Density-based Topology Optimization for Conductor Design of EMI filters with Improved Impedance Boundary Condition

This paper presents an automatic conductor pattern design method for a circuit board using density-based topology optimization. When density method is applied to the conductor design of circuit, grayscale elements create two issues: consistency with circuit diagram and surface impedance expression. To keep the consistency, we propose an optimization scheme using Heaviside projection with partial differential equation (PDE) filter, double-well potential, and circuit-preserving constraint. Moreover, the novel impedance boundary condition for density method enables precise simulation in wide-frequency range. The proposed method is applied to the design problem of pi type EMI filters, and it is demonstrated that the method has successfully derived the improved conductor pattern corresponding to the dominant noise propagation mechanism.