Large Inertia Load Research Articles

Optimal Coordinated Control for Speed Tracking and Torque Synchronization of Rigidly Connected Dual-Motor Systems

Dual-motor systems have been broadly used to drive large inertia loads. In this article, the optimal coordinated control problem of rigidly connected permanent magnet synchronous motor (PMSM) systems is investigated to enhance the speed tracking and torque synchronization performance. First, the mathematical model of rigidly connected dual-PMSM systems is established in terms of the model of the PMSM and the characteristics of gear transmission drive. Second, to minimize the speed tracking and torque synchronization errors, a novel optimal coordinated control scheme is proposed for rigidly connected dual-PMSM systems by combining the conventional master–slave control structure and the linear–quadratic regulator control strategy. Then, taking into account the inherent two-time-scale characteristics, a composite suboptimal coordinated controller is devised through optimal problems of slow and fast subsystems. Furthermore, the closed-loop stability is proved by singular perturbation theory. Finally, simulation and experimental studies are provided to corroborate our theoretical results. It is shown that the proposed method can effectively improve the speed tracking and torque synchronization performance of the rigidly connected dual-PMSM system simultaneously.

Research on Active Disturbance Rejection Controller for Electromechanical Servo System with Large Inertia Loads

In this paper, an Active Disturbance Rejection Controller (ADRC) based on an improved Particle Swarm Optimization (PSO) algorithm is proposed. The ADRC is conducive to addressing the situation that the electromechanical servo system is loaded with a large inertia barrel and is significantly affected by disturbances when working at high speed and precision. It can not only improve the anti-disturbance performance of the system but also ensure the dynamic performance of the system. Firstly, a simplified mathematical model of the electromechanical servo system is established and the non-linear factors of the system are analyzed. Secondly, the ADRC is designed and the parameters are optimized by utilizing the improved PSO algorithm. Finally, the control effect of the proposed method is simulated and analyzed. The simulation consequences demonstrate that compared with the traditional PID control, the proposed method can significantly increase the anti-disturbance capability of the servo system, and guarantee the accuracy index of the system.

Regenerative energy fed to the grid by DC–AC converter during deceleration for direct torque control of induction motor drive

This paper revealed efficient use of regenerative power of induction motor drives. Considerable energy wastage in the form of heat energy during the deceleration period of variable frequency drive by brake chopper resistor unit. An energy cost-saving approach using regenerative power unit for applications deals with frequent deceleration of large inertia load can be achieved. Various topologies are illustrated for effective utilisation of regenerative power during deceleration of induction motor drive. The proposed system is modelled and simulated in MATLABTM/ SimulinkTM. The simulation results are discussed regarding energy recovery of Direct Torque Control (DTC) drive during regenerative braking mode for three-phase induction motor. The main objective of the paper is to recover energy during deceleration for the DTC based three-phase induction motor drive and which in turn increase the efficiency of the system.

Dynamic simulation analysis of spur gear space driven system with large inertia load

The wide application of large inertia loads in space drive mechanisms is relatively rare in theoretical research. An 8-degree-of-freedom nonlinear dynamic model is established for the time-varying and nonlinear perturbation problems of a large inertia load space drive mechanism. The model is a two-stage spur gear model in which the effects of backlash and time-varying stiffness are considered. The 3D model was imported into ADAMS, and the nonlinear dynamic response of the system was studied by motion simulation. This paper sets up a large inertia experimental device to collect and process data. Comparing experimental results with Adams results, the correctness of the numerical model was verified, and the reasons for the differences between the two were explained. A comparative analysis of the load response under different inertia was performed to illustrate the importance of studying large inertia loads. The simulation results show that the output shaft has a great influence on the dynamic response. Changing the material of the gear can improve the transmission precision of the gear system. The analysis results in this paper enrich the research on the dynamic response of gear system, and provide a theoretical basis for the subsequent design of large inertia load gear system and improve vibration and noise during operation.

