Robotics and the New Demands on Motion-Control Power Design

Furthermore, the challenge changes with the application. Fixed industrial robots are typically designed for repeatability, reliability, and continuous operation, with greater packaging freedom, while collaborative robots add requirements for size, quiet operation, and safe interaction. Mobile robots must also manage battery capacity and weight.

Humanoids bring many of these pressures together across numerous tightly packaged joints. As the number of axes increases, the losses, wiring, and thermal demands associated with each motor controller can accumulate across the platform, making motor control as much an integration problem as an electrical one.

Where GaN Creates Useful Design Headroom

This is where GaN can become particularly useful. Low gate and output charge can reduce switching losses, while the absence of a silicon MOSFET body diode avoids the associated reverse-recovery charge. These characteristics give engineers more freedom to balance efficiency, switching frequency, and power-stage size where an inverter must fit close to the motor and its heat must be managed within a restricted volume.

The system benefit will depend on what constrains the actuator. A smaller power stage can create room for control electronics, sensing or mechanical components, while lower losses can ease cooling requirements and preserve more of the available power budget. In battery-powered robots, this may contribute to longer operating time, although the effect will depend on the inverter’s share of total energy consumption relative to the motors, computing, and other subsystems.

Voltage requirements vary widely across robotics. Compact humanoid joints and some collaborative or mobile platforms may use 48 to 60 V buses with 80 to 100 V-class switches, while industrial servo architectures can operate from DC links of several hundred volts and require high-voltage devices, commonly 650 V or above, depending on the supply. These are distinct GaN applications, with different devices, packaging, gate-drive and thermal requirements.

Engineers must also decide how much of the power stage to integrate. A discrete design keeps the switches, gate driver and protection separate, providing greater freedom over switching and thermal behaviour. Integrated power stages combine these functions to reduce sensitive loop lengths, PCB area and layout work, while modules can integrate multiple switches and supporting functions. The appropriate route depends on current, cooling, available volume, electromagnetic compatibility, protection and manufacturing priorities.

Raising the frequency beyond what the application needs increases total switching losses and power-stage heat, even where GaN reduces the energy lost during each transition. It also reduces the time available to acquire reliable current measurements. Switching-edge speed creates a related but separate trade-off: faster transitions can reduce switching loss, but parasitic inductance can cause overshoot, ringing, and electromagnetic interference (EMI), potentially increasing electrical stress on the motor windings and interconnect.

Engineers can therefore use GaN’s switching headroom selectively, choosing a PWM frequency that benefits motion while tuning the gate drive to manage each transition. Increasing the turn-on gate resistance can reduce the rate of voltage change and EMI, although the longer transition increases switching loss. Short gate-drive and power loops, controlled parasitic inductance and validation of the complete measurement chain remain essential.

Turning GaN Capability into Better Motion

The strength of GaN in robotics is the design flexibility created by lower switching losses, compact power-stage options, and the ability to use higher PWM frequencies where they improve the application. That does not mean every axis needs the same technology or architecture. GaN creates the most value when it addresses a defined electrical, thermal, or mechanical constraint within the robot.