| 摘要 |
PURPOSE:To perform current control with desired response characteristics by adjusting a relaxation coefficient when converting a current flowing through a coil into a digital signal and calculating a thyristor phase angle by digital signal processing. CONSTITUTION:A current C measured by a current sensor is converted by and A/D converter 5 into a digital signal Ck at every period Ts and processed by using a set value rR to output a voltage set value Uk after the next sample period. In this case, an optional value is selected as the parameter rho (relaxation coefficient) of closed loop characteristics Cz/Rz=z<-2>(1-rho)/(1-rhoz<-1>) to adjust a response speed. (Provided that Rz is the z-conversion of the set value rR). A voltage set value Uk is inputted to a reverse cosine calculator 7 to obtain a thyristor firing angle phik, which is D/A-converted to control a thyristor afterward. Consequently, a current conforming to the set value flows through a load. |
