Torque Control Method Research Articles

Driving Torque Control of Dual-Motor Powertrain for Electric Vehicles

This paper investigates the driving torque control method for the dual-motor powertrain in electric vehicles (EVs) to achieve the performance of accurate vehicle speed tracking, seamless driving mode shift, and high energy efficiency. The configuration of the dual-motor powertrain is based on the parallel axle transmission structure, which does not contain any clutch or synchronizer. The powertrain provides three driving modes that are two single-motor driving modes and one dual-motor combined driving mode. A detailed dynamic model of the dual-motor powertrain is built to simulate the dynamic response of an EV. An energy management strategy (EMS) is used to select the driving mode and determine the ideal driving torque of two motors. The dynamic control strategy tries to track the ideal vehicle speed when uncertain parameters existed and avoid power interruption or impact during the mode shift. Three dynamic control strategies are proposed, which are the backward dynamic control strategy (BDCS), combined forward and backward dynamic control strategy (CFBDCS), and nested forward and backward dynamic control strategy (NFBDCS). The simulation results demonstrate that the NFBDCS has the best comprehensive performance in vehicle speed tracking, seamless mode shift, and good system energy efficiency.

Improved current control loops in wind side converter with the support of wild horse optimizer for enhancing the dynamic performance of PMSG-based wind generation system

ABSTRACT The creation of optimization methods is relatively common and popular today for solving issues in engineering areas. In this paper, a new wild horse optimizer (WHO) method is adopted to design an optimal controller for a permanent-magnet synchronous generator (PMSG)-based wind turbine system (WTS). A control method consisting of two current control loops of the optimized controller is proposed for the control of the machine-side converter. The dynamic performance of PMSG can be improved during the different normal and abnormal conditions through effective tuning of the PI controller gains which enhances the overall response of the system parameters. This enhancement consequently results in the realization of the maximal power tracking during wind speed changes and the fault ride-through capability during faults and large-signal events. Furthermore, the power fluctuations due to the incoming wind speed variants can be smoothed by using the suggested controller. In addition, the proposed controller system employs an optimal torque control method and braking chopper system to help in achieving such tasks. MATLAB simulations of a 1.5 MW PMSG-WTS have been carried out and compared with the Ziegler Nichols-based PI controller in order to validate the feasibility and efficacy of the proposed controller.

Phase Current Reconstruction Method With an Improved Direct Torque Control of SRM Drive for Electric Transportation Applications

Acquisition of the accurate phase currents is indispensable for the control and protection of switched reluctance motor (SRM) drives for electric transportation applications. Existing phase current reconstruction techniques for SRM are implemented under the current control techniques, which generate large torque pulsations. Therefore, the direct torque control (DTC) method can be adopted to minimize torque pulsations and to enhance transient performance in electrified vehicles. However, the existing current estimation methods cannot be applied to DTC strategies due to the simultaneous conduction of all phases at any switching instant. Furthermore, it offers a lower torque per ampere ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$T/A$</tex-math></inline-formula> ) ratio and draws a high source current. This article addresses the aforementioned concerns by proposing a cost-effective phase current reconstruction method with an improved DTC strategy for a 4-kW four-phase SRM drive. This method employs a 16-sector partition method with a new voltage vector selection by detecting zero-current regions of each phase. As a result, the long-tail currents can be avoided, thereby limiting the simultaneous conduction of all phases. The simulation and test results show that the proposed DTC has minimal torque pulsations, high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$T/A$</tex-math></inline-formula> ratio, low converter losses, and lower source current ripple in comparison to the existing DTC schemes under various operating conditions. Also, the proposed phase current estimation method effectively reconstructs the phase currents under both steady-state and transient operating conditions.

