Speed closed-loop control system based on general-purpose inverter

The general-purpose inverters have the characteristic of low price, convenient operation. But they often need specialized feedback card when feedback closed-loop control is demanded. This results in high cost and limited range of application. This paper considers the problem from cost and precision of constant speed. So we deal with speed-measuring conversion by external single-chip,processor. Then the speed closed-loop control can be achieved by two ways. One is to utilize the process-input port of inverter and another is external PID. Therefore the cost of system is cut down and the range of application is expanded.