Model predictive Direct Flux Vector Control of multi three-phase induction motor drives

A model predictive control scheme for multiphase induction machines, configured as multi three-phase structures, is proposed in this paper. The predictive algorithm uses a Direct Flux Vector Control scheme based on a multi three-phase approach, where each three-phase winding set is independently controlled. In this way, the fault tolerant behavior of the drive system is improved. The proposed solution has been tested with a multi-modular power converter feeding a six-phase asymmetrical induction machine (10kW, 6000 rpm). Complete details about the predictive control scheme and adopted flux observer are included. The experimental validation in both generation and motoring mode is reported, including post open-winding fault operations. The experimental results demonstrate the feasibility of the proposed drive solution

Design of a repetitive controller as a feed-forward disturbance observer

From the structure point of view, a repetitive controller (RC) is considerably similar to a disturbance observer. By adding a correction term to the traditional RC and considering the disturbances as states, the repetitive controller can be designed in the same way as a disturbance observer. This paper presents therefore a new simple way of tuning a repetitive controller. Simulations show that, when compared with the traditional RC, the proposed RC configuration can achieve greater stability margin. As opposed to the traditional plug-in RC, the new RC structure studied in this paper is also shown to be robust against variations in the inner loop delays if it is used in a cascaded configuration. The immunity to plant parameter variations is another added benefit of the proposed controller

Self-commissioning of interior permanent- magnet synchronous motor drives with high-frequency current injection

In this paper, a simple and robust method for parameter estimation at rotor standstill is presented for interior permanent magnet (IPM) synchronous machines. The estimated parameters are the stator resistance through dc test, the dq inductances using high-frequency injection, and the permanent magnet flux by means of a closed-loop speed control maintaining rotor stationary. The proposed method does not require either locking the rotor or additional/special power supplies. The validity of the suggested method has been verified by implementation on two IPM motor prototypes. Finally, the estimated parameters have been compared against results obtained through finite-element simulations and with machine magnetic characterization, separately performed, to validate the method's effectiveness. Saturation and cross-saturation effects are taken care of through amplitude modulation and cross-axis current application, respectively

Modulated Model Predictive Direct Power Control of DFIM Considering Magnetic Saturation Effects

\ua9 2018 IEEE. In this paper, an optimal voltage vector based model predictive control strategy is investigated for the direct power control of a doubly fed induction machine. The model predictive control computes optimal voltage vector that minimizes the error in active and reactive power. The computed voltage vector, if within the linear regulation range, is passed onto a modulator to be applied in the next sampling instant. In the over-modulation range the voltage vector is linearly scaled down, before modulation, to maintain optimality. The paper also focuses on the saturation of main flux inside an induction machine and its impact on reactive power control when stator current sensors are not installed. The machine\u27s saturation characteristic is fully utilized to realize full-state stator flux observer that is used to estimate stator currents which give accurate prediction of reactive power. Consequently, stator current sensors can be excluded. Simulations and experimental analyses are conducted on a test machine to verify fast dynamics of predictive control and the estimation accuracy of stator current

Model Predictive Direct Flux Vector Control of Multi-three-Phase Induction Motor Drives

A model predictive control scheme for multiphase induction machines, configured as multi-three-phase structures, is proposed in this paper. The predictive algorithm uses a direct flux vector control scheme based on a multi-three-phase approach, where each three-phase winding set is independently controlled. In this way, the fault-tolerant behavior of the drive system is improved. The proposed solution has been tested with a multimodular power converter feeding a six-phase asymmetrical induction machine (10 kW, 6000 r/min). Complete details about the predictive control scheme and adopted flux observer are included. The experimental validation in both generation and motoring modes is reported, including open-winding postfault operations. The experimental results demonstrate full drive controllability, including deep flux-weakening operation. © 1972-2012 IEEE

A Novel Repetitive Controller Assisted Phase-Locked Loop with Self-Learning Disturbance Rejection Capability for Three-Phase Grids

