QPT has unveiled MicroDyno, a low-voltage motor drive test platform which demonstrates the key benefits of ultra-high frequency GaN-based motor drives.
The solution enables greater control and efficiency with lower system complexity and cost, providing significant benefits in the fast-growing cobot market.
Operating at 1MHz switching speeds, MicroDyno integrates a compact filter to deliver a true sine wave voltage to motors, a capability that fundamentally differentiates it from existing low-frequency PWM-based systems.
Whilst QPT’s IP scales up to very high power, this low-voltage platform will be used to show how it can transform the performance of cobots and general robotics through the dynamic correction of torque cogging and torque ripple, and high-fidelity sensing within the drive. All of this is achieved without expensive external sensors or encoders, to both significantly reduce the costs of these systems whilst also hugely improving the performance over standard PWM-based systems.
As Simon Hart, Director & CTIO of InnCat commented: “Even the best servos can have horrid cogging torque. I have spent much time with fast control loops and torque compensators to get the required speed smoothness. And then loop responses drift over time!”
A new standard for robotic drives
Most current robotic drives operate at 4-16kHz PWM frequencies, shaping current into a sine wave but leaving the voltage at the motor as high dv/dt PWM. Some specialist systems reach 100kHz, but these face electromagnetic challenges and are still too low frequency to enable small, cost-effective filtering required for true sine voltage output and EMI filtering.
MicroDyno breaks this barrier: by extracting the maximum performance from GaN transistors, it is able to operate at around 100x the standard frequency which enables a very small, cheap output filter, producing a clean sine voltage directly at the motor terminals with an extremely high signal-to-noise ratio. This also eliminates EMI, reduces bearing currents, enables ‘sensing without sensors’, and allows the use of unshielded cables or a fully integrated motor drive – a transformative shift for robotics integration.
Specific benefits for cobots and precision robotics
- Dynamic torque ripple & cogging correction – real-time compensation using QPT’s integrated qSense technology, detecting voltage and current disturbances in the time and frequency domains thanks to the very high signal-to-noise ratio of a sine wave drive. This drastically outperforms far more expensive encoder-based static methods, which drift over time and cannot react dynamically in real time to changes in the delivered torque
- Unprecedented precision and smoothness – QPT’s qControl technology is capable of generating the 1MHz signals with picosecond accuracy. The tiny filters deliver true sine voltage, enabling cleaner control signals, delivering smoother motion critical for delicate assembly and medical robotics
- High-fidelity sensorless diagnostics – clean sine wave output supports advanced torque and vibration monitoring for advanced sensing and predictive maintenance. The motor drive itself is able to detect and report on the exact cause of any vibrations in the system, all without the need for expensive external sensors
- Compact, lightweight integration – 1MHz switching dramatically reduces filter and drive size, enabling the motor drives to be fully integrated with the motors in the robotic joints
- Lower system & development costs – with the integrated filters, expensive shielded cabling is not required. EMC is also much simpler, motor life is extended, expensive encoders and sensors can be removed, and much higher performance can be achieved from cheaper motors
- AI enabled for next-generation designs – MicroDyno lays the foundation for local AI processing to further improve the performance of each motor, and a cloud-based solution to monitor and optimise across a fleet of electric motor systems, such as an entire production line of machine tools or robots
Scalable to higher voltage and power
MicroDyno demonstrates QPT’s architecture at 48V for robotics and cobots, but the underlying technology is fully scalable. Using QPT’s proprietary qAttach packaging, the same high-frequency sine-wave advantages extend to 400 and 800V systems – opening paths to deliver significant benefits in industrial automation, HVAC, and electric vehicle traction drives.
The unique sine wave output also unlocks the ability for the design of multiphase modules that can be used in parallel in order to reach megawatt levels of power with a much smaller range of modules for motor drive OEMs to contend with.
This scalability underscores MicroDyno’s significance not only as a demonstrator but as the foundation for a new class of motor drives across all voltage levels. With electric motors consuming nearly 45% of the world’s electricity, eliminating PWM-induced inefficiencies, noise and wear is a critical challenge across all motor-driven systems – from precision robotics to megawatt-scale industrial drives.
Rob Gwynne, CTO and Founder of QPT, commented: “MicroDyno shows what becomes possible when you combine ultra-fast GaN switching with intelligent filtering. For robotics, we’re not just improving smoothness. We can now dynamically correct torque ripple and cogging in real time, something that even expensive encoder-based systems cannot do to this level of precision. This opens the door to more precise, more compact and more reliable robots at a much lower system cost.”
