Shoudao Huang

Cogging Torque Reduction by Slot-Opening Shift for Permanent Magnet Machines

In this paper, an effective cogging torque reduction method based on shifting the slot-openings is presented. Stator teeth are divided into groups and proper slot-opening shift is applied for each group. The cogging torque can then be greatly reduced while the back-EMF waveforms remain symmetrical. No additional back-EMF harmonic components will be introduced by this method. Analytical analysis revealing the working principle of this method is given, which gives a clear guide about how this method may be applied to different permanent magnet machines.

Maximum torque per ampere and flux-weakening control for PMSM based on curve fitting

This paper describes the MTPA (maximum torque per ampere) control strategy of Salient-pole PMSM (permanent magnet synchronous motor) and its flux-weaking control strategy. Salient-pole PMSM often used the MTPA control strategy, the method that MTPA curves obtained from look-up table is usually used, but it will reduce the real-time performance and reliability of the system. In this paper, electromagnetic torque Tem and the relationship of the AC-DC-axis currents id, iq can be derived with the curve fitting method directly. It approximates the original nonlinear equations into a set of two-dimensional linear equation, and the error analysis shows that the error in line with engineering requirements, so it is greatly simplifies and facilitates the actual operation. On this basis, the paper also introduces the phase-shifting controlled manner to achieve flux-weakening control. The control performance of motor with improved algorithm is analyzed through simulation, and the simulation results verify the validity and feasibility of the algorithm and theory.

Transfer efficiency analysis of magnetic resonance wireless power transfer with intermediate resonant coil

Generally, for the magnetic resonance coupling wireless power transfer (WPT) system, the transfer efficiency and the transmission distance are contradictory. In order to simultaneously achieve the high transfer efficiency and the far transmission distance, some researchers have successfully proposed to use intermediate coils system to improve efficiency of WPT. In this paper, the expression for the efficiency of intermediate WPT system is obtained by applying coupled-mode theory. System efficiency is improved by optimizing key parameters of system. The intermediate WPT system via magnetic resonance coupling is designed. Simulation and experimental results validate the proposed optimization method.

Effect of the number of slots per pole on performance of permanent magnet generator direct-driven by wind turbine

The PMSG (permanent magnet synchronous generator) with the rated power of 2MW which is driven directly without gear system is designed by equivalent magnetic-circuit method. In order to study the characteristics of permanent magnet generator directly driven by wind turbine with the rated power of 2MW, comparative study of the performance both of no load and rated load was studied under different design features such as the choice of the number of slots per pole and the pole embrace. The results based on FEA (Finite Element Analysis) show that the appropriate choice of slot number per pole and pole embrace has a significant effect on the performance of direct-drive permanent magnet generators. It can weaken the effect of no load voltage harmonics and help the direct-drive permanent magnet generators to obtain the better performance

Sliding mode SVM-DPC for grid-side converter of D-PMSG under asymmetrical faults

This paper presents a new direct power control algorithm based on space vector modulation using sliding mode controller. For this algorithm, it introduces sliding mode controller to regulate the dc voltage, active and reactive power, and it is unnecessary to decompose the voltage and current into positive and negative sequence components, so its amount of calculation is greatly reduced. According to the simulation results, the proposed algorithm in this paper can achieve the smooth sine of input current at the grid-side converter of wind turbine under asymmetrical fault, which ensures the stable DC voltage and enhances the fairly good capability of fault ride-through for wind turbines under asymmetrical fault.

Some Practical Consideration of a 2MW Direct-Drive Permanent-Magnet Wind-Power Generation System

Nowadays, there has been much interest and studies in direct-drive permanent magnet synchronous generator (PMSG) due to its high efficiency and reliability with the rapid development of the power semiconductor devices. MW class permanent magnet synchronous generator (PMSG) is an important trend for larger capacity and higher power density. The present paper is aimed to outline the design, including optimal machine design, converter topology choosing and its control. Two 1MW back-to-back PWM converters with parallel connection are used to feed the power to the grid. The configuration, structure and control strategy of the converter are discussed. Some experimental results are given to illustrate the performance of the actual system.

A Novel Variable Step Hill-Climb Search Algorithm Used for Direct Driven PMSG

Introduced a new type of maximum power point tracking strategy (MPPT) based on variable step hill-climb which use power perturbation to search for maximum power and record the maximum power related to the turbine speed. Besides, adopted power feedback control for maximum power control based on direct-driven wind turbine with permanent magnet synchronous generator (D-PMSG). The algorithm was proved by MATLAB simulation.

Winding layers and slot/pole combination in fractional slot/pole PMSM—Effects on motor performance

This paper mainly studies the performance of fractional Slot/Pole permanent magnet synchronous motor (PMSM) due to different winding layer and slot/pole combinations. According to the proposed 2D models of 18 slot/8pole, 18slot/16pole and 18slot/20pole PMSM with single and double layer winding, we can obtain the winding arrangement. We can also get torque ripple, cogging torque, back-EMF and magnetic field distribution waveforms by finite element analysis. Then through the analysis of these waveforms we can get the discipline of their effects on fractional slot/pole PMSM performance.

A new fuzzy active-disturbance rejection controller applied in PMSM position servo system

A new fuzzy active-disturbance rejection position controller of permanent magnet synchronous motor (PMSM) servo system is presented in this paper. The improved position and speed loop controller not only maintains the original features of controller, but also reduces the adjustable parameters, which makes control performance better. Through the analysis of cross-axis output equation, a new position fuzzy active-disturbance rejection controller (Fuzzy-ADRC) scheme is proposed, ensuring the system dynamic performance, meanwhile improving the ability of the anti-load disturbance. Simulation and experimental results show that compared with classic PID control system the improved Fuzzy-ADRC system has characteristics of fast response, no overshoot and high control accuracy, and the system also has strong robustness to load and parameter changes. Besides, Fuzzy-ADRC runs steadily under high or low speed condition, which realizes higher control accuracy and stronger anti-interference of servo position control system, and makes control effect better.

Sensorless control for direct-drive PMSG wind turbines based on sliding mode observer

In order to obtain the accurate information of generator speed and angle, and alleviate the shortcomings of the speed sensor, this paper presents a sensorless vector control model of permanent magnet synchronous generator (PMSG) based on sliding mode observer (SMO) in the direct-drive permanent magnet wind power generation system. The proposed observer is easy to implement and less sensitive to parameter variations. But since it is the discontinuous control, the high frequency chattering problem would be produced in the conventional PMSG Bang-Bang control. In this paper, the saturation function is adopted to replace the discontinuous sign function and solve the problem successfully. The validity of the proposed estimation and control algorithms are shown by simulation studies on a 1MW PMSG wind turbine and are further demonstrated by experimental results on a 7.5KW practical PMSG wind turbine.