DC Motors Applications
Frequently Asked Questions
Frequently Asked Questions
Even though brushless motors have recently overshadowed DC Motors, DC motors are still used in a variety of different applications. Even though we may not see DC motors often, they are everywhere, ranging from cell phones, to toys, jacuzzi pumps. Many automatic car windows and automatic seat adjustments are operated by DC motors. DC motors have been a favorite in the automotive industry because of their low cost and simple design. DC motors are made in many different sizes, torque, and speed specifications; so regardless of your application, most likely there are DC motors that will meet your requirements.
Basic Types of Brushless Motors
Almost all Brushless Motors are permanent magnet motors. There are also two essential types labeled as a Trapezoidal Motor and the other as a Sine Wave Motor. The Trapezoidal Motor is similar to a DC servo motor and the Sine Wave Motor has close resemblance to an AC synchronous motor.
Brushless Motors Basics
The fundamental definition for Brushless Motors is an automated instrument that uses an error-correction routine to correct the motion of the Brushless Motors. The general term Brushless can be adjusted to systems other than a Brushless Motors that uses a feedback system such as an encoder or other feedback instrument to control the motion parameters. Commonly when the term Brushless is used it applies to a 'Brushless Motors' but this term is additionally 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 contrasting 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.
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 shown by a British scientist by the name of Michael Farady in 1821. A Hungarian physicist by the name of Ányos Jedlik began experimenting with instruments he called electromagnetic self-rotors in 1827. At the time, they were only used for instructional purposes. In 1828, he shown the first instrument to contain the 3 critical components of practical direct current motors; the rotor, commutator, and stator. The magnetic fields of both the revolving and fixed components were produced entirely 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 elevated costs of the prime battery power, also there was no practical commercial market for the motors at that time.
A modern DC motor was unintentionally 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 continual speed under variable loads was the first practical DC motor was invented in 1886 by Frank Julian Sprague.
What Industries are Brushless Motors Used In
Brushless Motors are rapidly growing in popularity and are being used in countless industries. Most of the industries are:
• Industrial Automation Equipmen
Brushless Motors Applications
A Brushless Motors are used in a variety of applications in several contrasting industries. Most of the applications are Appliances, Automotive, Aerospace, CNC, Consumer, Instrumentation, Medical, Packaging Apparatuses, and Semiconductor.
Modern Day Uses of Brushless Motors
Brushless Motors have and continue to rise in popularity for numerous contrasting applications. Although, A Brushless Motor may cost a little greater than DC Brushed Motors, they have far greater advantages than disadvantages. Various industries have turned to Brushless motors for their applications. For distinuishing Industries, please check the “What Industries are Brushless Motors used in” section.
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 requirements? 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 requirements, known ones along with possible ones. For example, do you need a particular 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 various contrasting motors and driver/controllers to choose from, as a result it is wise to do detailed research.
Brushless Motors Environmental Considerations
The following environmental and safety considerations must be observed during all stages 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 dangerous. Precaution must be observed by the user with respect to the load and operating environment. The customer is solely 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 acceptable 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 can 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 particular IP ratings. It is intelligent to install brushless motors and controllers in an environment which is free from condensation, electrical noise, vibration and shock.
Additionally, it is favored 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 devoted. Don't 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.
Tech Tip - About Brushless Motors
The main dissimilarity between brushless motors and their predecessors is the process of commutation. The newest brushless motors are electrically commutated; this is accomplished with Hall elements, by encoder feedback. , or counter EMF
Factors That Affect A Motors Life
Bearing failure is a considerable factor when it comes to brushless motors failing. As a result of using industrial grade components, most brushless motors have the ability to last lifetimes in excess of 20,000 hours or more. Integrated into these systems are permanently lubricated ball bearings that use unique grease, therefore eliminating the need for re-lubrication. Non-approved lubricants are not recommended for the motor components because they could conceivably shorten the life of the motor.
Temperature also plays a major role in the lifespan of a motor. The motor casing in particular ensures that the heat generated in the motor windings should be dispelled. The motor could face severe damage if it exceeds the qualification regarding heat. The motor's performance has a direct correlation with the maximum possible rotor temperature,duty cycle, and ambient temperature. As temperature increases, the winding resistance increases while the magnetic forces decrease, ultimately causing performance to dwindle. When running at high continuous loads, all of these factors should be taken into consideration. Heat sinking and forced air-cooling can lower operating temperatures. considerably.
