EPC Debuts Ultra-Compact GaN Motor Drive Reference Design

Efficient Power Conversion (EPC) has unveiled the EPC91132, a compact 3-phase brushless DC (BLDC) motor drive inverter reference design is built around the company’s EPC33110 GaN three-phase module, aimed specifically at the demanding size, weight, and efficiency requirements of humanoid robot joints and drones.

The compact EPC91132 motor drive inverter reference design is aimed at humanoid robot designs and drones.

Monolithic Architecture and Internal Integration

At the heart of the EPC91132 is the EPC33110, an ePower Stage IC utilizing EPC’s proprietary monolithic gallium nitride (GaN) technology. Rather than relying on discrete power components, the module co-packages three distinct half-bridges into a single 6 mm x 6.5 mm QFN package to minimize footprint and simplify system layout.

The ref design is built around the EPC33110, a GaN three-phase module.

The monolithic IC integrates:

• Six eGaN FETs: Providing the primary high-efficiency power stage switching capabilities.
• Integrated Gate Drivers: Eliminating the need for external driver components and drastically reducing parasitic loop inductance between the drivers and power switches.
• Bootstrap Circuitry & Level Shifters: Features synchronous high-side bootstrap charging and robust level shifters optimized to prevent false triggering during rapid high-voltage transitions.

This level of integration simplifies printed circuit board (PCB) layouts and significantly reduces component count. The resulting EPC91132 reference design inverter measures just 23 mm in diameter when the outer PCB breakout ring is removed, making it compact enough to fit directly inside small motor housings, such as the Vertiq 23-06 drone motor platform.

Performance in Tight Quarters

Despite its diminutive size, the EPC91132 is engineered for high-performance motion applications. The system supports a wide DC input voltage range from 10 V to 60 V. According to performance testing, the integrated EPC33110 module can deliver a steady-state output current of 11 ARMS (16 Apk) and can handle pulsed output currents up to 15 ARMS (21 Apk).

Detailed overview of the EPC91132 board

The use of GaN technology enables the inverter to operate at high switching frequencies exceeding 100 kHz. This high-frequency operation offers several benefits for robotics and drones, including:

• Reduced Passive Component Size: Smaller inductors and capacitors decrease total system volume.
• Enhanced Control: Improved dynamic response and control bandwidth.
• Thermal Efficiency: Minimized switching and conduction losses, essential for applications where space for bulky heatsinks is unavailable.

Comprehensive System-on-a-Board

The EPC91132 is a complete reference design, incorporating all the essential functions required to drive a BLDC motor. Beyond the power stage, the board includes a microcontroller for motor control, regulated housekeeping power supplies, and critical sensing capabilities, including DC bus voltage sensing, current sensing with embedded overcurrent protection, and an onboard magnetic encoder for precision rotor position and speed control.

For system developers, the platform provides real-time monitoring through an RS-485 interface and is fully programmable via a dedicated connector. The board’s flexible design, featuring an optional breakout-ring, allows it to adapt to various form factors, further accelerating the development cycle for next-generation robotic joints and drone propulsion systems. More information can be found in the EPC91132 data sheet.

The EPC91132 evaluation board is currently available for $406.25 through distribution partners including Digi-Key and Mouser. Complete design documentation, including schematics, bill of materials (BOM), and Gerber files, can be accessed via the EPC91132 product page.

All images used courtesy of EPC.