FOC Control of BLDC Motor: Intelligent and Self-learning

FOC in bldc motor control stands for Field Oriented Control [also known as vector control]. This article explains FOC control technology and how CJC's control algorithm optimizes bldc motor performance.

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BLDC motor motion control technology advances closely link to the use of FOC control. This article explains the main features of FOC control of BLDC motor. It covers intelligent algorithms, automatic PID configuration, and precision PID simulation algorithms in a simple way for readers to understand.

I. Glance at FOC Control of BLDC Motor

CJC BLDC motor Controller

Field Oriented Control(FOC) is an advanced motor control technique that optimizes efficiency and performance of BLDC motor. FOC control is essentially a brain of Brushless DC (BLDC) motor for controlling position and velocity. It uses advanced algorithms to precisely control the motor's correspondence to the position and movement. FOC achieves this by precisely aligning the motor's electromagnetic field with the rotor's axis. This fine-tuned control translates to:

  • Increased Efficiency: foc control of bldc motor minimizes wasted energy, leading to longer battery life or lower power consumption for the application that use bldc motor.
  • Improved Performance: FOC delivers smoother torque and faster response to changes in speed or load, resulting in more precise bldc motor control.

II. CJC's Unique FOC Control Intelligent Algorithm of BLDC Motor

Intelligent Vector Control Algorithm for BLDC motor Efficiency

BLDC motor controller utilizes intelligent Field-Oriented Control algorithm can achieve superior motor performance. By precisely measuring the motor's state (current and position)  our self-developed FOC algorithm intelligently adjusts motor input for optimized efficiency, simplified tuning, and faster response times. Notably, the control algorithm can automatically match bldc motors within a mere 10 seconds, adapting to different motor parameters through methods like line sequence (power, Hall, encoder), and phase learning.

Auto-generating Optimal PID Parameters

CJC MOTOT FOC Auto-generating Optimal PID Parameters:

Automatic PID configuration for BLDC motors: High bandwidth, fast response, stable and reliable

(only takes 0.08 seconds to respond from 0 to full speed step)

Self-Tuning FOC PID Control

CJC's FOC control features a high-performance PID simulation algorithm.

PID control is a widely used technique to adjust a system's output based on the difference between a desired setpoint (target value) and the actual measured value. In BLDC motor control, the setpoint could be the desired motor speed, and the measured value could be the actual motor speed derived from back EMF.

This algorithm simulates different motor operating conditions and loads to automatically generate optimal PID parameters. This eliminates the need for manual PID tuning, ensuring stable and reliable operation. Additionally, the system responds quickly to changes, reaching full speed from a standstill in just 0.08 seconds.

This means the system can evaluate various parameter combinations in a simulated environment to find the most suitable control parameters for the motor.

This mode provides convenience to users and reduces the potential risk of damage due to wiring errors. Instead, the motor’s back electromotive force (EMF) is used to estimate the rotor position. BLDC motors, known for their efficiency and versatility, often rely on sensorless control methods to determine rotor position. One technique leverages the motor's inherent back electromotive force (EMF) for this crucial task.

  • Back EMF Explained: Imagine a spinning conductor (rotor) within a magnetic field (stator) – the core components of a BLDC motor. According to Faraday's law of electromagnetic induction, whenever there's relative motion between the conductor and the magnetic field, a voltage is induced in the conductor. This induced voltage opposes the voltage applied to the bldc motor, hence the term "back EMF".
  • Back EMF and Sensorless Control: The magnitude of back EMF is proportional to the rotor's rotational speed and the strength of the motor's magnetic field. By measuring the back EMF, the BLDC motor controller can indirectly estimate the rotor's position. This eliminates the need for physical position sensors, simplifying motor design and reducing cost.

This method has the advantage of being simpler and less expensive than using a position sensor. In sensored matching, FOC control systems of bldc motor automatically configures Proportional-Integral-Derivative (PID) parameters, offering users a convenient and quick tuning experience while enhancing motor efficiency by optimizing control parameters based on real-time feedback.

Visualization of FOC PID Control Parameters

Visualization of PID Control Parameters

Through controller and the use of precise PID simulation algorithms, the visualization of PID control parameters is achieved. While bldc controller itself does not directly provide the visualization of PID parameters, CJC uses tools that enable users to monitor and analyze the motor’s status graphically, including the impact of PID control parameters. This allows customers to intuitively monitor and analyze the motor’s control status, providing a visual reference for debugging.

III. Advanced Motor Control Self-Learning BLDC Motor Matching

BLDC Motor Control: FOC with or Without Sensors?

BLDC motor controllers leverage Field-Oriented Control (FOC) to achieve optimal performance. FOC comes in two main flavors: sensor-based and sensorless. Sensor-based FOC utilizes an external position sensor (encoder or Hall effect sensor) for precise rotor positioning. This method offers excellent control accuracy but adds cost and complexity.

Sensorless FOC, on the other hand, eliminates the need for external sensors. It estimates rotor position by analyzing the motor's back EMF (electromotive force). This simplifies design and reduces cost. Additionally, sensorless FOC, like the one described here, often features self-learning algorithms. This allows the controller to automatically identify and adapt to different BLDC motors, even if the wiring sequence is incorrect. This flexibility simplifies motor connection and streamlines the user experience.

CJC FOC Control-Automatic Motor Matching in 10 Seconds

10s Automatic BLDC Motor Matching BY FOC

  • Sensor-based Motors: Automatic identification of power, Hall, and encoder wiring order Flexible wiring options for seamless integration.
  • Sensorless Motors: Parameterless operation for simplified setup Automatic wire sequence learning for hassle-free connection.
  • Automated PID Parameter Configuration: Effortless PID parameter optimization for enhanced motor performance.

IV. Unique Weak Magnetic FOC Control

CJC’s comprehensive technical foundation of FOC control of bldc motor makes it widely applicable in various types of motors, including single/dual/three-resistor motors. Its adaptability and flexibility stem from its weak magnetic control characteristics, effectively controlling the motor even in low-speed or light-load conditions, ensuring outstanding performance. This increases the applicability of the motor under different working conditions.

The all-encompassing field oriented control bldc systems, with its intelligent algorithms, self-learning motor matching, and precision PID simulation algorithms, reshapes bldc motor controller and provides unmatched efficiency and ease of tuning.

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