Experimental study on transmission error of space-driven gear system under large inertia load

There is a nonlinear disturbance problem in the operation of large inertia load space-driving mechanism, which seriously affects the normal operation of the system. A 14 degree-of-freedom nonlinear time-varying dynamic model was established for a two-stage spur gear system. The dynamic equations were solved numerically based on the Runge–Kutta method. The correctness of the dynamic model was verified through experiments. In the author’s previous research, the transmission error and dynamic response of gear system was analyzed. After the establishment of the dynamic model, a comparative analysis of the load response under different inertia was performed to illustrate the importance of studying large inertia loads. A large inertia load transmission error experimental device was set up to collect and process the transmission error data under different load inertia and different speeds. Comparing experimental results with numerical results, the correctness of the numerical model was verified, and the reasons for the differences between the two were explained. The analysis of the experimental results shows that for the transmission error of large inertia load gear transmission system, the influence of stiffness excitation on the transmission error amplitude is dominant. For the high-speed gear system, the pitch error plays a dominant role.

The method of restraining hydraulic impact with active adjusting variable damping

Hydraulic impact is a common phenomenon in the hydraulic transmission system, which has great influence on the smooth operation of hydraulic transmission system and the service life of hydraulic components, especially to the hydraulic system with large inertia load. In order to restrain the hydraulic impact, the causes for hydraulic impact are analyzed, and a new method of active adjusting variable damping was developed. The principle of this method is to make use of the reserving signal to predict the timing of the hydraulic shock wave actively and adjust the opening size of the damped hole accordingly to restrain the hydraulic impact. This method was applied to the hydraulic system of a cinder scraper's rail trolley as a case study through simulation and experimental testing. The results show that the method has the advantages of quick response speed, effective restraint of hydraulic impact in the system and low energy consumption. By using this method, the hydraulic impact in the hydraulic system of the cinder scraper's rail trolley can be effectively controlled without affecting the response speed of the system.

Slewing valve based on bypass pressure-compensation principle for dynamic control of large inertia load

Typical slewing valve is a three-position six-way proportional valve based on bypass throttle principle, whose output flow rate and opening dead zone of the main valve port are both affected by the load. Thus, it has poor performances in dynamic control of varying loads. This article presents a novel slewing valve based on bypass pressure-compensation principle, which has much better performance in dynamic control of varying loads and even for large inertia loads. A pressure-compensated valve is added to connect the out ports of the main valve port and the bypass port to keep the pressure differences at the main valve port and the bypass port in same. As a result, the flow distribution ratio of these two ports keeps stable for a certain spool position, which can avoid the output flow rate fluctuation despite the varying loads. In addition, the opening dead zone of the main valve port is very small and keeps almost unchanged. These advantages make the proposed valve to control large inertia load with great stability. In the article, a mathematical model formulating the dynamic performance of the valve is further established to provide guide for the optimization of the parameters, including the shapes and orifice areas of the main valve port and bypass port, the stiffness of the spring controlling spool motion, and so on. A prototype valve was manufactured based on the presented method. A series of tests on experiment bench and real crane validate its great performances on flow rate and dead zone stabilities as well as fast dynamic response.

Mathematical model of simple spalling formation during coal cutting with extracting machine

A single-mass model of a rotor shearer is analyzed. It is shown that rotor mining machines has large inertia moments and load dynamics. An extraction module model with selective movement of the cutting tool is represented. The peculiar feature of such extracting machines is fluid power drive cutter mechanism. They can steadily operate at large shear thickness, and locking modes are not an emergency for them. Comparing with shearers they have less inertional mass, but slower average cutting speed, and its momentary values depend on load. Basing on the equation of hydraulic fuel consumption balance the work of fluid power drive of extracting module cutter mechanism together with hydro pneumatic accumulator is analyzed. Spalling formation model during coal cutting with fluid power drive cutter mechanism and potential energy stores are suggested. Matching cutter speed with the speed of main crack expansion and amount of potential energy consumption, cutter load is determined only by ultimate stress at crack pole and friction. Tests of an extracting module cutter in real size model proved the stated theory.

