Energy-Efficient Traction Induction Machine Control
Published April 2, 2019 by SAE International in United States
Annotation of this paper is available
The article solves the problem of increasing the energy efficiency of the traction electric drive in the low load conditions. The set objective is achieved by analogy with internal combustion engines by decreasing the consumed energy using the amplitude control of the three-phase voltage of the induction machine. The basis of the amplitude control is laid by the constancy criterion of the overload capacity with respect to the electromagnetic torque, which provides a reliable reserve from a "breakdown" of the induction machine mode in a wide range of speeds and loads. The control system of the traction electric drive contains a reference model of electromechanical energy conversion represented by the generalized equations of the instantaneous balance of the active and reactive power and the mechanical load. The induction machine is controlled by two adaptive variables: the electromagnetic torque and the voltage amplitude. The synchronous frequency and angular speed of the rotor remain free coordinates depending on the load conditions. We considered general and private solutions for control variables obtained with the help of the energy model taking into account the nonlinear nature of the control object. The nonlinearity factor is taken into account by approximating the magnetization inductance and loss resistance in the magnetic circuit using the analytical dependencies on the synchronous frequency and the voltage amplitude. We presented a functional diagram of the traction drive. We considered the composition and algorithms of the information-measuring system operation. We presented the results of modeling the characteristics of an induction machine at the amplitude control of the electromagnetic torque. The energy efficiency of the amplitude control is manifested in the increase of the induction machine efficiency in a wide range of small loads as compared to the nominal mode.