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In this letter, a transformed unsaturated inductance characteristic-based method is proposed for the rotor position of the switched reluctance machine. Due to the magnetic saturation effect, the phase inductance characteristics have a narrow linear region, which increases the difficulty of their analytical expression. To reduce the complexity of the analytical expression, the unsaturated inductance characteristic is transformed from the phase inductance characteristics. Then, a linear model is presented to explicitly describe the relationship between the rotor position and unsaturated phase inductance. Experimental verification is carried out to verify the effectiveness and accuracy of the proposed method. The proposed method can serve as a low-effort way to provide the accurate rotor position for the industry application at medium and high-speed ranges. [ABSTRACT FROM AUTHOR]

To effectively find an optimal solution in the development process of electrical machines, it is essential to predict machine iron loss and thermal behavior in the predesign stage. Most existing publications only consider thermal behavior by roughly limiting the maximum current density. However, especially for high-speed application, iron loss can also be an essential part in thermal-behavior estimation. This paper proposes a simplified model to efficiently calculate iron loss and thermal behavior in the design procedure of switched reluctance machines. For this purpose, a maximum coenergy loop control method is implemented to facilitate the estimation of flux waveform and machine torque. Three different iron loss calculation methods are compared in terms of accuracy and time. Besides, a simplified lumped parameter thermal network is applied for machine sizing. Furthermore, the impact of number of turns and peak magnetomotive force on the losses and machine sizing is discussed. The efficiency and power density of various machine geometries are comparatively analyzed. Finally, the accuracy of the simplified model is verified by comparison with finite element simulations and experiment results. [ABSTRACT FROM AUTHOR]

In this paper, the intermittent control is proposed for switched reluctance machine (SRM) drive to both increase the efficiency and decrease the cost of the traction system for low-cost electric vehicles. With the purpose of maintaining the average machine torque required by the load, the intermittent control imposes a higher phase torque during a shorter time. The simulation and experimental results achieved with three different SRMs show that the intermittent control increases the system efficiency by reducing the converter losses and the core losses. Additionally, three different strategies of the control have been proposed to analyze their impact automotive application based on the criteria of efficiency, machine vibration, and torque pulsation. It can also be easily applied for any SRMs using average-torque-control-based methods. [ABSTRACT FROM AUTHOR]

This paper examines the efficiency performance of an automotive-size high-speed switched reluctance drive. It investigates the impact of a smooth torque control algorithm on the efficiency and losses in the drive. In automotive drives, the application of a dedicated algorithm for torque ripple reduction at low to medium speed is indispensable to avoid excitation of mechanical resonances in the drive train. The predictive direct instantaneous torque control method is compared with efficiency optimized hysteresis current control in terms of efficiency. Dynamic finite-element loss analysis is employed to investigate the source of the efficiency deviation and the results are verified by measurements. The study shows that the requirement for smooth torque leads to a decrease in the drives efficiency and altered loss distribution. The efficiency map comparison reveals that the efficiency degradation amounts to 4–9% for this particular drive. [ABSTRACT FROM PUBLISHER]

Zero-volt loop (ZVL) algorithms are known to be able to reduce peak flux linkages and resulting iron losses while keeping the same average torque in average torque control (ATC) of switched reluctance motors (SRMs). However, exploiting ZVLs to minimize the losses has been challenging due to the strongly nonlinear correlations between the torque and the control parameters of ATC caused by extensive magnetic saturation. In this paper, a fast optimization method for loss minimization is proposed, which can utilize all control parameters of ATC while operating with ZVL control. The proposed optimization method quickly calculates the current reference, which is one of the control parameters, so as to satisfy a torque reference, and consequently removes the time-consuming nonlinear constraint on the torque from conventional optimization methods. Using the proposed optimization method, the impact of ZVL control in loss minimization of SRMs is investigated with detailed simulations and experiments. The results verified that the utilization of ZVLs reduces iron losses without significantly increasing copper losses. It was found that the loss reduction was especially large (more than 15%) at medium speed and partial load. The loss reduction in the Japanese JC08 driving cycle for automotive propulsion for city driving was investigated and was as large as 15%. Furthermore, the vibrations that cause acoustic noise were also reduced. [ABSTRACT FROM AUTHOR]

This paper presents the design and an encoder-based starting strategy for a low-cost single-phase switched reluctance machine (SRM). The single-phase SRM cannot produce a continuous torque over one revolution. Therefore, applications that do not require a continuous torque, e.g., pumps and fans, are especially suitable. Another issue of single-phase machines is start up. The starting direction is affected by the initial rotor position. Due to the functional concept of SRM the machine produces no torque at aligned and unaligned position of the rotor and consequently, cannot be started from these positions. To start up from every rotor position a saturation-based starting method is used. The design of the rotor with the saturable area is shown and the principles of an encoder-based starting strategy for a fast start-up under 0.5 s are introduced. Finally, the build prototype and experimental results of the starting strategy are shown. [ABSTRACT FROM AUTHOR]

This paper presents a method to calculate the harmonic content of stator vibrations and acoustic noise resulting from radial force excitations in switched reluctance machines (SRM). The method is based on a thin cylinder approximation of the stator. The eigen modes are represented by their transmission impedance. The spectral composition of the vibrations can be calculated using superposition of the eigen modes and vibrations caused by all phases of the SRM. [ABSTRACT FROM AUTHOR]

We present a finite-element analysis of the temperature rise of switched reluctance motors (SRM) due to electromagnetic losses. We estimate the various components of electromagnetic losses, including core loss in the lamination as well as copper and eddy-current losses in windings, and then predict the temperature rise within the motor due to these losses. We present simulation results for an 8/6 SRM and discuss various aspects of thermal design of SRMs. To validate the procedure for the estimation of electromagnetic losses, we compare predicted and measured losses. [ABSTRACT FROM AUTHOR]

This paper presents a control scheme that allows minimization of dc-link capacitance in switched reluctance drives (SRDs). In switched reluctance motors (SRM5), the demagnetization energy of the outgoing phase causes a voltage increase in the dc-link. Therefore, large dc-link capacitors are required in conventional drives to absorb this energy to avoid over-voltages. The proposed control scheme balances the power flow between phases in such a way that the demagnetization energy of the outgoing phase does not flow back into the dc-link but directly into the incoming phase. Using this scheme, electrolytic capacitors can be replaced by film or ceramic capacitors leading to higher power density, longer lifetime, and higher reliability. [ABSTRACT FROM AUTHOR]