Sonsivri
 
Home Contact Us Help Search GoogleTagged Donations Login Register
*
Welcome, Guest. Please login or register.
Did you miss your activation email? 		April 19, 2024, 08:29:21 08:29


Login with username, password and session length


Sonsivri > Electronics > Projects (Moderators: bbarney, pickit2) > (req) soft start for 3 phase AC induction motor
Pages: [1]
« previous next »
Print
Author Topic: (req) soft start for 3 phase AC induction motor  (Read 6258 times)
0 Members and 1 Guest are viewing this topic.
marcosz67
Newbie
*
Offline Offline

Posts: 13

Thank You
-Given: 18
-Receive: 1
« on: January 29, 2010, 09:29:36 09:29 »
Hi all,
i want to build a soft start for a 3 phase 380Vac induction motor using triacs and a microcontroller.
Anyone can help me?
Thx in advance.
Logged
oldvan
Senior Member
****
Offline Offline

Posts: 372

Thank You
-Given: 154
-Receive: 107


If the van is a Rockin'...


WWW
« Reply #1 on: January 29, 2010, 09:38:31 09:38 »
There are members of the DSPIC family specialized for motor control, Microchip's app notes might be a good place to start.
Logged
Give a man a fish and you feed him for a day.
Teach a man to fish and he will sit around in a boat drinking beer all day.
marcosz67
Newbie
*
Offline Offline

Posts: 13

Thank You
-Given: 18
-Receive: 1
« Reply #2 on: January 29, 2010, 03:14:55 15:14 »
Not useful for me..
They use inverter solution, i need to use only triac with a small 8 bit microcontroller.
Logged
oldvan
Senior Member
****
Offline Offline

Posts: 372

Thank You
-Given: 154
-Receive: 107


If the van is a Rockin'...


WWW
« Reply #3 on: January 29, 2010, 10:40:24 22:40 »
Sounds like you want a three-phase version of a lamp dimmer.

Microcontroller needs to know zero crossing.  Can do with opto-isolator.

Initially fire triacs, for small amount of time, perhaps 1 mS, turn off at at their phase’s zero crossing.   Fire each triac  progressively earlier until firing full 360 degrees to apply soft-start.

The harsh switching of the triacs is going to create a very noisy electrical situation, filtering is EXTREMELY important to keep that noise from interfering with the world around you.

------------------------------

As a simplest alternative, correctly sized power resistors in series with the motor,
a triac in parallel with each resistor and the microcontroller turns on the triacs after
motor start-up time.

A relay could replace all 3 triacs.
« Last Edit: January 30, 2010, 12:05:03 00:05 by oldvan » Logged
Give a man a fish and you feed him for a day.
Teach a man to fish and he will sit around in a boat drinking beer all day.
Walkura
Active Member
***
Offline Offline

Posts: 123

Thank You
-Given: 56
-Receive: 82
« Reply #4 on: January 30, 2010, 08:38:09 08:38 »
The method marcosz67 with the resistors describes ,i use this for softstarting big transformers (upto 3 KW) .
Although i prefer to use a relay to bridge te resistor it turned out to be most reliable .
Logged
borberk
Senior Member
****
Offline Offline

Posts: 296

Thank You
-Given: 309
-Receive: 598
« Reply #5 on: January 30, 2010, 09:58:26 09:58 »
Standard method is star-delta switch:

http://www.patchn.com/index.php?option=com_content&task=view&id=42&Itemid=74
Logged
medik
Junior Member
**
Offline Offline

Posts: 41

Thank You
-Given: 75
-Receive: 4
« Reply #6 on: January 31, 2010, 12:01:22 00:01 »
Hi. I got a circuit and the triac BT131 is bad. I could not find it in my supplier"s shop. Please, anyone know of good triac to use to replace BT131?. It is just to power a fan coil.
Logged
oldvan
Senior Member
****
Offline Offline

Posts: 372

Thank You
-Given: 154
-Receive: 107


If the van is a Rockin'...


WWW
« Reply #7 on: January 31, 2010, 01:56:55 01:56 »
Quote from: medik on January 31, 2010, 12:01:22 00:01
Hi. I got a circuit and the triac BT131 is bad. I could not find it in my supplier"s shop. Please, anyone know of good triac to use to replace BT131?. It is just to power a fan coil.

BT131 datasheet:  http://www.nxp.com/documents/data_sheet/BT131_SER_D_E.pdf

$0.49 USD for exact replacement:  http://parts.digikey.com/1/parts/991298-triac-logic-600v-1a-5ma-92-bt131-600d-412.html
Logged
Give a man a fish and you feed him for a day.
Teach a man to fish and he will sit around in a boat drinking beer all day.
Pages: [1]
Print
« previous next »
Jump to:  


DISCLAIMER
WE DONT HOST ANY ILLEGAL FILES ON THE SERVER
USE CONTACT US TO REPORT ILLEGAL FILES
ADMINISTRATORS CANNOT BE HELD RESPONSIBLE FOR USERS POSTS AND LINKS

... Copyright © 2003-2999 Sonsivri.to ...
 Powered by SMF 1.1.18 | SMF © 2006-2009, Simple Machines LLC | HarzeM Dilber MC