Motor Performance and Limitations — Lesson 7

This lesson covers the fundamental aspects of motor performance, focusing on the concepts of current limit and voltage limit. It explains how these two limits define the performance of a motor, with the current limit primarily based on thermal considerations and the voltage limit determined by the battery supply. The lesson also introduces the concepts of rated current, rated torque, rated voltage, and rated speed, which are crucial specifications for any motor. It further discusses the torque-speed curve of a motor and the concept of flux weakening, a technique used to push the boundary beyond the rated speed.

Video Highlights

00:18 - Motor's performance: Current limit and Voltage limit
07:45 - What happens beyond rated speed?
11:06 - Explanation of the torque speed curve of the motor
14:36 - Home assignment
16:42 - The motor rapidly dies, soon after rated speed
18:12 - Concept of flux weakening

Key Takeaways

- The performance of a motor is defined by its current limit and voltage limit.
- The current limit is primarily based on thermal considerations to prevent overheating, while the voltage limit is determined by the battery supply.
- The rated current, rated torque, rated voltage, and rated speed are crucial specifications for any motor.
- The torque-speed curve of a motor shows how much torque can be achieved at different speeds.
- Flux weakening is a technique used to push the boundary beyond the rated speed by weakening the magnetic field, thereby reducing the back emf and gaining enough headroom on the voltage to increase the speed further.