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Cross magnetization (CM) is an inevitable phenomenon in electrical machines. It is more prominent in interior permanent magnet (IPM) brushless dc (BLDC) machines. This is because PMs demagnetize in overloaded and saturated conditions. It leads to cross coupling between the direct and quadrature-axes quantities, and a decrease in the resultant air-gap flux-density distribution under saturated conditions. In this paper, it is shown that CM leads to braking torque even in unsaturated IPM BLDC machines. Furthermore, the effect of CM on flux linkage, electromotive force, and dynamic torque is presented. Its mitigation using suitable selection of slot–pole combination is presented. It is observed that odd slot–pole combinations are least affected, and even slot–pole combinations are severely affected by CM. Furthermore, it is found that the overlap area of rotor pole arc with the stator pole arc influences the severity of CM, more particularly in fractional slot–pole combination machines. To verify these claims, finite-element method is used for modeling and analyzing various slot–pole combinations of a spoke-type IPM BLDC motor. The results obtained from these simulations are validated with a fabricated reference prototype, which support the claims. [ABSTRACT FROM AUTHOR]

This paper proposes a concept of fictitious “Electrical Gear” to analyze the flux pattern in the three-phase flux-reversal machine (FRM). The rotating-flux pattern of FRM has either two or four poles depending on the number of stator poles. FRM can be analyzed on similar lines as permanent magnet synchronous machine with the concept of this gear. The flux-density distribution in FRM is analyzed with Fourier analysis. The magnitude of various space harmonics and their contribution to the winding-flux linkages are determined. The procedure for finding the rms value of air-gap flux density from machine dimensions is described. In order to verify the aforementioned analysis, a 6/14 pole FRM with distributed and concentrated windings is designed and fabricated. The experimental results are compared with those obtained from finite-element method simulation studies and analytical results. [ABSTRACT FROM AUTHOR]

AC-to-DC converters based on one-cycle control exhibit instability in current control at light load conditions as well as when they are operating in the inverting mode. In this paper, a modified one-cycle controller for bidirectional ac-to-dc converter is proposed. A fictitious current component in phase with the utility voltage is synthesized. The sum of this current component and the actual load current is compared with the sawtooth waveform to generate the gating pulses for the switches. This modification not only renders stability to the converter at light load conditions and the inverting mode of operations but also enables the converter to seamlessly transfer its operation from the rectifying mode to the inverting mode and vice versa. Detailed simulation studies are carried out to verify the effectiveness of the proposed scheme. To validate the viability of the scheme, detailed experimental studies are carried out on a 2-kW laboratory prototype. [ABSTRACT FROM AUTHOR]

In this paper, a shunt active power filter (APF) based on unified constant frequency integration or one-cycle control [1] for compensating unbalanced loads in a three-phase four-wire system is explored. The APF provides compensation currents in such a way that the utility supplies only the balanced fundamental current at unity power factor, even if the load draws reactive and harmonic currents. The scheme neither requires the service of a phase-locked loop nor requires to sense the utility voltages. This makes the scheme insensitive to the distortions that are generally present in the utility voltages. First, the one-cycle control technique is applied to a topology involving a four-leg converter for the proof of concept. Then it is utilized to control a conventional three-leg converter having a split-capacitor dc link. The effectiveness and the viability of the schemes are demonstrated through detailed simulation and experimental verification. [ABSTRACT FROM AUTHOR]