作者机构：
[朱俊杰; 刘浩然; 蒋峰; 王湘中] School of Computer &Information Engineering, Central South University of Forestry and Technology, Changsha;410004, China;[朱俊杰; 刘浩然; 蒋峰; 王湘中] 410004, China
通讯机构：
[Liu, H.] S;School of Computer &Information Engineering, China
作者机构：
[粟梅; 朱俊杰] School of Information Science and Engineering, Central South University, Changsha 410083, China;[朱俊杰; 陈程; 王湘中; 杨龙] School of Computer and Information Engineering, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
School of Information Science and Engineering, Central South University, China
关键词：
无刷直流电机;闭环三段式启动;反电势;短时间脉冲电压矢量;优化定位
摘要：
针对无位置传感器无刷直流电机(brushless DC motor,BLDCM)启动问题,提出了一种转子初始位置精准预定位与加速过程中优化定位相结合的闭环三段式启动策略。在电机绕组中施加短时间脉冲电压矢量,通过检测直流母线电流可以将转子位置锁定在60°电度角范围内,在此基础上通过向指定绕组通电与检测电流比较阈值完成转子精准预定位。预定位后进入优化定位与加速阶段,此时电流比较阈值作为换相条件,保证转子在加速过程中准确换相,当转速达到一定值时系统切换到反电势运行状态(backelectro-motive-force,EMF)。实验结果表明,提出的三段式闭环启动方法无需传感器、成本低、可靠性高,能保证系统在整个启动过程中均处于闭环工作状态,不会出现失步或启动失败现象。
作者机构：
[王亮军; 杨龙; 朱俊杰; 王湘中; 廖迎新] School of Computer and Information Engineering, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
School of Computer and Information Engineering, Central South University of Forestry and Technology, China
作者机构：
[粟梅; 朱俊杰] School of Information Science and Engineering, Central South University, Changsha 410083, China;[朱俊杰; 王湘中; 马林] School of Computer and Information Engineering, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
School of Information Science and Engineering, Central South University, China
作者机构：
[粟梅; 朱俊杰] School of Information Science and Engineering, Central South University, Changsha 410083, China;[朱俊杰; 陈程; 杨龙] School of Computer and Information Engineering, Central South University of Forestry and Technology, Changsha 410004, China
通讯机构：
School of Information Science and Engineering, Central South University, China
摘要：
Principle of triangle carrier amplitude modulation is equivalent with sinusoidal modulator amplitude modulation, and principle of sinusoidal modulator phase-shifting is equivalent with the triangle carrier phase-shifting are proposed. A digital natural sampling based on multi-channel SPWM generator is developed using time-division multiplexed access (TDMA). Flip time computation by CPU is no needed in the generator which has an accuracy flip time. Design principle and implementation based on FPGA are introduced, and testing results are presented.
摘要：
In the construction elevator with high-speed inverter based on the single-chip microcomputer and single speed sensor, the response of the automatic smooth layer system is often too slow to guarantee the accurate leveling lift, so the system needs frequent calibration. This paper presents a fuzzy algorithm based elevator automatic leveling system using STC controller. Test results show that, under the condition that the load vary frequently and hoist cage fall inertia, the system can predict elevator weight-bearing state or delay in advance to control the inverter.
摘要：
In recent years, some research results show that many network college's teaching effectiveness is not good, and the modern distance learning can't be able to effectively facilitate learning process. In order to solve these problems, which the relationship between interaction and learning under the environment of computer network teaching is described in this paper. At the same time, the impact factors of interaction behavior promoting learning were analyzed in detailed. In order to exploited the function of e-learning potential promote learning in the process of teaching, and to full play to the social interaction promoting the effective learning in network teaching environment; This paper presents a number of constructive proposals about how to build high-quality interactive strategy program in network teaching environment.
