Ⅰ. Overview of ESC: The 'Power Commander' of multi-rotor drones.
The ESC is a core component of the multirotor drone's power system, connecting the flight controller, motor, and battery. Its main function is to convert the control signals output by the flight controller into current signals that can be recognized by the motor, precisely adjusting the motor's speed to control the drone's flight attitude, speed, and altitude. Without a matching ESC, even with high-performance motors and batteries, the drone cannot achieve stable and efficient flight.
II. Classification of electric adjustment: select the basic type as needed
Power supply method:
- Brushed ESC: Simple structure, low cost, compatible with brushed motors, commonly used in micro toy-grade drones (such as those with a wheelbase less than 150mm).
- Brushless ESC: High power density, good heat dissipation, compatible with brushless motors, is the mainstream choice for consumer and industrial-grade multirotors (wheelbase ≥ 150mm)
Functional features:
- Standard ESC: only supports basic speed adjustment, no special protection features, suitable for beginner practice aircraft.
- ESC with protection features: integrates over-current, over-voltage, low-voltage, and stalling protection, enhancing flight safety, suitable for aerial photography and operational drones.
- Programmable ESC: Supports adjusting startup mode, braking force, and response speed through software, suitable for professional players to customize flight performance.
Installation method:
- External ESC: independently packaged, large heat dissipation space, can be installed flexibly, suitable for drones with multiple motor distributed layouts (such as hexacopters, octocopters).
- Integrated ESC: Integrated with the motor mount/center board, reducing wiring and enhancing space utilization, suitable for small racing drones and mini aerial photography drones (like the design of DJI Mini series).
Ⅲ. Key Points for Core Selection: Accurately match the requirements of the drone.
When selecting an electronic speed controller, you need to focus on the three core aspects of "power matching, performance adaptation, and scenario adaptation," and confirm the following key parameters and characteristics one by one:
1. Current specifications: A key indicator for power matching.
Current is the primary parameter for selecting electric regulators and needs to be considered simultaneously.Continuous current与peak current,Both need to be strictly matched with the motor power and flight scenario.
- Continuous current:The maximum current (in A) for the electronic speed controller to work stably for a long time must be ≥ the actual current when the motor is operating at full load (calculation formula: actual motor current ≈ motor power ÷ battery voltage).
For example: If the motor power is 100W, using a 3S battery (nominal voltage 11.1V), then the actual current of the motor is approximately 100 ÷ 11.1 ≈ 9A, so a speed controller with a continuous current rating of ≥10A should be chosen (reserve 10%-20% margin to avoid overload).
- peak currentThe maximum current that the ESC can withstand in a short period of time must cover the instantaneous peak current during the drone's takeoff, rapid acceleration, and heavy load flight (generally 1.5 to 2 times the continuous current).
Note: If the peak current is insufficient, it is easy to trigger overcurrent protection during takeoff, causing the motor to stop; insufficient continuous current can lead to overheating of the electronic speed controller (ESC), shortening its lifespan or even burning it out.
2. Voltage compatibility: Matching the voltage of the battery and motor.
ESCThe working voltage range needs to be compatible at the same time.Number of battery cells与Rated voltage of the motor,to avoid equipment damage caused by voltage mismatch:
- Voltage parameter notation: common notations such as '6-14S LiPo' indicate support for 6 to 14 lithium polymer cells (each LiPo cell has a nominal voltage of 3.7V, 6S = 22.2V, 14S = 51.8V).
- Matching principle:
- The maximum working voltage of the ESC must be greater than or equal to the fully charged voltage of the battery (for example, for a 3S battery, the fully charged voltage is 12.6V, so the ESC's maximum voltage must be ≥12.6V);
- The minimum operating voltage of the ESC must be less than or equal to the battery discharge cut-off voltage (for example, if the cut-off voltage of a 3S battery is 9V, then the ESC minimum voltage must be less than or equal to 9V);
- The motor's rated voltage must be within the operating voltage range of the ESC (for example, if the motor is labeled "7.4-11.1V", the ESC must support 2-3S batteries).
3. Communication Protocol: Synchronized with flight control signals
ESCThe communication protocol with the flight control system determines the transmission efficiency and response speed of the control signals, and it is necessary to ensure compatibility between the two protocols.
- PWM protocol: Traditional analog protocols have slow signal transmission rates and higher response delays, suitable for entry-level flight controllers and low-speed flight scenarios (such as training aircraft).
- SBUS protocolDigital protocol, supports multi-channel signal transmission, fast speed, strong anti-interference ability, suitable for mid-to-high-end aerial drones.
- DShot protocolA digital protocol specifically designed for brushless motors, with extremely high rates and no risk of signal loss, supporting 'two-way communication', making it the top choice for racing drones and FPV (First Person View) drones.
4. Heat dissipation performance: Ensuring long-term stable operation.
ESCDuring operation, heat is generated due to current conversion. Poor heat dissipation may trigger 'overheat protection', so special attention should be paid to the heat dissipation design.
- Heat dissipation structurePrioritize selecting electronic speed controllers with aluminum alloy heat sinks and hollow shells; the larger the heat dissipation area, the higher the heat dissipation efficiency.
