A compact algebraic model for electric machine losses⁎

Simulations are used extensively while designing electric drive systems and developing energy-efficient control strategies for electric powertrains. The accuracy of the simulation results depend on the accuracy of the model and how well it describes losses in the system. A new model for electric machine losses is developed, where the idea is to divide it into a set of equations describing the elements that contribute to the machine losses. With a machine model expressed using a set of equations it is possible use the model for numerical optimal control that can utilize the equations to develop effective solution methods. This is especially interesting, when software tools can differentiate the model using algorithmic differentiation to compute and use gradients and Hessians while searching for the optimal control trajectories. The model for electric machine losses was developed using one machine as basis and then the model was evaluated on three other machines. The model is nonlinear in the parameters and an efficient numerical parameter tuning method is developed for the proposed model structure.