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Discrete space vector modulation (DSVM) is employed to synthesize large number of voltage vectors (VVs) to improve the steady-state performance of predictive torque control (PTC). However, enumerating all the VVs in the prediction process increases the computation load of the motor drive. To address this issue, this article proposes a unidirectional VV preselection (UVVP) method for optimizing the performance of DSVM-based PTC of ac motors. The proposed UVVP method divides both voltage space vector diagram (VSVD) and flux space trajectory into twelve 30° based sectors to reduce the impact of candidate VVs with negative effects. At each flux position, the UVVP strategy can restrict the nearest candidate VVs in the 30° based VSVD region within the circular flux trajectory. This is achieved by using the speed direction to avoid the candidate VVs, which are in the same flux sector for reverse flux rotation, hence resulting in significant flux and torque ripple reduction. The main benefit of the proposed method is its simplicity since it only requires the flux sector and speed information as well as it can generate the VV enumerations online while ensuring the reduction of computation burden. [ABSTRACT FROM AUTHOR]

Unavoidably, the controlsystem of any permanent magnet synchronous motor (PMSM) is subjected to perturbations, e.g., motor nonidealities and inverter nonlinearities. To reject these perturbations, a new super-twisting (ST) control variant, called speed adaptive super-twisting (S-AST) control, is proposed in this paper. In the S-AST control, a proportional-integral (PI) and a ST controllers are merged using an adaptive law that is based on the motor speed measurement. This is done to reduce the chattering problems that the standard ST control presents. In addition, a mathematical design for the S-AST control is proposed, where the relationship between the chattering amplitude, the switching frequency and the system perturbations is shown. The main contribution in this paper is the application of the S-AST controller to reduce the total harmonic distortion (THDi) of the PMSM currents. By comparing the S-AST control against PI control, the THDi is reduced from 9.9% to 1.27%, in simulation, and the THDi is reduced from 22.79% to 1.56%, experimentally. These results demonstrate how the S-AST control is an excellent alternative to improve the waveform of the PMSM currents. [ABSTRACT FROM AUTHOR]

This two-part article compares the torque performance of 12 types of ac machines based on the same surface current density, tooth flux density, and rotor dimensions. Part II examines the torque capability of machines more recently developed which utilize the wave shaping capability of a solid-state frequency inverter. Essen's equation, as utilized in Part II, is modified to accommodate machines requiring non-sinusoidal waveforms. The “tau” factor, introduced in Part I, is also modified and is again used as means for comparison of any ac machine with an “ideal” machine based now upon a modified form of Essen's equation. [ABSTRACT FROM AUTHOR]

This article proposes a new predictive current control (PCC) strategy for a dual-inverter fed four-level (4-L) open-end winding induction motor drive (OEWIMD). The individual inverters of the dual-inverter system are operated with dc-link voltages, which are in the ratio of 2:1. In general, the PCC for the 4-L OEWIMD requires the evaluation of all of the 37 available voltage vectors (VVs) to select the optimal one. An improvised PCC is proposed in this article, wherein the inverter with lower dc-input voltage is clamped, while the other inverter is switched around it. An important feature of the proposed PCC is that it evaluates only five candidate VVs to determine the optimal vector. The simulation and the experimental results reveal that the performance of the proposed PCC technique is superior to the conventional PCC in terms of voltage and current total harmonic distortion (THD), torque-ripple, and total drive loss. Furthermore, the proposed PCC results in the reduction of the computational burden on the controller. Also, as the reduction of switching frequency is inherent in the proposed PCC strategy, there is no requirement to add an additional constraint to reduce it in the cost function. [ABSTRACT FROM AUTHOR]

In this article, a new online continuous control set-predictive controller (CCS-PC) is proposed with the objective of minimizing the stator-flux and torque ripples. In this controller, a constrained optimization problem is constructed to optimize the phase, amplitude, and time duration of the voltage vector applied to the motor. Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) which is an advanced algorithm based on fast proximal gradient method is adopted to find the optimal solution in an online manner. In each control period, FISTA is executed 10 times where the voltage vector found in the last iteration is considered as the optimal voltage vector. Performance of the proposed controller is compared with the performance of an offline CCS-PC through various experiments. In these experiments, stator-flux ripple, torque ripple, stator-current total harmonic distortion, and computational complexity of the controllers are compared with each other. Based on the results, pros and cons of the proposed online CCS-PC are highlighted. [ABSTRACT FROM AUTHOR]

In this paper, an improved predictive torque control without weighting factor is proposed for a voltage source inverter-permanent magnet synchronous motor drive system, which possesses good control performance of torque and stator flux. By investigating the relationship among torque, the reference stator flux amplitude, and the phase angle of the stator flux, the reference stator flux vector is constructed. Then, the reference voltage vector is calculated by the reference stator flux vector based on the delay compensation and the deadbeat control. The extended control set is designed and two generalized base vectors that require further screening are determined based on the position of the reference voltage vector to improve the calculation efficiency. And the duty ratios used for the generalized base vectors are calculated, according to the geometric relations between the generalized base vectors and the reference voltage vector. Finally, by the duty cycle control between two generalized base vectors and between each generalized base vector and zero vector, the candidate vectors are gained and substituted into the cost function only with the flux vector error term. Experiment tests were carried out and the results validated the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In the recent years, the use of model predictive control in electrical drives has been widely reported both theoretically and experimentally. Predictive torque control has been developed to control induction motor drives, allowing high performance and fast dynamics. However, the optimization used in predictive torque control is based on a single cost function minimization, where control objectives are merged by using weighting factors. The selection of these scalar factors is achieved through offline and online search methods and they are heavily dependent on the system parameters. To avoid this drawback, a multiobjective fuzzy predictive torque control is presented. The proposed strategy replaces the minimization of a scalar cost function with a multiobjective optimization using fuzzy decision making. Experimental implementation is presented to validate the performance of the proposed control scheme. [ABSTRACT FROM AUTHOR]