The synchronization between the power grid and distributed power sources is a crucial issue in the concept of smart grids. For tracking the real-Time frequency and phase of three-phase grids, phase-locked loop (PLL) technology is commonly used. Many existing PLLs with enhanced disturbance/harmonic rejection capabilities, either fail to maintain fast response or are not adaptive to grid frequency variations or have high computational complexity. This article, therefore, proposes a low computational burden repetitive controller (RC) assisted PLL (RCA-PLL) that is not only effective on harmonic rejection but also has remarkable steady-state performance while maintaining fast dynamic. Moreover, the proposed PLL is adaptive to variable frequency conditions and can self-learn the harmonics to be canceled. The disturbance/harmonic rejection capabilities together with dynamic and steady-state performances of the RCA-PLL have been highlighted in this article. The proposed approach is also experimentally compared to the synchronous rotation frame PLL (SRF-PLL) and the steady-state linear Kalman filter PLL (SSLKF-PLL), considering the effect of harmonics from the grid-connected converters, unbalances, sensor scaling errors, dc offsets, grid frequency variations, and phase jumps. The computational burden of the RCA-PLL is also minimized, achieving an experimental execution time of only 12~mu ext{s}. © 2013 IEEE

MPC Using Modulated Optimal Voltage Vector for Voltage Source Inverter with LC Output Filter

Voltage source inverters with LC output filters are widely used for high-quality output of ac power supplies. They are also a potential solution for embedded electrical networks in more-electrical aircraft of the future. In this paper, a recently developed model predictive control technique that selects modulated optimal voltage vector is applied for high dynamic output voltage control of these systems especially when the required output frequency is well above the standard 50/60 Hz as required by aerospace applications. The studied predictive control optimizes the switch duty cycles when in linear regulation range by solving analytical equations. The over-modulation region is covered by optimized linear combination of the adjacent hexagon vertices unlike how it happens in classical space vector modulation. A load current observer is also designed in this paper which is made independent of output frequency for improving the disturbance rejection capability of the voltage control loop when the load current sensors are not present. Simulation and experimental results that validate the control and observer performance are presented under different steady state and dynamic operating conditions. © 2018 IEEE

Reuse of a damaged permanent magnet synchronous motor for torque ripple and acoustic noise elimination using a novel repetitive observer

A permanent magnet synchronous motor (PMSM) has its bearing damaged and is irreversibly demagnetized due to overcurrent. Due to the changes in its electromagnetic configuration, the motor suffers from extremely high torque ripple, which produces intolerable speed ripple and acoustic noise. The aim of this paper is to evaluate if a repetitive observer (RO) can be used to smooth the rotational speed and suppress acoustic noise. The RO is functionally the same as a repetitive controller (RC), but is preferred due to its simplicity of tuning. Its effectiveness of reducing acoustic noise will be evaluated in this paper for the first time. Experimental test results show that the speed ripple and acoustic noise are reduced significantly. The work opens the possibility of reusing the damaged motor and still achieve high performance. The RO can also be applied to enhance the fault tolerance capability of a healthy motor. © 2019 IEEE

A Novel Phase-lock Loop with Feed-back Repetitive Controller for Robustness to Periodic Disturbance in Three-phase Systems

While power networks evolve towards the new concept of smart grids, with the proliferation of power electronics embedded systems and distributed generation, the insurgence of system unbalance and voltage harmonic distortion, become more and more frequent. Also, often a noisy voltage sampling system can produce offsets in measurements. Such imperfections bring challenges to the phase identification using a traditional phase-lock loop (PLL), utilized in the control of all grid connected converters. However, since the imperfections lead to periodic harmonics in the corresponding dq-axis voltages, the repetitive controller (RC) can be useful for harmonic suppression. This paper presents a three-phase PLL using a feed-back RC. Specially, a novel running mean filter has been added to minimize the interaction between RC and the Proportional-Integral (PI) controller in the PLL. Simulation results show that the proposed PLL can track the phase of the three-phase voltage without being influenced by harmonic distortion. © 2018 IEEE