Other Parts Discussed in Thread: C2000WARE
Tool/software:
Hi team,
I am currently working on DC bus current calculation using our own custom board. Since we are not using any DC current sensor, we are approaching formula-based calculation.
We are able to run the motor in both speed and torque control modes (With encoder feedback) using 48V encoder motor in all BUILD_LEVELS. I am using UMC SDK (C2000Ware_Motor-control_SDK_5_02_00_00).
We are using Pico scope (External sensor) to validate our formula-based DC current.
Currently, I am calculating DC bus current using below formulas:
Electrical power (in dq frame) = (3/2) * (vd * id + vq * iq)
copper loss = 3 * Is^2 * motor stator resistance
mechanical loss = Motor torque constant * motor RPM * Is
DC bus current 1 = (Electrical power + copper loss + mechanical loss) / DC bus voltage
DC bus current = DC bus current 1 * factor
1. Here, at each RPM with single factor, under load condition, we are not getting proper DC current. We need to change factor based on RPM and phase current (torque). Is this approach being correct to calculate DC bus current?
2. Also, I used Idc = phase current * phase voltage * power factor. Since we are not getting proper phase voltage from divider circuit, we used voltage re-construction method for phase voltage but in this approach also same factors are not working in all torque regions at same RPM.
Need to change power factor based on speed and torque.
Can you please suggest the best formula to calculate DC bus current in UMC.
3. In dyno both testing (low power rating) and loading motors (high power rating) are mechanically coupled and we are doing testing. Here, when both the motors are running in same direction (Motoring condition), we are getting maximum and able match sensor DC reading with our formula-based DC current by using some factor.
But when both the motors are running in opposite direction (regeneration condition) our formula is giving maximum DC current at peak torque, actual DC current consumption is very low. since motors are running in opposite direction. How to identify, whether both the motors are running in same direction or opposite.
We are using 3 shunt resistors across phases to measure phase current. Whether it is possible to measure current direction using shunt in Universal motor code (UMC). Is there any method to identify above condition.
Thank you.
Regards,
Kirana H P