BLDC Motor ESC Using MOS FET 3-phase or 4-phase BDC Motor Circuit Diagram

Electronic systems that are trustworthy and efficient are increasingly in demand in today’s technological environment. The BLDC (Brushless DC) motor ESC is one such technology that is essential in many applications (Electronic Speed Controller). Robotics, electric vehicles, and many other industries depend on the BLDC motor ESC because it manages the speed and direction of the motor.

BLDC Motor ESC Using MOS FET 3-phase or 4-phase BDC Motor Circuit Diagram

What is a BLDC motor?

A motor type that runs without the use of brushes for commutation is referred to as a BLDC motor, also known as an electronically com mutated motor. BLDC motors use electronic commutation to provide more effective and dependable functioning than conventional DC motors, which depend on brushes and a commutator to flip the current direction in the rotor. In situations where dependability, strong torque, and precise control are essential, BLDC motors are the best option.

What is an ESC?

A motor’s speed and direction are controlled by an electronic device called an ESC, or electronic speed controller. When it comes to BLDC motors, the ESC is essential for driving the motor coils by sequentially switching the current flow. The ESC efficiently controls the timing and amplitude of the current pulses to control the rotational speed and direction of the motor.

In this blog post, I will show you how to build a simple electronic speed controller (ESC) for brushless DC (BLDC) motors using MOSFETs. BLDC motors are widely used in applications such as drones, electric vehicles, fans, and pumps because they have high efficiency, low maintenance, and precise speed control. However, BLDC motors require a special circuit to drive them, as they have three or four phases that need to be switched on and off in a specific sequence.

The basic principle of an ESC is to use a microcontroller to generate pulse width modulation (PWM) signals that control the gate voltage of the MOSFETs. The MOSFETs act as switches that connect or disconnect the phases of the BLDC motor to the power supply. By varying the duty cycle of the PWM signals, the speed and direction of the motor can be adjusted.

The circuit diagram for a 3-phase BLDC motor ESC using MOSFETs is shown below:


The circuit consists of three half-bridges, each composed of two MOSFETs and two resistors. The resistors are used to limit the gate current and prevent damage to the MOSFETs. The microcontroller generates six PWM signals, one for each MOSFET, and sends them to the gate terminals. The PWM signals have a frequency of about 20 kHz, which is high enough to avoid audible noise from the motor.

The circuit diagram for a 4-phase BLDC motor ESC using MOSFETs is similar, except that it has four half-bridges instead of three. The microcontroller generates eight PWM signals instead of six. The 4-phase BLDC motor has more torque and smoother operation than the 3-phase BLDC motor, but it also requires more components and wiring.

To drive the BLDC motor, the microcontroller needs to know the position of the rotor, which is determined by the back electromotive force (EMF) generated by the coils. The back EMF is proportional to the speed of the motor and has a sinusoidal waveform. By measuring the voltage across one of the phases, the microcontroller can detect the zero-crossing points of the back EMF and switch the PWM signals accordingly. This method is called sensorless control, as it does not require any external sensors such as Hall effect sensors or encoders.

The switching sequence for a 3-phase BLDC motor is shown in the table below:

| Phase A | Phase B | Phase C |

The symbols +, -, and Z indicate positive, negative, and floating states respectively. Only two phases are active at any given time, while the third phase is left floating. This reduces the power consumption and heat generation of the ESC.

The switching sequence for a 4-phase BLDC motor is shown in the table below:

Only two phases are active at any given time, while the other two phases are left floating.

I hope this blog post has helped you understand how to build a simple ESC for BLDC motors using MOSFETs. If you have any questions or comments, please leave them below. Thank you for reading!