Maximum Efficiency Volts-per-Hertz Control of Induction Motor Drives Considering Core Losses, Saturation, and Inverter Losses

Abstract

Inverter-driven induction motors are commonly used in many industrial applications. The conventional Volts-per-Hertz (V/Hz) control, although simple to implement, does not consider core losses, saturation, and inverter losses, thus resulting in poor performance at low speeds and suboptimal operation. However, it is desirable to consider various losses to improve the performance of scalar V/Hz controllers. This paper proposes an improved V/Hz control for inverter-driven induction machines to achieve maximum efficiency by including simplified core losses, saturation, and inverter losses. The losses associated with inverter-driven induction motors are represented in the modified equivalent circuit, whose values are dependent on the operating conditions. Based on analysis of the improved equivalent circuit model, the new maximum efficiency V/Hz ratio can be found for different operating points. The proposed scalar V/Hz control is demonstrated experimentally and by simulations, and it is demonstrated to have an improvement over the conventional scalar V/Hz control method.