, even at a low value of the carrier frequency, results in lower iron losses than the three-level converter at a relatively higher carrier frequency. [ABSTRACT FROM AUTHOR]

The study of iron losses in electrical machines represents a major interest in academic and industrial environment, especially in case of systems with high-frequency (HF) harmonic content in the supply voltage. In this context, this paper presents an analysis concerning the impact of HF injection on low-frequency (LF) iron losses. A new phenomenon is observed in a toroidal magnetic circuit with nonoriented electrical steel laminations, supplied by the superposition of two sinusoidal voltages at low and high frequencies. The experimental results show that the injection of HF harmonics (0–10 kHz) in the toroid affects the distribution of low frequencies in the steel in a way that the LF iron losses decrease of about 25%. An explanation for this phenomenon might be attributable to motion mechanism of Bloch walls. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of a load on the iron loss of an electrical sheet using a ring specimen with a secondary coil under pulse width modulation inverter excitation. In this experiment, the resistance load is connected to the secondary coil to simulate the motor load. To investigate the iron loss under load, we derive two methods to calculate the iron loss: the current difference method (CDM) and the power difference method (PDM). In the CDM, the iron loss is determined using the differential between the input current from the power amplifier to the specimen and the output current from the specimen to the load and voltage of the B-coil. In the PDM, the iron loss is derived using the differential between the input and output power. The iron loss calculated using the CDM and PDM agrees well when the secondary coil is open circuit, whereas the difference in the iron loss between the CDM and PDM increases as the resistance of the load decreases, especially when the carrier frequency is high. [ABSTRACT FROM AUTHOR]

For electrical machines with a 3-D geometry, such as axial flux permanent magnet machines, the computation of iron and magnet losses in the case of pulsewidth modulation (PWM) supply could be performed by a transient 3-D finite element model (FEM) coupled with an electrical circuit. To reduce the CPU time, in this paper, these losses are computed with acceptable accuracy without using a 3-D transient FEM. The multislice technique is used with a 2-D static FEM, combined with a state space model of the machine. A Preisach hysteresis model is considered to evaluate the iron loss during minor loops. The loss in the electrical steel and in the magnets is evaluated for several PWM frequencies as well as for different segmentations of the magnets. [ABSTRACT FROM AUTHOR]