High-order adaptive time-domain solution of nonlinear coupled electromagnetic-thermal problems

An adaptive time-integration algorithm is described for the solution of nonlinear one-way coupled electromagnetic-thermal problems. The thermal excitations are time-varying thermal loads or/and EM (electromagnetic) loss distributions due to dc or ac excitation sequences. The equations are discretized in time by an implicit Runge-Kutta one-step method. No Newton iteration is required in a time step; only one linear equation with multiple right hand sides has to be solved. High-order integration is achieved by incorporating the Jacobian into the time-integration formula. The thermal analysis of an induction hardening problem and an insulated gate bipolar transistor test module is presented to illustrate the efficiency of the algorithm.