Name: China Brushless DC Motor Manufacturers Suppliers Factory - Brushless DC Motor Wholesale
Brand: Duowei
SKU: 225283007

Duowei Electric: Your Leading Brushless DC Motor Supplier

Why Choose Us?

Wide Range of Applications

Our products can be used in various industries including automotive, industrial automation, robotics, household equipment, medical equipment, HVAC systems, office equipment, defense and aerospace, electrical equipment, and power tools.

Professional Services

We can provide customers with "customized services" to meet their long-term needs through tailor-made products. At the same time, we have more than 20 years of production experience and can provide large-scale electric motor production services.

Quality Assurance

ZWS series brushless DC motors, HC series motors, and YY series induction motors have passed UL certification. HC series motors, YY series induction motors, and YDK series air-conditioning motors have passed 3C certification and obtained "Export Product Quality License"

Mass Production of Various Motors

We have realized mass production of 57ZWS, 83ZWS, 120ZWS brushless DC motors. Besides, the linear motor was also successfully developed and put into mass production.

BLDC Motor For AGV

BLDC Motor For AGV is a brushless DC motor with an outer diameter of 95mm. The protection level is increased to IP65 on the premise of ensuring performance. Standard mounting flanges can be installed with gearboxes, brakes, or encoders according to customer requirements to cope with non-use The application scenarios are widely used in AGV, solar energy systems, and other applications.

83MM Brushless Motor

83MM Brushless Motor is a brushless motor with an outer diameter of 83mm, a rated power of 200W, and high-quality bearings, which can achieve a life span of tens of thousands of hours. At the same time, the noise is low and the efficiency is high. It is widely used in spray coating, textiles, medical equipment, and other fields. At the same time, we can customize development and provide solutions to customer requirements.

120MM Brushless Motor

120MM Brushless Motor is a brushless DC motor with an outer diameter of 120mm (square), which is mass-produced as a walking motor for Amazon's AVG robot. It can produce 2KW output power. Its reliability and overload capacity are excellent, and it is widely used in many fields.

57MM Brushless Motor

57MM Brushless Motor is a 24VDC brushless motor with a rated torque of 0.14Nm and a rated speed of 3000RPM. It has the advantages of small size, low noise, long life, etc., and is widely used in medical, financial, and other fields. At the same time, we can customize development and provide solutions to customer requirements.

48V 500W BLDC Motor

48V 500W BLDC Motor uses high-performance neodymium iron boron magnets and high-quality ball bearings, which can provide excellent motor performance to the maximum under the control of volume. It is widely used by domestic and foreign customers in various industrial control fields, spraying equipment, AGV, and so on.

24V 100W Brushless DC Motor

The highest efficiency of a 24V 100W Brushless DC Motor is more than 80%. With an encoder, it can be used as a drive motor or a control motor. The standard mounting flange can be assembled with many gearboxes on the market. We can also accept customization and try our best to meet your needs.

24V 150W Brushless DC Motor

24V 150W Brushless DC Motor operates continuously at 150W and can use round or square flanges to meet different installation requirements. Using Hall feedback, it can be used as a control motor in industrial applications.

48V 300W Brushless DC Motor

48V 300W Brushless DC Motor is an American standard 3-inch brushless DC motor, with low noise, stable operation, no sparks during operation, greatly reducing friction. Mass production has been mainly exported to Europe and the United States for decades, and it has been widely recognized by customers for its high performance and preferential prices.

48V 400W Brushless DC Motor

48V 400W Brushless DC Motor is a standard 3-inch brushless DC motor, with or without Hall options. Brakes, encoders, gearboxes, etc. can be installed at the same time to cope with different occasions. The motor has the characteristics of small size, light weight, and low noise, and can be widely used in intelligent industrial equipment, mobile robots, etc.

48V 300W BLDC Motor

48V 300W BLDC Motor is an American standard 3-inch brushless DC motor. It has many advantages: higher efficiency and reliability, lower noise, smaller and lighter, better speed and Torque characteristics, higher speed range, and longer service life. This product has been widely recognized by customers with high performance and favorable prices.

