2kW GaN Inverter For Compact Servo Drives And Robotics

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Silicon power transistors have dominated power-supply design for years, but more and more designers are looking for gallium-nitride (GaN) transistors in new designs thanks to the latest technology advances. Power inverter design engineers use GaN technology to increase power efficiency and to reduce inverter size and weight.

New 3-phase GaN Inverter Reference Design

These performance advantages have compelled TI to use GaN transistors in its new inverter reference design TIDA-00915. The design, says TI, helps engineers build 200V, 2kW AC servo motor drives and next-generation industrial robotics with 99 percent efficiency, more accurate speed and torque control. The reference design can be downloaded here.

The reference design is built around TI’s LMG3410 600 V 12-A gallium nitride (GaN) power module. It uses six of these power modules.

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The GaN module used in the reference design is said to allow the design to switch up to 5x faster than silicon FETs (field effect transistors) while achieving efficiency levels greater than 98 percent at 100 kHz and greater than 99 percent at 24 kHz pulse width modulation (PWM) frequency.

TI explained that with GaN, designers can optimize switch performance to reduce power loss in the motor, and downsize the heat sink to save board space. Operating the inverter at 100 kHz significantly helps improve torque ripple when used with low-inductance motors.

The GaN inverter power stage easily interfaces with microcontrollers (MCU), including TI’s TMS320F28379D drive control system-on-chip to help dynamically adjust voltage frequency and achieve ultra-fast current loop control.

Alongside the reference design, TI has also unveiled its new DesignDRIVE Fast Current Loop software with innovative sub-cycle PWM update techniques that help push current-loop performance in servo drives to less than 1 microsecond, potentially tripling motor torque response.

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The Fast Current Loop software outperforms traditional MCU-based current-loop solutions, and is available free with controlSUITE software, said TI.

The reference design also utilizes TI’s AMC1306 isolated delta-sigma modulators with current sensing to increase motor control performance. The firm’s ISO7831 digital isolator also provides reinforced isolation between the MCU and the design’s six PWMs.

Key features and benefits of the reference design:

  • High PWM switching frequency (up to 100 kHz) allows for driving low-inductance motor with minimum current ripple
  • 600V and 12A LMG3410 GaN FET with integrated gate driver reduces PCB form factor and layout complexity
  • Very fast switching transition < 25ns without any switch node voltage ringing reduces EMI
  • High-efficiency power stage (> 98% at 100kHz PWM, 99% at 24kHz PWM) reduce heat sink size
  • Protection against gate undervoltage, overcurrent and overtemperature

For further details, view the full Press release.

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