Full analysis of drone electric adjustment: from core principle to future trend
1. What is the "power heart" of a UAV —— electric control?
The electronic speed controller (Electronic Speed Controller, abbreviated as ESC) is the core hub of a drone's power system. It functions like a car's transmission, converting the battery's DC power into the three-phase AC power required by the motor, and precisely controlling the motor speed by receiving commands from the flight control system. In quadcopter drones, the relationship between the ESC, motor, and battery is particularly critical: the ESC receives PWM signals from the flight control (similar to the logic of a faucet switch), adjusting the duty cycle to achieve linear regulation of the motor speed from 0% to 100%, thereby controlling the drone's flight attitude, speed, and direction.
2. In-depth disassembly of the working principle of electric adjustment
Energy conversion mechanism
The core function of the motor controller is to convert the battery's direct current (DC) into three-phase alternating current (AC) required by the motor. This process is achieved through an inverter composed of six MOSFET power transistors, which works similarly to "cutting" the DC into pulses of different frequencies. For example, when the flight control sends a 1ms PWM signal with a pulse width, the motor controller outputs an AC signal with a 50% duty cycle, driving the motor to operate at 50% power.
Intelligent control algorithm
Modern electronic speed controllers typically feature microcontrollers like the ARM Cortex-M0, equipped with built-in PID speed control algorithms. Taking a racing drone as an example, the controller adjusts the P value (proportional coefficient) in real-time based on throttle changes, achieving a maximum response time of 0.1 seconds; meanwhile, it uses the D value (derivative coefficient) to suppress current surges during motor startup, preventing overloading of the power system.
Multiple security protection
1. Overcurrent protection: When the current exceeds 1.2 times the rated value (for example, 60A electric adjustment trigger threshold is 72A), the electric adjustment will cut off the output within 200 microseconds.
2. Overheat protection: NTC, thermistor real-time monitoring MOSFET, temperature, when exceeds 85℃, automatically reduce power operation.
3. Overrun protection: After detecting the loss of PWM signal for more than 1 second, the electric control will execute the logic of hovering or returning to avoid the crash of the UAV.
3. Classification and selection logic of electric adjustment
Classified by motor type
4. Brushed electric tuning: simple structure (only 2 control lines), low price (about 20-50 yuan), but low efficiency (only 60-70%), suitable for toy drones.
5. Brushless electric tuning: using three-phase inverter technology, the efficiency can reach more than 90%, supporting dynamic braking and precise speed control, is the standard of professional drones. For example, DJI Mavic 3 Pro uses 40A brushless electric tuning, which can complete the response from 0 to 100% throttle within 200ms.
Classified by degree of integration
6. Single electric control: each motor is independently controlled, with low maintenance cost (about 100 yuan for single electric control), but the wiring is complex (four quadcopters need 4 electric controls).
7. Four-in-one electric tuning: four electric tuning is integrated into one module, reducing the weight by 30% (about 150g), but the whole needs to be replaced after damage (cost about 500 yuan).
Key parameter selection guide
parameter | explain | Suggested selection |
Dynamic current | The maximum current that the electronic switch can work stably (such as 60A) should match the maximum working current of the motor | Select the continuous current as 1.2-1.5 times of the rated current of the motor |
Peak point current | The maximum current that can be tolerated in a short time (such as 120A) affects the burst force | For racing drones, it is recommended to choose a peak current that is twice the continuous current |
BEC output | The 5V/3A power supply for the flight control needs to match the power consumption of the flight control | To avoid overload caused by multiple devices sharing the BEC, it is recommended to use a separate BEC module |
Support battery number | The number of lithium batteries that the inverter can adapt to (such as 2S-6S) affects the voltage and speed range | The KV value of the motor is selected. For example, when the KV1000 motor is paired with a 4S battery, the no-load speed can reach 40,000 RPM |
4.Fourth, the cutting-edge technology and industry trend of electric tuning
Materials and process breakthroughs
8. Silicon carbide (SiC) MOSFET: Switching loss reduced by 70%, temperature resistance up to 150℃, making high power electric tuning above 200A possible. For example, DYS HD200 electric tuning uses SiC technology, efficiency increased by 8-10%, suitable for racing drones.
9. Three-dimensional heat dissipation design: ROCK 120A-H electric adjustment through fin array and embedded air duct, the temperature rise is reduced by 10℃, and it can operate stably under continuous current of 70A.
Intelligent and integrated
10. AI algorithm embedding: Some electric tuning (such as ROCK series) can predict motor load changes through machine learning, dynamically adjust PID parameters, and reduce attitude jitter during flight.
11. Integrated design: Matek F722-Wing and other products integrate the electric adjustment, BEC and flight control in one module, reducing the size by 40% and the wiring complexity by 50%.
High pressure and energy efficiency improvement
High voltage systems above 24S have become mainstream, and high KV motors can achieve high speed flight. For example, ROCK 220A-H electric control supports 26S battery, which can push a 30kg class UAV to cruise at 80km/h when equipped with a 15-inch propeller.
5. Installation and maintenance of electric adjustment and common problems
Installation points
12. Wiring specification: The power cable should be above 12AWG to avoid excessive length resulting in voltage drop (line resistance per meter ≤0.01Ω).
13. Thermal optimization: attach a thermal silicone sheet to the bottom of the electric switch and ensure that the air duct is unobstructed (such as the reserved air inlet of the UAV rack).
14. Firmware upgrade: New features (such as support for the DShot1200 protocol) can be unlocked by updating the firmware through parameter tuning software (such as BLHeliSuite).
troubleshooting
15. Motor does not rotate: check whether the electric tuning has received PWM signal (measure the signal line with oscilloscope), or whether MOSFET has broken down (measure the diode with multimeter).
16. Overheat alarm: Clean the dust on the heat sink, or replace the electric regulator with a higher current specification (such as upgrading the 60A electric regulator to 80A).
17. Abnormal noise: Adjust the PWM frequency (such as from 40kHz to 80kHz), or check the motor dynamic balance.
6. the selection strategy of electric adjustment in different application scenarios
scene | characteristics of demand | Recommend the model of the electric switch | key parameter |
aerial photo | Low noise, long endurance | Good Ying Le Tian 30A | Continuous 30A, supports DShot600 |
compete for speed | High explosive power, quick response | T-Motor F40 Pro | Continuous 40A, peak 80A,100kHz PWM |
Agricultural plant protection | Heavy load, resistant to harsh environment | Dji T100 electric tuning | Continuous 100A, IP67 waterproof |
Industrial inspection | High reliability, redundant design | Maide electromechanical dual backup electric control | Dual independent control, support CAN bus |
7. Industry Outlook: From "speed control" to "intelligent control"
In the future, electric adjustment will present three development directions:
1. Full scene adaptation: adaptive parameter adjustment is realized through AI algorithm, such as automatic compensation for the influence of pressure change on motor efficiency in plateau areas.
2. Integrated energy management: deeply linked with battery management system (BMS), real-time monitoring of cell state, and prolonging battery cycle life.
3. Wireless and cloud services: The electric tuning that supports 5G communication can upload flight data to the cloud to achieve remote fault diagnosis and performance optimization.
8.Conclusion
From toy drones to industrial-grade aircraft, the electronic speed controller has always been at the heart of the power system. With breakthroughs in silicon carbide materials, AI algorithms, and high-voltage technology, the electronic speed controller is evolving from a simple "motor controller" into an intelligent decision-making "power brain." For drone enthusiasts, gaining a deep understanding of how electronic speed controllers work and the logic behind their selection can not only enhance the flying experience but also lay the foundation for exploring complex mission scenarios.
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