Nonlinear dynamic response analysis of two-stage spur gear space driving mechanism with large inertia load

Large inertia load has been widely used in space driving mechanisms, but the research concerning theory is still an unexplored scientific field. Towards the problem of nonlinear disturbance in space driving mechanism with large inertia load, a 14-DOF (Degree of Freedom) nonlinear, time-varying, dynamic model of two-stage spur gear system was established, taking into consideration time-varying stiffness, backlash and transmission error. The dynamic response of the load, under large or small inertia was investigated, basing on the dynamic model. The results indicate that at starting, normal operation and braking, large inertia load system has obvious hysteresis, compared to small inertia. The factors that improve dynamic response speed under large inertia load were studied. The results indicate that improving the stiffness and damping of the output shaft and changing the material of second gear pair to titanium alloy are helpful in improving the dynamic response speed of the system. Some results enrich the research of two-stage spur gear nonlinear model and large inertia load, since they provide important reference for the actual design of the gear system.

Transmission Error Analysis and Disturbance Optimization of Two‐Stage Spur Gear Space Driven Mechanism with Large Inertia Load

For the nonlinear disturbance actual issues of the model space drive mechanism two‐stage spur gear system, a nonlinear dynamic model of 14‐DOF (degree of freedom) two‐stage spur gear with time‐varying stiffness and damping was established. This model has been developed previously by the authors to access the large inertia on the dynamic response of spur gear space driving mechanism, and its effectiveness was proved by a motion simulation experiment. In this paper, the profile error (PE) and the index error (IE) were enhanced in the dynamic model. The effects of profile error, index error, and variable load torque on transmission error (TE) were analyzed, while the optimization was proposed according to the analyzed result. The peak‐to‐peak value of the optimized load transmission error (LTE) was reduced by 60.7%, which improved the transmission accuracy and reduced the phenomenon of disturbance. The research of nonlinear dynamical model of two‐stage spur gear and the TE of the large inertia load were enriched, which provided an important reference for the actual design of the gear system.

Electro-hydraulic control of high-speed segment erection processes

Abstract To improve the efficiency of constructing a tunnel lining, an effective high-speed segment erection system is desired. Due to the excessive positioning errors and large joint forces caused by high speed and large inertia loads, a conventional segment erector is unable to achieve a high-speed erection process. To reduce the steady-state positioning error of a segment erector under high-speed working conditions, this work presents a speed and position compound control system (SPCS) based on the electro-hydraulic proportional control technology. A combined motion law with a smooth and continuous changing speed is adopted for the erecting motion to reduce joint force. Experiments are carried out on a Φ2.2 m segment erector test rig to evaluate the performances of the designed control system. Experimental results show that the SPCS is superior to the position feedback control system (PFCS) in terms of accuracy and joint force under high-speed working conditions. The maximum rotation speed of the erector with the SPCS can reach up to thrice that of the conventional segment erection system without decreasing the positioning precision and increasing the joint force. To further increase the segment erecting efficiency, a parallel speed and position compound control system (PSPCS) with multi-axis simultaneous movements is proposed. The coupling effects of the three positioning motions are analyzed. According to the experimental results, the time consumed by the erection system with PSPCS on the segment positioning process is further reduced to approximate one third of that by the erection system with SPCS.

Methods of Restrain the Hydraulic Impact with Active Adjusting the Variable Damping in System with Large Inertia Load

Hydraulic impact often occurs when the control valve shuts down or the load movement reverses suddenly in hydraulic transmission system. Hydraulic impact influences smoothness and stable running of hydraulic system, reduces the service life of hydraulic elements, and even makes the actuator have false action which leads to the accidents that can be illustrated by the hydraulic control circuit of the slipping arm of cinder scraper of steeling-making furnace. The high load inertia and frequent alternating direction lead to the serious hydraulic impact which shorten the age limit of the hydraulic motor driving the cinder scraper's slipping arm and make the hydraulic motor changed frequently, thus to affect the production efficiency. In order to improve this phenomenon, the hydraulic impact in large inertia load's hydraulic system is analyzed, and a method is proposed to alleviate the hydraulic impact. This method is to pre-calculate the time when the peak pressure arrives by controlling signals, and adjust the variable damping used in buffing the impact so as to reduce the hydraulic impact. The principle of this approach is explained in theory which is verified by digital simulation and field test. The result of simulation and field test testifies the method bears the advantages of being quick dynamic and having low energy consumption, which can reduce the hydraulic impact effectively in the premise of satisfying the characteristic of system response.

