Startup method of digital Coriolis mass flowmeter using alternating exciting of positive-negative step signal

Digital driving can improve the performance of Coriolis mass flowmeter effectively due to the flexibility of its control algorithm. To solve the startup problem, this paper presents a startup method using alternating exciting of positive-negative step signal based on model analysis and experimental simulation. The method tracks the sensor output signal phase and alternately stimulates the flow tube with positive-negative step signal, which can increase the vibration amplitude rapidly and reliably. Combined with non-linear amplitude control and frequency estimation, the startup time of the flow tube can be shortened significantly, and the limitations of traditional startup methods are overcome. For Micromotion-CNG050 type Coriolis mass flow sensors, a secondary instrument was developed based on DSP, and experimental studies were made to verify the reliability and superiority of the method.