Frequently Asked Questions
What is the difference between an AC Servo and a DC Servo?
A DC servo motor uses a DC Brush motor and PWM control circuitry to vary the current through a single phase. An AC servo motor uses a BLDC motor and controls the motor through sinusoidal currents of three phases. DC servo motors contain brushes and are thus prone to maintenance every 2000 hours of operation where the AC servo motor are brushless motors and thus do not have the maintenance issues. DC servo motors though do not have complex control circuitry required that the three phase AC servo motors need.
What is the primary difference between a Brush DC Motor and a Brushless DC Motor?
Brush DC Motors use commutation brushes which change the direction current flows periodically to maintain torque. Because of brush wear, a Brush DC Motor requires more maintenance and has shorter life than Brushless DC Motors. Instead of brushes, Brushless Motors use Hall Sensors which are placed at the back end of the motor. These Hall Sensors output high-low pulses when they detect a change in magnetic field. For this reason, Brushless DC Motors require the use of more complex circuitry found in Variable Speed Drives (VSD). Also, since Brushless DC Motors do not use brushes for commutation purposes, they are far more efficient, require very low maintenance and have a longer life than Brush DC Motors.
Will Anaheim Automation mount an encoder to a motor?
Yes. First, choose from Anaheim Automation's extended line of stepper and brushless motors. Second, select the appropriate encoder adder part number from our selection of single-ended and differential encoders which can be found in our 'Encoder Adders' section, and add it to the end of your Anaheim Automation motor part number. Its that simple!
Can I order stepper motors with encoders added? How do I go about it?
Yes. Encoders can not only be added to stepper motors, but brushless motors as well. Please refer to our Encoders located under Accessories on our web site. Anaheim Automation offers a line of single-ended or differential incremental rotary encoders. These encoders are available in sizes to cover NEMA 08 to 42 motors. These encoders have the capability to track from 0 to 100,000 cycles per second, with options of 32 to 2,500 cycles per revolution, with or without index features. Encoders are configured as motor adders, for dual shaft motors, or can be purchased separately, located on our Encoder web pages. Encoder cables are available, but also purchased separately.
Anaheim Automation provides many different accessories for our brushless motors. These accessories include a brake, encoder, connector, cable and a driver.
The brushless motors brake is a 24vdc system. These brushless motor brakes are perfect for any holding applications. They are available on any of Anaheim Automation brushless motors, and are already attached to the rear of the brushless motors. The brushless motor brakes have a low voltage design for applications that are susceptible to weak batter, brown out, or long wiring runs. When electric power is applied to the brushless motor brake the armature is pulled by the electromagnet force in the magnet body assembly, which overcomes the spring action. This allows the friction disc to rotate freely. When electrical power is interrupted, the electromagnetic force is removed and the pressure spring mechanically forces the armature plate to clamp the friction disc between itself and the pressure plate.
Brushless motor cables can be made with the supplied brushless motor connector, or can be purchased from Anaheim Automation.
Advantages and Disadvantages for a DC Brushless Motors
Some of the advantages of a Brushless Motors, but are not limited to are:
• Higher speed ranges
• High dynamic response
• Long operating life
• Better speed versus torque characteristics
• Noiseless operation
• High efficiency
Disadvantages for a Brushless Motors
• High cost
• Additional system wiring is required to power the electronic commutation circuitry
• Motion controllers/drivers electronics needed to operate Brushless DC Motors are more complex
Consumer Electronics Although Brushless motors may perform the same functions originally fulfilled by brushed DC motors, cost and control complications prevent Brushless motors from completely replacing brushed motors. However, Brushless motors have monopolized many areas of the consumer electronics industry, and are used in many different locations, including computer hard drives and CD/DVD players. Brushless motors are used to operate the small cooling fans that are located in electronic equipment as well. Cordless power tools also utilize DC Brushless motors because the need for increased efficiency of the BLDC motor allows for long periods of use before needing to recharge the battery. Furthermore, direct-drive turntables for ?analog? audio disks use low-speed, low-power Brushless motors.
