Читать книгу Analysis and Control of Electric Drives - Ned Mohan - Страница 58

Load torques normally act to oppose rotation. In practice, loads can be classified into the following categories [2]:

1 Centrifugal (Squared) Torque

2 Constant Torque

3 Squared Power

4 Constant Power

Centrifugal loads, such as fans and blowers, require torque that varies with speed², and load power that varies with speed³. Similarly, wind turbines produce torque that is proportional to speed².

In constant‐torque loads such as conveyors, hoists, cranes, and elevators, torque remains constant with speed, and the load power varies linearly with speed. In squared‐power loads such as compressors and rollers, the torque varies linearly with speed and the load power varies with speed². In constant‐power loads, such as winders and unwinders, the torque beyond a certain speed range varies inversely with speed and the load power remains constant with speed.