Magnetic Modelling of Synchronous Reluctance and Internal Permanent Magnet Motors Using Radial Basis Function Networks

The general trend toward more intelligent energy-aware ac drives is driving the development of new motor topologies and advanced model-based control techniques. Among the candidates, pure reluctance and anisotropic permanent magnet motors are gaining popularity, despite their complex structure. The availability of accurate mathematical models that describe these motors is essential to the design of any model-based advanced control. This paper focuses on the relations between currents and flux linkages, which are obtained through innovative radial basis function neural networks. These special drive-oriented neural networks take as inputs the motor voltages and currents, returning as output the motor flux linkages, inclusive of any nonlinearity and cross-coupling effect. The theoretical foundations of the radial basis function networks, the design hints, and a commented series of experimental results on a real laboratory prototype are included in this paper. The simple structure of the neural network fits for implementation on standard drives. The online training and tracking will be the next steps in field programmable gate array based control systems

Standstill Self-Commissioning Procedure for Synchronous Reluctance Motors based on Coenergy Model

This paper describes a fast and effective procedure to estimate the whole magnetic map of a synchronous reluctance motor at standstill. Flux linkage curves are approximated by using a coenergy-based model which only requires the knowledge of magnetic maps borders. To measure the necessary flux linkage curves, the proposed procedure is tailored for the chosen model, with the aims of minimising any rotor movements and keeping the computational effort at bay. The proposed procedure is composed by two consecutive tests and it is suitable for the self-commissioning of electric drives. Experimental results on a 3 kW synchronous reluctance machine are reported

Sensorless Drive for Salient Synchronous Motors based on Direct Fitting of Elliptical-Shape High-Frequency Currents

The paper deals with a position sensorless control for synchronous motor drive with an ease tuning procedure and a reduced number of tunable parameters. The rotating high frequency (HF) signals injection is implemented and the elliptical shape of the HF induced current trace is fitted by means of the least square (LS) algorithm. The ellipse tilt is related to the rotor position and the latter is estimated by processing the fitted coefficients of the ellipse mathematical equation. The proposed LS algorithm processes the measured currents, without the need to filter them as occurs in conventional injection methods. Furthermore, no motor parameters are required to tune the proposed rotor position observer. The method was validated throughout several experimental tests performed on an interior permanent magnet (IPM) synchronous motor

Robustness Analysis of Long-Horizon Direct Model Predictive Control: Permanent Magnet Synchronous Motor Drives

Model predictive control (MPC) lacks an integrating element. Thus, parameter mismatches can deteriorate its steady-state performance. To address this issue and enhance the robustness of MPC, analternative formulation of the prediction model is discussed in this paper. This model introduces an integrator to the optimization problem without increasing its size and consequently its computational complexity. An in-depth analysis of the effect of parameter mismatches on the control performance is performed when both the conventional and the proposed prediction model are used. Specifically, the aforementioned analysis is carried out for a range of switching frequencies as well as prediction horizon lengths, while a permanent magnet synchronous motor (PMSM) drive is used as a case study

Synchronous Motor Sensorless Drives based on Rotating Signal Injection and Direct Ellipse Estimation

The paper deals with a position sensorless control for synchronous motor drive with a reduced number of tunable parameters. The current response due to the high-frequency rotating signal injection describes an elliptical trajectory centered on the fundamental current vector and its major axis tilt is related to the rotor position. The proposed method fits the motor current response on the implicit ellipse equation by means of the least square (LS) algorithm. The proposed LS algorithm processes the measured currents, without the need to filter them as occurs in conventional injection methods. No motor parameters are required to tune the proposed position estimator. The method was validated throughout several experimental tests performed on a permanent magnet synchronous motor electric drive

A Computationally Efficient Robust Direct Model Predictive Control for Medium Voltage Induction Motor Drives

Long-horizon direct model predictive control (MPC) has pronounced computational complexity and is susceptible to parameter mismatches. To address these issues, this paper proposes a solution that enhances the robustness of long-horizon direct MPC, while keeping its computational complexity at bay. The former is achieved by means of a suitable prediction model of the drive system that enables the effective estimation of the total leakage inductance of the machine. For the latter, the objective function of the MPC problem is formulated such that, even though the drive behavior is computed over a long prediction interval, only a few changes in the candidate switch positions are considered. The effectiveness of the proposed approach is demonstrated with a medium-voltage (MV) drive consisting of a three-level neutral point clamped (NPC) inverter and an induction machine (IM)

Robustness Analysis of Long-Horizon Direct Model Predictive Control: Induction Motor Drives

Model predictive control (MPC) requires an accurate system model to achieve favorable performance. Thus, in presence of disturbances, model uncertainties and mismatches, MPC needs tools that provide high degree of robustness to them. Since MPC is, essentially, a proportional control technique, an effective method to deal with the aforementioned issues is the addition of an integrating element to the control scheme. This paper presents a prediction model that introduces an integrator tothe control strategy without increasing the size of the optimization problem. To examine its effectiveness, the sensitivity of the classical and the proposed MPC to parameter deviations are discussed and analyzed, considering a wide range of switching frequencies as well as prediction horizon lengths. The robustness examination is performed based on an industrial case study, namely a medium voltage induction motor drive

Injectionless Full Range Speed Sensorless Control for Synchronous Reluctance Motors based on PWM Current Ripple

This paper deals with a rotor position estimator algorithm for anisotropic motors based on current ripple, and no additional voltage injections are requested. The current trace in the αβ reference frame is fitted on the implicit ellipse equation by using the least square algorithm, and no parameters are requested for the estimator tuning. A modified modulation scheme is implemented to guarantee a suitable current ripple in all operating conditions. The estimated position is smoothen and adjusted by using a quadrature-PLL, exploiting the obtained sine and cosine components of the rotor position. Simulation results with a synchronous reluctance motor were carried out to prove the effectiveness and the accuracy of the proposed injectionless sensorless algorithm

Experimental Evaluation of Flux-Weakening Capability of Dual Three-Phase Synchronous Reluctance Motor

A dual three-phase synchronous motor is considered as a fault-tolerant solution for a hybrid electric vehicle. The study presented here compares the characteristics of the motor under nominal and flux-weakening operations in different operating conditions such as healthy, half control, and post-fault conditions. The post-fault characteristics are analyzed under open-circuit faults of a three-phase system and short-circuit faults of a three-phase system. All the results are validated by experimental tests