Transport Electric and hybrid vehicles use high power Brushless motors that are essentially AC synchronous with permanent magnet rotors. Brushless motors are used in Segway and Vectrix-Maxi-Scooters also. Electric bicycles sometimes build Brushless motors into their wheel hubs, with the stator solidly fixed to the axle and magnets attached to and rotating with the wheel. These electric bicycles have a standard bicycle transmission with pedals, sprockets, and chain that, if needed, can be pedaled along with or without the use of the Brushless motors.
Heating and Ventilation It has become a popular trend to switch from AC motors to Brushless motors (EC) because of the dramatic reduction in power needed o run them, versus the typical AC motor. Although shaded-pole and permanent split capacitor motors were the primary fan motor of choice, many fans today are being run by Brushless motors. Some use Brushless motors simply to increase system efficiency as a whole. Certain HVAC systems use ECM motors (electronically commutated BLDC motors). Particularly these are the HVAC systems that feature load modulation and/or variable-speed. Brushless motors not only have higher efficiency, but also a built-in microprocessor that allows for better airflow control, programmability, and serial communication.
Model Engineering and Hobbyists The most popular motor choice for model aircraft today are Brushless motors. The Brushless motors are available in a wide array of sizes, and have a favorable power to weight ratios. Brushless motors have transformed the market of electric-powered flight. The introduction of Brushless motors has displaced the use of almost all brushed electric motors in model aircraft and helicopters. Modern batteries and Brushless motors allow model airplanes to vertically ascend, versus gradually climb. Small glow fuel internal combustion engines that were used in the past are no comparison to the silent and clean Brushless motors.
Brushless motors have also increased in popularity among the Radio Controlled (RC) cars, buggies, and trucks, where sensor-type Brushless motors allow the position of the rotor magnet to be detected. Many Brushless motors feature upgrades and replaceable parts like sintered neodymium-iron-boron (rare earth magnets), replaceable motor timing assemblies, and ceramic bearings. As a result, these Brushless motors are quickly ascending to the top of the list as far as preferred motor types for electric on and off-road RC racers. Brushless motors have low-maintenance, high reliability and power efficiency ~ most Brushless motors with an efficiency rating of 80% or more.
Brushless Motors have become popular amongst the medical industry for its long-lasting design. Used in medical equipment, Brushless motors have a life expectancy of 10,000 hours, versus the 2,000-5,000 hour lifespan of the brushed motor. Brushless motors also have a top speed that is not limited by a large number of poles. It wasnt until the cost of these Brushless Motors decreased, that they became a viable option for most medical applications. Brushless motors can provide a more efficient, reliable, and compact motor that can be used in a variety of ways.
Basically, Brushless Motors aresynchronous electric motors that are powered by a DC power source. An electric commutation circuit replaces the standard commutator and brush assembly found in the brushed DC motor. Brushless motors and brushed DC motors are essentially polar opposites. While the windings of Brushed DC motors rotate around the rotating shaft or armature, the brushless motors have windings that are attached to the motor housing. The magnets of the Brushed DC Motors attach to the motor housing, while Brushless motors magnets are affixed to the rotor.
Commutation is the process of reversing the polarity of the phase currents in the windings of the motor at an exact time that will produce continuous rotational torque. If commutation did not occur, the magnets and magnetic fields would lock the rotating shaft in place by aligning themselves. The appropriate reversal time is crucial; the shaft of the brushless motors must continue spinning, and it does so as a result of the changing polarity of the windings.
The primary way Brushless Motors and a brushed DC motors differ is in their methods of commutation. Brushed DC motors use brushes and a commutator that acts as an electromechanical switch to connect the windings in the proper polarity. In Brushless Motors, electronic switches take the place of the mechanical switch, controlling the timing of the polarity-reversal by an electrical circuit. Usually, Brushless Motors sense rotor position and controls the electronic drive of Brushless Motors by using Hall-effect devices (HFD). However, because of the ability to monitor motor back-EMF, HFD can be eliminated to create a sensorless Brushless DC motors drive. These motors are far less expensive, and are a primary reason they appeal in medical equipment design.
