DRV10987: over current fault during open loop start
Part Number: DRV10987
We are using DRV10987 IC design with power supply 24V/ 1.5A(max) . Motor is successfully running in Open to closed loop but when speed command change 450 to 511 then supply current goes to 1.8A ( Tested in another power supply 24V/2A ) & then settle down to 1.5A . We have set software current limit setting is1.4A & Hardware current setting is 1.8A then motor is lock ( not transfer successfully open to closed loop ) . We already set closed accel is minimum value . set Please suggest which pararmeter to set our motor max current 1.5A .& how to control inrush current during speed change .
Thanks for posting your question in MD forum. Software current limit will only limit the current and not trigger any fault. Looks like hardware current limit is triggering the fault. Can you increase the hardware current limit to around 2.0 A and set the software current limit to 1.6 A and try again?
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In reply to Vishnu Balaraj:
When we set software current limit speed synchronization fail . set software current limit set 0000 then synchronization working fine .
In reply to Swapnil Urankar:
Looks like the load torque is higher at high speed. What is the closed loop accel set to? Do you see supply current settle down quickly to 1.5A when closed loop accel is set to min value? If you don't see any improvement then nothing much can be done because the load is higher at high speeds and the device provides phase current demanded by the load.
Motor is wobbling , please refer my below motor parameter & please send initial closed settings with IPD & ISD .
Motor vlge = 24V
Motor I = 1.5A
PH to PH resistance = 1.86 ohms
No of pole - 7 pairs
Motor max speed - 350 rpm
Motor back emf = 470mV
If the motor rated current is 1.5A, current will overshoot by 10%-15% at higher speeds. You cannot expect the current to settle down right at the edge of the rated value. Also, Supply current includes motor current and the device current. So it is recommended to use a power supply higher than the motor rated current say 20A.
Motor is wobbling ( application used for DRV10987 is celling FAN) , please refer my below motor parameter & please send initial closed settings with IPD & ISD .
Motor BEMF is a function of speed. At what speed is the BEMF 470 mV? We need BEMF constant Kt in mV/Hz to program in the device. You can find Kt in motor datasheet or measure yourself by checking this video link. Can you share your current EEPROM settings? I can recommend changes after reviewing your settings.
Yes ,We had measure back emf as per share video link . please refer below EEPROM setting using right now.
#define OL_C0_MSB 0b00010110 //0x90#define OL_C0_LSB 0b01001011
#define OL_C1_MSB 0b01011111 //0x91#define OL_C1_LSB 0b00111011
#define OL_C2_MSB 0b00001000 //0x92#define OL_C2_LSB 0b01000010
#define OL_C3_MSB 0b01010011 //0x93#define OL_C3_LSB 0b00111111
#define OL_C4_MSB 0b10111011 //0x94#define OL_C4_LSB 0b00001101
#define OL_C5_MSB 0b00110000 //0x95#define OL_C5_LSB 0b01100011
#define OL_C6_MSB 0b00000011 //0x96#define OL_C6_LSB 0b01101011
Is the Kt in mV/Hz? When you measured BEMF voltage, did you measure peak-peak or peak voltage? I checked your register settings. Can you program the motor resistance Rm to 0.93 ohms? Also, can you enable Abnormal Kt fault, and read back the fault register (register address 0x00) to know which lock is getting triggered?
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