Korean Journal of Air-Conditioning and Refrigeration Engineering (설비공학논문집)

The Society of Air-Conditioning and Refrigerating Engineers of Korea (대한설비공학회)
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Precise Temperature Control of Oil Coolers with Hot-gas Bypass Manner for Machine Tools Based on PI and Feedforward Control

PI와 피드포워드 제어를 이용한 공작기계용 오일쿨러의 핫가스 바이패스 방식 정밀 온도 제어

  • Jeong, Seok-Kwon (Dept. of Refrigeration and Air-conditioning Engineering, Pukyong National University) ;
  • Byun, Jong-Yeong (Dept. of Refrigeration and Air-conditioning Engineering, Pukyong National University) ;
  • Kim, Sang-Ho (Dept. of Refrigeration and Air-conditioning Engineering, Pukyong National University) ;
  • Yoon, Jung-In (Dept. of Refrigeration and Air-conditioning Engineering, Pukyong National University)
  • 정석권 (부경대학교 냉동공조공학과) ;
  • 변종영 (부경대학교 냉동공조공학과) ;
  • 김상호 (부경대학교 냉동공조공학과) ;
  • 윤정인 (부경대학교 냉동공조공학과)
  • Received : 2010.10.25
  • Accepted : 2010.12.09
  • Published : 2011.02.10
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Abstract

Recently, the performances of speed and accuracy are enhanced in machine tools. The high speed of the machine tools usually causes harmful thermal displacements on the objects. To reduce the thermal displacements, machine tools generally adopt oil coolers with precise temperature control function. This study aims at precise control of oil outlet temperature in the oil coolers with hot-gas bypass manner based on PI control logic. The control system was designed for obtaining steady state error within ${\pm}0.1^{\circ}C$ and maximum overshoot with 0.8% even though abrupt disturbances are added to the system. We showed that the PI gains could be easily decided by numerical simulations using practical transfer function which got experiments. Also, transient characteristics could be improved significantly by reflecting the inlet temperature of an evaporator to the output of a controller feedforwardly considering periodic abrupt disturbances. Through some experiments, excellent control performances were established by the suggested control.

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References

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