Sleep Apnea can also be treated with the help of Brushless Motors. Treatment for the disorder requires the use of Positive Airway Pressure (PAP) respirators. The PAP respirator is attached to a special breathing mask that the patient must wear to breathe through while sleeping. Within the respirator is a blower fan that pressurizes the air mask, according to the patients breathing pattern. As the patient inhales, the blower fan speeds up, allowing more air to reach the lungs. Oppositely, when the patient exhales, the blower fan slows down to reduce the amount of air the patient breathes out. Brushless Motors never need to operate underneath the minimum threshold speed of the drive, so they are the perfect power source for blower fans. Furthermore, there is no risk for any sudden changes in load.
Low-noise-level standards force hospital equipment to be as quiet as possible, thus making Brushless Motors a prime candidate due to how silent they are in operation. Brushless Motors can operate at high speeds with accuracy, and yet maintain a silent sound. Therefore, they can be used both in hospitals, and in the patients home. It is the absence of a commutator and brushes in Brushless Motors that removes even more of the motor noise.
Brushless Motors are used in a variety of applications in many different industries. Some of the applications are Appliances, Automotive, Aerospace, CNC, Consumer, Instrumentation, Medical, Packaging Equipment, and Semiconductor.
All Brushless Motors are permanent magnet motors. There are also two basic types labeled as a Trapezoidal Motor and the other as a Sine Wave Motor. The Trapezoidal Motor is said to be a DC servo motor and the Sine Wave Motor has close resemblance to an AC synchronous motor.
The basic definition for Brushless Motors is an automatic device that uses an error-correction routine to correct the motion of the Brushless Motors. The general term Brushless can be applied to systems other than a Brushless Motors that use a feedback mechanism such as an encoder or other feedback device to control the motion parameters. Typically when the term Brushless is used it applies to a Brushless Motors but this term is also used as a general control term with the meaning of a feedback loop to position whatever the item is including a Brushless Motors.
A Brushless Motors are different from other controlled motors in that they are controlled by a time-based derivative commonly referred to as the PID loop. A Brushless Motors are used to control position must be capable of changing the velocity of the output shaft because the time-based derivative, or the rate of change of position, is velocity.
The stator of brushless motors consists of stacked steel laminations the windings are placed in the slots that are cut inside the laminations. The stator of brushless motors is similar to that of an AC motor however the windings are different. Brushless motors have three stator windings connected in either a star or Delta configuration. Each of these windings are constructed from multiple coils connected together to form a winding. Anaheim Automation typically has six coils per brushless motor which are made into a three-phase winding. There is usually an even number of polls
There are mainly two types of stator windings trapezoidal and sinusoidal. The difference is made on the basis of the interconnection of the coils of the stator windings which results in a different type of back EMF the trapezoidal variant gives its back EMF in the shape of a trapezoid. The sinusoidal variation gives its brushless motors a back EMF in the sinusoidal fashion going along with the current the faulted also has the shape of a trapezoid and a sinusoid. The difference between the two brushless motors is that the sinusoidal brushless motor has smoother output torque than that of a trapezoidal brushless motor. The stator will winding can be wound for multiple folk voltages. This can be customized for almost any particular applications are speed and torque requirements.
The rotor is made up of permanent magnets in typically have between two and eight poles the magnets are bonded onto the rotor core in alternating north and south pole fields. Ferrite magnets are normally used to make the permanent magnet rotor. For higher power density applications rare earth magnets are being used more frequently the ferrite magnets are less expensive but have lower flux density when compared to the rare earth magnets. The cost of rare earth magnets is also coming down. Higher power density means that the brushless motors can put out more torque in a smaller volume which is advantageous to manufacturers that are continuously pushed provide smaller and smaller packages.
Rare earth magnet types:
Samarium Cobalt (SmCo)
The alloy of Neodymium, Ferrite, and Boron (NdFeB)
Brushless Motors vary in price. They can be anywhere from twenty dollars or less to several hundred dollars, possibly more. It just depends on the size and capabilities of the motor itself.