48V 400W BLDC Motor

48V 400W BLDC Motor is a standard 3-inch brushless DC motor, with or without Hall options. Brakes, encoders, gearboxes, etc. can be installed at the same time to cope with different occasions. The motor has a simple structure, is resistant to impact and vibration, and can withstand various wind and rain-sealed structures, to achieve a long life.

24V 50W Brushless DC Motor

24V 50W Brushless DC Motor, as our standard brushless DC motor, has been mass-produced for decades and has been widely recognized and praised by the market. It has the characteristics of small size, low noise, and long life. It is widely used in industrial control, medical, and other fields.

Definition of Brushless DC Motor

A brushless DC electric motor (BLDC), also known as an electronically commutated motor, is a synchronous motor using a direct current (DC) electric power supply. It uses an electronic controller to switch DC currents to the motor windings producing magnetic fields that effectively rotate in space and which the permanent magnet rotor follows. The controller adjusts the phase and amplitude of the DC current pulses to control the speed and torque of the motor. This control system is an alternative to the mechanical commutator (brushes) used in many conventional electric motors.

Working Principle of Brushless DC Motor

BLDC motor works on a principle similar to that of a conventional DC motor, i.e., the Lorentz force law which states that whenever a current-carrying conductor is placed in a magnetic field it experiences a force. As a consequence of reaction force, the magnet will experience an equal and opposite force. In the case BLDC motor, the current-carrying conductor is stationary while the permanent magnet moves. When the stator coils are electrically switched by a supply source, it becomes an electromagnet and starts producing a uniform field in the air gap. Though the source of supply is DC, switching generates an AC voltage waveform with a trapezoidal shape. Due to the force of interaction between the electromagnet stator and permanent magnet rotor, the rotor continues to rotate. The motor stator is excited based on different switching states. With the switching of windings as High and Low signals, corresponding winding energized as North and South poles. The permanent magnet rotor with North and South poles aligns with the stator poles causing the motor to rotate. The motor produces torque because of the development of attraction forces (when North-South or South-North alignment) and repulsion forces (when North-North or South-South alignment). In this way motor moves in a clockwise direction.

Benefits of Brushless DC Motor

Long Lifetime

The lifetime of brushless motors is much longer than that of brushed motors because the brush and commutator don't rub against each other and get worn down (like they do in brushed motors). In fact, brushed DC motors last about 1000 - 3000 service hours, whereas BLDC motors last about 20,000 service hours.

High Output Speed and Precision

Brushless motors also have a higher output speed, they can typically go about six times faster than brushed motors. The speed of BLDC motors is also thought to be more consistent. This is because there could easily be discrepancies between the speed of the rotor, and the speed of the revolving magnetic field of the stator in an AC motor. Slip does not occur in BLDC motors, which eliminates discrepancies in speed that would be caused by it. DC motors are able to immediately start, stop, and reverse, which is essential when it comes to controlling and operating production equipment. Many "motion control applications" use permanent magnet direct current (DC) motors for this reason.

Lower Operational Cost and Less Maintenance

Brushed motors have a lower capital cost than brushless motors because brushless motors require a controller to supply a "voltage sequence between the three phases". However, brushed motors do wear down more quickly; sometimes the brushes must be replaced, and this brings up maintenance costs. If you consider BLDC motors more of an investment, they can be less expensive in the long term because they require practically zero maintenance, and last much longer.

Efficient

Brushless motors are more efficient than brushed motors because, again, the lack of brushes means that no brushes will be constantly in contact with the commutator (like they are in brushed motors). This lack of contact, means there's also a lack of friction and heat created in brushless motors. Less energy lost in the form of heat, makes a brushless motor more efficient. In fact, BLDC motors typically have an efficiency of 85-90%, while brushed motors are usually only 75-80%. This means that for applications like power tools, for example, this improved efficiency extends battery life (meaning more can be done between charges).

Types of Brushless DC Motor

In-Runner Brushless DC Motor

This type of BLDC motor has the rotating part (rotor) inside an assembly of electromagnet coils (stator). This brushless DC motor construction allows for heat dissipation through conduction, since the stator coils are mounted on the motor's casing. An in-runner brushless DC motor attains peak speeds easily and is best for applications that require higher RPM characteristics. These motors often do not use many poles in the rotor. As a result, their performance reduces at lower speeds.

