Are my Leadshine DCS810 brushed Servo Drives fake

I have one DCS810 drive left that I repaired before and bench tested but have not installed. I'm going to keep it around to potentially investigate why these drive fail on a winter day when I have nothing else to do.

As far as wattage rating of a drive. I'm personally not concerned about watts since the drives are not a linear amplifier, but instead look more at the minimum motor inductance and resistance that the drive can handle which is more suitable for a device using pulse width modulation. In electrical horse power units 5600 watts equals roughly 7.5 horsepower which would be a lot of power for a drive like this to be able to put into its external load. If we just look at what the Mosfets are capable of per their absolute maximum ratings at 100 degrees C and the figure of 5600 watts it is likely that around a 100 of those watts would be dissipated as heat in the drive itself by the two active Mosfets. Since the drive has current limiting it will however never reach that power level except perhaps for a few micro seconds that the over current protection loop needs to respond.

It appears to me that the rated current and voltage ratings listed on a drives date sheet are the absolute maximum ratings of the output Mosfets used in a drive as listed by the Mosfet manufacture in their data sheets when such devices are set up and properly cooled in their selected test bed. These rating may be for a strictly resistive load and not one encountered while driving a more complex load. My thinking is that these ratings should just be used as reference to indicate the potential ruggedness of the devices used in a drives output stage.

The Mosfets used in the replacement drives are rated at 50 amps at 25 degrees C and 35 amps at 100 degrees C. The RDS on resistance in a fully conducting state is specified at 0.04 ohms when a current of 50 amps is passed thru the Mosfet with 10vdc applied to the gate turn on the Mosfet. Since the Mosfets when installed in a drive are not installed as in a perfect test bed these ratings may need to be reduced substantially for our applications when in actual use. For myself I would reduce the 35 amp rating at 100 degrees C by perhaps 50%. This would set my current limit setting to 17.5 amps which I feel would be sufficient for my application.

My motors originally calculated to have 801 uh of inductance using the simple ringing method of measurement and have a DC resistance of about 0.5 ohms. The replacement drives should drive the motors just fine especially when cable length characteristics are added in. When calculating the stalled motor current due to being driving past a limit switch or a axis running into obstacle shows that the current demand will cause the rating of the drive to be exceeded if there was no current limiting. In such a case the drives over current protection if set properly should kick in and shut the drive down until the problem is eliminated and the drive is reset. The Mosfets in the DG4S-16035 replacement drives have a absolute maximum drain pulse drain current current of 200amps per Mosfet mfg date sheet which should be enough to allow for the time required for the current protection loop to kick in.

I have finished installing the five DG4S-16035 drives and all five are working fine with no problems noted. I still need to fine tune the drives and then finish tuning in linuxcnc.