Do 4QD controllers have constant torque mode?

Torque mode is used on, for instance, a machine used to wind a continuous material onto a spool. Instead of the input controlling the speed, it ideally should control the motor current, hence the torque of the motor. This is not a very common application so it has not been designed into 4QD’s standard controllers – such features inevitably increase the cost so that all customers end up paying for features they do not actually need!

However all controllers made by 4QD incorporate a current limit and this current limit can be altered by adjusting a few components, so a controller could be used to supply a constant current, which in some applications is adequate.

Remember that the standard current limit is there solely to protect the MOSFETs from transient over-currents which could be destructive. If you run on the standard current limit for too long, then the controller will simply overheat and melt – quite literally, it is indeed possible to melt the solder on the MOSFET leads before the controller fails! So you will need to reduce the current limit quite significantly, to less than, say, 25-35% of the nominal current to prevent overheating. The exact allowable current will of course depend on your heatsinking, the application and the controller you use. Contact the factory for advice.


Category: Features

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