Development of Very Small-scale Permanent-magnet Wind Generator System

• Main Authors: Han-Chi Chen, 陳翰圻
• Other Authors: Jonq-Chin Hwang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/tbfr8n

碩士 === 國立臺灣科技大學 === 電機工程系 === 104 === This thesis presents the analysis and implementation of three-phase permanent-magnet synchronous generator (PMSG) and its drive system, including horizontal wind turbine, permanent-magnet synchronous machine, bidirectional power converter for motor as well as generator modes of operation. Finite element analysis (FEA) software Maxwell/2D is used to determine PMSG's geometry for physical build-up through the comparison of the total harmonic distortions (THD) of induced electro-motive-force for different pole numbers as well as magnet pole-arc to pole-pitch ratios. Three-phase three-leg bidirectional power converter using six-step square-wave pulse-width modulation is proposed to drive the synchronous machine. Specifically, in motor mode, speed closed-loop control is given to drive permanent-magnet synchronous motor. While in the generator mode, current closed-loop and maximum power point tracking controls are introduced for PMSG to yield optimum phase current commands corresponding to various wind speeds. Futhermore, digital Hall-effect sensors are used to detect the rotational speed with low cost. As for the wind turbine blades, three-blade horizontal wind turbine, which has the advantages of high tip-speed ratio and low pull-in torque, is proposed to result in the expected rotational speed and generate the power in the low wind speed environment. FEA shows the no-load voltage of this machine under generator mode at 180 rpm is 11.51 V, and the THD is 1.46 %. The corresponding experimental results are 11.43 V and 1.60 %, respectively. Close agreement between analysis and measurement is obtained. In addition, the 32-bit digital signal processor, TMS320F28069, is adopted as the control core, and most of the control strategy is accomplished by software program. Experimental results show that under the motor mode, with the dc-link input voltage of 12 V , the motor can reach the rotational speed of 60 rpm and operate stably. Whereas, in generator mode, under the wind speed of 6 m/s, which is equivalent to the rotational speed of 160 rpm, generator phase current command of 1.8 A will yield output dc voltage, current and power of 20 V, 1.2 A and 24 W, respectively, with the constant battery charging current of 0.8 A. In short, both the simulated and experimental results verify the feasibility of the proposed system design and control strategy.