Direct Torque Control With Phase Commutation Optimization for Single-Winding Bearingless Switched Reluctance Motor

Compared with the traditional control method, the direct torque control and direct force control method significantly reduces the torque ripple and the root-mean-square current of the phase winding in the single-winding bearingless switched reluctance motor. However, due to the unreasonable selection of voltage vectors and full cycle control, this method has some problems, such as too many control objects, excessive switching times, and low torque–ampere ratio. This article proposes an improved method for the abovementioned problems. First, the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> angle and conduction region of each phase winding are chosen as the control targets, and the operation principle is introduced accordingly. Second, according to the difference of the torque generated by the neighboring phases, the output torque can be distributed more properly to obtain the higher torque–ampere ratio in the commutation region. Finally, the sectors divided in the electrical space are reorganized and the corresponding voltage vectors are optimized. Experimental results show that the proposed method can secure lower torque ripples, fewer switching times, and copper loss. In addition, the torque–ampere ratio is improved as well.

Speed-Sensorless DTC of BLDC Motor with EKF-based Estimator Capable of Load Torque Estimation for Electric Vehicle

This study presents the simulation of brushless DC (BLDC) motor control in MATLAB/Simulink simulation environment with model-based and direct torque control (DTC) method with extended kalman filter (EKF). In this study, a control method based on DTC method is tested to control a nonlinear BLDC motor with extended kalman filter. In this method, an accurate control can be made thanks to the load moment estimation, which is not found in the literature. As a result of the tests have carried out at low and high speeds, it is concluded that the system can lead to real-time systems.

Research on the Asynchronous Motor Direct Torque Control

In this paper, we have adopted a more improved and advanced direct torque control (DTC) method. On this basis, we have also carried out in-depth research on many aspects of asynchronous motor direct torque control system. Some key conclusions are obtained as follows: (1) in this method, we use MRAC identification model with low pass filter and high pass filter to analyze. (2) A new speed observer is also designed. After comparing with the simulation results of other methods, it is proved that this method is effective and superior, its control performance is better and the identification accuracy is higher, which has important practical significance. (3) In this method, we use the digital signal processor TMS320F240 to build a matching experimental system. The experimental results show that this method is indeed effective. (4) Finally, the application scope and main research directions of the method are pointed out. In the future work, we need to strengthen the research on more advanced and efficient direct torque control (DTC) methods and improve it.

Doğrudan moment kontrolüne stator direncinin etkisinin incelenmesi ve sürekli mıknatıslı senkron motora uygulaması

Permanent magnet synchronous motors are a type of motor that is becoming more and more popular due to some superior features together with the technological developments in power electronics. The fact that these motors can produce maximum torque even at zero speed, low maintenance costs and high power/weight ratio has increased their use. In this study, the direct torque control method from vector control methods was used. This method has been investigated by considering the change in the stator winding resistance caused by the temperature increase depending on the operation of the motor and has been applied to a permanent magnet synchronous motor by using a voltage-sourced voltage-controlled inverter circuit. The modeling of the electric motor has done with the d-q model and this model has used in the simulation study. In order to realize the direct torque control of the motor, torque and flux calculations have been made using the current and voltage data applied to the motor. The obtained flux and torque errors have been applied as input to the hysteresis comparator. The switching strategies in the pulse width modulation method used in the inverter control have realized the torque and speed control of the permanent magnet synchronous motor by using the data obtained from the hysteresis output. The variation of winding resistance with temperature and its effect on different speeds and torque control of the motor has been investigated by keeping all other motor parameters constant. The effect of the stator winding resistance on the speed and torque control of the motor has been shown in simulation studies.

Efficient feedback linearization control for an IPMSM of EVs based on improved firefly algorithm

The conventional direct torque control (DTC) has high torque and stator flux fluctuation that causes the stator current distortion. This paper presents an efficient control method based on the feedback-linearization direct torque control (FL-DTC) method for an interior permanent magnet synchronous motor (IPMSM) drive by using an improved firefly algorithm. The proposed approach can greatly restrain the poor performance of torque and stator flux. Thus, it is suitable for IPMSM drives in electric vehicles. First, a decoupled linear model is derived to implement the proposed efficient feedback linearization control for the IPMSM. Two phase voltages in d-q axes and two additional control inputs take shape into an isomorphism mapping with the concept of orthogonal transformation. The torque generation is related to the additional control. Second, the Hamiltonian efficient control theory combined with an improved firefly algorithm is applied to obtain an analytical solution. An efficient linearization controller is designed with a cost function considering the maximum voltage of the inverter. Finally, simulation and experiment are carried out to compare the performance of the proposed efficient FL-DTC with the improved firefly algorithm and the conventional direct torque control. The results show that the proposed control method can reduce the torque and flux ripples at a steady state and maintains a good dynamic response with the variations of speed and torque.

