BLDC Driver

BLDC drivers control motor commutation and help ensure smooth, efficient operation. They are used in everything from HVAC systems to consumer electronics and medical devices.

Integrated BLDC drivers combine driver circuitry, power MOSFETs and current sensing capabilities in an IC package. They are compact in size and offer a one-stop solution for your commercial or industrial application.

Integrated BLDC drivers

Unlike AC induction or brushed DC motors, which can be controlled using simple adjustments to the supply voltage, BLDC motors require precise timing of coil energization bldc driver for speed and torque control. This requires supervisory circuits that ensure correct motor commutation. They also must guard against overload and other faults.

Integrated BLDC drivers reduce system component count and complexity by integrating key functions into a single chip. These drivers provide a complete solution for brushless DC motors that are used in a wide range of applications including power tools, pumps, fans, and e-bikes. These drivers have a number of selectable input modes, including PWM and enable inputs, HS and LS inputs, and Hall-Signal inputs. They also offer 100% duty cycle operation, robust protection functions, and integrated current sensing amplifier functionality.

One of the main attributes of a BLDC motor is its responsiveness and quick acceleration. These advantages make it the choice for many consumer electronics, including cooling fans, cordless power tools, and turntables. They work by dividing a full rotation into a series of smaller rotary motions called steps. The motor rotor is then sequentially driven to walk through each of these steps, which is what makes the motor so responsive and quick to accelerate. Compared to stepper motors, BLDC motors are also more reliable and have longer life spans.

Sensor-based BLDC drivers

BLDC motor drivers provide precise control over speed, torque and direction in a variety of applications. From industrial automation and electric vehicles to HVAC systems, consumer electronics, and medical devices, BLDC motors offer efficient and reliable motor control solutions.

Unlike traditional brushed DC motors, which rely on physical brushes and commutators to transfer current between the rotor windings and stator, BLDC motors use electronic commutation to switch current from one phase to another. They also require sensors to detect the rotor position and feedback this information to the motor controller. Sensor-based BLDC drivers are critical in these motor control systems and are available with various configurations to meet performance requirements.

Hall effect sensors, for instance, are a popular choice for sensor-based BLDC drivers. They are simple and cost-effective, making them easy to implement in advanced motor control systems for EVs and other automotive solutions.

Besides providing the motor with a stable speed, sensor-based BLDC drivers also ensure that each of its six phases provides a constant amount of torque. They do this by switching power between the phases in a six-step commutation sequence. During each step, the current flowing through one phase will be interrupted for a short time before it is switched to another. This process is known as back emf, and it is what creates the torque that drives the motor.

Trapezoidal BLDC drivers

The BLDC motor is the most common type of DC motor, used in a wide variety of applications. It is very efficient, has a high torque-to-volume ratio, and uses little primary energy. In addition, a BLDC motor requires little maintenance. There are two major types of commutation methods for a BLDC motor: trapezoidal and sinusoidal. Both techniques have different effects on the motor back electro magnetic force waveform and rotor position sensing, but they are comparable in terms of power utilization.

Trapezoidal commutation uses the induced voltage to estimate rotor position. However, this technique requires a high-resolution shaft-position sensor and may have low efficiency below a certain speed. The commutation method can also cause a significant amount of noise and vibration. Sinusoidal commutation eliminates this problem by driving the motor with currents that vary smoothly. These currents, referred to as IR, IS, and IT, create a smooth rotating current space vector.

The control circuit is the brain of a BLDC driver. It generates commands that are followed by the power circuit, which consists of power switching devices (MOSFETs or IGBTs). The power circuit switches the currents in each phase to energize the proper windings. The resulting induced voltage is the motor back EMF waveform, which varies with each turn of the motor. BLDC drivers can use either edge-aligned or center-aligned PWM signals to control the phase currents.

Sinusoidal BLDC drivers

A BLDC motor overcomes the need for mechanical brushes by electronically switching current to and from the permanent magnet rotor motor driver assembly. This is called commutation, and it is performed by a six-MOSFET bridge controlled by pulse-width modulation (PWM). The rotor position is sensed using Hall sensors or more sophisticated encoders and used to determine the sequence in which the motor windings are powered.

Compared with 120-deg commutation linear-current driving, sinusoidal commutation provides superior control accuracy, efficiency, and noise performance. However, implementing sinusoidal commutation requires more complex algorithms and an external digital computation device like a microcontroller. To help make sinusoidal control less daunting, TI offers a suite of integrated motor driver and controller chips that combine the control logic and power electronics in a single device.

The key difference between sinusoidal PWM and Space Vector Pulse-Width Modulation (SVPWM) is how they compare a reference voltage signal to the triangular carrier. Both generate the same phase current, but SVPWM applies it to each of the three phases independently. This is a key distinction for sensorless systems, which cannot directly measure the BEMF and must rely on estimates of the motor speed and rotor position. At startup, the motor must first start accelerating in open-loop mode until the estimated BEMF feedback is large enough to enable closed-loop control. At this point, the controller is able to synchronize the windings and begin driving them in the correct sequence.

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