What is Electronic Speed Control (ESC) & Its Working

At present, we can observe the electric motors’ speed control all over modern society. So, the list of speed control mainly includes an extensive range of machines which ranges from basic electrical appliances used in a household like in the garage, garden to large industrial plants through pumps, machine tools, conveyor belts, etc. So we can notice that how important and necessary this speed control technique is for several electrical machines. We cannot perform longer without an efficient method to control speed. So, the electronic speed control method is used to control the machinery as well as motors rotational speed. This article discusses an overview of electronic speed control for motors, drones, vehicles, etc.


What is Electronic Speed Control or ESC?

The term ESC stands for “electronic speed control is an electronic circuit used to change the speed of an electric motor, its route, and also to perform as a dynamic brake. These are frequently used on radio-controlled models which are electrically powered, with the change most frequently used for brushless motors providing an electronically produced 3-phase electric power low voltage source of energy for the motor. An ESC can be a separate unit that lumps into the throttle receiver control channel or united into the receiver itself, as is the situation in most toy-grade R/C vehicles. Some R/C producers that connect exclusive hobbyist electronics in their entry-level vehicles, containers, or aircraft use involved electronics that combine the two on a sole circuit board.

Electronic Speed Controller
Electronic Speed Controller

ESC Design

An electronic speed controller can be designed with three essential components like a voltage regulator/ BEC (Battery Eliminator Circuit)), a Processer & the switching includes FETs. The BEC is a separation of the electronic speed control that will transmit power back to your receiver after that to servos.


This also includes one secondary function like when the motor is operated through a battery then the motor gets its smallest voltage, then the BEC will keep some power for the flight control in dangerous situations so the motor doesn’t consume total the power from the battery. At present, the processor is completely enclosed within a single Si semiconductor chip.

The main function of this processor is to decode the data being provided to it from the receiver within the model as well as to regulate the power toward the motor using FETs. In an ESC, this transistor plays a key role by performing all the works. It observes the complete current & voltage of the motor as well as a battery. This transistor works like a switch to control the current flow to throttle the electric motor.

The Function of Electronic Speed Control

An ESC or electronic speed control mainly follows a speed reference signal to change the speed of a switching network of field-effect transistors. The motor speed can be changed by changing the switching frequency or the duty cycle of the transistors.


For BLDC motors, different kinds of speed controls are necessary because this motor speed can be controlled by changing the voltage on its armature. This kind of motor needs a diverse operating rule like the motor speed can be changed by varying the timing of pulses for current transmitted to the different motor windings.

Generally, the Brushless ESC systems make 3-phase AC power such as a variable frequency drive (VFD) to make the brushless motors work. These kinds of motors are more popular due to their power, efficiency, lightweight, longevity as compared to usual brushed motors. BLDC motor controllers are very complex as compared to brushed ones.

The exact phase changes through the rotation of the motor, which can be taken into account using the electronic speed control. Generally, the rotation of this motor can be detected through back EMF, but variations that exist will utilize optical detectors otherwise separate Hall Effect sensors.

In general, the speed controllers based on programming mainly include some options which are specified by the user that permits braking, acceleration, timing & direction of revolution. The reversed motor’s direction can be accomplished by switching any 3 leads of the ESC toward the motor.

Features of an Electronic Speed Control

As we know, an ESC controls the speed of the motor spin of an airplane. It helps a similar purpose as the throttle servo of a glow-powered airplane. It is an edge between the radio receiver of an airplane and the power plant. Electronic speed control will have 3- sets of wires. One wire will plug into the main battery of an airplane. The second wire will have a typical servo wire that plugs into the receiver’s throttle channel. And lastly, a third of the wire is used for powering the motor. The main features of an electronic speed control include a battery eliminator circuit, low voltage cutoff, brake, and to.

Components used in ESC

The components used in ESC mainly include the following

  • Solder pads for the 3-BLDC motor phases
  • Negative (-) LIPO connections
  • Positive (+) LIPO Connection
  • Servo signal or input of the PWM signal
  • GND reference of PWM Signal
  • Solder jumper, for altering the direction of Rotation (CW/CCW)
  • Solder jumper, for varying the type of the PWM input signal
    State LED
Assembly of ESC
Assembly of ESC

Types of an Electronic Speed Controller

There are two kinds of electronic speed controllers based on the specific requirements, you can acquire the exact one existing in RC Models shops such as brushed ESC and brushless Electronic Speed Control.

Types of Electronic Speed Control
Types of Electronic Speed Control

Brushed ESC

Brushed ESC is the first electronic speed controller, which has been around for several years. It is very cheap to use in various RTR electric RC vehicles.

Brushless ESC

Brushless ESC is the modern advancement in technology once it comes to Electronic Speed Controls. It is also a bit more costly. Connected to a brushless motor, it carries more power higher performance as compared to the brushed ones. It can also last a longer period.

Electronic Speed Controller Circuit

The term ESC is frequently used as a contraction for ‘electronic speed controller. The basic function of ESC is to change the amount of power to the electric motor from the aircraft battery based upon the location of the throttle stick. In earlier, speed controllers are mainly used in remote control boats and cars which use a variable resistor with a wiper that was stimulated by a servo motor.

