Revisiting the closed loop response of PWM converters controlled by voltage feedback

The closed loop response of voltage feedback converters was re-examined theoretically and tested by simulations and experiments. It was found that the classical second order representation of the closed loop response of a PID controlled system is incomplete due to the contribution of previously neglected factors, such as a closed loop zero and low loop gain, to the real response. Mathematical expressions of the closed loop responses that take into account these added factors were derived and the time domain attributes (rise time and overshoot) were extracted. The method is exemplified by an experimental buck and boost converters that were operated in voltage mode control using a lag-lead phase compensation network.