Gene, So It seems like you have verified that the PSU shutdown is not caused by a shoot through current in the H bridge and that is good. Now if the motor is running at 24V and you instantly reverse the power supply, the current going into the motor will not instantly reverse direction because of the motor inductance. But if the inertia is large compared to the inductance (large in terms of stored energy) then like you say, the current will soon get very large as you will have essentially 48V (24 from PSU and 24 from back EMF) across the winding, limited only by the resistance.
Now I am working on making some torque mode drives for my lathe retrofit. But I would like to see if I can make a decent motor and drive simulation using LTSpice. I already have what I think is a reasonable motor model. I intend to share the simulation model once I am confident in it. It can also be used to show any benefit in true torque mode, where the current is the command input to the drive, rather than voltage mode - what I think you have. I have found that if a simulation can be set up and validated it gives much more insight into a particular problem - you can make changes quickly and you can measure things that would be otherwise very difficult. It would be cool if I could get more info about your motor and mechanics. Like: No Load Speed - maybe not feasible for you since you would need to take your machine apart. Nominal voltage and speed Stall current Stall torque DC resistance Inductance Inertia of rotor and worm - that one may be hard to find. but maybe it can be estimated by the mass, and diameter of the armature and connected load. The mass on the worm gear side will probably not be significant because of the high gear ratios. Regards, John > > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