- Installation environment：External ESCs should avoid being blocked by the fuselage or battery, which can obstruct the cooling air vents; integrated ESCs must ensure that the mounting surface has good ventilation, and thermal pads can be pasted on if necessary to enhance heat dissipation.
- Power redundancy：If the flight scenario requires continuous full-load operation for a long time (such as agricultural protection or long-duration aerial photography), it is recommended to choose an electronic speed controller (ESC) with a continuous current rating 20%-30% higher than the calculated value, in order to reduce heating by lowering the load ratio.
5. Size and weight: Suitable for drone space and load capacity.
Multirotor drones are sensitive to weight and space; the size and weight of the electronic speed controller must match the fuselage layout and payload capacity.
- Size adaptationMeasure the space (length, width, thickness) for the installation position of the fuselage motor to ensure that the ESC can be installed smoothly, avoiding interference with the motor, battery, and flight controller.
- Weight controlFor small drones (wheelbase < 200mm), it is recommended to choose lightweight electronic speed controllers (weight 500mm), the weight limit can be relaxed, but it must be included in the total payload (to avoid affecting endurance).
6. Protective functions: Enhance flight safety
High-quality electronic speed controllers must have multiple protection functions to reduce the risk of sudden failures:
- Low voltage protection: off by default (can be customized on).
- High voltage protection: prohibit the motor from starting when the power supply voltage exceeds the allowable value.
- Startup protection: If the startup is unsuccessful, the startup current will be limited, and the startup will be restarted automatically.
- Stall protection: If a stall occurs during normal operation (usually caused by external force), try to restart (note that the stall may damage the ESC when the throtor is high).
- Over temperature protection: When the temperature exceeds the threshold, the maximum output power gradually decreases, down to 40% of full throttle power at most, and it recovers to the original power when the temperature decreases.
- Over-current protection: limit the peak current and do not exceed the limit value.
- Overload Protection: When an overload is identified on the motor, the maximum throttle is limited to protect the powertrain.
- Loss of control protection: 200ms after the loss of signal gradually reduce the output power, in 1~2 seconds for rapid throttle reduction to less than 50%, and then slowly reduce the throttle to stop.
Ⅳ. Purchasing process: Lock in the compatible electronic speed controller in one step.
- Clarify the purpose and configuration of the drone.Determine the type of drone (racer / aerial photography / work drone), motor power, battery cell count, flight control protocol, and calculate the actual working current of the motor (motor power ÷ battery voltage);
- Preliminary screening parameters: Lock 3-5 ESCs based on current (continuous current ≥ calculated value with 10% redundancy), voltage (matching battery cell count), and protocol (matching flight control).
- Verify the details and characteristicsCheck whether the selected electronic speed controller has the required protection functions, whether the heat dissipation structure is suitable for the installation environment, and whether the size and weight meet the restrictions of the aircraft body.
- Refer to user reviews: Check the brand's official website for specifications and user reviews on e-commerce platforms (focus on 'overheating issues', 'compatibility', 'durability'), and exclude models with common faults;
- Confirm after-sales guaranteeChoose brands that offer a warranty of more than 1 year and support returns and exchanges, to avoid being unable to use the product due to misjudgment of parameters.
V. Frequently Asked Questions (FAQ)
- Q：Will there be a problem if the ESC current is set too high?
A：As long as the voltage matches, a slightly higher current (for example, choosing 15A instead of the required 10A) will not affect usage; instead, it can reduce the load ratio, decrease heat generation, and improve stability. However, excessively high current will increase weight and cost, so a balance of needs is required.
- Q：Can electronic speed controllers from different brands be mixed?
A：It is not recommended to mix and match. Even if the parameters are the same, different brands of electronic speed controllers may have variations in response speed and startup modes, which can lead to inconsistent motor speeds and cause the drone to tilt or become uncontrollable.
- Q：Does the electronic speed controller need to be calibrated? How to calibrate it?
A：When using a new ESC for the first time, it must be calibrated with the flight controller to match the 'throttle range' (ensure that the flight controller's 'minimum/maximum throttle signal' matches the ESC). Specific steps should refer to the ESC manual (usually performed via flight control software or the remote control).
- Q：Why do racing drones prefer DShot protocol ESCs?
A：Multirotors have fast flight speeds and intense maneuvers, requiring the electronic speed controller to quickly respond to flight control signals (such as rapid acceleration and hard braking). The high rate and anti-interference capability of the DShot protocol can prevent "crashes" caused by signal delays.
Ⅵ, Summary
The core of selecting electronic speed controllers (ESC) for multi-rotor drones is 'precise matching'—it must meet the power demands of the motors, adapt to the flight control system, batteries, and airframe layout, while also considering heat dissipation, weight, and safety. Beginners should prioritize brands that offer 'clear parameters and comprehensive protection,' while professional users can customize the parameters of programmable ESCs based on their specific scenarios. By following the principle of 'calculating parameters first, then checking compatibility, and finally choosing quality,' one can select an ESC with high cost-effectiveness and strong stability, ensuring safe flight for the drone.Escort.