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A sensorless brushless dc motor system
Author(s) -
Ogasawara Satoshi,
Suzuki Kazuto,
Akagi Hirofumi
Publication year - 1992
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.4391120512
Subject(s) - control theory (sociology) , dc motor , counter electromotive force , chopper , universal motor , rotor (electric) , brushed dc electric motor , wound rotor motor , stator , ac motor , position sensor , voltage , synchronous motor , direct torque control , computer science , inverter , direct current , electronic speed control , induction motor , engineering , electrical engineering , control (management) , artificial intelligence
This paper describes a brushless dc motor system without position or speed sensor. The brushless motor consists of a permanent magnet synchronous motor and a voltage‐source inverter capable of controlling the amplitude and frequency of voltage. The rectangular‐shaped stator current with a conducting interval of 120° (electrical) is controlled to be in phase with the trapezoidal back electromotive force. This results in producing maximum torque. Variable speed is achieved by adjusting the average motor voltage similarly to chopper control of dc motors. In this paper, two sensorless position detecting methods, i.e., an “indirect method” suited for the lower‐speed range and a “direct method” suited for the higher‐speed range are proposed. The combination of the two makes it possible to detect the rotor position over a wide‐speed range. Furthermore, a speed‐sen‐sorless PLL control is proposed in applying the principle of the direct method. Experimental results obtained from a prototype brushless dc motor are shown to confirm the validity of the sensorless drive. The starting procedure of the motor also is discussed because it is impossible to detect the rotor position at a standstill.