Variable Speed Control Research Articles

Hybrid LVRT Control of Doubly-Fed Variable Speed Pumped Storage to Shorten Crowbar Operational Duration

Hybrid LVRT Control of Doubly-Fed Variable Speed Pumped Storage to Shorten Crowbar Operational Duration

Comparative study of the two DTC (6S - 12S) approaches applied to PMSM equipped with an IP regulator

Direct torque control was introduced in 1980 for induction machine for torque and flux control and developed for MSAP in 1990. DTC is gaining popularity due to its simple control structure and easy implementation. The principle of direct torque control (DTC) of the asynchronous machine was introduced in 1985 by I. Takahashi as an alternative to flux-directed vector control (FOC). It is thanks to its simple control structure that it gains popularity and its easy implementation that it has opened a new horizon in the field of variable speed control of electric drives. Indeed, direct torque control (DTC) has benefited in recent years from significant methodological advances in operation and technological development following the introduction of power electronics and digital electronics and the implementation of possible and very usable control algorithms. In conjunction with these technological advances, the scientific community has developed several control approaches to control the operation of electrical machines. In this context, this article presents a comparative study of the different direct torque control (DTC) strategies and structures of the permanent magnet synchronous machine (MSAP). We propose the algorithm of this control making it possible to provide solutions to the ripples of the torque and the stator flux in order to reduce them by adopting a method of compensating the effects of progression by passing from the six sector DTC (DTC – 6S: classic and modified) then develop the twelve-sector DTC (DTC-12S) whose purpose is to minimize ripples and control the switching frequency of the inverter. The simulation graphs presented will clearly show the difference between the different controls techniques cited.

A Variable-speed Control Method to Reduce Ducted-fan Thrust Fluctuations for Flying Car Utilization

A Variable-speed Control Method to Reduce Ducted-fan Thrust Fluctuations for Flying Car Utilization

Application of improved fish school algorithm in variable frequency speed control system

In order to solve the problems of long adjustment time and poor stability of the commonly used speed current variable frequency negative feedback speed control system in engineering, the author proposes an improved fish school algorithm application method in variable frequency speed control systems. A fish swarm algorithm optimized based on the arena method is applied to a variable frequency speed control system, and the optimization algorithm is applied to the speed control system to screen the PI parameters that meet the requirements of the speed control system. The simulation results show that compared with manual parameter tuning, the controller parameters optimized by the improved fish school algorithm have better control performance. In the absence of overshoot starting, the starting time was shortened by 0.21s, and the system response speed was improved. When a sudden load of 6 N m is applied, the speed drop is reduced by 3 r · min−1, and the recovery time is shortened by 0.15 s, resulting in stronger anti-interference performance of the system. Conclusion: The new algorithm shortens the control time and improves the robustness of the system.

A Knee-Guided Evolutionary Algorithm for Multi-Objective Air Traffic Flow Management

Air traffic flow management plays a crucial role in efficient aviation. Most existing studies assume the flight speed as constant throughout the trip, leading to ineffective fixed-speed schedules. To address this issue, we propose a new problem model, which allows variable speed control to improve the flexibility and maneuverability of the management. In addition, we consider two conflicting objectives, which are minimizing the total flight delays and conflicts between flights, where the conflicts depend on the flight 4D trajectories (3D position plus time). To solve this new challenging problem, we propose a novel multi-objective evolutionary algorithm with new problem-specific individual representation and search operators. Specifically, the multi-chromosomes encoding scheme is designed to adapt to different types of operations. Then, to search the huge search space effectively, we develop a hybrid crossover operator that recombines the parents based on their flight routes. Furthermore, to balance the exploration and exploitation, we develop a new mutation strategy to utilize the heterogeneous search potential of different individuals. For exploitation, the knee individual in the Pareto front is improved by a new time shift operator for exploitation, and other non-dominated solutions are mutated by fixed-route mutation. For exploration, the dominated solutions are mutated randomly. To verify the effectiveness, we compare it with the real air traffic flow management schedules and the state-of-the-art algorithms on a range of real-world air traffic datasets. Extensive results show that the proposed algorithm can significantly outperform the baselines in generating safe and efficient 4D trajectories.

