11/19/2022 0 Comments Field oriented control bldc toolEach method produces harmonic artifacts which contribute to acoustic noise. There are several advantages and disadvantages to either control scheme employed to control BLDC motors. How the MCx8316A Chips Reduce Acoustic Noise The result of these two transforms brings direct torque control through the translation of the stator current vector from a three-phase time-variant system to a two-coordinate time-invariant system. Screenshot used courtesy of Texas Instruments The output of the 3-phase inverter produces a sinusoidal signal, which is sampled and fed through a Clarke transform and then through a Park transform.īasic block diagram for field-oriented control. In 120° mode, BLDC drivers will use a High-Z state for the remaining 60° of each cycle.Ĭonversely, the field-oriented control scheme requires significantly more complexity in the transformation of feedback control. The effect of this scheme results in a ripple at every 60° zero phase crossing, which results in harmonics. Consequently, there is no torque produced during the zero crossings of any phase, as seen above. Trapezoidal control operates on a principle where two phases are asserted at any given time. The timing diagram for the trapezoidal control scheme. For sensorless operation, two control schemes emerge. Although more complex, sensorless architectures are the more preferred option. There are two general types of BLDC motors, including Hall effect sensor-driven architectures and sensorless architectures. One family, two chips, and two control schemes, thus it begs the question, what is the difference between trapezoidal control and field-oriented control? Meanwhile, the MCF8316A, which uses a FOC scheme, utilizes automatic deadtime compensation to reduce the harmonic content fed to the motors, thereby reducing acoustic noise in the audible range. Specifically, the MCT8316A supports 120° and 150° modulation, which improves acoustic performance through trapezoidal control schemes. One of the defining features of the MCx8316A family of drivers is its reduction of acoustic noise. Also, these chips are designed for applications in speed-controlled motors requiring 12 V to 24 V BLDC or permanent magnet synchronous motors. The MCT8316A and MCF8316A operate with common electrical parameters, including a 4.5 V to 35 V operating range with up to 8A peak output. With these goals in mind, let's take a look at TI's latest offering. The overall goal of these new chips is three-fold: reducing audible noise sources coming from everyday applications, shrinking the solution board size by up to 70%, and finally, lessening the overall design time for BLDC tuning (potentially down to 10 minutes). These drivers claim to be highly integrated, code-less chipsets that use advanced trapezoidal control and field-oriented control (FOC), respectively.Ī few examples of common noise levels for appliances. To help aid in these noise-related issues, Texas Instruments (TI) is announcing today two new 70 W sensorless BLDC motor drivers, the MCT8316A and the MCF8316A. However, the modulation of BLDC motors can generate acoustic noise, which contributes to ambient background noise, especially with open-concept floor planning being so popular for both the office and home environment. Brushless DC motors (BLDC), replacing AC induction motors, have become increasingly common in applications for general appliances, including fans, air purifiers, washer and dryer pumps, and medical CPAP blowers.
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