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VESC and T500 Thruster - Problems obtaining right speed

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SIGURD
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VESC and T500 Thruster - Problems obtaining right speed

Dear all,

I hope that someone can help clarify some things for me regarding the use of the VESC. 

I am using the HD60 VESC and the newest firmware (6.0). 

I am powering it at 24 V from a mean well DPU3200 power supply.

I am using the VESC for an ROV project where I would like to obtain some feedback from the ESC, this is provided by the VESC, which also allows me to use CAN as communications which is also preferred. 

When I use the T500 thruster (BlueRobotics) together with the Basic ESC (standard)  (Running BLheli_S) i obtain a free spin speed of approx. 2000 rpm at 20% duty cycle, when dropping the propeller in the water there current naturally rises, but the speed is almost the same.

When using the VESC and asking it to run at 0,2 duty cycle, it only obtains approx 980 RPM both in free spin and in water, can anyone help me understand the difference? As the duty cycle increases the difference gradually becomes less, and at full speed, the rpm (Force) is the same for the basis ESC and VESC.

Is it correctly understood the average value for the input voltage to the motor should be 20 % of the power supply input voltage when the duty cycle is set to 20%? This does not seem to be the case for the VESC.  

 

Best Sigurd

frank
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Typically Duty Cycle and Volts towards the motor are linear. Do you run it in FOC?

SIGURD
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Hi Frank. 

I have tried to run in both BLDC and FOC mod, in FOC mod o have some trouble ensuring that the motor starts every time I ask it to. Sometimes I just wrinkle. But when running both modes, obtain a free spin velocity at 980 RMP. I have tried to correct an oscilloscope to one phase of the motor, but I have a hard time understanding the output in BLDC as the on the period of the voltage seems to vary over one phase cycle. 
For FOC mode, I do not understand a thing of what I see, I looks like it is on the entire time but the on-time of the voltage signal just varies. I will provide some pictures in the morning.