Fast response digital speed and current regulators for thyristor fed reversible regenerative DC motor drives

This paper describes a digital technique for the speed control of a separately-excited DC motor fed by a three-phase dual power converter. A cascaded proportional-plus-integral controller is used to achieve good dynamic response and steady-state performance of the drive. Two 16-bit microcontrollers are used to achieve the required drive response. Practical problems such as synchronisation with noisy mains supply and generation of PWM signals are discussed. The firing control based on the capture/compare feature of the 80C186EB timer/counter unit is presented. The controller was tested with a 6.5 kW DC motor and test results are given