Bldc tool move motor
As AMR technology is not dependent on the field strength, it is tolerant to variations in the air gap. In this configuration, a direct rotor angle reading is realized without contact between the mechanical and electrical components. The magnet provides a magnetic field that passes through the plane of the sensor. BLDC systems with ADA4571 (a) end of shaft system (b) off-axis system.Ī typical end of shaft configuration includes a diametrically magnetized disc magnet mounted to a rotating shaft, such as inside the motor assembly shown in Figure 3 (a). A simplified picture of how an AMR sensor works can be seen in Figure 1.įigure 3. The resistance is a maximum when the external field and current direction are parallel and a minimum when the applied field is perpendicular to the plane of the current carrying permalloy.
An AMR sensor operates in magnetic saturation, and thus the contribution of the external magnetic field dominates the resistance change. The sensor is typically deposited as a thin film permalloy (a magnetic iron-nickel alloy). AMR TechnologyĪ sensor based on the AMR principle is one where the material resistivity depends on the orientation of magnetization with respect to the direction of the current.
With a production tested maximum angular inaccuracy of 0.5° over the extended operating temperature range of −40☌ to +150☌, built-in diagnostics, large output levels, EMC protection, and low offset drift, the ADA4571 is an ideal sensor to realize high performance BLDC motor control with speeds in excess of 25,000 RPM.
This makes it possible to realize a very small sensor subsystem and offers opportunities for positioning the sensor within the motor assembly.Īnalog Devices has partnered with the leader in MR technology, Sensitec GMBH, to offer the ADA4571, which integrates a high precision AMR sensor with a high performance instrumentation amplifier in a single package. With an AMR sensor, high angular accuracy is achieved, and a single sensing element can be integrated with the electronic circuit in the same package. In addition, the sensors are not collocated, leading to potential space and mounting challenges.Īn alternative approach is to use an inexpensive, yet precise, angle sensor based on anisotropic magnetoresistive (AMR) technology. In this case, resolution is achieved, and three signals need to be monitored. Other solutions, such as utilizing three Hall effect sensors to detect the position of the motor’s magnets, are often used in cost sensitive applications. A sensorless approach can also be used to sense back EMF currents, reducing sensor weight and cost, but motor start-up performance can be problematic because there is no back EMF generated and thus no position data available. In a typical resolver-based system, the resolution and accuracy can be very high, but the end solution can be expensive and bulky, due to the physical footprint of the resolver itself. The Role of Angle Sensors in BLDC Motor Controlįor accurate control and high efficiency commutation of the motor, high resolution current and rotary position information is critical. With the automotive industry driving toward optimum fuel efficiency, BLDC motors enable on-demand performance and help to reduce engine load in powertrain, power steering, and HVAC (heating, ventilation, and air conditioning) systems, in addition to starter motors/generators and multiple variations of pumps (water/fuel/oil). In the automotive sector, BLDC motors have been used to replace hydraulic actuators and brushed motors in order to reduce weight/size, extend operating life, lower maintenance cost, and boost overall system performance and efficiency. Because of these benefits, BLDC motors are making their way into a host of existing and new applications. In addition, given that BLDC motors are commutated electronically, it’s easier to control torque and speed parameters throughout the speed range of the application, as well as gain more complex control, like maintaining a holding torque or speed limitation. Some of the key benefits of using BLDC motors include: higher power and thermal efficiency, improved space/weight efficiency, higher reliability (brushless), and safer to operate in dangerous environments (no brush dust or sparks generated, as in brushed motors). In recent years, there has been a significant move to replace ac motors or mechanical pumps with high efficiency, brushless direct current motors (BLDC) in many end markets and applications.
#Bldc tool move motor pdf#
Mark Donegan Download PDF The Move to BLDC Motors New Sensor Developments Drive BLDC Motor Control Performance