Modeling and Simulation of Voltage-Controlled DC-DC Converters Using Dynamic Phasors

Modeling and simulation of DC-DC converters are essential in the design of efficient and robust energy systems, telecommunication equipment, transportation infrastructure, and healthcare devices. This paper presents computationally efficient frequency-dependent average models (FDAMs) of voltage-controlled DC-DC converters (buck, boost, and buck-boost) developed using the dynamic phasor (DP) method. By recognizing that in a DC-DC converter, the DC component dominates in the circuit variables, this paper neglects the pulse-width modulation (PWM) stage in developing control algorithms used in generating time-varying duty cycle unlike in the existing FDAMs. Rather, the time-varying duty cycle is produced by using the output voltage zeroth DP component as feedback signal while neglecting the high frequency components. This approximation simplifies the control process thereby enabling faster simulations of the FDAM models. Comparative studies involving step changes in output voltage reference and the load resistance are conducted using the detailed DC-DC converter models implemented in Simulink/Simscape (SS) platform, and the DP-based FDAMs developed in MATLAB environment in order to validate the proposed DP model's control scheme. Simulation results obtained reveal that the DP-based models are capable of accurately depicting the switching transients and steady-state conditions as the fully detailed switched models developed in SS while being more computationally efficient than the SS models. Thus, the DP-based FDAM is suitable for conducting a detailed system-level study of DC-DC converter-based power systems.