For permanent magnet synchronous machines (PMSMs), magnetic saturation is a key challenge to parameter estimation and saturation modeling using polynomials is popular with dq- axis inductances ...estimated independently. However, dq-axis inductances are mathematical terms derived from stator frame and are indeed correlated, which is not fully explored for improving estimation performance. Hence, this paper proposes a correlated inductance model to represent the relationship among dq- axis inductances and model their nonlinear variations with respect to stator currents due to magnetic saturation. The idea is to model the saturation in the stator frame and derive the correlated inductance model in the rotating frame. The estimation model is established based on the correlated inductance model, in which dq- axis inductances are represented using the same components and the correlation can be fully explored to improve the estimation accuracy. Moreover, the proposed estimation approach does not involve the division by the dq- axis currents, which can ensure the estimation accuracy especially under conditions with small current magnitude. While existing methods often involve the division and result in limited accuracy under such conditions. The proposed approach is evaluated on two test machines and compared with existing methods to demonstrate the performance improvement.
Multiphase permanent-magnet synchronous machines (PMSMs) are receiving more and more interest in safety-critical modern industries owing to their higher reliability when compared with conventional ...three-phase PMSMs. Rotor magnets are critical components, which, in case of fault, directly affect the performance of the PMSMs. Thus, monitoring the rotor magnets status is essential to ensure both high level of efficiency and service continuity. The present study focuses on the investigation of a new approach for the detection of rotor magnet demagnetisation in a vector-controlled asymmetrical six-phase surface-mounted AC PMSM. The main contribution of the proposed technique is the assessment of a rotor demagnetisation fault index derived from the fifth and seventh harmonics of the stator voltage space vector evaluated in the α5–β5-plane, and already available in the control system platform. The performance of the proposed approach is evaluated using finite element analysis and numerical simulations, both validated by experimental tests.
The SiC devices have attracted more and more attention due to the capability of withstanding higher blocking voltage, higher switching frequency, and higher temperature. However, challenges for SiC ...devices applied in voltage-source-inverter (VSI) fed motor drives such as electromagnetic interference (EMI) issues and limited over-current capability still limit the further application of SiC devices. In this paper, a novel SiC devices based zero-voltage-switching (ZVS) current-source-inverter (CSI) is proposed for permanent-magnet synchronous motor (PMSM) drive. The key is to propose an auxiliary resonant circuit, which achieves ZVS conditions for all switches in power circuits and reduces the dv/dt of high speed SiC devices. The resonant capacitor in the auxiliary circuit can clamp overvoltage caused by possible open-circuit faults. To further reduce the EMI, the random switching frequency PWM (RSFPWM) is designed for the proposed CSI motor drive. The system configuration, working principle, circuit design and control schemes are described in detail. Both simulations and experiments are presented to verify the effectiveness of the proposed ZVS CSI fed PMSM drive system.
The permanent magnet synchronous motor (PMSM) has become a core component of electromechanical energy conversion in the modern industrial field. In order to expand the application of the PMSM in the ...field of high-power traction, a robust predictive torque control (R-PTC) strategy for the N -segment three-phase PMSM ( N *3-phase PMSM) is proposed in this article. First, the output characteristics of the N *3-phase PMSM are illustrated with the finite-element analysis method, and the mathematical model is established. Then, the six-segment three-phase PMSM predictive control system driven by six parallel inverters is designed to generate the required torque. Furthermore, the influence of the parameter mismatch on the predicted torque and stator flux is taken into consideration based on the conventional predictive torque control (PTC). Finally, a novel R-PTC method with the proportional controller is developed for the N *3-phase PMSM, which can effectively improve the accuracy and robustness of predictive control performance under the parameters mismatch. The simulation and experimental results verify that, compared with the conventional PTC, the proposed R-PTC method can make the predicted stator flux and torque value accurately track its reference values while achieving lower stator flux and torque ripple.
This paper presents an adaptive-linear-neuron (ADALINE)-based dead-time compensation method for vector-controlled permanent-magnet synchronous motor drives. The proposed strategy is achieved by ...suppressing the sixth-order current harmonics in the dq-axes synchronous reference frame. Four ADALINEs are employed in the proposed algorithm. Two ADALINEs are used for estimating the sixth-order harmonic components of dq-axes currents and the other two are used for generating the dq-axes compensation voltages. The voltage compensators are self-tuned by minimizing the estimated current distortion by means of the least mean square algorithm. The proposed compensation algorithm does not require any additional hardware or complicated signal processing algorithms. Experimental results validating the proposed compensation method are also presented.
To improve the tracking performance of the current controllers of permanent-magnet synchronous motor (PMSM) drive systems that are subject to internal disturbances, such as parameter variations, a ...novel active-disturbance-rejection-based sliding-mode current control (ADR-SMCC) scheme for PMSM drives is proposed in this paper. First, a fast-response SMCC is designed based on the upper bound of the internal disturbance. Then, an extended state observer (ESO) is designed to estimate the internal disturbance in real time without the need for an accurate mathematical model of the PMSM. The parameters of the ESO can be easily designed based on the desired bandwidth of the ESO. The estimated internal disturbance is then used to update the control law of the SMCC in real time. The resulting ADR-SMCC has improved steady-state and transient current tracking performance and enhanced robustness to internal disturbances. The stability of the closed-loop PMSM drive system with the ADR-SMCC is proven by the Lyapunov theory. The ADR-SMCC is validated by experimental results for a 200-W salient-pole PMSM drive system.
The effectiveness of nonlinear flux observer has been validated in practical application. However, it is not easy to tune the gradient search gain. The observer is sensitive to the parameter ...variation and also the stability can be greatly affected by the gradient search gain. This paper proposes an improved nonlinear flux observer to enhance the performance. The proposed method utilizes the gradient search for both magnitude and phase of the rotor, which changes the error dynamic equations. Further, it brings the benefits of smaller estimation error and quicker dynamic responses, since the convergence path is more reasonable. In addition, it has the advantages of better steady-state performance, robustness against parameter variation and stronger stability against larger observer gain value. By comparisons of simulations and experiments, the superiority is demonstrated.
On the one hand, with the use of direct torque control (DTC) for a six-phase permanent magnet synchronous motor (PMSM) and a three-phase PMSM series-connected system supplied by a six-phase inverter, ...it is possible to realize fast torque control for two PMSMs. On the other hand, because the number of inverter output voltage vectors (VVs) is increased to 64, it is difficult to divide sectors for traditional switching table DTC (ST-DTC). Furthermore, it is difficult to choose an optimal switching vector to reduce torque and flux ripples of two PMSMs in ST-DTC. A predictive control strategy of torque and stator flux is introduced into a two-PMSM series-connection DTC system, including winding fault, in this paper. Based on the principle of minimum errors of torque and stator flux amplitude and minimum zero-sequence current, an optimal VV is predicted. In order to realize uninterrupted torque control before and after open-phase fault, open-phase winding flux is considered in stator flux, and the inverter VV considering open-phase voltage is constructed in an open-phase control strategy. The experimental results show that the steady-state torque and stator flux ripples of a series-connected drive system are greatly reduced, and the drive system can operate without interruption from failure-free to failure operation.
Owing to the competitive advantages of cost reduction, system downsizing, and reliability enhancement, position sensorless control methods for permanent magnet synchronous machine drives have drawn ...increasing attention from academia to industrial applications. In this article, a survey of the major sensorless control techniques for a wide speed range from low to high speeds is presented. The different high frequency signal injection schemes, fundamental pulsewidth modulation excitation methods, and model-based sensorless control are displayed and compared, which is able to facilitate the sensorless control implementation.
PDF