Out-Runner Brushless DC Motor

This out-runner BLDC motor is basically the opposite of the in-runner type. It's also called outer rotor BL motor and uses rotating outer case around a stationary inner piece. Out-runner BLDC motors generally use a higher number of permanent magnet poles on the rotor. That translates to more torque and smoother operation. The main disadvantage of the out-runner brushless DC motor lies in its slow speed. These types of motors are, therefore, better suited for low-speed, high-torque applications.

Sensored Brushless DC Motor

A sensored BLDC motor is one that relies on sensors to provide rotor position data. These types of brushless motors offer reliable performance at lower speeds. At lower rpm, the sensors provide accurate data to enable a smooth rotation. The main drawback of sensored motors shows up at higher speeds when the sensor feedback becomes unreliable. Harsh conditions such as dusty or high-heat environments also affect the sensors and, therefore, motor operation. These motors fit low rpm applications best.

Sensorless Brushless DC Motor

This type of motor does not use sensors. Instead, the controller relies on the back electromotive force generated in the stator coils to calculate the rotor position. These types of brushless DC motors offer the best performance at high speeds. You can also use them in tough environments, seeing that they do not use sensors. Their shortcoming becomes evident at low speeds when the back EMF is too low to be read by the controller, or when starting from a stationary situation. These motor types suit high-speed, low-cost applications and harsh conditions.

Single Pole Brushless DC Motor

A single pole BLDC motor uses a rotor that consists of a single pair of poles, North and South. This type of brushless DC motor design has its advantages and disadvantages. Starting with the benefits, the motor can attain very high speeds of rotation. On the downside, the performance of single pole motors drops significantly at lower rpms, affecting rotational stability and efficiency. They are, therefore, best used in high speed applications.

Multi Pole Brushless DC Motor

Multi pole motors use several poles on the rotor, mostly up to eight. As mentioned earlier, these are placed so that opposite poles face each other. More poles provide a smoother rotation, but at the expense of speed. As a result, these types of brushless motors do not achieve high rpm levels and are mostly used in low-speed applications that require high torque levels.

Applications of Brushless DC Motor

Brushless DC Motor in Car Parts

One of the sectors where the BLDC motor is becoming increasingly popular is the automotive industry. The motor is being used in major vehicle parts such as fans, window elevators, and HVAC motors. When used in these components, BLDC motors perform exceptionally well, and for a long time due to their higher durability.

Brushless DC Motor for Fan

The fans for cooling and heating appliances commonly use brushless motors. The electronic control of these motors allows manufacturers to include features such as speed variation, programmable operation, and remote communication. BL motors are also quiet devices, which makes them suitable for use in fans where noise is unwanted.

Brushless DC Motor for Robot

With the advancement of robot technology, BLDC motors have become the most preferred type of drive and holding device. There are many reasons for their use, such as efficiency, low-heat operation, and compact construction. But the most important advantage for the application is the precise control that brushless motors are capable of, which helps produce accurate robotic systems and devices.

Brushless DC Motor for Electric Bike

E-bikes are a popular with many people. In an e-bike, a BLDC motor is usually affixed to the wheel hub. The rotor then forms part of the wheel, rotating along with it. In turn, the stator is typically built into the wheel hub. The brushless DC motor commutation that requires no physical brushes is one of the reasons for its suitability. The high torque too and efficiency, which are necessary to propel the bike.

Brushless DC Motor for Drone

One of the most popular brushless DC motor applications is in the making of drones. A drone uses several rotors, each with own electronic circuit. These must be controlled separately to achieve ascent, decent, and direction change. BL motors allow that with ease. A brushless DC motor for drone must also be lightweight and small enough to avoid introducing too much weight. Compactness is one of the BL motor characteristics.

Brushless DC Motor for Lathe

BL motors are common in power tools such as lathes, where they offer the advantage of low weight and high efficiency. They also generate higher levels of torque in high rpm, a major requirement for lathe operation. Most of the time, a brushless DC motor for lathe is a heavy-duty type capable of both high torque and speed.

