ESCs for drone and eVTOL motors

An electronic speed controller (ESC), called an inverter or motor controller at higher power, converts the DC power from the battery into the three-phase AC current that drives a brushless motor. It sets the motor speed or torque on command from the flight controller, and protects the motor and battery.

From hobby ESCs to aerospace inverters

At small scale, ESCs are compact boards driven by PWM or digital protocols. Professional drones need controllers that report telemetry, survive vibration and temperature, and fail safely. eVTOL inverters run at hundreds of volts, use silicon carbide (SiC) power semiconductors for efficiency, and are designed with redundancy and certification in mind.

Key specifications

• Voltage range (or battery cell count) and continuous / burst current.
• Control method: trapezoidal control or field-oriented control (FOC). FOC gives smoother, quieter and more efficient operation.
• Command interface: PWM, DShot, CAN (including DroneCAN or CANaerospace) or serial. CAN is preferred in professional systems for its robustness and telemetry.
• Telemetry: current, voltage, rpm, temperatures and fault flags returned to the flight controller.
• Efficiency and cooling: losses become heat; check the cooling assumed by the ratings.
• Protections: over-current, over-temperature, under-voltage and desynchronisation detection.
• Environmental qualification: vibration, humidity and EMC testing, for example to DO-160.

Matching controller and motor

The controller must deliver the motor’s peak current with margin, at the full battery voltage range, and support its pole count and maximum electrical frequency. Many manufacturers specify tested combinations; integrated motor-drives remove the choice altogether. See electric motors and batteries.

Manufacturers in the directory

Examples include KDE Direct and MGM Compro, alongside the inverters that some motor manufacturers supply with their machines.