Brushless Motors Encoder Feedback
For low-speed applications we recommend use of an encoder for the feedback rather than Hall sensors. The Hall sensor count per revolution can only be as great as a number of polls times the number of Hall Sensors. The brushless motor 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 motor. Even though the cost is much greater for encoders when compared to Hall sensors this fee can be justified as it can result in very precise control for a much lower cost than other technologies such as Servo motors were AC motors or synchronous motors.
Brushless Motors Housing
Various 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 laminations from rusting. Some brushless motor types are housed in an extrusion or steel or aluminum cylindrical housing and the laminations of the stator are placed and secured in that housing.
Brushless Motors Cost
Brushless Motors vary in cost. They can be anywhere from twenty dollars or less to several hundred dollars, possibly even more. It depends on the capabilities and size of the motor itself.
Physical Properties of Brushless Motors
Brushless Motors have the physical appearance of a 3-phase permanent magnet that is anchored which is located on the outside, which is known as the Stator. The rotating armature is located inside and is called the rotor. Brushless Motors can be constructed in various different physical configurations. One configuration is known as the “Inrunner” type where the permanent magnets are a part of the rotor and three different stator windings are surround the rotor. Another configuration is the “Outrunner” type, where the radial-relationship amidst the coils and magnets is reversed. The stator coils form the core of the motor, while permanent magnets spin within an overhanging rotor surrounding the core.
How Do Brushless Motors Work
Brushless motors have electronic commutation systems, no mechanical commutators and no brushes. This allows the brushless motors to operate at much higher speeds. There can be different amounst of poles on the stator for each motor.
Brushless Motors Accessories
We provide many different accessories for our brushless motors. These accessories include an encoder, brake, connector, cable and a driver.
The brushless motors brake has a 24vdc system. These brushless motor brakes are ideal for any holding applications. They are available on any of our brushless motors, and are already attached to the rear of the brushless motors. The brushless motor brakes have a very 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. 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 the pressure plate and itself.
Brushless motor cables can be made with the supplied brushless motor connector, or can be purchased from us.
Brushless Motors 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 consecutively. The controller needs to know the rotor position in order to understand the next winding to be energized following the accurate 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 different 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 shaft and back. They give a digital signal signifying whether or not a south or north Pole has passed the censors using the signals from these sensors the brushless motor controller can effortlessly 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.
What are Brushless Motors
Brushless motors are also called a BLDC Motor; synchronous electric motors that are DC (Direct Current) powered. They are electronically commutated without the use of brushes making them “Brushless”. Brushless Motors consist of a fixed armature along with permanent magnets that rotate, hall sensors, stator windings, rotor magnet South and North, hall sensor magnets, an accessory shaft, and a driving end of the shaft.
How are Brushless Motors With Integrated Controllers controlled
Many Brushless Motors With Integrated Controllers need a controller/driver to run. There are many different types of controllers/drivers that are produced around the world for different applications. Many come with different options and are sometimes custom made. Many are referred to as Electronic Speed Controller (ESC).
In Brushless Motors with Integrated Controllers, either a Hall Effect Sensor or the Back EMF (Electromotive Force) is used to run a motor. The Hall Effect uses three hall sensors within the motor in order to detect the position of the rotor. This method is primarily used in positioning, speed detection, current sensing, as well as proximity switching. The magnetic field will change in response to the transducer that varies its output voltage. A feedback is created by directly returning a voltage since the sensor works as an analogue transducer. The distance amid the a known magnetic field and a Hall Plate 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 incorporated with circuitry.
The Back EMF, AKA 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 amid the external magnetic field and the armature of the motor. In other words, the voltage is developed in an inductor by and pulsating current or alternating current. At every moment, the polarity of the voltage is the reverse of the input voltage. This method is often used to measure the motor’s position and speed indirectly.
How are Brushless Motors Controlled?
Nearly all Brushless Motors require a controller/driver to run. There are multiple kinds of controllers/drivers that are produced around the world for varying applications. Many options for customizationare available. Most are known as Electronic Speed Controllers (ESC).
With Brushless Controller/Drivers, either a Hall Effect Sensor or the Back EMF (Electromotive Force) is employed to run the motor. The Hall Effect uses three hall sensors in the motor to help detect the position of the rotor. This method is used most commonly in speed detection, positioning, current sensing, as well as proximity switching. The magnetic field alters in response to the transducer that varies its output voltage. A feedback is created by directly restoring a voltage since the sensor operates as an analogue transducer. The distance between the Hall plate and a magnetic field can be established with a group of sensors, in this case, three, and the relative position of the magnet can be inferred. A Hall sensor can act as an on/off switch in a digital mode when used with circuitry.
