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Speed control of BLDC motor using H Infinity Controller in MATLAB

Speed control of BLDC motor using H Infinity Controller in MATLAB

This video explains the how to design H infinity controller for speed control of bldc motor in matlab simulink.

Speed Control of BLDC Motor Using H Infinity Controller in MATLAB

Introduction to BLDC Motors

BLDC motors are electric motors that are widely used in various applications such as robotics, automotive systems, and industrial automation. Unlike conventional DC motors, BLDC motors do not have brushes, which results in reduced maintenance requirements and improved efficiency. BLDC motors are known for their high torque density, fast response, and precise speed control capabilities.

Understanding Speed Control in BLDC Motors

Speed control is a crucial aspect of BLDC motor operation, as it allows us to regulate the motor's rotational speed based on the desired application requirements. By controlling the motor's speed, we can achieve accurate positioning, maintain constant speed, and ensure smooth operation. Various control techniques are used to achieve speed control in BLDC motors, and one such technique is H Infinity control.

Introduction to H Infinity Control

H Infinity control is a robust control technique used to design controllers for systems with uncertainties and disturbances. It provides a systematic approach to handle uncertainties and achieve desired performance specifications. In the context of BLDC motor control, the H Infinity controller aims to regulate the motor's speed while considering the uncertainties in the motor dynamics, variations in the load, and external disturbances.

Advantages of H Infinity Control for BLDC Motors

Implementing an H Infinity controller for speed control in BLDC motors offers several advantages. Firstly, it provides robustness against uncertainties and disturbances, ensuring stable operation even in challenging operating conditions. Additionally, H Infinity control allows for better disturbance rejection, improved tracking accuracy, and reduced sensitivity to parameter variations. These advantages make the H Infinity control technique suitable for applications that require precise speed control and high-performance operation.

Mathematical Modeling of BLDC Motors

Before designing the H Infinity controller, it is essential to have a mathematical model of the BLDC motor. The mathematical model describes the motor's behavior and allows us to analyze its dynamics and design appropriate control strategies. The mathematical model typically consists of equations representing the electrical and mechanical characteristics of the motor.

Designing an H Infinity Controller in MATLAB

MATLAB provides a powerful platform for designing and simulating control systems. To design an H Infinity controller for the BLDC motor, we can utilize MATLAB's control system toolbox. The toolbox offers various functions and tools for controller design, analysis, and simulation. By specifying the desired performance requirements and system model, MATLAB can assist in designing an effective H Infinity controller.

Simulation and Analysis of the BLDC Motor Control System

Once the H Infinity controller is designed, it is crucial to evaluate its performance through simulations. MATLAB enables us to simulate the complete BLDC motor control system, considering the controller, motor dynamics, and external disturbances. Through simulation, we can analyze the system's response, evaluate the controller's effectiveness, and make necessary adjustments if required.

Performance Evaluation of the H Infinity Controller

The performance of the H Infinity controller can be evaluated based on various metrics such as speed tracking accuracy, disturbance rejection capability, and stability. MATLAB's simulation capabilities allow us to analyze these performance metrics and assess the effectiveness of the controller. By fine-tuning the controller parameters and conducting performance evaluations, we can optimize the speed control of the BLDC motor.

Comparison with Other Control Techniques

In the field of BLDC motor control, several other control techniques are available, such as Proportional-Integral-Derivative (PID) control and Sliding Mode control. It is essential to compare the performance of the H Infinity controller with these techniques to determine its superiority. MATLAB provides the flexibility to implement and compare different control strategies, enabling engineers to choose the most suitable technique for their specific application.

Practical Implementation Considerations

When implementing the H Infinity controller in a real-world BLDC motor system, several practical considerations must be taken into account. These include sensor selection, noise filtering, hardware limitations, and system integration. MATLAB allows for the seamless transition from simulation to real-time implementation by providing tools and resources for hardware-in-the-loop testing and code generation.


In conclusion, the implementation of an H Infinity controller in MATLAB offers a robust and efficient solution for speed control in BLDC motors. The H Infinity control technique provides stability, robustness, and improved performance in the presence of uncertainties and disturbances. By leveraging MATLAB's control system toolbox and simulation capabilities, engineers can design, evaluate, and optimize the H Infinity controller for their BLDC motor applications, ensuring precise speed control and reliable operation.


Q1: Can I implement the H Infinity controller in any BLDC motor system?

Yes, the H Infinity controller can be implemented in various BLDC motor systems, as long as the system dynamics and parameters are adequately modeled.

Q2: Is MATLAB the only platform for designing an H Infinity controller?

While MATLAB is a popular choice for control system design, there are other software tools available for designing H Infinity controllers, depending on the specific requirements and preferences of the engineer.

Q3: How can I determine the performance requirements for the H Infinity controller?

The performance requirements for the H Infinity controller can be determined based on the desired speed accuracy, disturbance rejection capability, and stability criteria specific to the application.

Q4: Can I use the H Infinity controller for torque control in BLDC motors?

The H Infinity control technique primarily focuses on speed control, but it can be extended to incorporate torque control by modifying the control objectives and system modeling.

Q5: Where can I find additional resources to learn more about H Infinity control in MATLAB?

To learn more about H Infinity control in MATLAB, you can refer to MATLAB's documentation, online tutorials, and academic research papers on control system design.

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