Magnetic Angle Sensors with Highest Performance for BLDC ControlsOctober 30, 2014 by Jeff Shepard
Analog Devices, Inc. claims the industryâ€™s highest precision, highest speed magnetic angle sensor. The high-resolution ADA4571 sensor is four times more accurate (0.5 degrees max), 60 percent faster and uses 40 percent less power than competing angle sensors. The ADA4571 directly measures motor position to reduce noise, optimize smoothness and torque performance, and help designers of brushless dc (BLDC) motors meet tighter environmental, noise and energy requirements. The new sensor is automotive qualified and integrates a custom mixed-signal signal conditioning IC and sensing element based on Anisotropic Magneto-Resistive (AMR) technology. The new sensor enables direct, non-contact and wear-free angle measurement in a range of motor applications, including automotive systems such as electric power-assisted steering, braking, active suspension and stability control.
The integrated AMR and precision signal conditioning technology allows the ADA4571 to operate independently of magnet drifts due to lifetime, thermal influences or mechanical stress, which enables high-accuracy readouts in harsh environments. High accuracy position feedback information enables more effective commutation of the motor and better control of torque and speed performance especially in low RPM applications. The new sensor also enables high-speed motor operation up to 50,000 RPM while the direct angle measurement principle reduces the effects of vibration and noise that can degrade motor performance.
Better torque control improves motor efficiency, lowers emissions and heat and extends operating life. Additionally, the low phase delay (2Âµs) enables fast closed loop control and improves responsiveness in high-dynamic applications such as industrial servo motors, robotics and electric power steering.
The ADA5471 runs on a 2.7- to 5.5-V supply, consumes just 6.5 mA of power, and includes a low-power sleep mode that expands application usage to remotely powered systems. Additionally, the sensor does not get damaged under high magnetic field conditions and has negligible hysteresis; while the low temperature and lifetime drift performance reduces or eliminates the need for calibration. The sensor also supports advanced diagnostics for use in high availability and safety critical applications.
ADA4571 Magnetic Angle Sensor key features include: Low angular error of 0.5 degrees maximum; High speed of 50,000 RPM with a 2Âµs phase delay; Low noise of 500 uVrms; Low power of 6.5 mA; and -40 degrees C to 150 degrees C operation. The ADA4571 is delivered in an 8-lead SO package and costs $1.98 in lots of 10,000. It is available for immediate delivery.