Brushless DC Motor for Golf Cart

Brushless motors are popularly used to propel small vehicles such as golf carts. There are many reasons for the application. One of the most important is the motor's high efficiency, which makes it save energy better than a conventional brushed motor. The reduced maintenance requirements and high torque-to-weight ratio also makes a BL motor suit golf carts.

Brushless DC Motor in Computers

Brushless motors are also commonly used in computers. Examples include use in hard disks, CD-ROM drives, and the cooling fans of computers. One of the advantages of BLDC motors when used in a computer is low noise. The motor is also a zero-maintenance device, which means a user will not need to change parts to keep the motor going. Other benefits include the compact size and longer life than the brushed types.

Components of Brushless DC Motor

Stator
The stator of a brushless DC motor consists of stacked steel laminates to carry the windings. These windings are placed in slots that are axially cut along the inner and outer circumference of the stator. These coils can be arranged in a star or triangle shape. However, most small brushless DC motors have three-phase star connected stators. Each winding consists of many interconnected coils, with one or more coils placed in each slot. In order to form an even number of poles, each winding is distributed around the periphery of the stator. The stator must select the correct rated voltage based on its power supply capacity. For robot, automotive, and small drive applications, high power brushless DC motor with a voltage of 48V or less are preferred. For industrial applications and automation systems, use motors with a rating of 100V or higher.

Rotor
A 24V brushless DC motor is equipped with a permanent magnet in the rotor. The number of poles of the rotor can vary from 2 to 8 pole pairs, with alternating north and south poles depending on application requirements. In order to achieve maximum torque in the motor, the material should have a high magnetic flux density. In order to generate the required magnetic field density, it is necessary to select suitable magnetic materials for the rotor. Ferrite magnets are cheap, but they have a given volume with a low flux density. Rare earth alloy magnets are commonly used in new designs. Some of these alloys are samarium cobalt (SmCo), neodymium (Nd), ferrite, and boron (NdFeB). The rotor can be constructed in different core configurations, such as circular core and peripheral permanent magnets, circular core and rectangular magnets, and so on.

Hall Sensor
The Hall sensor provides information to synchronize the stator armature excitation with the rotor position. Since the commutation of high torque brushless DC motors is electronically controlled, the stator windings should be sequentially energized to rotate the motor. Before energizing a particular stator winding, the position of the rotor must be confirmed. Therefore, a Hall effect sensor embedded in the stator can sense the position of the rotor. Most brushless DC motors incorporate three Hall sensors embedded in the stator. Each sensor generates low and high signals when the rotor pole passes nearby. According to the response combination of these three sensors, the accurate commutation sequence of the stator winding can be determined.

Maintenance Tips for Brushless DC Motor

Regular Inspection and Cleaning

A routine visual inspection of your brushless DC gear motor can reveal early signs of wear, contamination, or damage. Inspect the motor housing, wiring, and connections for any visible issues. Dust and debris can accumulate over time, affecting the motor's performance. Regularly clean the motor and surrounding area to prevent buildup.

Lubrication Matters

Lubrication is crucial for the smooth operation of gear motors. Ensure that you use the appropriate lubricant recommended by the motor's manufacturer. Over-lubrication can be as harmful as under-lubrication, so follow the guidelines carefully. Regularly check the lubrication levels and replenish them as needed to prevent excessive friction and wear.

Protect Against Moisture and Contaminants

Moisture and contaminants can be detrimental to the motor's components. To protect against these threats, consider using IP-rated enclosures or covers when the motor is exposed to harsh environmental conditions. Seal any openings or access points to prevent moisture and dust ingress. Regularly inspect and maintain these protective measures to ensure they remain effective.

Check for Loose Fasteners

Vibration and mechanical stresses can cause fasteners, such as bolts and screws, to become loose over time. Periodically check for any loose fasteners in the motor and its mounting brackets. Tighten them to the manufacturer's specifications to prevent excessive vibrations that can lead to premature wear.

Temperature Monitoring

Monitoring the operating temperature of your brushless DC gear motor is essential. High temperatures can degrade the motor's components and reduce its lifespan. Install temperature sensors or use thermal imaging equipment to track temperature variations during operation. If the motor consistently operates at or near its maximum temperature rating, consider implementing cooling solutions such as fans or heat sinks.

