Direct Torque Control for Series-Winding PMSM with Zero-Sequence Current Suppression Capability

The series-winding permanent-magnet synchronous motor (SW-PMSM) has the merits of high output power and excellent control performance, as does the open-winding permanent-magnet synchronous motor (OW-PMSM). Meanwhile, it can greatly reduce the number of power devices. However, due to the existence of the zero-sequence path, zero-sequence current occurs, which can cause additional losses and torque ripples. Thus, this paper proposes a novel direct torque-control strategy for the SW-PMSM with zero-sequence current suppression capability (ZSCS-DTC). First, the series-winding topology (SWT) and the voltage vector distribution in the SW-PMSM drives are analyzed. Secondly, the basic DTC (B-DTC) scheme for the SW-PMSM is investigated, and the defects of zero-sequence current open-loop control in the B-DTC scheme are revealed. Thirdly, a new voltage vector synthesis scheme is proposed for suppression of zero-sequence current while ensuring bus voltage utilization. A switching table is reconstructed with the newly synthesized voltage vectors. On this basis, a ZSCS-DTC scheme for the SW-PMSM is proposed based on zero-sequence current closed-loop control so that electromagnetic torque, stator flux linkage and zero-sequence current can be controlled simultaneously. Finally, the effectiveness of the proposed ZSCS-DTC scheme for the SW-PMSM drives is verified

Simultaneous identification of multiple mechanical parameters in a servo drive system using only one speed

In some servo applications, restricted by the measurement noise and the stiffness of the mechanical system, the bandwidth of the disturbance observer cannot be high enough to realize a good robust control to parameters uncertainties, it is essential to identify the mechanical parameters. In the existing mechanical parameter identification methods, the viscous and Coulomb friction torque coefficients are usually identified using two different constant speeds, and the moment of inertia can be identified with various methods. However, no one method can identify these three parameters at the same time using only one speed. The contribution of this paper is to propose a method that can identify the three mechanical parameters simultaneously using only one speed. A low pass filter is used to suppress the measurement noise in the speed feedback, thus parameters are identified with high precision. A unidirectional sine-wave speed is used to decouple the viscous friction torque and the Coulomb friction torque, two speeds with different amplitudes and the detection of the speed amplitude are no more required. Adaptive extended state observer (ESO) is designed based on Lyapunov’s stability theory, can be easily changed to the normal ESO used in active disturbance rejection control. The proposed method is easy to understand and implement. The effectiveness of the method is verified by both the simulation and experimental results.Accepted versionThis work was supported in part by the Start-Up Grant from Nanyang Technological University under Grant 04INS000574C140, and in part by the Natural Science Foundation of China under Grant 51807080

Model-free predictive current control of SPMSM drives using extended state observer

Conventional predictive control (PC) has been employed for machine drives due to good dynamic response and easy implementation. However, the disturbance caused by machine parameter mismatch is one of main barriers to its widespread application. In order to deal with this issue, this work proposes a novel model-free predictive current control (MFPCC) for surfaced permanent magnet synchronous machines (SPMSM). The contribution of this work is that a novel extended state observer (ESO) is proposed and the proposed MFPCC only utilizes the input and output knowledge of the plant without using any machine parameter in controller, which can effectively suppress the disturbances. In addition, the effect of the initial machine inductance parameter mismatch on the conventional ESO of MFPCC is analyzed in detail. The proposed MFPCC is validated and compared against three methods, namely PC without ESO, PC using ESO, and MFPCC using ESO. The experimental results have been carried out to verify the effectiveness of the proposed MFPCC.National Research Foundation (NRF)Submitted/Accepted versionThis work was supported by National Research Foundation (NRF) Singapore, under its NRF Fellowship Grant NRF-NRFF12- 2020-0003

Different active disturbance rejection controllers based on the same order GPI observer

As the higher-order or generalized extended state observer (ESO), generalized proportional-integral (GPI) observer (GPIO) have been proposed to enhance the active disturbance rejection (ADR) control (ADRC) systems disturbance rejection ability. However, different ADR controllers can be deduced based on the same order GPIO, resulting in different dynamic performances. In this paper, ten different ADR controllers based on the fourth order GPIO are present. In order to reveal the relationship between these ADR controllers and the conventional ADR controllers based on the third order ESO, six different third-order-ESO-based ADR controllers are present and compared with the fourth-order-ESO-based ADR controllers. To ease the comparison between different ADRC systems, a common expression is built for different ADR controllers. A novel frequency-domain analysis method is also introduced to reveal how the observer and feedback control law affects the closed-loop control systems dynamic performance. The effectiveness of the proposed method is verified on the test bench based on dSPACE DS1103.National Research Foundation (NRF)Submitted/Accepted versionThis work was supported in part by the National Research Foundation (NRF) Singapore, under its NRF Fellowship under Grant NRF-NRFF12-2020-0003 and in part by the Natural Science Foundation of China under 51807080

A Dual-Permanent-Magnet Machine with Asymmetric Stator Teeth-Tips

Dual-permanent-magnet machines (DPMMs) have attracted increasing attentions due to their merit of high torque density. Nevertheless, DPMMs suffer from low PM utilization ratio owing to large PM consumption. To improve the situation, this paper presents a DPMM with asymmetric stator teeth-tips, termed as AST-DPMM. The key of the proposed design is to arrange wide and narrow stator teeth-tips alternatively. By building an analytical model of the AST-DPMM, the impact of asymmetric stator teeth-tips is investigated. It is found the asymmetric stator teeth-tips can enhance the working harmonics by generating new magnetomotive force harmonics and permeance harmonics. Hence, it can achieve high torque density and improve PM utilization ratio simultaneously. The performance comparisons together with other machines are conducted to evaluate the investigated AST-DPMM. Finally, a prototype of the AST-DPMM is fabricated, and the experimental testing is conducted to verify the proposed ideas

