Qiji Ze

Fault-tolerant performances of switched reluctance machine and doubly salient permanent magnet machine in starter/generator system

The reliability of aeronautic starter/generator system is very important to the safety of aircraft. This paper investigates a starter/generator system with one dual-channel switched reluctance starter/generator and one dual-channel doubly salient permanent magnet starter/generator. By analyzing the mathematic models of two starter-generators considering magnetically coupling between channels and phases, a Matlab/Simulink model is built. To achieve fault-tolerant operations, a speed closed-loop control strategy and a voltage closed-loop control strategy are proposed for motor mode and generator mode, respectively. The dynamic performance of two starter/generators under normal and open-circuit fault conditions are analyzed and compared. Using the proposed approach, the simulated performances are shown to provide reference for further research.

Finite-Control-Set Model Predictive Control for DFIG Wind Turbines

This paper presents a time efficient finite-control-set model predictive control (FCS-MPC) scheme for the doubly fed induction generator system. In this scheme, the switching states of the rotor side converter are directly taken as control inputs. This way, the optimized control action can be directly applied to the converter. Compared with the existing FCS-MPC approaches, the salient feature of the proposed scheme is the reduction of the computation time. By introducing a set of augmented decision variables, the original intractable binary quadratic programming problem in FCS-MPC can be analytically transformed to a binary linear programming problem, which can be solved efficiently. By this means, the computation time of the proposed scheme is much less than that of the existing schemes. This reduction in computation time enables FCS-MPC with longer prediction horizons, thus yielding better control performance.Note to Practitioners—This paper was motivated by the problem of improving the control performance for the doubly fed induction generator (DFIG). Because of its advantages, such as high energy efficiency, low acoustic noise, variable speed operation, and reduced converter rating, DFIG has emerged as a promising solution for the wind power generation. However, existing DFIG controllers have limitations, such as difficult to tune the parameters, inefficient to handle constraints, and do not consider the discrete operation of the power converters. To overcome these limitations, this paper proposes a new DFIG control scheme based on finite-control-set model predictive control (FCS-MPC), which has the abilities of online optimal control, explicitly handling constraints, and directly generating the switching signals for the power converters. A computationally efficient algorithm is proposed to reformulate the FCS-MPC problem as a linear program, thereby significantly reducing the computational efforts and rendering the proposed scheme more practical for implementation. Simulation results validate the effectiveness of the proposed control scheme. This scheme can be implemented in the field-programmable gate array, which will be our future work.

Dual-redundancy PMSM servo system: Using single neuron PID controller

With the development of More-Electric/All-Electric aircraft technique, dual redundancy or more redundancy becomes a valid method for enhancing the reliability and security of motors in aircrafts. In this paper, based on the dynamic mathematic model of a 3.6kw dual-redundancy permanent magnet synchronous motor (DRPMSM), a single neuron PID controller is proposed in place of the conventional linear PID controller, thus improving the adaptability and robustness. The modified weight learning algorithm is obtained by combining the non-supervisory Hebb learning rule with the supervisory Delta learning rule to adjust the controller parameters on-line. By using this controller, the dynamic characteristics of the DRPMSM servo system was modelled and simulated by MATLAB/Simulink. The results showed that the single neuron PID controller could change its parameters automatically so enhanced dynamic performance of DRPMSM servo system and reduced torque fluctuation comparing with the system adopting conventional PID controller.

Analysis and experimental verification of fault-tolerant performance of a mutually coupled dual-channel SRM drive under open-circuits

The mutually coupled dual-channel switched reluctance machine (DCSRM) is a kind of special machine, which inherently offers high fault-tolerant feature. The purpose of this paper is to analyze and investigate the fault-tolerant performance of the DCSRM at open-circuits. Firstly, the faulty mathematic model of the DCSRM under open-circuit fault is developed with combination of a state and a fault functions. The simulation model of the DCSRM drive based on Matlab/simulink is established for dynamic analysis. To achieve fault-tolerant operation, a speed closed-loop control is performed to maintain the speed as the normal operation. The dynamic performances of the DCSRM under normal and open-circuit faults are predicted. Finally, an experimental setup for a 12/8 DCSRM drive is built for verification. The experimental results at normal, various open-circuit faults and sudden changes of load torque operations are presented to verify the analytical and simulation results and fault-tolerant control strategy of the DCSRM drive system.