After designing and optimizing an electric machine, efficiency maps are needed to predict a vehicle’s performance in a dynamic simulation. Calculating efficiencies at various torque and speed points, however, requires prior knowledge of the input excitation conditions, such as the current magnitude and advance angle, in an electromagnetic finite-element analysis simulation. Hence, this paper derives and uses nonlinear motor control equations (MTPA, FW, MTPV) in the study of efficiency map calculation while accounting for both saturation and cross-coupling effects. Two synchronous ac motors are considered in this paper, including the 2010 Prius IPM and a PM-assisted synchronous reluctance machine, with all procedure steps outlined in detail. [ABSTRACT FROM AUTHOR]

This paper presents an input–output feedback linearization (FL) control technique for rotating induction motors, which takes into consideration the magnetic saturation of the iron core. Starting from a new formulation of the dynamic model taking into consideration the magnetic saturation expressed in a space-state form in the rotor-flux-oriented reference frame, the corresponding FL technique has been developed. To this aim, a particular care has been given to the choice of nonlinear functions interpolating the magnetic parameters versus the rotor magnetizing current and the corresponding magnetic characteristic. The proposed FL technique has been tested experimentally on a suitably developed test setup and compared, under the same bandwidths of the speed and flux closed loops, with both the FL technique not taking into consideration the magnetic saturation and with the industrial standard in terms of high performance control of the induction motor: field-oriented control. A further comparison with the unique example present in the scientific literature of the FL control technique including the magnetic saturation has been shown, highlighting consistent improvements achievable by the proposed FL in terms of reduced computational demand and better dynamic performance. [ABSTRACT FROM AUTHOR]

This paper investigates the loss manipulation capabilities of deadbeat direct torque and flux control (DB-DTFC) induction machine drives. For each switching period, a volt-second-based inverse model provides a range of volt-second solutions to achieve the desired torque at the end of each switching interval, whereas the stator flux magnitude provides another degree of freedom to manipulate machine losses. With a flux-based DB-DTFC loss model proposed, losses can be manipulated each switching period without compromising torque dynamics. For a steady-state operation and typical process trajectories, the minimum loss can be achieved with corresponding energy savings. Alternatively, significant losses can be rapidly induced to dissipate kinetic energy in a machine during braking transients. This loss maximization technique provides significant braking torque without requiring additional hardware to transfer/dissipate energy. DB-DTFC induction machine drives provide an effective and elegant solution for continuous loss manipulation without compromising dynamic performance. [ABSTRACT FROM PUBLISHER]

In this paper, an investigation into an alternative topology for reluctance synchronous machine rotor flux barriers is presented. The investigated topology employs a high number of flux barrier variables with an alternative asymmetric rotor structure. The focus in this paper is on maximizing average torque and minimizing torque ripple, using finite element-based design optimization, in order to study the possibility of achieving acceptably low torque ripple. A subsequent investigation into the effect of rotor skew on the proposed optimized design to reduce torque ripple even further is also conducted, as well as the manufacturing and testing of the proposed flux barrier prototype. [ABSTRACT FROM PUBLISHER]

This paper proposes a remote and sensorless stator winding resistance estimation method for thermal protection of soft-starter-connected induction motors. By changing the gate drive signals of the thyristors in the soft starter, a small adjustable dc bias can be intermittently injected to the motor for the estimation of the stator winding resistance. Based on online and continuous monitoring of the stator winding resistance, the stator winding temperature can be monitored using only motor voltage and current. In addition, the torque pulsation caused by the injected dc bias is analyzed. It can also be controlled under an acceptable level by adjusting the level of the injected dc signal. The influence of cable resistance is also studied, and a compensation method is proposed. The proposed method has been verified by experimental results from two induction motors. The proposed stator resistance estimation method can provide remote, sensorless, and accurate thermal protection for soft-starter-connected induction motors. [ABSTRACT FROM AUTHOR]

In this paper, first, the effect of the interior permanent-magnet synchronous-motor (IPMSM) stator resistance to the maximum available motoring or regenerative braking torque is clarified. Then, a drive operating point is interpreted geometrically as the intersecting point of the torque-demand curve with either the maximum torque per ampere (MTPA) trajectory or the voltage-constraint curve inherently imposed by the motor and inverter under different control modes. Based on this principle, a novel voltage-constraint- tracking (VCT) field-weakening control scheme for IPMSM drives is proposed. The proposed method can automatically determine the desired MTPA or field-weakening control modes and provide a smooth transition between these two modes. No machine parameters are required in the field-weakening control mode, and no dc-link voltage sensor is used, rendering the proposed scheme rather robust. In addition, the minimum copper- loss operation can be preserved in the VCT-based control to achieve high efficiency. The proposed control method has a simple structure so that it can easily be implemented by modifying a conventional vector-controlled drive system for practical applications. Finally, a DSP-based prototype drive is constructed to verify the feasibility of the proposed scheme, and some experimental results are provided to demonstrate the satisfactory features. [ABSTRACT FROM AUTHOR]