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In this article, a low-ripple continuous control set (CCS) model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed. The inherent high nonlinearity of the SRMs makes it difficult to solve the optimization problem in the CCS MPTC algorithm analytically. To address this issue, an equivalent linear SRM model is adopted, and the cost function is also properly modified. Then, with the torque boundary values provided by executing the voltage vectors of an improved switching table, the optimization problem in the CCS MPTC method becomes simple and analytically solvable. The Lagrange multiplier method is employed to solve this optimization problem analytically and generate the optimum torque reference values for the active phases. Based on the estimated torque variation rates, the duty cycles for each phase are calculated. Extensive simulation and experimental tests are carried out in a four-phase 8/6 SRM setup. These testing results reveal that the proposed CCS MPTC method shows much lower torque ripples and current ripples in a wide speed range with a low computational burden than the existing finite control set MPTC methods. [ABSTRACT FROM AUTHOR]

In this article, a novel model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed based on the equivalent linear SRM model and the improved switching table. First, an improved switching table with only six switching states is developed based on the inductance characteristics. The adoption of this improved switching table not only reduces the computational burden by 25% but also improves the torque control performance and system efficiency at high-speed region. However, the look-up-table (LUT) based MPTC methods suffer from occupying numerous storage space. To ease this issue, the simple linear SRM model is utilized. The flux-linkage and torque equivalent transformations are introduced to address the difference between the linear and nonlinear SRM models. With these transformations, the MPTC realized on the linear SRM model is proposed. Compared to 1530 storage units consumption to store three two-dimensional (2-D) LUTs in the LUT-based MPTC methods, the proposed method only occupies 228 storage units. Experimental results on an 8/6 SRM setup verify that the proposed method effectively eliminates the commutation torque ripple with lower execution time, less storage space, and improves the torque control performance at a high-speed range compared with the conventional LUT-based method. [ABSTRACT FROM AUTHOR]

In this article, a general-purpose low-speed position estimation scheme using pulse injection is proposed for sensorless switched reluctance motor (SRM) drives. For the conventional low-speed sensorless control methods, magnetic characteristics are often used for position estimation, but it requires offline measurement and reduces the generality of sensorless control algorithms. To solve the issue, a new position estimator based on a regional phase-locked loop (RPLL) is designed. The approach utilizes a self-commissioning process to capture the unsaturated inductance adaptively at the initial stage. The RPLL is then adopted to estimate the full-cycle rotor position from the idle-phase inductance during sensorless operation. The speed-reversible sensorless control capability is also realized by a simple heterodyne design. Furthermore, stability analyses and parameter design are given to prove the robust local stability and convergence. Finally, comparative experimental validation is conducted on a 5.5-kW 12/8 SRM setup to verify the proposed method's effectiveness under both no-load and load conditions. [ABSTRACT FROM AUTHOR]

This article from a discrete-time model and stability analysis is developed using a Lyapunov approach, taking into account the one sample implementation delay present in digital control applications. Experimental results are provided to demonstrate the effectiveness of the proposed approach, where a conventional hysteresis controller is used as a benchmark. Results show that the proposal is able to deliver adequate reference tracking while using significantly lower sampling frequencies. Moreover, when compared to the hysteresis controller, superior tracking is observed at low speeds, while maintaining a similar level of computational complexity. [ABSTRACT FROM AUTHOR]

The article proposes a nonlinear state observer (NSO) for robust position-sensorless control of switched reluctance motor (SRM) drives over medium- and high-speed range. A classical reference flux-linkage method is adopted to capture a feature position of the SRM, which avoids the use of 3-D magnetic characteristics and has better universality. However, the estimation accuracy of this method would be deteriorated due to flux-linkage errors. To ease the problem, the NSO is developed to enhance the robustness against flux-linkage distortions for more accurate position and speed estimation. This observer can first reconstruct complete position information from a low-resolution feature position. The adverse impact of flux-linkage errors on position estimation is then investigated through a novel small-signal approximation and suppressed by an augmented state estimator. Afterward, a parameter design scheme is given to ensure the observer's stability and improve the capability in distortion suppression. To baseline the performance, comparative experimental validation between the proposed NSO and a widely used linear prediction method is conducted on a 12/8 SRM setup. The results show that the proposed strategy can improve the overall position-sensorless control performance in both the steady and transient states. [ABSTRACT FROM AUTHOR]

According to the modular power converter, a novel phase current reconstruction method using single dc-link current sensor is proposed for three-phase switched reluctance machine (SRM), and the control method is implemented with the reconstructed phase current as well. A highly integrated modular power converter is constructed by a three-phase full bridge and a dual switch module. The phase windings are in star-connection, and the bipolar phase currents are applied. Based on the special operating modes and single pulse width modulation signal injection, the dc-link current is decoupled and the phase current in both magnetization and demagnetization regions is reconstructed, which is very critical for the implementation of some advanced methods that require complete period phase current. The conventional control methods of the SRM, such as single-pulse voltage and hysteresis current control methods, are carried out under different operating conditions with both simulation and experiment to verify the effectiveness of the proposed method, and the reconstruction errors and performance influences are detailed analyzed as well. [ABSTRACT FROM AUTHOR]