Hello Musharraf, Monday, July 26, 2004, 3:38:20 PM, you wrote:
MH> Dear All, MH> I am attempting to implement a sensor based brushless motor drive as a part MH> of my MSc and have a few questions in that regard. First the details of the MH> motor: MH> Supply voltage: 32V MH> Rated current: 1.5A MH> 1. I plan to use a three phase inverter drive for the motor. I will be using MH> IRFI540 power mosfets for this. These transistors have internal antiparallel MH> diodes. What is the current capacity of these diodes? Will i need to install MH> external free wheeling diodes? Look it up in the datasheet. The diode parameters are there under "source-drain ratings". In general it's a good idea to use additional, external diodes... And in case you wonder: you can find the datasheet on the manufacturer's homepage! MH> 2. Any hints as to how I should implement a break mechanism? I was thinking MH> of powering up the transistors corresponding to the lookup table for MH> rotating in the other direction. I think that this would have the same MH> effect as reversing the voltage on a brushed permanent magnet DC motor. Will MH> there be some problem with this? There are many books and internet sources on this or similar topics. I would think that trying to drive the motor in the exact opposite direction is about the worst thing to do. What would be the rotational frequency you would use for the brake signal? When would you know the motor has stopped? I am not expert on motors, but as far as I know braking is done by either short-circuiting the motor windings or even driving them with a DC signal. But please, look it up - it's there! MH> Best regards, MH> Musharraf Hanif Uwe. -- Author: Uwe Zimmermann INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