A modified constant-torque spring hinge toward synchronous deployment

Spring hinges, due to their lightweight and energy-saving characteristics, have emerged as an imperative power source for deploying spacecraft appendages. In this paper, a modified constant-torque spring hinge (MCTSH) is proposed for aerospace applications. The conventional constant-torque hinge (CCTSH) is enhanced to bridge the gap toward new applications, resulting in a more compact structure with less friction and wide-range output torques. A novel torque control method is elaborated on for deployable, MCTSH-driven and multi-link mechanisms, thereby simplifying the design procedure via reducing the design variables by half. Given the intricate coupling effects of multi-link mechanisms, a synchronous deployment technique integrating the Newton-Euler dynamics, the design of experiments (DOE) method and the optimization is introduced, and its performance is verified by both simulations and experiments on multi-link grippers. The results demonstrate the high potential of the proposed method for deployable mechanisms toward aerospace applications, e.g., solar array panels and antennas.

Methods of Anterior Torque Control during Retraction: A Systematic Review.

Background: There are various methods of controlling the inclination of the incisors during retraction, but there is no evidence as to the advantages of some methods over others. The purpose of this systematic review and meta-analysis was to determine the effectiveness of the methods used to control torque during anterior teeth retraction. Methods: In accordance with the PRISMA guidelines, the main research question was defined in the PICO format [P: patients with complete permanent dentition; I: the maxillary incisor torque after (I) and before I retraction with straight-wire appliance and different modes of torque control; O: statistically significant differences in torque values of the upper incisors after orthodontic treatment]. The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched for keywords combining: retraction orthodontics, torque control orthodontics, torque orthodontics, inclination orthodontics, torque control retraction. The articles were subjected to risk of bias and quality analyses with the ROBINS-I protocol and the modified Newcastle–Ottawa QAS, respectively. Meta-analyses were performed with both fixed- and random-effects models. Results: 13 articles were selected in which total number of 580 subjects took part. In all studies, incisors were retroclined during retraction by 2.46° (mean difference), which was statistically significant. Considering the articles separately, the differences in torque between the study group and the control group were statistically significant in six articles. The Q statistic was 36.25 with p = 0.0003 and I2 = 66.9%, which indicated a high level of study heterogeneity. Conclusion: Both properly performed corticotomy and en-masse retraction using orthodontic microimplants seem to be the most effective and scientifically validated methods of torque control. Further high-quality research is needed to perform better quality analyses and draw more reliable conclusions.

Computationally Efficient Model Predictive Torque Control of Permanent Magnet Synchronous Machines Using Numerical Techniques

This study presents a computationally efficient model predictive torque control (MPTC) method for permanent magnet synchronous machines (PMSMs). The existing MPTC methods require solving complex optimization problems in iterations; this approach is computationally demanding. In contrast, the proposed MPTC transforms the optimization problem into two subproblems and derives the corresponding solutions explicitly using numerical techniques, which entail linearization of the torque function and current constraint; the proposed approach can significantly reduce the computational burden. Additionally, the proposed MPTC does not involve any control gains and weighting factors; hence, gain tuning is not required for the proposed MPTC. These features are advantageous when implementing torque control. Using a 4-kW PMSM drive, the effectiveness of the proposed MPTC is demonstrated both numerically and experimentally in terms of dynamic performance and computational efficiency. This is realized by comparing the proposed method with the existing methods.

Model Predictive Direct Torque Control of Switched Reluctance Motors for Low-Speed Operation

In this paper, a finite-control-set model predictive direct torque control (FCS-MPDTC) method is proposed to reduce the torque ripple of a segmented switched reluctance motor (SSRM) at the low-speed stage. Firstly, the prediction dynamic model is established, and the phase torque can be predicted by detecting phase current and rotor position signals. Then, the principle of power converter and selection of voltage vectors are introduced and presented. Considering torque ripple reduction, flux tracking performance and copper losses reduction, the cost function with phase torque, the amplitude of flux linkage and phase current, is established to select optimal voltage vector to control the power converter. In addition, the torque sharing function (TSF) is employed to distribute total torque to phase torque for further torque ripple reduction. Finally, the direct torque control (DTC) is selected as the comparison method, performance of MPDTC is verified by simulation and experiment results. It can be found that the proposed MPDTC can achieve lower torque ripple and copper losses, and high robustness.

