DC Motor Precise Speed Control System by Applying PLL-IC (2nd Report)

On the preceding paper, the authors expressed the DC Motor precise speed control with PLL-IC and the stability of PLL speed control loop as a sampled data feedback control was emphasized. This paper (2nd Report) is the research and experimental report on the wide range speed control of DC motor with PLL-IC. On the stereo turn table drive and the most typical motor speed control with PLL-IC, the speed control range is comparatively small, but on industrial services of motor application wide speed control range is generally expected. We have developed a new control system, which enables wide range speed control by applying the parallel reference voltage proportional to the setting speed upon the phase comparator output. In this system, a wide range speed control is roughly operated by the minor speed control loop and only the precise speed control necessitated with motor load torque is executed by the PLL speed control loop. Accordingly we can decrease the PLL gain and improve the stability of PLL speed control loop. Two examples, one has an adjustable frequency devider inside of PLL loop and the other outside of PLL loop, are theoretically and experimentally compared.