ESC Circuit
ESC Circuit

This technique works reasonably at full throttle as the battery is associated straight to the motor, though at part throttle situations the flow of current through the resistor producing power to be lost in the form of heat. As a model, the aircraft will use most of its time at the portion of the throttle. This is not a very practical means of power control.

Current speed controllers differ the power to the motor by fast switching the power ON and OFF. Here, MOSFET Transistor is used as a switch instead of a mechanical device, and the amount at which it is switched is about 2000 times a second. So, the power to the motor is diverse by changing the amount of ON time, against off time in a specified cycle. Here is the simple ESC circuit with a waveform diagram that may help with the description.

When the MOSFET is switched ON, the current rises as the magnetic field in the windings of the motor increases. When the MOSFET is switched OFF, magnetic energy stored in the windings has to be absorbed by the ESC. By cabling a diode across the motor, we return the energy into the motor as current, which rises down as the magnetic field fails.

ESC Firmware

Most of the modern electronic speed controllers mainly include a microcontroller to understand the input signal & controlling the electric motor properly through an inbuilt program which is known as firmware.

In some conditions, it is achievable to modify the factory in-built program for an alternate. So this can be done by adapting the ESC toward a specific application. Some kinds of ESCs are inbuilt with the upgradeable firmware by the user whereas some types need soldering. Generally, these are sold like black boxes through proprietary firmware.

Electronic Speed Controller for Drone

In most of the drone’s applications, the spread is constantly rising in a different range of applications which ranges from the hobbyist, industrial and commercial & in most superior military applications.
The main benefits of Drones are, they can be operated remotely, so flying over regions is very difficult, inconvenient, or dangerous to attain in person. The commercial applications of the drone are many like monitoring buildings, plants, agriculture, shooting areas & delivery of medicines, packages otherwise essential goods.

Generally, the high-range of drones mainly equipped with BLDC motors but these motors need cautious & continuous speed regulation for the relative direction of revolution. For that, the ESC circuit is responsible. So the ESC design mainly includes the following features.

  • The topology utilized for controlling the motor
  • Compromise among efficiency & cost
  • The kind of battery used on the drone
  • Necessary performance
  • EMC (electromagnetic compatibility) and resistance to interference

In drones, there are two kinds of brushless motors are used like BLDC, BLAC and also called PMSM or permanent magnet synchronous motors. So the choice of motor mainly depends on the preferred control algorithm like trapezoidal otherwise FOC (field-oriented control).

How does an ESC Work?

ESC plays a key role in automobiles by preventing a car from skidding & the vehicle driver from losing his control while driving a vehicle. This technology automatically activates the brakes to help steer the vehicle in the right direction.

It is one of the main active safety systems that are already connected to cars as well as commercial vehicles. In a European country, a maximum number of cars are available with ESC technology. Technology like active safety can prevent disasters from occurring altogether otherwise actively assists the driver to decrease the impact of a crisis. These systems provide the driver extra control in dangerous situations. So, different safety systems frequently monitor the vehicle’s performance & its surroundings.

Choosing the Right ESC

The number one significant consideration to keep in mind is to match the Electronic Speed Control to the sort of motor you used. Be sure to purchase the correct ESC for the exact motor: brushed ESC is used for the brushed motor, brushless ESC is used for the brushless motor, never vice versa. Usually, apart from the labels, you will directly know that it’s a brushed motor if it has 2-wires. If the motor has three wires, then it is brushless.

For people who are not aware of electronic speed control, most of the models like the RTR RC model are provided with a pre-installed Electronic Speed Control. Most of these are brushed digital units that carry a decent act in their operations. If the RC car comes with analog speed control, which needs a servo to work the swing arm, consider receiving a digital one as soon as you can.

It is also fine to get an ESC with the opposite functionality. This way you will remove all the disturbances and preventions going down from the area of the driver’s stand to recover your RC car every time it becomes stuck in the track.

Applications of ESC

Electronic speed control systems are used in remote control and vehicle applications.

  • Electric cars
  • Electric bicycles
  • Electric aircraft
  • Cars
  • Helicopters
  • Airplanes
  • Boats
  • Quadcopters
  • ESC Firmware

Thus, this is all about an overview of the electronic speed controller. We hope that you have got a better understanding of this concept. Furthermore, any doubts regarding this concept or to implement any electrical projects, please give your valuable suggestions by commenting in the comment section below. Here is a question for you, What is the function of ESC?

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8 Comments

  1. Hey, which voltage of motor that can flying throne?

    1. Tarun Agarwal says:

      Hi Michael
      I didn’t get you, please be specify your query so that I can give you answer.

  2. georgios papamichael says:

    Hello
    I have one driil motor 18v what controller does it need? for rc boat?

    1. Tarun Agarwal says:

      Hi Georgis
      That depends on the current draw of your motor, and it is not possible for us to suggest the controller.

  3. Constantinescu says:

    Hi, I have a Turnigy ESC from an old Quadrocopter which I want to use as a triphase AC generator. Unfortunately it is impossible to obtain any AC from the ESC if it is not connected to a brushless motor.
    I should be very indebted to you if you would let me know :
    a) which are the initialisation tests of the ESC
    b) how to avoid the necessity of having connected a motor
    Yours sincerely, Georges

  4. Waleed Raza says:

    Perfectly explained, easy to understand, thanks alot!

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