Anaheim Automation was established in 1966 as a manufacturer of turnkey motion control systems. Its emphasis on R&D has insured the continued introduction of advanced brushless motor driver/controller, such as the brushless motors product line. Today, Anaheim Automation ranks high among the leading manufacturers and distributor of motion control products, a position enhanced by its excellent reputation for quality products at competitive prices. The brushless motors product line is no exception to the Companys goal.
Anaheim Automation offers a wide variety of standard brushless motors. Occasionally, OEM customers with mid to large quantity requirements prefer to have brushless motors that are custom or modified to meet their exact design requirements. Sometimes the customization is as simple as shaft modification, brake, oil seal for an IP65 rating, mounting dimensions, wire colors, or label. Other times, a customer might require that a brushless motor meet an ideal specification such as, speed, torque, and/or voltage.
Engineers appreciate that Anaheim Automations brushless motor product line can answer their desire for creativity, flexibility and system efficiency. Buyers appreciate the simplicity of the one-stop shop, and the cost savings of custom brushless motors design, while engineers are pleased with Anaheim Automations dedicated involvement in their specific brushless motor system.
Anaheim Automations standard brushless motors are a cost-effective solution, in that they are known for their rugged construction and excellent performance. A considerable size of its sales growth has resulted from dedicated engineering, friendly customer service and professional application assistance, often surpassing the customers expectations for fulfilling their custom requirements. While a good portion of Anaheim Automations brushless motors sales involves special, custom, or private-labeling requirements, the company takes pride in its standard stock base located in Anaheim, California, USA. To make customization of a brushless motors affordable, a minimum quantity and/or a Non-Recurring Engineering (NRE) fee is required. Contact the factory for details, should you require a custom brushless motor in your design.
All Sales for a customized or modified brushless motors are Non-Cancelable-Non-Returnable, and a NCNR Agreement must be signed by the customer, per each request. All Sales, including a customized brushless motors, are made pursuant to Anaheim Automations standard Terms and Conditions, and are in lieu of any other expressed or implied terms, including but not limited to any implied warranties.
Anaheim Automations customers for the brushless motors is diverse: companies operating or designing automated machinery or processes that involve food, cosmetics or medical packaging, labeling or tamper-evident requirements, assembly, conveyor, material handling, robotics, special filming and projection effects, medical diagnostics, inspection and security devices, pump flow control, metal fabrication (CNC machinery), and equipment upgrades. Many OEM customers request that we private-label the brushless motors, so that their customers stay loyal to them for servicing, replacements and repairs.
PLEASE NOTE: Technical assistance regarding its brushless motors, as well as all the products manufactured or distributed by Anaheim Automation, is available at no charge. This assistance is offered to help the customer in choosing Anaheim Automation products for a specific application. However, any selection, quotation, or application suggestion for brushless motors, or any other product, offered from Anaheim Automations staff, its representatives or distributors, are only to assist the customer. In all cases, determination of fitness of custom brushless motors in a specific system design, is solely the customers responsibility. While every effort is made to offer solid advice regarding the brushless motor product line, as well as other motion control products, and to produce technical data and illustrations accurately, such advice and documents are for reference only, and subject to change without notice.
For low-speed applications it is recommended to use an encoder for the feedback rather than the Hall sensors. The Hall sensor counts per revolution can only be as great as a number of polls times the number of Hall Sensors. The brushless motors controller can use this higher count to its advantage when operating the brushless motors. With more counts per revolution at its disposal, the brushless motor controller can use this additional information to more precisely control the velocity of the brushless motors. The higher the resolution on the encoder to more finely the brushless motor controller can control the brushless motors. Even though the expense is much greater for encoders when compared to Hall sensors this price can be justified as it can result in very precise control for a much lower cost than alternative technologies such as Servo motors were AC motors or synchronous motors.
The following environmental and safety considerations must be observed during all phases of operation, service and repair of a brushless motor system. Failure to comply with these precautions violates safety standards of design, manufacture and intended use of the brushless motors and controllers. Please note that even a well-built brushless motor products operated and installed improperly, can be hazardous. Precaution must be observed by the user with respect to the load and operating environment. The customer is ultimately responsible for the proper selection, installation, and operation of the brushless motor system.