Research and Simulation Analysis of Fuzzy Intelligent Control System Algorithm for a Servo Precision Press

With the rapid development of the manufacturing industry toward intelligence and flexibility, traditional mechanical presses are unable to meet the increased stamping requirements due to the difficulties in achieving variable speed control and changing slide motion trajectories. Servo presses, driven directly by servo motors, can realize the flexible control of press movement and have become the trend in the industry for future development. The independent research and development of servo press control systems has become a popular topic and challenge in the domestic press industry. This paper proposes a new type of press transmission mechanism suitable for high-precision stamping, analyzes the working principle of its transmission mechanism, and provides a detailed analysis and discussion on the main research methods of fuzzy intelligent control for servo presses, including fuzzy model and basic control algorithms, fuzzy modeling and control of nonlinear systems, fuzzy predictive control, and stability analysis of fuzzy control systems. Based on the principle of the control scheme, a closed-loop control system block diagram and mathematical model for servo high-precision presses are established. Taking the physical prototype parameters of the STSZG1-250 as an example, the control system is dynamically simulated and verified using Simulink modules. Finally, their role and effects in intelligent control, and prospects for the development of fuzzy intelligent control, are discussed.

Interval Type-2 Fuzzy Logic Controller for Speed Control of DC Motor in an Intelligent Manner

The method of variable speed control use in direct current motors adopting a fuzzy logic controller is fast replacing as compare some of the earlier conventional methods. In Electrical drive system a dc motor is fed from a fully controlled single phase convertor but the control is fails in the uncertain condition. This type of problem makes a critical issue in power plant where lots of motor are working. So, there is need to control dc motor in such uncertain condition. This work gives a design based on simulation of intelligent control by Interval Type-2 Fuzzy Logic Controller (IT2FLC). The designed fuzzy controller is effective in control performance in abnormal or uncertain conditions. The simulation study has been carried out and result are compared with type-1 FLC. The Result clearly demonstrate the superiority of the IT2FLC and compare to other methods proposed system is capable to control dc motors and performed better in both steady-state and cyclic conditions with more reliability

Rotating speed pulling-back control and adaptive strategy of doubly-fed variable speed pumped storage unit

When the doubly-fed variable speed pumped storage unit (DFVSPSU) adopts the power priority control, the rotating speed may change excessively during the transient process, potentially causing the rotor side power to exceed the converter capacity, which may damage the converter. Therefore, this study aims to analyze the mechanism underlying rotor side power overlimit and conventional rotating speed pulling-back control (RSPBC), proposing an adaptive rotating speed pulling-back control (ARSPBC). First, the unit's speed operating range and the converter capacity were determined based on the characteristic curve of the pump-turbine. Second, the optimal speed and speed limit were compared, indicating that the unit's operation is closer to the lower speed limit, which increases the likelihood of power overlimit occurrences. Third, the mechanism of rotor side power overlimit and conventional RSPBC were analyzed. It was noted that although conventional RSPBC can prevent rotor side power overlimit, it can result in significant generator power fluctuations. Finally, an ARSPBC incorporating speed change rate feedback was proposed. The numerical simulation showed that the ARSPBC can not only prevent the rotor side power overlimit, but also reduce the generator power fluctuations. Compared to the conventional RSPBC, the power fluctuation was reduced from 70 % to 62.5 %–4 %.

