Modeling and analysis of DC link bus capacitor and inductor heating effect on AC drives. I

The overall performance and efficiency of a voltage source inverter (VSI) can be improved by selecting a combination of DC link capacitance and DC link inductance based upon a weighted optimization criterion. Developments of semiconductor technology have enabled present semiconductor devices to operate with improved power losses, to a great extent. However, there is still a considerable amount of power loss in the DC link capacitor bank and DC link inductor. These loss components are normally ignored to a certain level in terms of design/efficiency optimization, in the design phase of the drive. Therefore, there are additional opportunities to optimize the design by selecting the capacitor/inductance combination for minimum power losses or for any other optimum such as size and weight or cost. This paper describes the modeling of the PWM AC drive, AC motor and special modeling of the DC bus capacitor and DC link inductor, using the SABER simulator. The paper compares the SABER simulation results with the experimental data to verify the accuracy of the model, for given values of DC link inductance and bus capacitance as the first step towards modeling the overall system for accurate prediction of the drive performance.