A new method to plan the optimal field excitation current trajectory in a hybrid excitation machine

The field current in the hybrid excitation machine affects the flux, torque, voltage, power factor and efficiency. The machines used in the EV and HEV are working in a wide range, the optimization of the efficiency should be applied in the whole working range. The core losses are hard to predict especially with distorted waveform. In this paper, a dynamic equivalent core losses resistance is applied to count the core losses in the d- and q-equivalent circuit, which includes the copper losses and the core losses. The whole losses can be minimized by optimal control of the armature current and the filed current at different working condition. The experiment is fulfilled on a 4kW parallel magnetic path hybrid excitation machine, the efficiency maps are compared in the paper.