Generally, an electric motor is a machine that converts electrical energy into mechanical energy and uses the generated electrical energy to generate rotational motion and thereby perform work.
Although there are many different types of motors, this page focuses on DC motors, which are motors driven by direct current (DC). DC motors are used in various devices and appliances that affect our lives.
This passage is going to talk about the followings of DC motor:
(1) Introduction to ac motor
(2) The working principle of ac motor
(3) The wide usage of ac motors
A direct current (DC) motor is a motor that converts electrical energy into mechanical energy. A DC motor obtains electrical energy from direct current and converts the energy into mechanical rotation.
A DC motor uses a magnetic field generated by a generated current, which powers the movement of a rotor fixed in the output shaft. The output torque and speed depend on the electrical input and the design of the motor.
How does a DC motor work?
The DC motor includes two key components: the stator and the armature. The stator is the fixed part of the motor, while the armature rotates. In a DC motor, the stator provides a rotating magnetic field to drive the armature to rotate.
A simple DC motor uses a set of fixed magnets in the stator and generates an electromagnetic field aligned with the center of the coil in a wire coil through which current passes. One or more windings of insulated wires are wound on the iron core of the motor to concentrate the magnetic field.
The winding of the insulated wire is connected to a commutator (rotary electrical switch), which applies current to the winding. The commutator allows each armature coil to be energized in turn, thereby generating a stable rotational force (called torque).
When the coils are opened and closed in sequence, a rotating magnetic field is generated, which interacts with the different magnetic fields of the fixed magnets in the stator to generate a torque, thereby rotating the torque. These key operating principles of DC motors enable them to convert electrical energy in DC power into mechanical energy through rotational motion, and then use it for the propulsion of objects.
This amazing electrical device has changed our lives in many ways, but who invented the DC motor? As with all major innovations, many people have a role to play in developing similar mechanisms.
In the United States, Thomas Davenport is recognized as the inventor of the first electric motor. There is no doubt that he was the first person to obtain a patent for a usable electric motor in 1837. However, Davenport was not the first to make an electric motor with various functions. When Davenport applied for a patent, European inventors had already developed a more powerful version.
In 1834, Moritz Jacobi proposed a kind of power, its power is three times that of Davenport later patented, and Sibrandus Stratingh and Christopher Becker was the first to demonstrate the practical application of electric motors by driving a small model car in 1835.
A few years later, in 1886, Frank Julian Sprague invented the first practical DC motor. This invention invented the first electric trolley system in 1887 and invented it in 1892 The first electric lift. Various applications will reshape the face of industry and manufacturing.
The term "DC motor" is used to refer to any rotating electrical machine that converts DC electrical energy into mechanical energy. The size and power of DC motors may vary, from small motors in toys and household appliances to large mechanisms that power vehicles, traction lifts and hoists, and large mechanisms that drive steel rolling mills.
Although each type has its advantages, in a broad sense, DC motors have many uses. At home, small DC motors are used for tools, toys and various household appliances. In retail, applications for DC motors include conveyor belts and turntables, while in industrial environments, applications for large DC motors also include braking and commutation applications.
The following are some specific uses of DC motors:
Fan DC motor
DC motor for pump
Toy DC motor
DC motors for electric vehicles
Robot DC motor
Bicycle DC motor
If you want to work with electric motors at home or in the workplace, it will be helpful to understand some of the working principles of electric motors. In some cases, you may need to reverse the direction of a single-phase Ac motor. Fortunately, this is a fairly simple task, because most single-phase induction motors will move forward and backward based on their wiring and the generated magnetic field. However, before carrying out such projects, certain safety procedures must be followed like any electrical work. How to reverse the direction of an Ac motor?
This passage is going to talk about the followings of ac motor:
(1) Electrical safety tips of ac motor
(2) Single-phase motor basics
(3) Single-phase Ac motor direction change
Before you start, you must fully understand all the necessary steps of an electrical project. For safety reasons, you should always inform other people present that you will use electricity, and ask them not to flip any circuit breakers or switches before completing the operation. Turn off all power to ac motor to be used at the circuit breaker box. Whenever possible, wear high-pressure rubber gloves and use rubberized tools.
The core of an induction motor is the rotor. The rotor is composed of permeable iron and aluminum circuit windings. The aluminum winding makes ac motor resistant to rapid magnetic field changes. This means that any field that ac motor will sense is a field to follow. Therefore, the direction of ac motor can be reversed by reversing the magnetic field it follows.
To reverse the rotation of a single-phase AC capacitor starter motor, you will need to reverse the polarity of the starter winding. This will cause the magnetic field to change direction and ac motor will follow. To achieve this, you can swap the connections at both ends of the winding. Always reverse the wire leading to the starter winding.
Please note that most motors, if still marked with the manufacturer's instructions, will indicate that they are irreversible. If this is the case, it may be because the wires you need to use are all located inside ac motor. If your device has this warning, it is the most difficult to proceed. However, if your motor is reversible, you may notice that it provides a reverse indication. Usually, these instructions tell you which wire to change. For example, some devices may switch the red and green wires in the junction box at the end of the enclosure. In other cases, the blue and yellow wires may need to be swapped. The color of the wires is highly independent and depends on the make and model of ac motor you have. It is best to read the instructions provided by the manufacturer before continuing.
If you determine which wires can be reversed, use a flat-head screwdriver to remove the end cap of ac motor. Your motor may have a junction box. In either case, you need to access the terminal to which the designated wire is connected. You may be able to use needle-nose pliers to remove the wire and switch the terminal to which it is connected. Some systems use nuts to connect wires. In this case, you will need to use a nut driver to access the terminals.
