Other Parts Discussed in Thread: MSP430F5529, DRV8350, DRV8350S-EVM
Dear TI Team,
I am trying to control a BLDC Motor using DRV8350H-EVM in sensored operation. But as soon as I increase my Motor Speed over 50%, my motor stops and an Overcurrent Fault is triggered in the DRV8350x EVM GUI Software.
Below are the specifications of motor:
- No. of Pole Pairs : 8 Pairs
- Max peak current: 10A
- Operating Voltage: 24V
- Hall Sensors: 3 (120deg)
- Nominal Current:25A
- Power: 150W
Steps performed:
- Flashed the EVM, with Sensored Firmware Provided by TI, installed in the following path: C:\ti\DRV8350x_EVM_BLDC_FW_1.0.0\DRV8350x_EVM_FW\DRV8350x_EVM_BLDC_FW_1.0.0\DRV835X_MSP430F5529_Trapezoidal_Sensored_BLDC.
- Connected to DRV8350x EVM GUI Software and tried to control motor speed.
Observations:
- Initially, the overcurrent fault was triggered as soon as we tried to increase the motor speed over 20%. Increasing the PWM Switching Frequency from 25kHz to 60kHz (maximum) helped in increasing the Motor Speed upto 50%.
- As per the documentation available, MOTOR_PHASE_CURRENT_LIMIT is the parameter that triggers over-current fault. The default value of this parameter in the firmware is 900.
Considering the above formula,
MOTOR_PHASE_CURRENT_LIMIT = 900;
CSA = 5V/V
We get amperes as 20.71 A.
My motor has peak current of 10A. So ideally with these settings I should not get an overcurrent fault.
- We were unable to verify the value of the current sense amplifier (CSA) from the Hardware. Also, from the documentation below, it was inferred that the DRV8350-H must have 4 pins, GAIN, IDRIVE, MODE & VDS
4. But in the schematic, I am unable to find the GAIN pin
5. As per my understanding this GAIN pin is required to set/read the value of CSA as shown below:
6. Kindly help us identify the actual reason for this overcurrent fault so that we can run the motor at its full RPM.
Thanks & Regards
Gagandip Singh Dadhwal