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SOLO Uno V2-BLDC draw high current at start up

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I have been using a Solo UNO V2 for around 1 month to drive a BLDC motor. I had no issue with the driver previously and I could drive the BLDC motor perfectly in both Speed and Torque modes.
The configurations of the motor is as follows:

48 V
8 Poles
2500 Lines encoder and the encoder is selected for the feedback control mode.

A couple of days ago, one of my colleagues has updated the Firmware of Solo UNO V2 and ran the Calibration Wizard. During the calibration, the motor rotated very fast a couple of degrees and stalled. Since then, we face a strange issue when we turn on SOLO and the motor is connected as well. In this case, my source short circuits and voltage drops to 0 for a few seconds. The motor also rotates for a fraction of a degree in this time and stops.

Due to short circuit, SOLO turns OFF for a few seconds and it turns ON again. After turning ON, then the source short circuits again and SOLO restarts. This happens two or three times and then the E1 LED turns RED and nothing happens afterwards.

I have checked this with different configurations (SOLO USB connected and disconnected & Encoder connected and disconnected to SOLO) in all cases the same problem happens.

I have also checked the motor separately and with another driver and I can verify the motor has no problem.

The SOLO connection is as follows:

48 V is connected to the input
Motor wires are connected to A B C ports and their order has been selected based on the available guide on your website.
I have checked with and without connecting the USB and encoder cable. The result is the same.
The controller is in Closed-loop mode (Pin 5 down).

I also checked without connecting the motor. Then there would be no problem. However, when I check the output pins (ex. pin A vs pin B) using a scope, I can see a PWM voltage between -24 and +24 V (Its duty cycle varies when I rotate the rotor by my hand when the encoder cable is connected). I do not know if this should be the case at start up but when I put it in open-loop, the voltage becomes 0. It seems that the PWM voltage results the motor to draw a big current when it is connected which results in short circuiting of the source.

I also changed the motor type to DC in Motion Terminal and I could observe that the voltage is always 48 V between two pins when no motor is connected. 

I have no idea why I am facing this issue and I do not know if it is related to firmware update or not. My current firmware version is 0003B00E.

Can anyone help me with this matter?



Posted : 13/01/2023 12:28 am
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Hello @af19,

Sorry for the trouble, first of all, I believe the issue is not related to the firmware updating as your problem seems to be a hardware failure, usually these issues happen when the Mosfets or the other electronics internally are damaged, it can happen due to improper handling of the hardware ( shorting I/Os, outputs, motor failures...) or over-voltage caused on the BUS during the motion of the motor that is causing the input rising above its max absolute ratings.

I believe the best is for you to get in touch with our team at support@solomotorcontrollers, so they can take care of Repair or Warranty based on our Terms of Service.




If you found the answers helpful and you could solve your problems, please kindly verify here to help others in the future.

Posted : 13/01/2023 9:13 am
af19 reacted
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Hey @milad 

Thank you very much for your reply.

I have contacted the support team and I am waiting for their response. I just have one more question.

The fact that the driver is porducing PWM voltages in the output doesn't mean that the MOSFETs are still working properly?

Could it be another component?

And is it normal to have PWM voltages in the output of the driver at the startup of SOLO in closeD loop and having no voltage when I switch to open loop?


Best regards

Posted : 13/01/2023 12:51 pm