Electrical Connections

Ensure that all electrical connections, including wiring and connectors, are secure and free from corrosion. Loose or corroded connections can lead to voltage drops and erratic motor performance. Regularly inspect and clean electrical connections, and replace any damaged components promptly.

Brushless DC Motor Selection Guide

Brushless DC (BLDC) motor uses semiconductor switching devices to realize electronic commutation, namely replacing traditional contact commutator and brush with electronic switching devices. It has the advantages of high reliability, no commutation spark and low mechanical noise, and is widely used in electronic instruments and automated office equipment. Next is how to select a high power and high torque BLDC motor.

Torque, Speed Selection
On occasions of adjustable power supply voltage, the BLDC motor specifications whose torque and speed are close to the corresponding rated value of the product can be selected according to the actual needs, and then getting the required speed by changing the voltage. On occasions of constant power supply voltage, if there is no suitable BLDC motor for selection, the appropriate specifications can be selected according to the torque, and the voltage and speed of the product can be adjusted appropriately.

Power Selection
Maximum output power of the motor is limited. If the selected power is too small, the brushless DC motor will be overloaded when load exceeds its rated output power, and there will be motor heating, vibration, speed drop, abnormal sound and other phenomena. When the brushless DC motor is seriously overloaded, the motor will be burned down. But if the selected power is too large, it will cause economic waste. Therefore, it's very important to choose a reasonable power for motor.

Voltage Selection
Voltage is supplied by an electronic switching circuit controlled by the output of a position sensor. A right voltage should be firstly selected when choosing a brushless DC motor product, and the rated voltage should be according to customer's needs, then the driver voltage parameters should be selected correspondingly. Notice that the voltage used should not exceed the range specified by the driver in free-load and full-load.

Current Selection
When choosing the peak current of the controller, if the rated input current of motor is known to be Ir(A), then the peak current Ip(A)=2*Ir, otherwise, there is no engineering allowance for the output current during the operation of the controller. If the rated output power (or maximum output power) Pr(W) and driving voltage of the BLDC motor are known, then the peak current Ip(A)≧ 4*Pr/Vr.

Resistance Selection
Another key point is the insulation requirements of power. In order to ensure the normal operation of the controller, the insulation resistance between the Hall wire ground wire and the motor winding wire, the Hall ground wire winding wire and the housing of the motor shall be greater than 100 megao.

Certifications

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Our Factory

Changzhou Duowei Electric Co.,Ltd. was founded in 1997 and has more than 200 employees. It has developed hundreds of different product applications and established extensive strategic partnerships around the world with these products. Duowei Electric, the manufacturer of Wit Motors, our company does not use "conflict minerals", and the broad service industries include: automotive, industrial automation, robotics, household equipment, medical equipment, HVAC systems, office equipment, defense and aerospace, Electrical equipment and power tools.

Ultimate FAQ Guide to Brushless DC Motor

Q: How does a brushless DC motor work?

A: It uses an electronic controller to switch DC currents to the motor windings producing magnetic fields that effectively rotate in space and which the permanent magnet rotor follows. The controller adjusts the phase and amplitude of the DC current pulses to control the speed and torque of the motor.

Q: What is the lifespan of a brushless DC motor?

A: A typical lifespan of a DC motor in normal conditions is around 2000 hours, whereas a brushless DC motor typically averages 10000 hours.

Q: What is the efficiency of a brushless DC motor?

A: Brushless motors have higher efficiency rates of up to 85 to 90. This means that the mechanical power of a BLDC motor can be up to 90% of the total electrical power input. This efficiency rate is much better than those of brushed DC motors, which have an efficiency output power rating of around 75 to 80.

Q: How can the speed of a brushless DC motor be controlled?

A: By adjusting the frequency of the pulse signal that drives the BLDC motor, the motor speed will be changed. This type of speed control is usually achieved through specific electronic speed controllers or inverter. These devices are installed in the motor control system and connected to the motor windings.

Q: What is a Hall effect sensor and how is it used in a brushless DC motor?

A: BLDC motors use electronic instead of mechanical commutation to control the. power distribution to the motor. Latching Hall-effect sensors, mounted in the motor, are used to measure the motor's position, which is communicated to the electronic controller to spin the motor at the right time and right orientation.