Assessment of energy saving and CO2 emission mitigation of low-lift cooling in computer hardware manufacturing industry: A case study in Thailand

Abstract Released heat from production process contributes the largest proportion of cooling load in computer hardware manufacturing industry. According to traditional design practice, chiller plant produces chilled water at a temperature of 7°C to treat the entire load from the production process and from the comfort air-conditioning in buildings. However, the heat from the process is solely the sensible component where high-temperature chilled water (e.g., 15°C) can be used for the heat removal, the chillers equipped with low temperature-lift technology thus offer a great opportunity to improve the plant’s cooling performance. Under the critical global warming situation and the need of decarbonizing industry, this paper investigated the energy saving and CO2 emission mitigation potential of the low-lift technology by which the chiller plant of high-temperature chilled water (15°C) is dedicated for the production process cooling, and the traditional chiller plant of the low-temperature chilled water is used to serve the building air-conditioning. The study site was a large factory of computer hardware manufacturing in Thailand. Through detailed energy auditing, the cooling load profile of the production process was established, and it was used to design the low-lift chiller plant. The annual simulation results showed that in our study case the low-lift chiller plant together with variable motor speed control had 31.6% higher cooling performance than the traditional chiller plant. The plant could reduce the energy consumption by 5,550 MWhelec/year. As the CO2 emission of the grid power in Thailand was 0.47 kgCO2/kWh in 2023 and it was expected to reduce to 0.35 kgCO2/kWh in 2050, the CO2 emissions from implementing the low-lift cooling could be reduced by 49,400 TonCO2 over a course of the 20-year project lifetime. The study results encouraged the low-lift cooling technology as a practical energy efficiency measure in computer hardware manufacturing industry. To our knowledge, while past research focused on the low-lift cooling in building air-conditioning, the study was the first potential assessment project of the low-lift cooling as a deep decarbonization technology for the computer hardware manufacturing industry in Thailand.

Study on the hydrodynamic and wake characteristics of variable speed control of horizontal axis tidal turbine under surge motion

Study on the hydrodynamic and wake characteristics of variable speed control of horizontal axis tidal turbine under surge motion

Speed Control for PMSM with Fast Variable-Speed Sliding Mode Control via High-Gain Disturbance Observer

Since robustness only exists on the sliding mode/surface, sliding mode control is non-globally stable. Therefore, shortening the time to reach the sliding mode is an important method of improving sliding mode robustness. However, there is an inherent contradiction between rapidity and overshoot. Therefore, ensuring rapid convergence without overshoot is a worthwhile research problem. Consequently, this paper proposes a design for a fast variable speed reaching law (FVSRL) to improve the quality of sliding mode control. The constructed approach rate is based on a variable speed term, an exponential term, and a fast term, ensuring rapid convergence without overshoot. At the same time, a high-gain disturbance observer is employed for feedforward compensation. Finally, the designed reaching law is validated by comparing it with conventional exponential approach rates and a new sliding mode reaching law, demonstrating its superior performance. Detailed comparative and quantitative analyses of the simulation results using the conventional exponential reaching law, the new sliding mode reaching law, and the FVSRL are performed, utilizing metrics such as integrated square error, integral time square error, integrated absolute error, and integral time absolute error.

Electro-Hydraulic Variable-Speed Drive Network Technology—First Experimental Validation

