Research On The Control Characteristics Of A Reciprocating Double-Pistons Gas Prover

Piston prover is widely used as a standard gas flow device for its advantages of short construction period, high accuracy in standard volume, flow stability and repeatability. But it also has disadvantages that its maximum verification flow and verification time are limited by the volume of the piston cylinder. This reciprocating double-pistons gas prover has solved these problems well. A research on the low speed control and cooperative control of the double-pistons gas prover is proposed in this article. The main contents are as follows.First of all, the background and significance were introduced. The definition of low-speed crawling was explained. The phenomenon of low-speed crawling movement was described. And the significance and status at home and abroad of the low-speed control and motors cooperative control were described.Secondly, three kinds of working principles and mathematical models were introduced for the three different operating modes. This article has carried on the massive experiments. It is shown that the proposed reciprocating double-pistons gas prover is capable of precisely calibrating gas flow meter. Comparisons between the experimental results and data obtained using the piston prover based on the balance adjustment principle are presented.Then, a research was conducted on the creeping phenomenon which was caused by low speed running of the motor. When the motor runs at a low speed, the motor error stop was induced by the motor torque command rising. So the device can not meet the requirement of verification of low flow nozzle. This article analyzes the mechanism of the creeping phenomenon, and proposed a way to improve this phenomenon. Experiments show that the method can improve the low speed working condition, and the motor torque command was decreased obviously. This minimum flow was expanded from 0.064m3/h to 0.04m3/h by this method.Finally, the fuzzy PID cross-coupling control mode was proposed for motor coordination control. A model was established in the Matlab/Simulink environment to research the cooperative control and anti-interference. The advantages of the fuzzyPID cross-coupling control mode were verified, and the cooperative control characteristics of the prover were improved.