Part Number: TMS320F28027
Other Parts Discussed in Thread: DRV8305
i am using ti processors TMS320F28027 microprocessor, C2000 compiler and DRV8305 motor driver IC. I use instapin lab to control my BLDC motor( 24V, 2500WT) with instaspin FOC lab 11a. i would like to discuss about the instaspin labs and motor torque performance. we are a company who makes industrial stirrers and our requirement is to make the stirrer go from 100RPM to 2500RPM with a peak torque of 80Ncm and a continuous torque of 50NCM(across speed range of 100RPM to 2500RPM). we need the stirrer to intermittently reach 80Ncm for a minute or so as and when required and run continuously at 50Ncm, as per our spec. we are facing issues in reaching the 80Ncm when the motor cuts out after 65Ncm.
we use a 24V 210W Ac to Dc switched mode power supply to run the stirrer(rated current 8A, max current is 10A). The motor is rated at 24V, 5.3A rated current and peak current is 15.6A. i measured the current draw by the motor with respect to our continuous torque and how much ever the peak torque can be obtained. i observed that at different speed the motor cuts out at different current value and am not able to coorelate how exactly instaspin controls the current. From our end, we only vary the speed on the code and allow lab 11a to make achieve the torque. Please can you let me know how torque and corresponding current value is correlated with respect the speed range in lab 11a.
please refer attached measurement of current vs torque obtained across diff speed range.
| Speed(RPM) | torque brake expected(Ncm) | torque brake Actual(Ncm) | current(A) |
| 100 | 50 | 50 | 3.2 |
| 80 | 71 | 5.45 | |
| 300 | 50 | 50 | 2.58 |
| 80 | 72 | 5.9 | |
| 500 | 50 | 50 | 3 |
| 80 | 66 | 6 | |
| 600 | 50 | 50 | 3.15 |
| 80 | 67 | 6.1 | |
| 750 | 50 | 50 | 3.65 |
| 80 | 75 | 8.35 | |
| 1000 | 50 | 50 | 4.25 |
| 80 | 69 | 10.6 | |
| 1500 | 50 | 50 | 5.5 |
| 80 | 70 | 10.4 | |
| 2000 | 50 | 50 | 7.2 |
| 70 | 66 | 10.7 | |
| 2300 | 50 | 50 | 7.7 |
| 65 | 66 | 10.8 | |
| 2500 | 50 | 50 | 7.9 |
| 60 | 65 | 10.4 |
Also, for another stirrer we use the same motor and use lab 10a. this stirrer has relatively lower peak torque than what we use with lab11a since the stirrers capacity is lower, however for the same 65+Ncm torque, the lab 10a is comparatively smoother & has better performance than lab 11a. i am wondering how lab 10a overmodulation feature is different from lab 11a features.
Thank you.
