Author Topic: Driving ultrasonic transducers with motor full-bridge drivers  (Read 596 times)

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Offline KaneTWTopic starter

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Driving ultrasonic transducers with motor full-bridge drivers
« on: September 05, 2019, 07:18:02 pm »
Motor full-bridge drivers (e.g. DRV8412) are mostly designed for inductive loads. I'm looking to drive 60W 40khz/100khz dual transducers with a static capacitance of 5nF and <25 Ohm resonance impedance with those.

Ultrasonic transducers are a RLC series resonant, high-Q circuit, with the static capacitance in parallel.

Is there anything to watch out for when driving potentially capacitive loads (at f < f0) with drivers designed for inductive loads? TI app notes (SLAA780A) just send the output directly to the transceiver, but that shows a lot of ringing in simulations. Adding some inductance and common-mode and differential capacitors helps a bunch, but leads to significant 2nd harmonic content at 40kHz switching frequency.

Am I overthinking this? Most high-power applications just drive transducers with a square wave, so it can't be that difficult.
 


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