The influence on the rotor loss of the high-speed motor by optimizing the rotor structure

Rotor Eddy current loss of high speed permanent magnet synchronous motor makes the motor efficiency drops, which can cause more serious problems, such as permanent magnet rotor demagnetization and affect the safe operation of the motor. The effect of segmenting permanent magnets on rotor loss was analysed with finite element analysis, Along with the axial segments increased, the eddy curent loss in the magnets can be reduced by segmenting,Loss in the permanent magnet is obviously reduced when permanent magnet is segmented around the circumference as the axial segment number exceeds a certain value. By using the shielding effect of the eddy-current magnetic field, Copper plating on inner and outer surface of rotor retain sleeve, although copper layer will produce eddy current losses, the magnetic field generated by the eddy currents counteract the harmonic components of the air gap magnetic field and reduce the permanent magnet rotor core, rotor protection loss set by analysing the thickness of the inner and outer coating distribution on the rotor eddy current loss, we obtained the optimal distribution of the copper layer.

A novel modular E-core stators and segmental rotors switched reluctance machine for electric vehicles

This paper presents a novel modular switched reluctance machine (SRM) with E-core stators and segmental rotors for electric vehicles. Unlike the conventional SRMs, there are both radial and axial fluxes in the E-core stators due to the particular construction. To evaluate the motor performance, a simplified 2D model and 3D model finite-element analysis (FEA) are utilized to calculate its magnetic characteristics. A comparative study between the modular SRM and a conventional SRM is made. Furthermore, the fault tolerant performances of this modular SRM under open-circuit faults are also predicted. Finally, a prototype machine is fabricated and tested. The flux linkage characteristics are experimentally obtained to compare with FEA results. More experimental results such as single-pulse operation, closed-loop control operation, fault-tolerant operation at open-circuits and sudden change in load torque operation are also presented to validate the analysis and simulation of the modular SRM and its performance.

Control method of dual-channel hybrid excitation doubly salient starter/generator

Aeronautic starter/generator System is the key technology of aircraft electric power system of more electric aircraft(MEA) and all electric aircraft(AEA), which can effectively improve the efficiency and environmental protection property of hybrid vehicles. Base on the analysis of the principle of a dual-channel hybrid excitation doubly salient machine, this paper selects asymmetrical half-bridge topology and H-bridge topology to control it. Furthermore, a co-simulation model of finite element model and control system was made to analyze two topologies with Maxwell 2D module and Simplorer module in Ansoft. By comparing steady performances when the starter-generator operating at the single channel mode and the dual-channel mode with different turn-on and turn-off angles, the paper provided reference for further experiment and industry application.

Linearized model and control strategy for dual three-phase PMSM based on small signal theory

Nowadays, with the development of More-Electric/All-Electric aircraft and hybrid/pure electric vehicles, the high reliability of motor servo system is required. This paper presents a little magnetically coupled structure dual three-phase permanent-magnet synchronous machines (PMSMs). Considering the mutual inductance between two sets of windings, a linearized model for a kind of dual three-phase PMSMs has been built. Small signal theory is used to linearize the model at the steady-state operating point. The linearized model simplified the analysis of the machine behavior at steady state and facilitate the controller design. The effectiveness of the proposed modeling method and control strategy has been verified by the simulation results.

The frequency response of parallel misalignment in PMSM test bench

In the dynamic test system of PMSM, the tested machine, dynamic torque meter and load machine are connected in a coaxial rotating machinery by two couplings. More than 70% of mechanical faults are caused by misalignment. The frequency response of parallel misalignment in a PMSM test bench was studied in this paper. A motion equation of shafting based on Lagrange method is established. The frequency response of the shafting with parallel misalignment was analyzed by the numerical method.