清华大学电力电子与电机集成第二章.pdf

Tsinghua Univ. DEEA Chapter Two Tsinghua Univ. DEEA Analysis of Inverter-driven Motor 1 Chapter Two: Tsinghua Univ. DEEA Inverter-driven Motor Tsinghua Univ. DEEA “In fact, with the inverter as the power supply, the operational conditions of an induction machine are much different from the conventional supply with fixed voltage and frequency, which implies that the design of induction machines should be reconsidered to make them more suitable for the inverter-driven variable speed systems. ” ——IEEE Transaction on Energy Conversion 2-1 Influence of Inverter on the Motors Tsinghua Univ. DEEA Tsinghua Univ. DEEA The mechanical characteristics Two key points: • There are different combinations of U and f for a fixed 1 1 running point. • A speed may have different torque with different T-s curve. r m pU 2 2 1 1 T s em r 2