The improvement of the energy efficiency of hydraulic systems remains an essential challenge for industry, and the demand for more sustainable solutions is increasing. A main focus in this endeavor is the ability to eliminate or strongly reduce the use of throttle control valves which have been the preferred control element in industrial hydraulic systems for decades. Components have been subject to continuous evolution, and current industrial grade hydraulic pumps and motors are both efficient and reliable. Even though few percentages of energy efficiency can still be achieved, the main achievements in terms of efficiency are associated with novel system designs rather than further development of components. An area subject to increasing attention is the field of variable-speed displacement control, allowing to avoid the main control valve throttle losses. Systems using this technology are, however, mainly developed as standalone drive systems, necessitating maximum force, speed, and power installed in each axis, with limited hydraulic power distribution capability compared to valve-controlled systems. An emerging field addressing this challenge is that of so-called electro-hydraulic variable-speed drive networks, which allow to completely eliminate the use of control valves and enable power sharing both electrically and hydraulically, potentially reducing the necessary installed power in many cases. The idea of such a technology was first proposed in 2022, and so far developments reported in the literature have mainly been of a theoretical nature. This article presents the first ever experimental results for a dual-cylinder electro-hydraulic variable-speed drive network prototype. The prototype was developed for an industrial application, but has initially been implemented in a laboratory testbench. Extensive data acquisition has been conducted while subject to the associated industrial motion cycle, under different load conditions. The data obtained are further used in combination with models to predict the total efficiency of the drive network prototype under higher loads than what could be achieved in the laboratory, suggesting a total efficiency from the electric supply to the cylinder pistons of 68%. Re-configuring the prototype to a known standalone drive system structure implies comparable efficiencies. Finally, the drive network is theoretically compared to a valve drive solution, generally suggesting that the prototype drive network can provide efficiency improvements of at least 40% in comparison.

Numerical analysis of the transient characteristics of internal flow in the acceleration process of variable speed regulation of a centrifugal pump

Abstract In this study, a method of combining Flowmaster and ANSYS CFX software was adopted. Based on the consistency between the numerical calculation results of the hydraulic performance of a centrifugal pump and the test results, an operating model of a centrifugal pump system is established, variation law of the external characteristic parameters in the transient process is obtained, and different acceleration times and modes are set. The change law of the transient external characteristics and the evolution mechanism of the internal flow field during the variable speed regulation and acceleration of the centrifugal pump are disclosed. By introducing a control system evaluation index, the effects of acceleration time and mode on performance and internal flow field of variable speed control process of the centrifugal pump are analysed in detail. The results show that the turbulent kinetic energy in the pump changes violently, and the high turbulent kinetic energy and high vorticity are widely distributed, which has an obvious transient effect. An exponential acceleration method can effectively reduce the peak value and overshoot of external characteristic parameters while reducing the speed regulation time.

Real-time optimization control of variable rotor speed based on Helicopter/ turboshaft engine on-board composite system

In order to adequately leverage the advantages of coaxial compound helicopters (CCH) to enhance overall performance and efficiency through variable rotor speed, and to improve the fuel economy of the composite propulsion system, a real-time optimization control method of variable rotor speed based on helicopter/turboshaft engine on-board composite system is proposed. Firstly, a steady-state model of the CCH required power and an on-board inverse model of the turboshaft engine based on an improved deep neural network propulsion system model (AdamDNN-PSM) are established. On this basis, an on-board adaptive model based on adaptive square root Kalman filter (ASRUKF) estimator is employed to correct the precision of the on-board inverse model and to track the real engine state. Finally, by adopting the feasible sequence quadratic programming (FSQP) method, an optimal speed rotor (OSR) is obtained through real-time optimization control, which reduces fuel consumption during cruising while considering both the geometric and aerodynamic constraints of the rotor. The simulation results demonstrate that the accuracy and real-time performance of the on-board inverse model have been significantly improved. The real-time optimization control method for OSR effectively reduces fuel consumption during cruising and enhances the CCH performance of the entire flight envelope.

Comparison of Different MATLAB Environments for Designing DC Motor Main Dimensions

Abstract: DC motor is an important device for various industries due to its variable speed control, efficiency, reliability and versatility. The Design calculations of DC Motor are long and tedious process if done manually. A program can be made in any programming language, but again the program length is large, and it is difficult to understand and summarize the design steps in short. In this paper an effort has been made to understand the Design Procedure of a DC Motor using different MATLAB environments. Design of main dimensions of DC Motor was done in three MATLAB environments. First by writing program in editor file, second using Simulink block sets and lastly by forming MATLAB GUI interface. Comparison between each method is discussed in short.

