Fault-Tolerant Control Strategy for Primary–Secondary Chilled Water System

Multi-phase motors and generators are regarded with great fault tolerance capability, especially on open-circuit faults. Various mathematics analytical methods are applied for their fault control. In this paper, a fault-tolerant control strategy with asymmetric phase current for the open-circuit faults with arbitrary phases in the six-phase PMSM (six-phase permanent magnetic synchronous motor, 6P-PMSM) system, is proposed for better electrical and dynamical performance of the machine. An innovative mathematical model for PMSM under one to four-phase-open circuit faults are established considering the asymmetry of the machine. Combining with time-varying relations in machines’ working conditions, targeted decoupling transformation matrixes of every kind of open-circuit faults are settled by voltage equations under different faults. Modified control strategy with a connection between the neutral point and the inverter’s DC side is presented, which aims at increasing the system redundancy and reducing the amplitude of phase currents. Besides, improved control loops with two layers are put forward as well, with which the PMSM system acquires fewer harmonics in phase current and smoother electromagnetic torque. Simulation and experimental results of open-circuit faults are provided for verification of the theoretical analysis.

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A New Model Predictive Control Method for Eliminating Hydraulic Oscillation and Dynamic Hydraulic Imbalance in a Complex Chilled Water System

Energies ◽

10.3390/en14123608 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3608

Author(s):

Yang Yuan ◽

Neng Zhu ◽

Haizhu Zhou ◽

Hai Wang

Keyword(s):

Model Predictive Control ◽

Predictive Control ◽

Control Method ◽

Water System ◽

Energy Performance ◽

Effective Control ◽

New Model ◽

Chilled Water ◽

Chilled Water System ◽

Hydraulic Oscillation

To enhance the energy performance of a central air-conditioning system, an effective control method for the chilled water system is always essential. However, it is a real challenge to distribute exact cooling energy to multiple terminal units in different floors via a complex chilled water network. To mitigate hydraulic imbalance in a complex chilled water system, many throttle valves and variable-speed pumps are installed, which are usually regulated by PID-based controllers. Due to the severe hydraulic coupling among the valves and pumps, the hydraulic oscillation phenomena often occur while using those feedback-based controllers. Based on a data-calibrated water distribution model which can accurately predict the hydraulic behaviors of a chilled water system, a new Model Predictive Control (MPC) method is proposed in this study. The proposed method is validated by a real-life chilled water system in a 22-floor hotel. By the proposed method, the valves and pumps can be regulated safely without any hydraulic oscillations. Simultaneously, the hydraulic imbalance among different floors is also eliminated, which can save 23.3% electricity consumption of the pumps.

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Optimization for the Chilled Water System of HVAC Systems in an Intelligent Building

2010 International Conference on Computational and Information Sciences ◽

10.1109/iccis.2010.220 ◽

2010 ◽

Cited By ~ 1

Author(s):

Ming-hai Li ◽

Qing-chang Ren

Keyword(s):

Water System ◽

Hvac Systems ◽

Intelligent Building ◽

Chilled Water ◽

Chilled Water System

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