High efficiency sensorless control for three-phase brushless DC fan motors
碩士 === 國立交通大學 === 電控工程研究所 === 99 === This paper proposes a high efficiency sensorless control strategy for three-phase brushless dc (BLDC) fan motors and develops a control structure using on small fan motor sensorless control IC. This paper proposes a novel sensorless control strategy. Zero-crossin...
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| Format: | Others |
| Language: | zh-TW |
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2011
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| Online Access: | http://ndltd.ncl.edu.tw/handle/60066622722855632918 |
| Summary: | 碩士 === 國立交通大學 === 電控工程研究所 === 99 === This paper proposes a high efficiency sensorless control strategy for three-phase brushless dc (BLDC) fan motors and develops a control structure using on small fan motor sensorless control IC. This paper proposes a novel sensorless control strategy. Zero-crossing point (ZCP) estimation accomplished by specific voltage sampling and mask schemes. ZCP signal shifts for 30 degrees by digital phase shifter for corresponding commutation signals to maintain sensorless commutation. It’s hard to start-up due to low signal-to-noise ratio (SNR) when motor at low speed operation or in standstill. Therefore, this paper proposes a current limit soft-start control which combined open-loop starting and current limit strategies. Start-up current increases gradually to make start-up more robust and maximum start-up current reduced under this start-up strategy. 120 degrees conduction control results large torque variation during commutation interval and caused low efficiency. This paper proposes a soft-commutation control to decrease the torque ripple by slowing down the changing rate of commutation current. Soft-commutation angles at each operation point are analyzed by simulation. Motor current exists phase delay with voltage and it results in low efficiency. To solve this problem, phase advance control adopted to compensate the phase delay. The combination of soft-commutation control and phase advance control achieves high efficiency within speed control range. This paper uses a single chip DSP controller (TMS320LF2407A) to verify the performance and feasibility of proposed control strategies. According to experimental results, high efficiency control strategy has same or better efficiency than commercial IC Sanyo LV8805 with different three fan motors.
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