After the wires are switched, please reinstall the end cover or close the terminal box of ac motor. Restore power to the circuit and test ac motor to ensure that the magnetic field has switched and that the magnetic field does indeed rotate in the opposite direction.
After correct handling, electric motor can last a long time. In many cases, the premature motor failure is not due to any design, manufacturing or installation problems, but due to the most fundamental root cause: poor lubrication. In short, many people are killing our motors through bad lubrication practices.
Motor lubrication is not complicated. You only need to choose the correct lubricant, apply the correct lubricant every time, and then apply it at the required frequency.
Choose an excellent lubricant for your electric motor
Precautions of greasing the electric motor
Relubrication frequency of electric motor
The purpose of any lubricant is to separate the moving surface with an oil film. The amount of separation is called the film thickness. If the film thickness is too low, metal-to-metal contact will occur. Too much film thickness and internal agitation will cause fluid friction and temperature rise. To a large extent, the viscosity of the oil (relative to the load and speed of the bearing) determines the thickness of the film. As the viscosity increases, the film thickness increases. Conversely, as the viscosity decreases, the spacing between the filling thickness and the metal surface decreases.
It is important to consider the thickness of the grease. The most common mistake in selecting motor grease is to use multi-purpose grease. Multi-purpose grease is formulated with base oils in the range of ISO VG 220 to 460 cSt, which is too high for motor bearings at typical operating speeds. In order to solve this problem, multi-purpose greases usually contain EP additives. In some cases, EP additives will volatilize and corrode the copper windings of electric motor. Multi-purpose greases are designed for low-speed bearings or high-load bearings, such as pillow bearings used on conveyors. Do not use it for motor lubrication.
In contrast, a well-formulated motor grease usually contains a base oil with a viscosity of approximately 100 cSt at 40°C, a shear and temperature stable thickener (such as polyurea), and a mild anti-wear additive for mixed film lubrication.
Pumping grease into electric motor bearings is not complicated. However, some basic precautions should be taken. First, any pipe connecting grease fittings to motor bearings should be pre-filled with grease. Failure to do so may result in no grease entering the bearings in the first few guns, because the grease sprayed from the spray gun is only filling the oil supply pipe. Second, don't worry. Rapidly filling the bearing with grease can cause sudden shocks. It is best to shoot for three to five seconds at a time to ensure that a complete shot is allocated each time.
If equipped, it is good practice to remove the purge port, but it is not necessary to blow out the grease. Machinists often pump grease into electric motor to make the grease flow out of the purge port. Do not use grease that exceeds the calculated amount. Although not always feasible, some motor experts recommend applying grease when electric motor is not running. Since many bearing failures are caused by particle contamination, the best practice is to clean the grease fitting and the end of the grease gun before applying grease to electric motor.
Unlike calculating the amount of grease, determining the optimal replenishment interval is slightly more complicated. There are several ways to do this, but the easiest is probably to use Lloyd Tex Leugner in his "Machine Lubrication Practical Manual" (Maintenance Technology International Inc.) For the first time. The Leugner equation uses shaft diameter, rotation speed, and bearing type to estimate the number of hours between relubrication.
As the formula shows, as the speed increases, the number of hours between lubrication decreases because the stress on the lubricant will be higher. In addition to speed, dimensions and bearing working conditions should also be considered.
This is an embarrassingly simple question, but... how do you actually connect the part to the server? Obviously, this situation is easy to implement because it has mounting points, but the actual rotating part of the servo system is much more difficult.
The holes on the attached fixtures are too small for any type of screw, and glue is not an ideal solution (the screw cannot be inserted into the servo/removal part). 3D printing is almost impossible to achieve correct keying, and I don't know of any tool that can cut this type of spline (even then the screw hole will be blocked by the part). How to connect the servo system to the part?
This passage is going to talk about the followings of servo motor:
(1) How does the servo motor work?
(2) What is inside the servo motor?
(3) Servo motor applications
How to attach servo motor? You can try to solve these problems in this way.
The standard amateur servo system usually consists of a small motor, potentiometer, control electronics and gearbox. The position of the output shaft is continuously measured by the internal potentiometer and compared with the target position set by the controller.
Based on the error, the control electronics will adjust the actual position of the output shaft to match the target position. This is the so-called closed loop control system. The gearbox reduces the speed of the electric motor, thereby increasing the torque on the output shaft. The maximum speed of the output shaft is usually about 60 RPM.
To fully understand how the servo system works, you need to take a closer look. There is a very simple setup: a small DC motor, potentiometer and a control circuit. The motor is fixed on the control wheel by gears. As the motor rotates, the resistance of the potentiometer changes, so the control circuit can accurately adjust the amount and direction of movement.
When the shaft of the motor is in the desired position, the power supply to the motor is stopped. If not, turn the motor in the proper direction. The desired position is sent through the signal line by electrical pulses. The speed of the motor is proportional to the difference between the actual position and the desired position. Therefore, if the motor is near the desired position, it will spin slowly, otherwise it will spin quickly. This is called proportional control. This means that the motor will only do its best according to the tasks that need to be completed. This is a very efficient little guy.
Servo systems are used in radio-controlled aircraft to locate control surfaces, such as elevators, rudders, robot walking or operating grippers. The servo motor is small in size, has a built-in control circuit, and has good power suitable for its size.
In food service and medicine, these tools are designed to be used in more demanding environments because they are repeatedly cleaned under high pressure and high temperature to maintain strict hygiene standards, so the possibility of corrosion is high. Servos is also used in online manufacturing, in this case, high repeatability and precise work is required.
Of course, you don't have to know how the servo system works to use it, but as with most electronic devices, the more you understand, the more opportunities you have to open doors and project capabilities for expanding projects. Whether you are a hobbyist of construction robots, an engineer designing industrial systems, or just constant curiosity, where will servo motors take you?