Satellite Attitude Control Using Faulty Double Gimbal Variable Speed Control Moment Gyroscope

A rigid satellite attitude control requires stable finite-time attitude convergence in the presence of rotation unwinding, external disturbances, and actuator faults. To achieve this, a new nonsingular fast fixed-time sliding mode controller is proposed to ensure finite-time convergence independent of the initial conditions of the system. Rotation unwinding is addressed using the body and shadow pair of the Modified Rodrigues Parameters (MRPs). Convergence behavior of the states errors in the neighborhood of the MRPs switching surface is also addressed. Attitude control is achieved using a double-gimbal variable-speed control moment gyro (DGVSCMG). For the first time, a DGVSCMG having all possible electrical and mechanical faults is considered for control design. A novel nonsingular fast fixed-time anti-unwinding fault-tolerant sliding control using a new sliding surface is proposed. This eliminates switching of the sliding surfaces and minimizes control chattering. Four new propositions are proposed and proved to establish fast fixed-time global stability of the system for tracking maneuver in fault and fault-free conditions with anti-unwinding. Simulation results are presented and compared with existing fixed-time sliding control approaches. The results show superiority of the proposed anti-unwinding fault-tolerant fast fixed-time control for the tracking maneuver in terms of convergence time, energy efficiency, and fault tolerance.

Virtual position predictive control with system delay observer to improve PMLSM position tracking accuracy

AbstractTo improve the position tracking accuracy of permanent magnet linear synchronous motors (PMLSM), this paper introduces a virtual position predictive control (VPPC) with a system delay observer (SDO). Un‐like conventional position predictive control (CPPC), which ignores the complexity of prediction models and velocity adjustments, the proposed VPPC combines a simplified position model with an active variable speed control. This design accelerates mover response and increases maximum reference speeds through active adjustments to better estimate the predicted output. Since the prediction period in CPPC often misaligns with the system delay, resulting in additional prediction errors, this paper further explores the relationship between predictive periods and system delay. Based on this analysis and a unified modelling concept, an SDO is included to observe and compensate for system delay, correcting the prediction period and optimising the control model. Experimental results on a PMLSM platform confirm the superior position tracking performance of the VPPC with SDO compared to conventional controllers.

Active power optimization control of speed closed-loop engine for energy saving in hydraulic excavator

ABSTRACT Most hydraulic excavators use passive power control to adjust the engine speed according to the load torque to achieve power matching, which has very limited effectiveness in energy saving. In this paper, an active power optimization control of speed closed-loop engine is proposed to improve its tracking performance for the dynamic energy-saving operating points. The inertia movement of the engine during variable speed control is analyzed to determine the kinetic energy requirements for different start and end operating points. An RBF-based neural network controller is designed based on power optimization to actively compensate the strong hysteresis of the engine speed relative to the optimal torque. The simulation and the experimental results show that the proposed control method has a much faster response for the energy-saving operating points, which reduces the energy consumption by 9.28% and 5.56% without adding any energy storage devices to the hydraulic excavator.

Analysis, simulation and experimental strategies of 5-phase permanent magnet motor control

This paper presents a study of control strategies for 5-phase permanent magnet synchronous motors (PMSMs) supplied by a five-leg voltage source inverter. Based on the vectorial decomposition of the multi-phase machine, fictitious machines, magnetically decoupled, allow a more adequate control. In this paper, our study focuses on the vector control of a multi-phase machine using a linear proportional-integral-derivative (PID) current regulator in the cases of sinusoidal and trapezoidal back-electromotive force (EMF) waveforms. In order to determine currents' references, two strategies are adopted. First one aims to minimize copper losses under constant torque, while the second one targets to increase torque for a given copper losses. These techniques are tested under a variable speed control strategy based on a proportional-integral (PI) regulator and experimentally validated.

Automatic control method of AC asynchronous motor variable frequency speed control based on CEEMDAN-wavelet threshold

Automatic control method of AC asynchronous motor variable frequency speed control based on CEEMDAN-wavelet threshold