Study Of Multi-motor Coaxial Control Instrument Base On Modbus Synchronous Communication Protocol

Oil drilling mud pump is the key equipment in the oil production process, Early dieselengine drived drilling mud pump. In this case, change the mud pump discharge and headonly by changing the rotating speed of diesel engine, diesel engine speed range is narrow,speed adjustment will influence the output efficiency. Ac frequency range is wide,smoothing, convenient, safety, environmental protection and energy saving. In oil field,use low speed high torque asynchronous motor replaces the original diesel engine at large.But, asynchronous mud pump motor is also heavy and the transmission efficiency is low,in the rated speed, especially in low speed operation, efficiency is often only at about20%.In view of the above questions, this topic studies vector control theory withoutposition sensor, using Simulink software build simulation model. And raise a new type ofelectronic control system, using Vacon-NXP high-performance converter which hassensorless rotor position detection function, driving low speed high torque mud pumpPMSM, the control system controls frequency converter by Siemens S7-224-PLC xp andSiemens S7-200extension module. This topic is the new transformation of the mud pumpcontrol system, including the mud pump motor control strategy and control circuit design,use S7-224xp-PLC as the control core. Prepare the whole system control program, throughthe PLC and frequency converter communication to control system work mode, mainmotor start, stop, speed, and equip safety protection measures, once motor is overload orfailure, it will automatically alarm to stop working, and troubleshooting, can automaticallyreset and return to work, it is safe, reliabe and easy to operate, it will greatly improve thework efficiency.Build PLC control platform, debug system in the laboratory, simulate the spot controlcommand to verify the feasibility of the system. Study LabVIEW software, use dataacquisition card building power test system, do performance comprehensive experiment, prove the synchronicity of the system and energy conservation though analysis of date andgraph draw.