The Back EMF, aka the Counter-Electromotive Force is produced by a changing electromagnetic field. In a Brushless Motor, the back EMF is a voltage that happens where there is motion between the external magnetic field and the armature of the motor. In other words, the voltage is produced in an inductor by and alternating current or pulsating current. At every moment, the polarity of the voltage is the converse of the input voltage. This method is frequently used to measure the motor’s position and speed indirectly.
Motor Life Cycle
The main difference between brushless motors, a.k.a. Brushless motors, and their predecessors is the process of commutation. New model Brushless motors are electrically commutated; this is acheived with Hall elements, by counter EMF, or encoder feedback.
Brushless motors are exceptionally useful and cost-effective by their design and construction. Unforturnately, there are some factors that can negatively affect the life expectancy of the Brushless motor:
Key Points to Remember -
• Bearing failure and lack of lubrication are main factors when it comes to Brushless motors failing. As a result, manufacturers now employ industrial grade components so that some Brushless motors now have the ability to last lifetimes in excess of 20,000 hours! Integrated into these Brushless motors are permanently lubricated ball bearings that use unique grease, eliminating the need for re-lubrication. IMPORTANT NOTE: Non-approved lubricants are in no way recommended for the Brushless motor components, because they may potentially shorten the life of the Brushless motor.
• Temperature plays a key role in the lifespan of Brushless motors as well. The motor casing, in particular, has to ensure that the heat generated in the Brushless motors windings must be dispelled. Brushless motors may face extreme damage if it exceeds the Brushless motor specification with respect to heat. Brushless motor performance directly correlates with the maximum possible rotor temperature, ambient temperature, and duty cycle. As temperature rises, the winding resistance rises, and magnetic forces decrease, ultimately causing Brushless motors to perform less efficiently.
• When Brushless motors run at large continuous loads, heat sinking and forced air-cooling can considerably lower operating temperatures. In other words, it is highly advised that all of these factors be taken into consideration when designing and installing motion control systems that include Brushless motors.
Brushless Motors Customizing
Anaheim Automation was established in 1966 as a maker of "turnkey" motion control systems. Its' emphasis on R&D has insured the continued introduction of excellent brushless motor driver/controller, such as the brushless motors product line. Today, Anaheim Automation ranks high among the leading makers and distributor of motion control products, a position enhanced by its wonderful reputation for quality products at competitive prices. The brushless motors product line is no exception to the Company's 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 enjoy that Anaheim Automation's brushless motor product line can answer their desire for creativity, flexibility and system efficiency. Buyers enjoy the simplicity of the "one-stop shop," and the cost savings of custom brushless motors design, while engineers are pleased with Anaheim Automation's dedicated involvement in their particular brushless motor system.
Anaheim Automation's standard brushless motors are a cost-effective solution, in that they are known for their rugged construction and admirable performance. A considerable size of its sales growth has resulted from dedicated engineering, friendly customer service and professional application assistance, often surpassing the customer's expectations for fulfilling their custom requirements. While a large portion of Anaheim Automation's 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 Automation's standard Terms and Conditions, and are in lieu of any other expressed or implied terms, including but not limited to any implied warranties.
Anaheim Automation's customers for the brushless motors is diverse: companies operating or designing automated machinery or processes that involve cosmetics, food, 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, repairs and replacements.
PLEASE NOTE: Technical assistance regarding its brushless motors, as well as all the products distributed or manufactured by Anaheim Automation, is accessable 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 Automation's staff, its' representatives or distributors, are only to assist the customer. In all cases, determination of fitness of custom brushless motors in a particular system design, is solely the customers' responsibility. While every effort is made to offer 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.
Brushless Motors Mounting
The following information is intended as a general guideline for the mounting and installation of the brushless motor system. WARNING - Hazardous 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 extremely important that the wiring of the brushless motor and controller be taken into consideration upon mounting and installation.
Subpanels installed inside the enclosure for mounting brushless motor system components, need to be a flat, rigid surface that will be free from shock, vibration, moisture, vapors, oil, or dust. Remember that the brushless motors and controllers will produce heat during work, therefore, heat dissipation should be considered while designing the system layout. Size the enclosure so as not to exceed the maximum environment temperature rating. It is recommended that the brushless motor controller be mounted in position as to provide acceptable airflow. The brushless motors should be mounted in a stable fashion, secured tightly. NOTE: There should be a minimum of 10mm in between the brushless motor controller and any other devices mounted in the system/electric cabinet or panel.
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 sheilding 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 fully recommended that the brushless motor controller be protected against electrical noise interferences. Noise from signal wires can cause mechanical vibration and malfunctions.
