Study And Manufacture Of A New Type Spwm Variable Frequenecy Drive System Based On Digital Control

This paper designs two systems. One applies to fan or pump load in the opened-loop drive system. The other applies to quite accurate cortrol in the closed-loop drive system. In the opened-loop system, this kind of drive system uses the power IGBT as main switch, the 16 bit single chip microcomputer 87C 1 96MC as the control unit The wave form generator can generate directly three phase PWM waveforms by software in the 87C196MC. The IGBT drive circuit uses EXB 840 driver. Adopting constant V/F control and low frequency compensation regulation. The experimental results show that the system work well The closed-loop system bases on the opened-loop system, its main switch element is the IPM(intelligent power model). 1PM includes drive circuit, protected circuit and IGBT. 1PM can improve the stability of system Besides adopting constant V/F control and low frequency compensation regulation, we lead in exPert colltrOl regulation in order to bolement realtlme control. The exPerimental results show that this kind of control mode canreach expectat aim.In this paPer, the software, hardware protected circuit and anidammingstrategy are discussed. The exPerimelltal results show that these designs canmake system work more reliably and reach eXPectant aim.