Purpose -The purpose of this paper is to present an effective optimization strategy applied in a physical structure optimization of a semiconductor power metal oxide semiconductor field-effect transistor (MOSFET), with an expensive integration constraint computation. Design/methodology/approach -In order to deal with inaccuracy due to inevitable numerical errors in the objective function calculation (the power losses of the power MOSFET) and in the constraint computation, the paper proposes to use the progressive quadratic response surface method (PQRSM). Findings -The paper focuses on four aspects: the inevitable numerical errors in the power loss and the integration constraint computation; the response surface approximation (RSA) method; the PQRSM principle; and finally the comparisons of several optimization methods applied on this application problem. Originality/value -An original optimization method, PQRSM, is proposed for reducing the oscillation problem of a semi-analytical model. The optimization results of PQRSM have been compared with the evolution strategy (ES) algorithm, with similar results but faster computation.
I. Introduction
I.1 Numerical oscillations of the objective function computationIn our application, the power losses (switching and conduction) of the integrated power metal oxide semiconductor field-effect transistor (MOSFET) within a period are the objective function. The conduction losses are defined as in Hu et al. (1984). The switching losses are the sum of the losses at each switching transition over an operating period. The power MOSFET has three parasitic equivalent capacitors between its electrodes C dg (V d , V g ), C gs (V g ), C ds (V d ) and a current source as shown in Figure 1. These components are nonlinear, discontinuous, and depend on the electrode voltages. So, the dynamical switching of a power MOSFET is difficult to simulate.The switching model is presented by nonlinear differential equations. Therefore, for the power MOSFET design, a quasi-static modelling is used for the modelling of the objective function calculation and requires the time differential solving.