Brushless Motors Wiring
The following information is intended as a basic guideline for wiring of the Anaheim Automation brushless motors product line. Be aware that when you route power and signal wiring on a system or machine, radiated noise from the nearby relays, transformers, and other electronic devices can be inducted into the brushless motor and encoder signals, input/output communications, and other sensitive low voltage signals. This can cause systems faults and communication errors.
WARNING - Hazardous voltages capable of causing death or injury, may be present in the brushless motor system. Use great caution when handling, wiring, testing, and adjusting during installation, set-up, tuning, and operation. Don't make extreme adjustments or changes to the brushless motor system parameters, which can cause mechanical vibration and result in loss and/or failure. Once the brushless motors are wired, do not run the brushless motor controller by switching On/Off the power supply directly. Continual power On/Off switching will cause fast aging of the internal components, which will reduce the lifetime of brushless motor system.
Strictly obey the following rules:
- Follow the Wiring Diagram with each brushless motor
- Route high-voltage power cables separately from low-voltage power cables.
- Segregate input power wiring and brushless motor power cables from control wiring and brushless motor feedback cables as they leave the brushless motor controller. Maintain this separation throughout the wire run.
- Use shielded cable for power wiring and provide a grounded 360 degree clamp termination to the enclosure wall. Allow room on the sub-panel for wire bends.
- Make all cable routes as short as possible.
NOTE: Factory made cables are recommended for use in our brushless driver and motor systems. These cables are purchased separately, and are designed to minimize EMI. These cables are recommended over customer-built cables to optimize system performance and to offer additional safety for the brushless motor system and the user.
WARNING - To avoid the possibility of electrical shock, perform all wiring and mounting of the brushless motors and controller system prior to applying power. Once power is applied, connection terminals can have voltage present.
Brushless Motors Construction
The stator of brushless motors is made up of stacked steel laminations the windings are placed in the slots that are cut inside the laminations. The stator of brushless motors is comparable to that of an AC motor however the windings are different. Brushless motors have three stator windings connected in either a Delta or star configuration. Each of these windings are constructed from multiple coils connected together to form a winding. Anaheim Automation commonly 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 sinusoidal and trapezoidal. 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 commonly 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 pricey but have lower flux density when compared to the rare earth magnets. The price 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 constantly pushed provide smaller and smaller packages.
Rare earth magnet types:
Samarium Cobalt (SmCo)
The alloy of Neodymium, Ferrite, and Boron (NdFeB)
Consumer Electronics Although Brushless motors can perform the same functions originally fulfilled by brushed DC motors, price and control complications prevent Brushless motors from completely replacing brushed motors. However, Brushless motors have monopolized several 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 little cooling fans that are located in electronic equipment as well. Cordless power tools also make use of DC Brushless motors because the need for increased efficiency of the BLDC motor allows for lengthy 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 basically 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 joined 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 broad 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 nearly 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 clean and silent Brushless motors.
Brushless motors have also increased in popularity among the Radio Controlled (RC) buggies, cars, and trucks, where sensor-type Brushless motors allow the position of the rotor magnet to be detected. Several 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 rapidly 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 common 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 wasn't until the price of these Brushless Motors decreased, that they became a viable option for many medical applications. Brushless motors can provide a more reliable, efficient, and compact motor that can be used in a variety of ways.
Basically, Brushless Motors are synchronous 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 baiscally 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 fixed 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 proper 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 basic 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 suitable polarity. In Brushless Motors, electronic switches take the place of the mechanical switch, controlling the timing of the polarity-reversal by an electrical circuit. Mostly, 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 costly, 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 needs to wear to breathe through while sleeping. Within the respirator is a blower fan that pressurizes the air mask, according to the patient's 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 machines 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 patient's home. It is the absence of a commutator and brushes in Brushless Motors that removes even more of the motor noise.
Advantages and Disadvantages
Brushed DC Motors are some of the earliest of all electrical motor designs. It is mostly the motor of choice for the majority of torque control and variable speed applications. This Tech Tip discusses the advantages and disadvantages of using Brushed DC motors in machinery and processes.
Advantages of Brushed DC Motors
• Brushed DC Motors have a simple construction, consequently requiring a cheap drive design
• Understandable design/technology facilitates in quick application of Brushed DC Motors.
• The design of Brushed DC motors are quite basic, in that a permanent magnetic field is created in the by either of two means:
• Permanent magnets
• Electro-magnetic windings
• If the field is created by permanent magnets, Brushed DC Motors are said to be a "permanent magnet DC motor" (PMDC). If created by electromagnetic windings, the brush motor is frequently said to be a "shunt wound Brush DC motor" (SWDC). Today, because of cost-effectiveness and reliability, the PMDC motor is the motor of choice for applications involving fractional horsepower brushed DC motors, as well as many applications up to about 2.0 horsepower.