Q: What is the torque formula for a brushless DC motor?

A: The equation for the torque constant of a BLDC motor: Kτ=602πKv(RPM)=1Kv(SI), where Kτ is the torque constant in N⋅mA, and Kv is the speed constant, in either rpm or rad/s.

Q: Can a brushless DC motor run in reverse?

A: Yes. To reverse direction of the motor just swap any two wires. The normal way is to change the sequence in which you power the motor winding by the motor controller.

Q: What is the maximum speed of a brushless DC motor?

A: The unique design of a BLDC motor allows for several key benefits: Diameters as small as 12.7 mm. Speeds up to 100,000 rpm.

Q: What is a three-phase brushless DC motor and how does it differ from a single-phase brushless DC motor?

A: A single-phase BLDC motor can only turn in one direction. For this reason, it is generally used in pump and fan applications. Three-phase motors have three sets of windings in the stator and are able to turn clockwise and counter-clockwise.

Q: How do I know what size brushless DC motor I need for my application?

A: Typically the best place to start when sizing a brushless DC motor is matching motor size (diameter, length). Diameter ranges from 13 mm to 30 mm. Brushless DC slotted motor diameter and length are specified in inches.

Q: What type of power supply is needed for a brushless DC motor?

A: BLDC Motor, or Brushless DC Motor, is a motor that uses DC electric power supply. It differs from the standard electric motors as it doesn't have brushes and uses an electronic drive to feed the windings of the stator.

Q: How do you troubleshoot issues with a brushless DC motor?

A: ● Correctly judge functions of various outgoing lines of the BLDC motor controller.
● Visual inspection of the BLDC motor controller.
● Use the multimeter for inspection when there is no connection.
● Measure the DC working points under the electrification.
● Try power-on operation.

Q: How does regenerative braking work in BLDC motor?

A: After driving the BLDC motor and when a stopping command is given to the motor, the motor will stop after a certain time with own inertia. It will produce back EMF. A regenerative braking will also be activated during this time. The regenerative braking system will induce the back EMF.

Q: What is the operating temperature range for a brushless DC motor?

A: Generally, the working temperature range of brushless motors is between -20 to +100 degrees, and more stringent ranges are between -40 to +140 degrees.

Q: What lubrication is needed for a brushless DC motor?

A: A NLGI 2 grade grease is the most commonly used in electric motor applications.

Q: What is meant by the term "cogging" in relation to brushless DC motors?

A: Cogging is a characteristic of permanent-magnet brushed, brushless, or AC synchronous motors. Cogging torque is generated when the sides of the rotor teeth line up with the sides of the stator teeth and the motor requires torque to break that attraction.

Q: What is the maximum current a brushless DC motor can handle?

A: The datasheet for the BLDC motor below is saying that the "Maximum Continuous Current" is 21 A (205 s).

Q: How much noise does a brushless DC motor make during operation?

A: Brushless DC motors do not have brushes and commutator rubbing against one another in electrical and mechanical contact and therefore do not produce electrical noise due to sparking nor mechanical noise due to the inevitable friction.

Q: Why do they make great alternatives to conventional brushed motors for automotive?

A: Brushless motors are becoming increasingly excellent alternatives to conventional brushed motors for automotive applications due to their many advantages, including:

Brushless DC motors offer higher operating efficiencies, greater torque density, quieter operation, more precise speed control, and longer life span than conventional brushed counterparts. These qualities make brushless motors well-suited for various automotive applications, from electric and hybrid cars to power steering and braking systems.

The core components of a brushless motor are also much smaller than those of a brushed motor, allowing for greater flexibility in design and packaging options.

Brushless motors are inherently more efficient due to their lack of friction between moving parts, resulting in reduced energy consumption and improved fuel economy.

Brushless motors can be easily integrated into existing electronic control systems due to their digital nature, making them an excellent option for modernizing older automotive systems.

Q: What are the advantages of brushless DC motor?

A: The advantages of a BLDC motor are.

Brushless motors are more efficient as its velocity is determined by the frequency at which current is supplied, not the voltage.

As brushes are absent, the mechanical energy loss due to friction is less which enhanced efficiency.