Modeling and optimizing method for axial flux induction motor of electric vehicles

Axial flux induction motors have attracted attention in electric vehicles due to their advantages over conventional motors, including higher efficiency, compact structure, high utilization of materials, and good ventilation and cooling. This paper provides a fast design method for two-stator-one-rotor axial flux induction motor of electric vehicle applications. The proposed method consisting of an accurate motor analytical model and a design variables optimization method based on genetic algorithm. Unlike traditional design of axial flux induction motor with single objective, multi-objective is considered in this work. Based on the proposed method, the performance of axial flux induction motor can be simulated and optimized in much shorter time compared with finite element analysis in ANSYS Maxwell. The comparison results from ANSYS Maxwell can prove the effectiveness and accuracy of the proposed method, and the performance of the final designed motor can meet all the design requirements

Natural speed observer for nonsalient AC motors

This letter addresses experimental validation of the reduced-order natural speed observer design for position sensorless drive with nonsalient permanent magnet synchronous motor. The natural speed observer and the active flux estimator are connected in a cascaded fashion, which results in a simple sensorless algorithm that needs only to tune one bandwidth parameter for flux estimation and one bandwidth parameter for speed observation. Experimental results of high speed reversal test, zero speed stopping test, and slow speed reversal test are included, where the practice of applying nonzero d-axis current at zero speed has shown to be effective for loaded zero speed stopping test, but it causes zero-speed lockedup at slow speed reversal with acceleration rate of 50 r/min/s. Four remedies are compared to improve the slow speed reversal test and the proposed method gives almost ramp actual speed waveform, nondiverging q-axis current and smooth transition in position waveform during slow zero speed crossing. A new dynamic expression of the active flux is proposed and with the aid of the active flux concept, the proposed sensorless algorithm is also applicable to various types of ac motors.National Research Foundation (NRF)Accepted versionThis work was supported by National Research Foundation (NRF) Singapore, under its NRF Fellowship under Grant no: NRF-NRFF12-2020-0003

Stochastic optimization of multi-energy system operation considering hydrogen-based vehicle applications

In response to the challenge of improving energy efficiency, multi-energy systems composed of electrical power, natural gas, heating power, cooling power networks and energy storage are attracting more attention and being developed rapidly. Traditionally, different energy infrastructures are scheduled and operated independently, which results in less efficient energy usage and resource wasting. Through integrating as a multi-energy system, different energy carriers can be coupled and optimized as one unit. In this paper, a two-stage stochastic optimization method with forecast updating for optimal scheduling of a real multi-energy system with hydrogen-based vehicle applications is proposed from an economic point of view. Simulation results suggest the proposed scheduling method can help quantify the daily operating cost, balance real-time power demands and PV output solar power, and achieve considerably operating cost savings by appropriately arranging and utilizing all the devices in the system

Deep-investigated analytical modeling of a surface permanent magnet vernier motor

Permanent magnet vernier motors possess the advantage of high torque density for high performance applications. However, the low power factor challenge makes it unacceptable for direct-drive applications. A lack of accurate model based on the motor sizing law raises difficulties for machine designers to further conduct research on the performance metrics. This paper presents a deep investigation into the analytical model for surface permanent magnet vernier motors (SPMVMs) to identify an accurate approach to obtain the performance metrics, including torque and power factor. The modeling technique is developed based on conformal mapping with both radial and tangential permeability functions calculated to obtain the magnetic loading considering leakage flux. Then, slotting effect on both air gap flux density and winding function is analyzed to achieve a precise formula for torque and power factor computation. The new modeling technique is applied to integral-slot SPMVMs with various parameters on high power factor and torque density design. Finally, an SPMVM with high torque density and power factor is fabricated to verify the analytical model at the power rating of 0.8 kw and the speed of 500 r/min. The experimental results shows good consistence with the analytical model.National Research Foundation (NRF)Submitted/Accepted versionThis work was supported by National Research Foundation (NRF) Singapore under its NRF Fellowship Grant NRF-NRFF12-2020-0003

A novel current measurement offset error compensation method based on the adaptive extended state observer for IPMSM drives

Offset error from the measured phase current mostly causes a performance afflicted for interior permanent-magnet synchronous motor (IPMSM) drives, and innovative solutions are eagerly sought. Considering this, this article proposes an adaptive extended state observer (AESO) to compensate the current measurement offset error (CMOE) without additional hardware. In the proposed scheme, the AESO is designed in a stationary coordinate system to estimate CMOE in dc form. Notably, the proposed AESO possesses a second-order low-pass filtering characteristics. With this, the proposed method shows a high robustness against the disturbances from the ac components caused by motor parameter changes, etc. Furthermore, the adaptive gains enable the proposed scheme to maintain a satisfactory performance under the motor frequency changes. The feasibility of the proposed scheme is thoroughly verified by extensive experimental tests based on the test bench of a 3-kW IPMSM drives.This work was supported in part by the High-Speed Railway Joint Funds of the National Natural Science Foundation of China under Grant U1934204, in part by the National Natural Science Foundation of China under Grant 52177060, and in part by the National Natural Science Foundation of Sichuan Province under Grant 2023NSFSC0824