The Torque Ripple Optimization of Open-Winding Permanent Magnet Synchronous Motor With Direct Torque Control Strategy Over a Wide Bus Voltage Ratio Range

Due to the battery voltage performance of the dual power supply open-winding permanent magnet synchronous motor (OW-PMSM) system in electric vehicles, the dc bus voltages of the dual power supply varies and the traditional direct torque control (DTC) method will not be suitable and may lead to obvious torque ripples. Thus, in this article, based on the analysis of the effect of voltage vector on torque variation, a bus voltage ratio is employed in the switching table optimization strategy of DTC for OW-PMSM, the voltage vector selection method is also modified according to different voltage ratio, and then, the optimized control scheme for OW-PMSM over a wide bus voltage ratio is achieved to diminish the torque ripples. Finally, simulation models of the proposed method are built to verify the theory, and the corresponding experiments are also conducted to verify the feasibility and effectiveness of the proposed optimized control strategy.

Computational-Efficient Model Predictive Torque Control for Switched Reluctance Machines With Linear-Model-Based Equivalent Transformations

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.

A multi-bolt tightening method based on elastic interaction coefficient and gasket creep relaxation

Flange connections are widely used in various mechanical components. The most important purpose of tightening for flanged bolts is to achieve designed clamping force for the maintenance of overall performance. In this work, a multi-bolt tightening algorithm is proposed based on elastic interaction coefficient and gasket creep relaxation. Firstly, dispersion of the individual bolt clamping forces for torque control method is considered in the algorithm. Relationship between the nut factors of the flange bolts in multi-pass tightening is established through experiment. Subsequently, the elastic interaction coefficient matrix was updated during the multi-pass tightening process to reduce the error. Two cases, without gasket and silicone gasket, are considered in the multi-bolt tightening experiment. Without gasket, the elastoplastic deformation at the initial stage after tightening will also cause a loss of clamping force. When using gasket, the clamping force loss due to gasket creep relaxation is more pronounced. Through experimental verification, the proposed multi-bolt tightening algorithm are able to achieve the target range of designed clamping forces and reduce its dispersion. Finally, the main influencing factors of the multi-bolt tightening are analyzed to provide a reference for the design of flange connections.

Torque Ripple Suppression Method of Switched Reluctance Motor Based on an Improved Torque Distribution Function

Currently, torque ripple is a crucial factor hindering the application of the switched reluctance motor (SRM). Hence, it is of crucial importance to suppress this undesirable torque ripple. This paper proposes a new torque ripple suppression method of SRM based on the improved torque distribution function. Firstly, the electromagnetic characteristic model of a 8/6-pole four-phase SRM is established, and the cerebellar model articulation controller (CMAC) is used to complete the learning of each model. Then, the improved torque distribution function is planned based on the torque model to give the reference torque of each phase, and the inverse torque model is used to realize the mapping of the reference torque to the reference flux linkage. Finally, the duty of each phase voltage PWM wave modulation is output based on the PID control theory. The proposed accurate model-based planning scheme is implemented on the simulation platform, and the results shows that the maximum torque fluctuation of the output results is reduced to within 3%, and the average error is reduced to within 1%, which is much lower than the error of 15% under the traditional direct torque control method.

Sensorless torque and flux control of induction motor fed by photovoltaic system

This paper presents a new direct torque and flux control method for induction motor fed from Photovoltaic (PV) System. The proposed strategy is based on Stator Field Orientation with deadbeat torque and flux control. The deedbeat control approach is based on establishing the voltage vector necessary to supply the motor and reach the electromagnetic torque and flux references at the end of a sampling period T. In order to create the voltage shape and frequency to control the induction motor, the inverter is supplied by a DC voltage extracted from a PV system. Model Reference Adaptive System and Luenberger Observer are designed to determine the stator flux and rotor speed. Extensive simulation work was carried out, which demonstrated that the proposed strategy is capable of reducing the torque and flux ripples and maintaining a constant switching frequency.