The atmosphere in which brushless motors are used must be conducive to good general practices of electrical/electronic equipment. Do not operate brushless motors in the presence of flammable gases, dust, oil, vapor or moisture. For outdoor use, the brushless motors and controllers must be protected from the elements by an adequate cover, while still providing adequate air flow and cooling. Moisture may cause an electrical shock hazard and/or induce system breakdown. Due consideration should be given to the avoidance of liquids and vapors of any kind. Contact the factory should your application require specific IP ratings. It is wise to install brushless motors and controllers in an environment which is free from condensation, electrical noise, vibration and shock. Additionally, it is preferable to work with the brushless motor and controller system in a non-static protective environment. Exposed circuitry should always be properly guarded and/or enclosed to prevent unauthorized human contact with live circuitry. No work should be performed while power is applied. Dont plug in or unplug the connectors when power is ON. Wait for at least 5 minutes before doing inspection work on the brushless motor system after turning power OFF, because even after the power is turned off, there will still be some electrical energy remaining in the capacitors of the internal circuit of the brushless motor controller.
Plan the installation of brushless motors and controllers in a system design that is free from debris, such as metal debris from cutting, drilling, tapping, and welding, or any other foreign material that could come in contact with circuitry. Failure to prevent debris from entering the brushless motor system can result in damage and/or shock.
First Use of Brushless Motors
It is said that Brushless motors have been in commercial use and possible since 1962, although the first Brushless motor appeared during the 1800s. This was made possible by the conversion of electrical energy into mechanical energy by electromagnetic means, which was demonstrated by a British scientist by the name of Michael Farady in 1821. A Hungarian physicist by the name of Ányos Jedlik began experimenting with devices he called electromagnetic self-rotors in 1827. At the time, they were only used for instructional purposes. In 1828, he demonstrated the first device to contain the three main components of practical direct current motors; the rotor, commutator, and stator. The magnetic fields of both the revolving and stationary components were produced solely by currents flowing through their windings and the motors did not contain permanent magnets in those times. In 1832, William Sturgeon, also a British scientist invented the first commutator-type direct current electric motor capable of turning machinery.
Americans, Thomas and Emily Davenport built a commutator-type direct current electric motor with the intention of commercial use in following Sturgeon’s work and patented in 1837. The motors were used for a printing press and powered machine tools. They were said to have ran up to 600 revolutions per minute (RPM). The motors were commercially unsuccessful due to the high costs of the primary battery power, also there was no practical commercial market for the motors at that time.
A modern DC motor was accidently invented in 1873, when a dynamo was to a similar motor driving it as a motor by Zénobe Gramme. He then created the Gramme Machine, it was the first electric motor that was successful in the industry. A non-sparking motor capable of constant speed under variable loads was the first practical DC motor was invented in 1886 by Frank Julian Sprague.
Hall Sensor Feedback
The feedback for brushless motors is done by the use of Hall sensors when rotating the brushless motors in the stator windings need to be energized sequentially. The controller needs to know the rotor position in order to understand the next winding to be energized following the correct energizing sequence. The rotor position is sensed by the Hall sensors embedded in the back end cap of the brushless motors housing. The brushless motors utilize three Hall sensors. They are separated by either 60° or 120°. The Hall sensors sense either the rotor magnet or an external magnet placed on the back and shaft. They give a digital signal signifying whether or not a north or South Pole has passed the censors using the signals from these sensors the brushless motor controller can easily maintain the brushless motor velocity. The Hall sensors are normally mounted on a PC board and fixed to the back end cap on the non-driving end of the brushless motors
Many brushless motors types today are being made with the housing less design. In this design the laminations are exposed and are coated with a paint to prevent the laminations from rusting. Some brushless motor types are still housed in an extrusion or aluminum or steel cylindrical housing and the laminations of the stator are placed and secured in that housing.
