Energy-Efficient Traction Induction Machine Control
To be published on April 2, 2019 by SAE International in United States
The paper describes the new method of increasing the energy efficiency of the traction electric drive in the low load conditions. The objective 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 lies in criterion constancy of the overload ability 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 electro-mechanical energy conversion represented by the generalized equations of the instantaneous balance of the active and reactive power and the mechanical load. The induction machine 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 non-linearity factor 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. The functional circuit of the traction drive control system described. We considered the composition and algorithms of the information-measuring system operation. The results of modeling the characteristics of an induction machine at the amplitude control of the electromagnetic torque presented. The energy efficiency of the amplitude control explained by increase of the power factor and reduction current in a wide range of small loads.