James
The 2200A current is between the motor and the FETs, putting a cap like this across the motors would just be seen as a short circuit to the controller. Putting it across the battery would not resolve this particular issue.
Paul
Paul if u willing to replace the controller if you blow it up (not that they should) Im willing to let you try the 48330esc on power drives email me if u interested
6.3lbs weight!!!
1 channel
http://www.teamwhyachi.com/motor.htmhttp://www.teamwhyachi.com/motor.htm
Thats 5.7Kg of speed controller for drive!
yea and?
call it an insentive to loose weight
thanks kane/paul, as I said, didnt look into it, just something from the old boyracer days
Maybe a small device that monitors the voltage on the motor wires what will switch the motor leads to a something that will burn up this voltage spike when braking until the voltage drops back to a level that the fets will take and then connects the motor back to the controller? Im sure it could be done with a picaxe chip and some smart thinking. Just a brainstorm and Im sure someone will pick holes in the idea.
Euhmm.. hey youve got it all figured out
Im sure theyd have a solution if it where an easy fix.
Id try to use a higher switching frequency and a lower duty-cycle on regenerative breaking. But Im sure theyve tried all the easy fixes.
Maybe they cant upgrade the cpld contents with the normal firmware upgrade software.
You guys do realise that the maker of the Roboteq is working on this problem to produce a more refined fix!
Knightrous, the problem is current spikes rather than voltage. The Roboteq has built in hardware suppression against normal voltage spikes and additional means of isolating the motor from the output stages built into the software. Some spikes from low impedance motors like the LEM and Power Drive have so much energy and are of such short duration that even this protection is not adequate. Fortunately this issue has recently been resolved and works well.
The method of dumping regen energy into some switched load has been considered not just by myself but by other speedo designers I could mention and it is far from being a desirable solution.
Stefan, it is all about the duty cycle but a lower duty cycle is what is causing the problem at the moment. You need to be able to detect when in regen and also measure the regen curent in the bridge but very few bridge designs appear to allow for this. You are also quite right that the firmware upgrades cannot alter all functions, some are embedded as you suggest in the PLD which includes how the bridge is controlled.
We remain optimistic that a solution exists and I certainly do not mind suggestions, you never know it may just prompt a new thought process.
Thank you to those who have emailed direct with suggestions.
Paul
Following both successful bench and field trials (thanks to Dantomkia Mike), a new version of the Roboteq is now available - AX2550HR.
The development has also led to improvements on the standard version. A new version of the software will be available next week (waiting for me to upload) which will amongst a number of continual developments now feature regen current monitoring. What this means is that the controller will send a minimum of 25% of the regen current back to the batteries until it falls below a fixed threshold. Once it falls below this threshold, the controller will bring the motor to a halt. Effectively this means the deceleration ramps may be paused during periods of high regen current. This is very unlikley to be even noticed with motors such as the Bosch 750W, its there for LEMs and Perm Power Drives etc.
There is also a small hardware mod of 4 diodes to cope with spikes during regen. All motors generate these spikes and the standard Roboteq can cope with these for motors except the disc type LEMs etc. There is a risk that a faulty motor could also generate these spikes. These diodes are fitted to all units shipping from 1 Jan 2005 but can be retro-fitted to previous controllers.
Even with these changes, the disc motors (especially the Power Drive) still generate enormous regen currents so a new version is available that has twice the number of output FETs which means is can cope with twice the regen current as well as running cooler. Existing standard controllers can also be upgraded to the HR version.
It would be unrealistic to say that the Roboteq is now unbreakable, but surely it must be close.
See http://www.technobots.co.uk/en-gb/dept_332.html>here
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