Power converter analysis and design using Matlab: a transfer function approach

The design and steady-state analysis of static power converters has usually been realized in the time domain. This approach however is subject to numerical convergence problems and long simulation times, which worsen as the converter´s switching frequency increases. This paper proposes a novel design and steady-state analysis method to overcome these problems using Matlab. The method is based on the Fourier transform (FT) and a generalized converter transfer function. Thus obtains steady-state results without requiring the transient power-up, neither the circuit components´ initial conditions. The FT and converter transfer function are used to model and solve the converter in the frequency domain. Desired variables are then obtained in the time domain using the inverse FT. The method eliminates numerical problems and reduces simulation times significantly. For example, the simulation of a PWM voltage source inverter operating at 5 kHz takes 320 times longer in PSpice than in the proposed method. It also presents a minor processing time dependency from the converter´s switching frequency. The paper includes a detailed presentation of the proposed method, a complete analysis example using Matlab 4.02, together with an evaluation comparing it to conventional simulating techniques. Finally, experimental results with a 10 kVA AC motor drive are presented to validate the proposed analysis and design method