BLDC motor can operate at high-speed under any condition.

There is no sparking and much less noise during operation.

More electromagnets could be used on the stator for more precise control.

BLDC motors accelerate and decelerate easily as they are having low rotor inertia.

It is high performance motor that provides large torque per cubic inch over a vast sped rang.

BLDC motors do not have brushes which make it more reliable, high life expectancies, and maintenance free operation.

There is no ionizing sparks from the commutator, and electromagnetic interference is also get reduced.

Such motors cooled by conduction and no air flow are required for inside cooling.

Q: The What are the two types of BLDC motor?

A: Two main styles of the BLDC motor exist: inrunner and outrunner.

Outrunner BLDCs have permanent magnets on the outer section that moves as it turns the output shaft. BLDCs typically have more torque for a given size than inrunners and operate at a lower speed. Electromagnets are arranged on the inner stator section. They don't cool as well as their inrunner counterparts, and the housing doesn't provide as much protection from the elements.

Inrunner BLDCs arrange electromagnets inside a fixed outer housing, while permanent magnets are on the internal rotor. Inrunners typically spin faster than outrunners, producing lower torque at a given size. Inrunner motors have the advantage of better protection from the elements and better cooling since the electromagnet coils are attached directly to the external housing.

The electromagnetic sections of both the inrunner and outrunner remain stationary while the magnets turn. That's different than on a traditional DC motor, where the magnets remain stationary (affixed to the housing) while the electromagnetic section rotates. The other fundamental difference is that instead of timing coil energization based on a Hall effect sensor or back EMF, brushed DC motors use physical brushes to transmit electricity in a "mechanically programmed" sequence.

Q: How does BLDC motor work?

A: The BLDC motor has three main parts. First is the rotor, the part that rotates. Our brushless motor's magnets are located on its rotor core which consists of a four-pole permanent magnet and a smaller four-pole sensor magnet. The sensor magnet provides excitation to the second part, the sensor board which is an array of hall effect transistors. The on/off state of the sensors is how the control determines the rotor's angular position. The sensor board can be replaced with a commutating encoder to provide higher resolution position information. Third is the stator. This is the part that holds the windings. The three phase windings are placed such that when current is supplied to the coils making up the winding it creates North and South poles that attract the magnet.

Let's put it together: When the control and motor are powered on, the position of the rotor is read and the control will allow current to flow through two phases. The selected phases are predetermined based on an input/output table. When current is flowing through the stator magnetic poles are created that attract the rotor and rotary motion begins to happen. As the rotor turns the states of the sensors will change signaling the control to energize the next set of phases in the stator while the rotor continues to follow the generated magnetic field. The current is always switched before the magnets catch up insuring continual motion. The speed of the motor corresponds to the current switching rate. Two windings are always energized at a time with the third one off; combining the torques of two phases at once, increasing the overall torque output of the motor.

Brushless DC motors, in general, have characteristics of 3 phase AC induction motors in their construction. BLDC motors have a rotor core that rotates within a stator. The winding pattern of both can be the same. The difference is really in the rotor core. The induction rotor is made of a stack of laminations and then the slots of the laminations are cast with aluminum or copper. The BLDC rotor is constructed using permanent magnets. Both designs are considered maintenance free because the only wear item is the bearings which are lubricated for life. There is quite a bit of difference in performance between the BLDC and AC induction motors. AC induction motors hold a fairly constant speed while torque increases to the breakdown point. BLDC motors have in general a linear speed vs. torque curve. This means as torque increases that speed will go down at a rate equal to the change in torque. The BLDC motor also has a much higher starting torque.

The PMDC brush type motor actually has the same speed vs. torque characteristics as the BLDC motor, but from a construction stand point, the only thing in common is that it uses permanent magnets. The largest difference is the maintenance free design of the BLDC motor. The brush type motor uses brushes in order to commutate the coils. The brushes are normally the first thing to wear out, which can happen between two and three thousand hours. This is much less than the 20,000 hour life of the BLDC. Because the windings are on a BLDC are in the stator as opposed to the armature on the PMDC, the BLDC can dissipate generated heat easier allowing higher continuous duty power output in the same motor size.

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