Closed Loop Voltage Control of a Three-Phase PWM CSR for SMPS Applications

G Rao, P Scholar, M Kondalu
Switched-mode power supplies have applications in various areas. A switched-mode supply is chosen for an application when its weight, efficiency, size, or wide input range tolerance make it preferable to linear power supplies. Initially the cost of semiconductors made switch-mode supplies a premium cost alternative, but current production switch-mode supplies are nearly always lower in cost than the equivalent linear power supply. It maintains a constant output voltage irrespective of change in
more » ... ective of change in load current or line voltage. Many different types of voltage regulators with a variety of control schemes are used. With the increase in circuit complexity and improved technology a more severe requirement for accurate and fast regulation is desired. This has led to need for newer and more reliable design of dc-dc converters. The dc-dc converter inputs an unregulated dc voltage input and outputs a constant or regulated voltage. The regulators can be mainly classified into linear and switching regulators. All regulators have a power transfer stage and a control circuitry to sense the output voltage and adjust the power transfer stage to maintain the constant output voltage. Since a feedback loop is necessary to maintain regulation, some type of compensation is required to maintain loop stability. In this paper, a PI controller is designed and analyzed for a buck-boost converter. Stability analysis and selection of PI gains are based on the closed-loop error dynamics. PI controller, being the most widely used controller in industrial applications, needs efficient methods to control the different parameters of the plant. The output of the conventional PID system has a quite high overshoot and settling time. In this project, three-phase pulse width modulation (PWM) current source rectifiers (CSRs) with a closed loop voltage regulation capability that applied as dc voltage power supply include capacitors in the dc bus to obtain dc output voltage, control strategy is proposed. Here dynamic model of the three-phase PWM CSR is established in the dq-rotating frame for capacitive load applications.