Quasi-state variable method for precise modeling of DC-DC converter circuits

For modeling DC-DC power converter circuits, the state space averaging method is the representative method. However, its application field is restricted to small amplitude operation and is rather narrow. For large amplitude operation of a DC-DC power converter, a novel approach is proposed which composes the state equations by taking the initial values of the circuit variables at the starting point of each switching period as the state variables. All instantaneous values of the current and the voltage within each switching period can be represented by a linear combination of the initial values. So, discrete space state equations can be formulated, and all kinds of information about circuit operation such as average values, waveform envelopes and instantaneous values at an arbitrary instant are given. The solution can be calculated with an accuracy as high as one desires, without excessive work.<>