Sensorless pressure calculation for parallel redundancy in pumping systems

A converter-fed system with dubbed feedback is proposed for pumping applications. Increased reliability is provided by an alternative way of the pressure estimation using the information about the process state variables of a frequency converter and the model built on the principles of hydrodynamics. The system can be used for monitoring and fault detection of the pressure transducer, which serves as the primary feedback source. Along with the pressure transducer, the pressure is calculated using the data obtained from the frequency converter of the variable speed drive. An effective computation algorithm was developed in the paper. The testing methodology, test setup, and trial results are described. While the pressure transducer works correctly, its information is used for control whereas in the case of a faulty situation, the system switches to the sensorless control and the fault signal appears. The benefits and drawbacks of the proposed pumping system with dubbed pressure feedback are discussed.