Three Phase Inverter: Difference between revisions
Jump to navigation
Jump to search
| Line 1: | Line 1: | ||
=Introduction= | =Introduction= | ||
Brushless, brushed, AC, and DC - all these are different | Brushless, brushed, AC, induction, and DC - all these are different | ||
==Induction== | |||
#Field is rotor is induced via AC. These are not permanent magnet. | |||
#Induction motors are 10% less efficient than permanent magnet motors | |||
#Note that in extreme cases, electromagnets can have higher magnetic fields than permanent magnets, so induction motors can have higher energy density, but still lower efficiency. | |||
==Brushless AC (Induction)== | ==Brushless AC (Induction)== | ||
Induction motors are brushless - [https://www.google.com/search?q=do+induction+motors+have+brushes&oq=do+induction+motors+&aqs=chrome.0.0j69i57j0l6.3982j0j4&client=ubuntu&sourceid=chrome&ie=UTF-8] | Induction motors are brushless - [https://www.google.com/search?q=do+induction+motors+have+brushes&oq=do+induction+motors+&aqs=chrome.0.0j69i57j0l6.3982j0j4&client=ubuntu&sourceid=chrome&ie=UTF-8] | ||
Revision as of 21:26, 14 June 2020
Introduction
Brushless, brushed, AC, induction, and DC - all these are different
Induction
- Field is rotor is induced via AC. These are not permanent magnet.
- Induction motors are 10% less efficient than permanent magnet motors
- Note that in extreme cases, electromagnets can have higher magnetic fields than permanent magnets, so induction motors can have higher energy density, but still lower efficiency.
Brushless AC (Induction)
Induction motors are brushless - [1]
3 phase motor control has significant advantages over 1 phase in AC induction motors:
- Self-starting
- More efficient
- Higher power factor - better aligment of applied power to used power - better coordination of windings with power application.
Brushed AC Motors: Universal Motors
- Can run on AC or DC. [2]
- Only 30-75% efficient, with 30% for small ones.
- Starters for engines are universal motors, as are many power tool, appliance, vacuum cleaner motors.
More
- At each point of time, 3 phases are active, but offset by 120 degrees:
https://www.youtube.com/watch?v=l60p4G7Bdi0
There is a 60 degree dead spot in the 120 degree (instead of 180 degree) mode of operation, allowing time for commutation. Makes sense - that could allow for energy saving in transition as commutation is occuring (by turning power off)
- In the Colombian paper, the coils are run 60 degrees out of phase.
https://www.emworks.com/ckfinder/userfiles/files/Axial%20Flux%20Motor.pdf
- How do you control a motor with 3 phase power?