Power design drives robotics with 99% efficiency

27th June 2017

Lanna Deamer

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Datasheet Whitepaper

Texas Instruments has introduced an innovative three-phase, Gallium Nitride (GaN)-based inverter reference design that helps engineers build 200V, 2kW AC servo motor drives and next-generation industrial robotics with fast current-loop control, higher efficiency, more accurate speed, and torque control.

Three-phase inverter GaN power stage
The three-phase high frequency GaN Inverter Reference Design features TI's newest LMG3410 600V, 12A GaN power module with an integrated FET, gate driver and protection, announced last year. The GaN module allows the design to switch up to five times faster than silicon FETs, while achieving efficiency levels greater than 98% at 100kHz and greater than 99% at 24kHz Pulse Width Modulation (PWM) frequency. With GaN, designers can optimise switch performance to reduce power loss in the motor, and downsize the heat sink to save board space. Operating the inverter at 100kHz significantly helps improve torque ripple when used with low inductance motors.

Power, speed and performance
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 fast current loop control. TI also introduced 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. The Fast Current Loop software outperforms traditional MCU-based current-loop solutions, and is available free with controlSUITE software.

In addition to the GaN module, the reference design relies on TI's AMC1306 isolated delta-sigma modulators with current sensing to increase motor control performance. TI's ISO7831 digital isolator also provides reinforced isolation between the MCU and the design's six PWMs.

Key benefits of TI's three-phase inverter design

High-efficiency power stage: 98% at 100 kHz PWM, 99% at 24kHz PWM reduce heat sink size.
High pulse width modulation (PWM) frequency: High PWM switching frequency allows for driving low inductance motor with minimum current ripple.
Fast switching transition: Less than 25ns without any switch node voltage ringing reduces EMI.
600V and 12A LMG3410 GaN FET power stage with over 7 million device reliability hours: Allows for fast and easy PCB layout and small form-factor design.