Abstract: There is provided a digital controller which can reduce a variation in output voltage as compared to the conventional digital controller at the time of abrupt changes in load and in input of a power amplifier. The digital controller is built in the power amplifier for supplying an output voltage vo to a load and is equipped with a manipulated variable calculating unit which detects the output voltage vo to calculate a manipulated variable ?1 and a signal generating unit which converts the manipulated variable ?1 into a signal for making the power amplifier operate. A feedforward function from an equivalent disturbance qy caused by the variation in the load is replaced by a feedback function from the output voltage vo and the manipulated variable ?1, thereby allowing a transfer characteristic from the disturbance qy to the output voltage vo to result in a quadratic differential characteristic.

Abstract: A robust digital controller is equipped with a high degree of approximation and is able to incorporate a novel two-degree-of-freedom robust digital control system without substantially considering the magnitude of the control inputs and there is provided its designing device. A control compensating means is configured as an integral type control system in which a discrete transfer function Wry (z) between a target value r and a controlled variable y is approximated to a higher-approximate quadratic approximate model transfer function Wm (z) and an arithmetic processing can be performed within the digital controller based on the model transfer function Wm (z). Further, the designing device automatically calculates parameters constituting the control system. Consequently, a robust digital controller can be easily realized that is equipped with a high degree of approximation as compared with a conventional approximate digital control system for realizing a first-order model and is robust against output noises.

Abstract: There is provided a digital controller which can generate no oscillation even if sensing a load side and enables control of supplying a desired voltage to the load. In an power amplifier which supplies an output voltage vo to the load connected via a load connecting line, a load voltage vL and the output voltage vo are periodically sampled to calculate a manipulating variable ?1 from the output voltage vo, the load voltage vL and an arbitrary target value r. Based on the manipulating variable ?1 calculated, a control signal is output to the power amplifier. As a result, when connecting an LC filter with a load device 9 of the power amplifier intended for a control target and besides the load connecting line is long, a robust digital controller without generating oscillation even if sensing the load side is performed can be realized.