Three Phase Inverter

Introduction

Brushless, brushed, AC, and DC - all these are different

Brushless AC (Induction)

Induction motors are brushless - [1]

3 phase motor control has significant advantages over 1 phase in AC induction motors:

1. Self-starting
2. More efficient
3. 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.

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?