• Opposing the stator field is the armature field, which is generated by a changing electromagnetic flux coming from windings located on the rotor of Brushed DC motors. The magnetic poles of the armature field will attempt to line up with the opposite magnetic poles generated by the stator field. Next, the section of the rotor where the electricity enters the rotor windings is called the commutator. The electricity is carried between the brush motor rotor and the stator by conductive graphite-copper brushes (mounted on the rotor) which contact rings on stator.
Important to Note: If Brushed DC motors suffer a loss of field (if for example, the field power connections are broken), the Brushed DC Motor will immediately begin to accelerate to the top speed which the loading will allow. This can result in the motor flying apart if the motor is lightly loaded. The possible loss of field must be accounted for, particularly with shunt wound Brushed DC Motors.
Imagine power is supplied:
Brushed DC Motors rotate toward the pole alignment point. Just as Brushed DC motors would get to this point, the brushes jump across a gap in the stator rings. Momentum carries brushed DC motors forward over this gap. When the brushes get to the other side of the gap, they contact the stator rings again and - the polarity of the voltage is reversed in this set of rings! The brush motor begins accelerating again, to the opposite set of poles. (The momentum has carried Brushed DC motors past the original pole alignment point.) This continues as Brushed DC Motors rotate. In most DC motors, several sets of windings or permanent magnets are present to level out the motion.
Brushed DC Motors are basic to control speed
• Simple to control speed - Controlling the speed of Brushed DC motors are basic. The higher the armature voltage, the faster the rotation. This relationship is linear to the brush motor's maximum speed.
• The maximum armature voltage which corresponds to the rated speed of the brush motors (these brush DC motors are usually given a rated speed and a maximum speed, such as 1750/2000 rpm) are available in certain standard voltages, which roughly increase in conjunction with horsepower.
• The smallest industrial-type brush DC motors are rated 90 VDC and 180 VDC. Larger units are rated at 250 VDC and even higher (dependent upon the individual manufacturer).
• Most industrial brush DC motors operate reliably over a speed range of about 20:1 - down to about 5-7% of base speed. This is much better performance than the comparable AC motor. This fact is in part due to the fact of the mere simplicity of control. However, it is also partly due to the fact that most industrial DC motors were designed with variable speed operations in mind. The addition of heat dissipation features/ devices provided for lower operating speeds of DC motors.
• NOTE: Specialty Brushed DC motors are used in mobile applications and are typically rated 12, 24, or 48 VDC. Other tiny brush motors can be rated as low as 5 VDC. These Brushed DC Motors are very popular among hobbyists.
Brushed DC Motors are simple to control torque
• In Brushed DC motors, torque control is also easy to achieve. Output torque is proportional to current. So, if the current is limited, you have just limited the torque which brush DCmotors can achieve.
• This fact makes Brushed DC brushs motor ideal for delicate applications such as textile manufacturing.
Simple and inexpensive drive/control design
The result of this design is that variable speed or variable torque electronics are simple to design and manufacture. Varying the speed of Brushed DC motors requires little more than a large enough potentiometer. In practice, these have been replaced for all but sub-fractional horsepower applications by the SCR and PWM drives (sometimes referred to as controls), which offer relatively precisely control voltage and current. Common drives for a Brushed DC motor is available at the low-end of the product offering (up to 2 horsepower). The price will depend on the accuracy requirement, but many brush motors can be accompanied with drives ranging from $29.00 - $199.00 USD.
Disadvantages of Brushed DC Motors
• Brushed DC motors can be a bit costly to produce, in that the raw materials have become more pricey in recent years
• Brushed DC motors are less reliable in control at lowest speeds
• Brushed DC motors are physically larger than other motors with the same torque
• Brushed DC motors are much more high maintenance than are brushless motors
• Brushed DC motors become vulnerable to dust which decrease
What is a brushless DC motor?
A brushless DC motor also referred to as electronically commutated motors are a type of synchronous motor that is powered by a DC electric source by way of a integrated inverter. This inverter will produce an AC electric signal to drive the motor. Additional sensors will control the inverter output. Brushless motors are often referred to as stepper motors, however stepper motors are designed to be frequently stopped at predetermined intervals and angular positions.
I hear a lot of debate about brush and brushless motors. What are the benefits of a brushless motor design?
A brushless motor is fundamentally more reliable than a brush motor. With no brushes to wear out, they require less maintenance and have a longer life. Due to the lack of brushes, they can characteristically attain higher speeds than brush motors. And because the winding is generally on the outside element, they offer better heat dissipation. Brushless motors also run more quietly.
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