Grainger CEME

Srikanthan Sridharan with Adviser P. T. Krein

Typical ac traction drive electrical components include the motor, inverter, dc link and filter elements. Drive design parameters and component values are chosen to minimize system-level drive losses. This research presents a systematic approach for selecting machine flux levels and passive component values in an induction motor drive using a comprehensive system-level loss-minimization algorithm. The total losses obtained are found to be lower for the system-based minimization than for machine-based algorithms previously reported in the literature. The effect of individual loss components and their sensitivities to machine parameters are also studied. It can be observed from Fig. 8 that there are significant losses even outside the machine, justifying the need for overall loss minimization.

Figure 8: Individual percentage loss contribution to total system losses

Use of passive inductance-capacitance (LC) filters at the inverter output results in resonant oscillations. A transfer function approach is suggested to design a virtual-damping loop to suppress these oscillations. A standard extra-urban drive cycle is used as an example to illustrate the implementation of overall cycle-energy loss minimization. Ongoing work includes detailed simulation and experimental validations.

This research is supported by the Grainger Center for Electric Machinery and Electromechanics.