How are Brushless Motors controlled
Most Brushless Motors need a controller/driver to run. There are many different types of controllers/drivers that are manufactured around the world for different applications. Many come with different options and can be custom made. Most are referred to as Electronic Speed Controller (ESC).
In a Brushless Controller/Driver, either a Hall Effect Sensor or the Back EMF (Electromotive Force) is used to run the motor. The Hall Effect uses three hall sensors within the motor to help detect the position of the rotor. This method is primarily used in speed detection, positioning, current sensing, as well as proximity switching. The magnetic field changes in response to the transducer that varies its output voltage. A feedback is created by directly returning a voltage since the sensor operates as an analogue transducer. The distance between the Hall plate and a known magnetic field can be determined with a group of sensors, in this case, three, and the relative position of the magnet can be deduced. A Hall sensor can act as an on/off switch in a digital mode when combined with circuitry.
The Back EMF, also known as the Counter-Electromotive Force is caused by a changing electromagnetic field. In a Brushless Motor, the back EMF is a voltage that occurs where there is motion between the external magnetic field and the armature of the motor. In other words, the voltage is developed in an inductor by and alternating current or pulsating current. At every moment, the polarity of the voltage is the reverse of the input voltage. This method is commonly used to measure the motor’s position and speed indirectly.
How Do Brushless Motors Work
Brushless motors have electronic commutation systems, no brushes and no mechanical commutators. This allows the brushless motors to operate at higher speeds. There can be a different amount of poles on the stator for each motor.
How to select Brushless Motors
When selecting Brushless Motors, you want to ask yourself a few questions. Such as, what is my application? What are my specifications? How much do I want to spend? What controller/driver and I going to use/need? These are some of the questions you want to think about to narrow down your selection. You will definitely want to do your research.
The type of application will need to be determined for your Brushless Motors. You will then need to determine all specifications, known ones along with possible ones. For example, do you need a specific frame size, weight, power, speed, length, etc. Once you have determined all those things, you will need to take into consideration on what controller/driver you will be using. This goes hand in hand with the selection of the motor. Keep in mind there are many different motors and driver/controllers to choose from, therefore it is wise to do detailed research.
Modern day uses of Brushless Motors
Brushless Motors have and continue to rise in popularity for many different applications. Although, A Brushless Motor may cost a little more than DC Brushed Motors, they have far more advantages than disadvantages. Many industries have turned to Brushless motors for their applications. For specific Industries, please check the “What Industries are Brushless Motors used in” section.
The following information is intended as a general guideline for the installation and mounting of the brushless motor system. WARNING - Dangerous voltages capable of causing injury or death may be present in the brushless motor system. Use extreme caution when handling, testing, and adjusting during installation, set-up, and operation. It is very important that the wiring of the brushless motor and controller be taken into consideration upon installation and mounting.
Subpanels installed inside the enclosure for mounting brushless motor system components, must be a flat, rigid surface that will be free from shock, vibration, moisture, oil, vapors, or dust. Remember that the brushless motors and controllers will produce heat during work, therefore, heat dissipation should be considered in designing the system layout. Size the enclosure so as not to exceed the maximum ambient temperature rating. It is recommended that the brushless motor controller be mounted in position as to provide adequate airflow. The brushless motors should be mounted in a stable fashion, secured tightly. NOTE: There should be a minimum of 10mm between the brushless motor controller and any other devices mounted in the system/electric panel or cabinet.
NOTE: in order to comply with UL and CE requirements, the brushless motor system must be grounded in a grounded conducive enclosure offering protection as defined in standard EN 60529 (IEC 529) to IP55 such that they are not accessible to the operator or unskilled person. As with any moving part in a system, the brushless motors should be kept out of the reach of the operator. A NEMA 4X enclosure exceeds those requirements providing protection to IP66. To improve the bond between the power rail and the subpanel, construct your subpanel out of a zinc-plated (paint-free) steel. Additionally, it is strongly recommended that the brushless motor controller be protected against electrical noise interferences. Noise from signal wires can cause mechanical vibration and malfunctions.