The core function of a FPV ESC is to receive control signals from the flight control system (such as signals of protocols like PWM, Oneshot, Multishot, Dshot) and adjust the current or voltage output to the motor through internal circuits, thereby precisely controlling the motor speed. Its internal structure mainly includes:
- Microcontroller: Acting as the "brain", it is responsible for parsing flight control signals and generating control commands;
- Gate driver: Amplifies the low-voltage signal from the microcontroller to drive power devices;
- MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor): Serves as a power switch to control the supply current of the motor;
- Battery Elimination Circuit (BEC): Some ESCs integrate this circuit to provide stable power for low-voltage devices such as flight controllers and receivers.
These components work together to achieve precise speed regulation of brushless motors. For example, common models like the Afro Race Spec 20A ESC are designed based on this principle.
To ensure a good match between the motor and ESC and stable output, calibration is a key step. Taking the PX4 flight control system as an example, for ESCs of different protocols (such as PWM ESC and OneShot ESC), the calibration process usually includes:
- Meeting prerequisites, such as ensuring sufficient battery power and correct wiring between the motor and ESC;
- Following the guidance of the flight control software to gradually complete steps such as throttle stroke calibration and voltage detection;
- Conducting tests after calibration. If problems such as abnormal motor noise or speed occur, it is necessary to check the wiring or recalibrate.
Proper calibration can effectively avoid issues such as insufficient motor power and UAV flight deviation.
The design of ESC needs to balance performance and reliability, with core key points including:
- Selection of control algorithms: Trapezoidal control is suitable for low-cost scenarios, while Field-Oriented Control (FOC) can provide smoother speed regulation and higher efficiency;
- Decision on system type: Open-loop control has a simple structure but low precision, while closed-loop control (combined with sensor feedback) can improve stability;
- Reference for hardware schemes: Manufacturers such as Texas Instruments and STMicroelectronics provide mature reference designs, including circuit block diagrams and core chip selection, which help simplify the development process.
In addition, open-source projects (such as BLheli) provide developers with rich firmware and hardware design materials, facilitating customized development.
Different types of UAVs have significantly different parameter requirements for ESCs:
- Small quadcopters (such as MJX Bugs 3) often use small ESCs around 20A, focusing on lightweight;
- Fixed-wing UAVs or high-power models require ESCs with higher power (such as 60KW UAV motor speed controllers) to meet the needs of high-load flight.
In terms of resource acquisition, multiple platforms provide abundant materials and resources:
- Technical blogs (such as CSDN, Sohu Network) elaborate on the principles and calibration methods of ESC;
- E-commerce platforms (such as Amazon) offer various ESC products adapted to different models;
- Design communities (such as Lichuang Electronic Design Competition, Mufeng Network) share ESC schematic diagrams, physical pictures, and drawing downloads, providing references for research and development as well as maintenance;
- Image material websites include physical pictures of ESC products, which can be used for document or demonstration production.
In summary, as a core component of the FPV power system, the performance and reliability of ESC directly affect the flight effect. Understanding its principles, calibration methods, and design key points, and making rational use of various resources, is helpful for better selection, use, and development of ESC, providing a guarantee for the stable flight of FPVs
