The frequency modulation automatic Batching system uses PLC as the lower-level computer. PLC communicates with the weighing instrument and the frequency converter to collect, process on-site data and perform simple control. PLC uses the Ethernet module and the upper-level computer for communication to exchange system operation data. In the lower-level computer, various powder weighing on-site displays, processes and settings are mainly completed; the recording, saving and querying of on-site data, alarm for important data, simulation operation of the production site, setting of the batching formula and the simulation operation of the screw conveyor are also carried out. The system collects and controls data for powder weighing, batching and feeding processes, and realizes monitoring of the material weighing, batching and feeding processes.

The batching system uses the weighing module and the rotation speed of the screw conveyor to measure the powder. The screw conveyor in the metering unit rotates at a constant speed, and there are multiple small compartments distributed along the guide cone on the screw conveyor. During the rotation process of the screw conveyor, the powder is distributed along the cone distributor at the center of the screw conveyor to various small compartments, and then slides along the wall of the metering compartment to the curved discharge pipe. The rotational torque of the screw conveyor is transmitted to the weighing module through the bin, and the output voltage of the weighing module is proportional to this rotational torque and is converted from analog to digital by the analog-to-digital converter. The rotation speed of the screw conveyor is measured by the speed measurement and weighing module and converted to digital by the frequency converter. Finally, the rotational torque and rotation speed are input into the weighing instrument for calculation, thereby obtaining the instantaneous flow rate of the powder.

The batching system can be divided into three units: the set value control unit, the PID action unit and the manual/auto switching unit. The set value unit I receives the flow measurement value of the screw conveyor and the set value given by the control device. The PID action unit receives the error signal generated by the set value control unit and calculates the closed-loop control signal according to the given control law. When the manual/auto switching unit is in the "automatic" position, the output signal of the PID unit is sent to the industrial process in a closed-loop control mode. While in the "manual" position, the manual signal directly adjusted by the user on the controller is sent to the industrial process, and thus the system adopts an open-loop control mode.

The batching system is controlled by a frequency converter, which has dual control functions of on-site machine-side manual control and upper-level computer centralized control to control the feeding amount of the screw Feeder. The feeding amount is mainly determined by the rotation speed of the screw and is in a linear proportional relationship with the rotation speed. In the machine-side manual operation mode, the operator can manually adjust the potentiometer on the operation box to control the frequency of the frequency converter, thereby controlling the rotation speed of the screw feeder. In the automatic operation mode, the personnel in the batching control room can set the flow to the PLC from the upper-level monitoring computer, and the actual flow signal of the screw conveyor is fed back to the PLC for PID calculation, and finally a control quantity is obtained, which is controlled by the frequency converter to control the rotation speed of the screw feeder, achieving the purpose of controlling the material flow.