Hierarchical robust fuzzy sliding mode control for a class of simo under-actuated systems with mismatched uncertainties

The development of the algorithms for single input multi output (SIMO) under-actuated systems with mismatched uncertainties is important. Hierarchical sliding-mode controller (HSMC) has been successfully employed to control SIMO under-actuated systems with mismatched uncertainties in a hierarchical manner with the use of sliding mode control. However, in such a control scheme, the chattering phenomenon is its main disadvantage. To overcome the above disadvantage, in this paper, a new compound control scheme is proposed for SIMO under-actuated based on HSMC and fuzzy logic control (FLC). By using the HSMC approach, a sliding control law is derived so as to guarantee the stability and robustness under various environments. The FLC as the second controller completely removes the chattering signal caused by the sign function in the sliding control law. The results are verified through theoretical proof and simulation software of MATLAB through two systems Pendubot and series double inverted pendulum

A Common-Mode Voltage Suppression Strategy Based on Double Zero-Sequence Injection PWM for Two-Level Six-Phase VSIs

A common-mode voltage (CMV) suppression strategy, namely double zero-sequence injection common-mode voltage (DZICMV), is proposed in this paper for an asymmetrical six-phase induction motor fed by two-level dual three-phase voltage source inverters (VSIs). In this strategy, the sinusoidal waveforms injected by double zero-sequence signals are employed as modulation signals, and two opposite triangular waveforms are used as carriers. The fundamental period is divided into 24 sectors. In each sector, the carrier used by the medium amplitude phase is distinct from the carriers used by the other two phases in each set of three-phase windings. Using this method, the zero vectors (000) and (111) in each set of three-phase windings can be eliminated, and the peak values of sub-CMV and total CMV can be reduced from ±Udc/2 to ±Udc/6. The experiment results show that the root mean square (RMS) value of common-mode leakage current in DZICMV can be reduced by 51.83% compared with the double zero-sequence injection PWM (DZIPWM) strategy. It is also found in the other four existing benchmark CMV suppression strategies that the peak values of sub-CMV therein are nearly all ±Udc/2, and only in the low linear modulation region could one of these strategies suppress sub-CMV peak values to ±Udc/6. However, the proposed DZICMV can suppress the sub-CMV peak values to ±Udc/6 in the whole linear modulation range. Moreover, the maximum linear modulation index of the DZICMV is 1.15, which is larger than that of the four benchmark strategies, whose maximum modulation index is 1

Torque Enhancement of Dual Three-Phase PMSM by Harmonic Injection

The torque enhancement of dual three-phase permanent magnet synchronous machine (DT-PMSM) drive system by full exploitation of flux-linkage and current harmonics are comparatively studied in this paper. The torque capability of DT-PMSM is previously evaluated with strategies of harmonics utilization, i.e. Strategy-1 of 3rd harmonic utilization and Strategy-2 of 5th and 7th harmonic utilization, which can extend the torque capability by 18.2% and 9.0% respectively. However, the full exploitation of harmonics including 3rd, 5th and 7th harmonics in the dual three-phase system are not addressed. In this paper, the Strategy-3 of 3rd, 5th and 7th harmonic utilization is also included. Its corresponding harmonic current control is proposed and the average torque and harmonic torque are analyzed in detail. Based on a test rig with existing prototype DT-PMSM, the torque with Strategy-3 is increased up to 26.5%, which is superior to the previous strategies

Operational Performance Analysis of the Cryogenic Electrical Machine for Submerged Liquefied Natural Gas Pumps

The electrical machine is one of the key components for submerged liquefied natural gas (LNG) pumps. This study deals with a cryogenic permanent magnet synchronous motor (CPMSM) for submerged LNG pumps. An 18.5-kW CPMSM prototype was developed according to the needs of users. The basic design of the CPMSM was proposed by using a cryogenic temperature (CT) design method. To analyze the operational performance accurately, simulation modeling and analysis are carried out, and a liquid nitrogen (−196°C) experimental platform is built. The test results verify the rationality of the design and the accuracy of the simulation. Based on the simulation and experimental data, the working characteristics and mechanical properties of the prototype in liquid nitrogen are analyzed. In addition, the performance of the prototype operating in liquid nitrogen (−196°C) and LNG (−161°C) are compared and analyzed, and the results show that the operating characteristics of the prototype in the two fluid environments are similar

Design and Implementation of Recursive Model Predictive Control for Permanent Magnet Synchronous Motor Drives

In order to control the permanent-magnet synchronous motor system (PMSM) with different disturbances and nonlinearity, an improved current control algorithm for the PMSM systems using recursive model predictive control (RMPC) is developed in this paper. As the conventional MPC has to be computed online, its iterative computational procedure needs long computing time. To enhance computational speed, a recursive method based on recursive Levenberg-Marquardt algorithm (RLMA) and iterative learning control (ILC) is introduced to solve the learning issue in MPC. RMPC is able to significantly decrease the computation cost of traditional MPC in the PMSM system. The effectiveness of the proposed algorithm has been verified by simulation and experimental results

Flux-Weakening Control of Dual Three-Phase PMSM Based on Vector Space Decomposition Control

This paper proposes a flux-weakening (FW) control for dual three-phase ermanent magnet synchronous machine (DT-PMSM) based on vector space decomposition (VSD) control, where the output voltage in αβ sub-plane is employed for voltage feedback in the flux-weakening control loop. As the fundamental components are mapped to αβ sub-plane while the 5th and 7th harmonics are projected to harmonic z1z2 sub-plane, the flux-weakening current from this new control in αβ sub-plane is sixth harmonic-free regardless of the 5th and 7th harmonics being resulted from the non-sinusoidal back EMF or inverter non-linearity. The proposed control is compared with the conventional FW feedback control extended for DT-PMSM, where the FW control is applied to the two sets of three-phase windings separately. The experimental results show that the proposed FW control based on VSD is superior to the conventional FW control in terms of reduction in current unbalance and harmonic currents

A Robust Adaptive Control using Fuzzy Neural Network for Robot Manipulators with Dead-Zone

In this paper, a robust-adaptive-fuzzy-neural-network controller (RAFNNs) bases on dead zone compensator for industrial robot manipulators (RM) is proposed to dead the unknown model and external disturbance. Here, the unknown dynamics of the robot system is deal by using fuzzy neural network to approximate the unknown dynamics. The online training laws and estimation of the dead-zone are determined by Lyapunov stability theory and the approximation theory. In this proposal, the robust sliding-mode-control (SMC) is constructed to optimize parameter vectors, solve the approximation error and higher order terms. Therefore, the stability, robustness, and desired tracking performance of RAFNNs for RM are guaranteed. The simulations and experiments performed on three-link RM are provided in comparison with neural-network (NNs) and proportional-integral-derivative (PID) to demonstrate the robustness and effectiveness of the RAFNNs