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DRV8323: Motor Driver ICs burn through

Joachim Althof
Prodigy 20 points
Part Number: DRV8323

Dear TI-Team,

we (the development team of the company I work for) have designed a tiny PCB for a motor control application. The design is based on a DRV8323S and is relatively straight forward. As a reference, we took the schematic from the drivers datasheet.

The motor is a 4kW PMSM, nothing special here. Supply voltage is 24V from a laboratory PSU currently, but will be up to 50V from LiIon-batteries in the future.

I am the software engineer in this project. Actually I am designing a sensorless control algorithm based on a classic sliding-mode current observer/controller. The algorithm is currently under development, so it is not yet finally parameterized and not fine-tuned. And here is where the trouble begins.

The open-loop spin-up phase where I control the current and accelerate the rotor works quite ok. In the moment, where I switch over to the SMC the control loop is getting unstable (which is not too bad actually, because it is still under development). The motor is making the well known strange noise and then the DRV8323S blows up.

I also managed to blow up the DRV8323S during the open-loop phase by just applying to much current to the windings.

The configuration of the DRV is the default one.

So my question now is: what could cause the driver IC to blow up? For my understanding, it does not "see" any high power, it acts like a "link" between the power-part (3-phase inverter circuit) and the logic-part (microcontroller).

Thank you very much in advance,

greetings,

Joachim

  • 0
    TI__Guru** 114905 points
    Hi Joachim,

    The device does not "see" any high power, but can see voltages outside the ratings depending on currents.

    Have you examined the signals around the device during the open loop phase? This may provide a clue.
    Sometimes lowering the voltage of the power supply will allow you to see possible causes.
  • 0 in reply to Rick Duncan
    Prodigy 20 points

    Hello Rick,

    thank you for your reply!

    During open-loop operation (which is only open-loop for speed, but closed loop for current), everything seems ok. The current is stable in the desired range, the PWM pattern is sinusodial (with third harmonic injection). Dead-time between high-side and low-side switches is configured and checked (500ns).

    So thinking about too high currents (when control-loop becomes unstable) might be the right direction. But I am wondering how this is possible. I thought the DRV would monitor various voltages to prevent such events (Vds, Sense-level). So I am wondering, why these safety mechanisms are not triggered.

    Greetings