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I'm facing issue with IR2110S driver while driving 3 winding BLDC motor (24V, 8A rating with Hall sensor feedback) using IFR3710 MOSFET (half bridge configuration).

Issue:

When varying duty cycle from 0 to 95 present with 5 percent interval, motor running fine. But when varying duty cycle (PWM) from 0 to more than 50 percent suddenly, IR2110S driver IC getting failed sometime. there is no IC heat observed. MOSFET not get damaged. after replacing IC its working fine with 5% duty cycle increment.

With driving the motor, observed some spike on low side MOSFET drain and source terminal. I think low side output section of IR2110 driver circuit failed. This will fail when LO pin voltage with respect to ground less than 0.3V and more than VCC+0.3V. After driver failed, 555 timer IC threshold and discharge pin varying continuously from 0 to 5 voltage linearly and RED gets turned ON then we are stopping low side MOSFET PWM signal.

Schematic diagram:

Driver circuit

Current sensing circuit

Operating condition:

50 kHz switching frequency 24 V, 8 A bldc motor 24 V input power supply to board (main board) 0.05 ohm external resistor board which has 10 cm distance between main board. Maximum duty cycle should be 90 percent. I want to spinsup directly 0 to 90 percent.

Observation:

I read relavent answer to "Driver failure when driving IRF3710 mosfet using IR2101 driver" question, which is same like my schematic. Difference is current sensing circuit, 4.7 uF bootstrap capacitor (in my circuit, using 47 uF electrolytic), 50 kHz switching frequency. Gate to source resistor.

Am having doubt on following,

1) Is 47 uF electrolytic and .1 uF ceramic decoupling capaictor enough for my load?

2) Switching frequency is 50 kHz, 47 uF bootstarp capacitor is ok or due to high frequency can I reduce it to 4.7 uF for quike charging and discharge?

3) I plan to use 15 V working voltage, unidirectional TVS diode across gate and source of all MOSFETs to maintain 15V max across all MOSFET G-S terminal. If this is OK then voltage rating is fine for TVS diode?

4) Is external sensing resistor long return path will affect driver performance(10cm length wire connected to external having two 0.1/5W resistor parallel connection)?

5) In driver application note, driver COM pin connected directly to lower side MOSFET source pin. But i connected through sensing resistor which is connected externally (due to lack of space in main board). I plan to remove resistor and connect COM pin directly to Low MOSFET source pin. Is that OK (removing current sensing circuit)?

6) Motor control has three phase sequence, we not found cross conduction condition, so not provided dead time delay. Is this will affect?

7) Is the TVS diode across 24 VDC supply rail is required?

Please provide me the suggestion to resolve this issue.

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  • 2
    \$\begingroup\$ How good is your PCB layout? \$\endgroup\$ – Andy aka May 23 '18 at 8:04
  • \$\begingroup\$ add 5) connect both GNDs together and test. For such high frequency the PCB has to be fully optimized with short leads, etc... \$\endgroup\$ – Marko Buršič May 23 '18 at 8:05
  • \$\begingroup\$ A bad layout may lead to voltage transients between COM and Vss. I've had IR2113 (basically the same thing) low side outputs die upon the high side MOSFET switching off at high current, caused by the stray inductance of the traces. As andy aka said, post the board layout. \$\endgroup\$ – jms May 23 '18 at 8:53
  • \$\begingroup\$ 10 $ it's failng due to negative voltage spike. I've let the magic smoke out of tubes worth of IR2110/2113 due to that. \$\endgroup\$ – winny May 23 '18 at 9:00
  • \$\begingroup\$ 1. Measure it with your oscilloscope. 2. See 1. 6. Sounds like a recepie for disaster/cross conduction. Again, measure the voltage and see how much deadtime you need. \$\endgroup\$ – winny May 23 '18 at 9:16

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