FOC vs Trapezoidal ESC: Which Should You Use?

An electronic speed controller (ESC) turns the signal from your flight controller into the three-phase power that spins a brushless motor. There are two common ways to do that: trapezoidal (also called six-step) commutation and field-oriented control, usually shortened to FOC.

How trapezoidal control works

A trapezoidal ESC switches current between pairs of motor windings in six steps per electrical revolution. It is simple, well understood and widely used, and it can deliver high current at a sensible size. The current waveform is not perfectly smooth, which can cause some torque ripple, audible noise and extra heat, particularly at low speeds.

How FOC works

FOC measures the motor’s phase currents and rotor position and drives the windings with smooth, sinusoidal currents. In general, that gives quieter operation, smoother torque, and good efficiency across the speed range, and it makes features such as fast, precise throttle response and rich telemetry easier to provide. The trade-off is a more complex controller.

Which one should you choose?

• Choose FOC for mid-size and large multirotors where smooth torque, efficiency, and telemetry over CAN are important. Our FOC ESCs start with the RD A-Series ESC 60A (30 A continuous, 60 A peak) and go up to the RD A-Series ESC 150A (75 A continuous, 150 A peak), all for 6S to 12S packs (the RD A-Series ESC 120A also supports 4S).
• Choose trapezoidal when you want a proven, simple drive for PWM or DShot flight controllers. Our trapezoidal ESCs range runs from the RD S-Series ESC 25A for 2S to 6S small drones to the RD Q-Pro V2 ESC 120A with a 120 A peak for 4S to 12S systems.

Read the ratings carefully

Whichever type you choose, look at the continuous current, the peak current and the time the peak can be held. Those figures depend on cooling. The datasheet for the A-Series FOC range, for example, states test conditions of around 30 °C ambient with 12.5 m/s of airflow. Our ESC sizing guide explains how to leave a safe margin.

Browse all of our UAV ESCs, or read how to choose a drone motor and propeller to size the full set.

Need help choosing? Email [email protected] with your take-off weight, battery voltage and number of motors, and the Reflex Drive team will suggest a matching set. Reflex Drive is a brand of Sunmint Electronics LLP, and all of our products are designed and manufactured in India.

Amrit RD