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Journal of Zhejiang University SCIENCE C

ISSN 1869-1951(Print), 1869-196x(Online), Monthly

Extracting DC bus current information for optimal phase correction and current ripple in sensorless brushless DC motor drive

Abstract: Brushless DC motor (BLDCM) sensorless driving technology is becoming increasingly established. However, optimal phase correction still relies on complex calculations or algorithms. In finding the correct commutation point, the problem of phase lag is introduced. In this paper, we extract DC bus current information for auto-calibrating the phase shift to obtain the correct commutation point and optimize the control of BLDC sensorless driving. As we capture only DC bus current information, the original shunt resistor is used in the BLDCM driver and there is no need to add further current sensor components. Software processing using only simple arithmetic operations successfully accomplishes the phase correction. Experimental results show that the proposed method can operate accurately and stably at low or high speed, with light or heavy load, and is suitable for practical applications. This approach will not increase cost but will achieve the best performance/cost ratio and meet market expectations.

Key words: Brushless motors, Electric motors, Motor drives, Phase control, Phase estimation, Sensorless control

Chinese Summary  <32> 撷取母线电流信息 优化无传感器无刷直流电机驱动相位与转矩

研究目的:无刷直流电机进行无传感器驱动时,常因低通滤波电路或高速、高负载运行造成驱动相位不正确,从而产生较大的驱动电流涟波。目前,用于改善电流涟波的算法过于复杂。本文提出一种简单算法,可以减少微处理器计算量,使得利用一般功能的微处理器即可实现相位优化的无感驱动控制。
创新要点:提出撷取母线电流的新算法:将一个电气周期的电流分成二个区间,由这二个区间的变化得知电机驱动时的相位信息,藉由相位控制达到驱动相位优化目的。整个算法只需加、减运算,微处理器无需乘法器或数字讯号处理相关的高级数学运算单元,即可达到实时驱动相位的效果。
方法提亮:只使用一个电流侦测电阻,配合简单算法,即可分辨电机驱动时的相位信息,从而藉由相位控制对死循环作相位补偿,改善了驱动电流的涟波,以达到最小涟波的驱动相位,有效地提高了电机运转效率。
重要结论:本文研究顺利简化了对无刷直流电机无传感器驱动时相位讯息的判断。实验证明,在相同脉冲宽度调制下,所提算法不仅改善了无传感器驱动电路或Hall安装偏移造成的相位不正确问题,更可以改善高转速下电感效应造成的电流拖尾问题,进而减小了转矩涟波的波动,还可以得到提升转速的效果。此算法简单的结构使得未来转矩优化将不再受限于高阶微处理器的运算能力。

关键词组:无刷直流电机;电动机;电机驱动;相位控制;相位估测;无传感器控制


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DOI:

10.1631/jzus.C1300247

CLC number:

TM301.2

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On-line Access:

2014-04-10

Received:

2013-09-06

Revision Accepted:

2014-01-15

Crosschecked:

2014-03-17

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