Foreword
With the development of new power electronic devices, AC frequency conversion technology has emerged and, almost like computer control, has become one of the main hallmarks of modern AC drive speed control technology. The DCS process control experimental system is an experimental research model integrating the controlled object and the control system, based on actual field processes. The constant pressure water supply and storage tank liquid control system uses a Sanken (SAMCO-V[sub]m[/sub]05) frequency converter. It consists of a frequency converter, sensors, and transmitters, forming a closed-loop electrical signal control system. The controlled object is the water supply pressure. The frequency converter manually/automatically controls the start and stop of two motors to maintain stable water supply pressure. The built-in PID adjustment module of the frequency converter automatically adjusts the pressure, and the pressure setpoint can be arbitrarily modified according to the process conditions. Figure 1 shows the PID adjustment block diagram for constant pressure water supply.
2. Design of Variable Frequency Speed Control System Circuit
1.1 Composition of the inverter control section
The inverter control unit mainly consists of a circuit board, a control board, and an operation panel. Encoder interfaces and fieldbus interfaces are selected as needed, and a PC can also be used for parameter setting. Figure 2 shows the structural block diagram of the variable frequency speed control system. Figure 3 shows the inverter wiring diagram.
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