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Brushless DC Motor Driver

This document describes a sensorless brushless DC motor driver circuit that uses a DRV10866 driver IC to control the speed of a small BLDC fan motor without position sensors. The circuit uses a NE555 timer IC to generate a pulse-width modulated signal that is fed to the DRV10866 IC to control the motor speed by varying the duty cycle. A 150-degree sensorless back EMF scheme is employed for commutation. The circuit provides a simple and low-cost way to control a BLDC motor without needing position sensors.

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357 views3 pages

Brushless DC Motor Driver

This document describes a sensorless brushless DC motor driver circuit that uses a DRV10866 driver IC to control the speed of a small BLDC fan motor without position sensors. The circuit uses a NE555 timer IC to generate a pulse-width modulated signal that is fed to the DRV10866 IC to control the motor speed by varying the duty cycle. A 150-degree sensorless back EMF scheme is employed for commutation. The circuit provides a simple and low-cost way to control a BLDC motor without needing position sensors.

Uploaded by

kvamsee112
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Brushless DC Motor Driver

Use of brushless DC motors (BLDCs) is on the rise. But their control usually requires rotorposition information for selecting the appropriate commutation angle. Normally, a Hall Effect
sensor is used to sense rotor position. But in cost-sensitive applications, a sensor-less
commutation scheme is often desirable. The circuit described here uses a DRV10866 driver
IC to drive a small BLDC fan, without using any position sensors. A BLDC fans speed can be
varied smoothly, without the usual steps associated with a normal AC fan.
Circuit and working
Fig. 1 shows the circuit of a sensor-less BLDC motor driver. The circuit is built around an
NE555 (IC1), a DRV10866 (IC2) and a few other components.

Fig. 1: Circuit of brushless DC motor driver

Fig. 2: An actual-size, single-side PCB for the


Fig. 3: Component layout for the PCB
brushless DC motor driver
Download:http://www.electronicsforu.com/electronicsforu/circuitarchives/my_documents/m
y_files/Brushless_DC_Motor_Driver.zip
DRV10866 driver IC from Texas Instruments is used to
drive a small three-phase BLDC motor (M1). The circuit
is of a three-phase, sensor-less motor driver with
integrated power MOSFETs having drive-current
capability up to 680mA peak. DRV10866 is specifically
designed for low noise and low component-count fanmotor drive applications. A 150 sensor-less back emf
scheme is used to control the three-phase motor.
A 100k pull-up resistor (R2) is used at pin 1 of IC2. Pins
2, 4, 7 and 6 of IC2 are connected to common, phase A,
phase B and phase C of the BLDC motor, respectively.
Pin 10 of IC2 is connected to pin 7 of IC1 to get the
pulse-width modulated (PWM) signal from IC1 to control
the speed of the BLDC motor.
The output signal (PWM) is available at IC1s pin 7 (DIS)
and not from the usual output pin 3 of the IC. The 25kHz
(approx.) PWM signals duty cycle can be adjusted from
5% to 95% using potentiometer VR1. The speed of the BLDC motor can be controlled by
varying the duty cycle of the PWM signal. Turning VR1 counter-clockwise lowers the duty
cycle which, in turn, lowers the speed of the motor, and vice versa.
Construction and testing
An actual-size, single-side PCB for the brushless DC
motor driver is shown in Fig. 2 and its component layout
in Fig. 3. Assemble the circuit on the recommended PCB
to minimise assembly errors. IC2 should be fitted on
solder side of the PCB.
After assembling the components, connect a 5V DC
supply to CON1 connector. To test the circuit for proper

functioning, verify correct 5V supply for the circuit at TP1 with respect to TP0. Turn VR1
clockwise or counter-clockwise to increase or decrease the speed of the motor.
The author is a B.Tech (electronics and communication) from GGSIPU, New Delhi

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