PROPORTIONAL AND INTEGRATING CONTROLLER

PURPOSE:To perform accurate proportional and integrating operation at the restoration of saturated output, by comparing an output of a controller with a limit level set with an output limit circuit. CONSTITUTION:The titled controller is so constituted that an output of limit amplifiers A4 and A5 is operated to an integrator only and no effect is given to an output of an amplifier A1. A charging voltage of an integration capacitor Cf is kept to a voltage just before the output limit. Thus, since no overcharging is not to be caused to the capacitor Cf, even if the polarity of input deviation E1-E2 is inverted, instantaneous response can be made possible. Thus, the transient responsiveness at the restoration of saturation due to the integration capacitor Cf can be improved and the closed loop characteristics can also be improved. If the output of the amplifier A1 is limited to the same value as an output limit value of a summing amplifier A2, the output of integrator is taken 0V at the saturation of an output E0 finally and the inversion of the deviation of input can always be provided.