The Development of a High-Speed Segment Erecting System for Shield Tunneling Machine

The present study is focused on developing an effective high-speed segment erecting system, which is specific for modern shield tunneling machine. The big steady-state error and large impact force caused by high motion speed and large inertia load are main restrictions for the conventional segment erector to realize high-speed segment erecting. To overcome the bottleneck, a new hydraulic system that is based on electrohydraulic proportional control technology is designed, the actuator speed of which is adjustable and controllable. The kinematic and dynamic models are established to determine the displacement of each actuator and calculate joint force, respectively. A combined motion law is then selected to reduce joint force during acceleration and deceleration stages. Furthermore, a superior control strategy that is able to precisely and smoothly control the segment erector at high speed is chosen by comparing the experimental performances of four different control strategies. Experiments are carried out on a segment erector test rig. The experimental results show exceptional performances of the speed and position compound control system in terms of accuracy and impact force. The maximum rotation speed of the new system can be increased to more than three times of that of the present erecting system. In addition, high steady-state accuracy can be achieved with the new system while its impact force is just about one-third of the position control system.

Robust synthesized control of electromechanical actuator for thrust vector system in spacecraft

A kind of robust control of electromechanical actuator (EMA) system for thrust vector control in a spacecraft was investigated. In the flight of a spacecraft, the EMA system must overcome the influence of load disturbance and working point alteration to improve the robust control performances. Addressing this problem and considering the large inertia and low stiffness load of the EMA system, this paper studied the robust control technology of the EMA system by H∞ control and μ synthesis theory based on the degree of freedom (DOF) mathematical model. The H∞ hybrid controller was designed and the EMA system experiments of three controllers including proportion-integral-differential controller, H∞ controller and H∞ hybrid controller were conducted. Furthermore, the μ synthesis controller was designed and the simulation was made on the μ synthesis controller and the comparison between the control effects of the H∞ controller and the μ synthesis controller was conducted. The comparison results show that the robust synthesis control can more effectively handle the parameters perturbation and load disturbance.

Rotational Speed Control of Hydraulic Motor Using Sliding Mode Control.

Rotational speed control of a hydraulic motor with a large inertia load has issues on stability and sometimes falls into unstable. In this paper, the discrete-time sliding mode control (SMC) is applied to rotational speed control of a hydraulic motor for improving its robustness. Modeling of the control components and design of the sliding surface (switching line) in the state space are discussed. Furthermore, one of the means attenuating chattering due to SMC is presented. The control characteristics is evaluated by a testing apparatus which consists of the hydraulic motor of 28 cm3/ rev coupled to the fly-wheel with large inertia load of 0.88 kg·m2. The results of a theoretical and experimental study of SMC show several benefits such as short settling time and low sensitivity to disturbances and system parameter variations.

ROTAIONAL SPEED CONTROL OF A HYDRAULIC SERVOMOTOR WITH A LARGE INERTIA LOAD USING SLIDING MODE CONTROL

Rotational speed control of a hydraulic motor with a large inertia load has issues on stability and sometimes falls into unstable. In this paper, the discrete-time sliding mode control (SMC) is applied to rotational speed control of a hydraulic motor for improving its robustness. Modeling of the control components and design of the sliding surface (switching line) in the state space are discussed. Furthermore, one of the means attenuating chattering due to the SMC is presented. The control characteristics is evaluated by a testing apparatus which consists of the hydraulic motor of 28cm3/rev coupled to the large inertia load of 0.88kg·m2. The results of a theoretical and experimental study of the SMC show several benefits such as shorter settling time, lower sensitivity to disturbances and system parameter variations.