Explosive Electric Actuator and Control for Legged Robots

Unmanned systems such as legged robots require fast-motion responses for operation in complex environments. These systems therefore require explosive actuators that can provide high peak speed or high peak torque at specific moments during dynamic motion. Although hydraulic actuators can provide a large force, they are relatively inefficient, large, and heavy. Industrial electric actuators are incapable of providing instant high power. In addition, the constant reduction ratio of the reducer makes it difficult to eliminate the tradeoff between high speed and high torque in a given system. This study proposes an explosive electric actuator and an associated control method for legged robots. First, a high-power-density variable transmission is designed to enable continuous adjustment of the output speed to torque ratio. A heat-dissipating structure based on a composite phase-change material (PCM) is used. An integral torque control method is used to achieve periodic and controllable explosive power output. Jumping experiments are conducted with typical legged robots to verify the effectiveness of the proposed actuator and control method. Single-legged, quadruped, and humanoid robots jumped to heights of 1.5, 0.8, and 0.5 m, respectively. These are the highest values reported to date for legged robots powered by electric actuators.

Dynamic Operation Loss Minimization for Permanent Magnet Synchronous Generator Based on Improved Model Predictive Direct Torque Control

During permanent magnet synchronous generator (PMSG) operation, aside from improving the rapid response of torque and reducing the rippling of torque and flux to guarantee the operational reliability, the loss of the PMSG itself cannot be ignored either. Aiming at this problem, an improved model predictive direct torque control (MPDTC) method is proposed, which suppresses the torque ripple and achieves PMSG efficiency optimization. Firstly, based on the conventional MPDTC and the loss model of PMSG, the predicted stator active current is determined, which is utilized for obtaining the predicted torque. Secondly, combined with the generator loss model, the set value of the stator energetic current is obtained; combined with the wind power system maximum power point tracking method, the set value of generator torque is obtained. Thirdly, by converting the torque control error and current control error into a per unit value, the influence of the weight coefficient in the cost function on the control effect is reduced. Finally, the key results verified the effectiveness and superiority of the proposed control scheme by simulation and experiment.

Simplified Super Twisting Sliding Mode Approaches of the Double-Powered Induction Generator-Based Multi-Rotor Wind Turbine System

This work proposes a new indirect filed-oriented control (IFOC) scheme for double-powered induction generators (DPIGs) in multi-rotor wind turbine systems (MRWTS). The IFOC strategy is characterized by its simplicity, ease of use, and fast dynamic speed. However, there are drawbacks to this method. Among its disadvantages is the presence of ripples in the level of torque, active power, and current. In addition, the total harmonic distortion (THD) value of the electric current is higher compared to the direct torque control method. In order to overcome these shortcomings and in terms of improving the effectiveness and performance of this method, a new algorithm is proposed for the super twisting algorithm (STA). In this work, a new STA method called simplified STA (SSTA) algorithm is proposed and applied to the traditional IFOC strategy in order to reduce the ripples of torque, current, and active power. On the other hand, the inverter of the DPIG is controlled by using a five-level fuzzy simplified space vector modulation (FSSVM) technique to obtain a signal at the inverter output of a fixed frequency. The results obtained from this proposed IFOC-SSTA method with FSSVM strategy are compared with the classical IFOC method which uses the classical controller based on a proportional-integral (PI) controller. The proposed method is achieved using the Matlab/Simulink software, where a generator with a large capacity of 1.5 megawatts is used. The generator is placed in a multi-rotor electric power generation system. On the other hand, the two methods are compared in terms of ripple ratio, dynamic response, durability, and total harmonic distortion (THD) value of the electric current. Through the results obtained from this work, the proposed method based on SSTA provided better results in terms of ripple ratio, response dynamic, and even THD value compared to the classical method, and this shows the robustness of the proposed method in improving the performance and efficiency of the generator in the multi-rotor wind system.