From construction technology and automation equipment for manufacturers and construction companies, to imaging and diagnostic systems for hospitals, and electric motors for industrial and mobile purposes, Siemens seems to be everywhere.Since its founding more than 150 years ago, Siemens has grown into one of the world's leading electrical machinery manufacturers.
One of the world's leading diversified manufacturers and solution providers, entered the motor industry in 1970 and has since formed a prominent tradition of manufacturing some of the most reliable and robust motors in the global market.The company offers a wide range of low and medium voltage motors that set new standards for extreme performance and durability.
With a history of more than 130 years of technological innovation, ABB has become a world leader in electrified products, industrial automation and power grids, robotics and sports.It serves customers in the global utility, industrial, transportation and infrastructure sectors.
Nippon power is a leading Japanese manufacturer of electrical motors and control equipment for industrial, household and consumer products.Completed the previously announced acquisition of Emerson electric co. 's power generation, motor and drive businesses.The acquired enterprise has a solid business foundation, strong brand and a good customer base, mainly in the north.The United States and Europe.It also agreed to form a joint venture with PSA group, a French carmaker, and invest $261m to make motors in France for global and domestic sales.
Rockwell automation was founded in 1903 with an investment of $1000.Since then, American industrial automation suppliers have proven to be a successful example of becoming one of the global leaders in automation technology.Over the past decade, its investments in globalization and technology have enabled it to expand its target market to more than $90 billion
AMETEK is a world-class organization dedicated to providing key solutions to our customers' most complex challenges through unique technological innovations.Headquartered in Kent, Ohio, Atimek's affiliate Atimek advanced motion solutions (AMS) provides dc motors, controllers/drivers, fans, pumps, precision controlled blowers, and custom-engineered linear motion systems.
Regal Beloit is a global energy efficient, efficient motor and power transmission system that has a history of success by delivering world-class products and services where customers need them.Its Genteq brand of dc motors can be found in almost all household air-conditioning transmission devices in the United States, and its Marathon motor, Leeson and GE commercial motor brands are widely used.
With more than 50 years of experience in a range of industry verticals and businesses, the Johnson group has become a global leader in motors, motion subsystems, actuators and related electromechanical components.Application-specific technology and technology leadership are key drivers that have made Johnson a global leader in its industry.Johnson offers the largest set of engineering electrical and motion systems available in the market today, and these systems can be standardized to mass production or personalized to meet the needs of strategic departments and key customers.
From a small motor manufacturing company to one of the world's leading suppliers of fuel and water delivery systems and components, franklin electric's aggressive and comprehensive expansion has made it one of the best motor manufacturers in the world.Franklin electric serves customers worldwide in commercial, residential, industrial, agricultural, municipal and fuel applications.
Allied Motion is a leading manufacturer of precision Motion control products and solutions, known for its knowledge of electromagnetic, mechanical and electronic Motion technology.The company's growth strategy is focused on becoming a leader in its selected target markets, leveraging its expertise to develop precision sports solutions that leverage a variety of combined sports technologies to create higher value solutions for its customers.
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The dc generator works by taking the induced alternating electromotive force in the armature coil,
By means of commutator and brush commutating action, it changes from the brush end to the dc electromotive force.
The direction of the induced electromotive force is determined according to the right hand rule (the magnetic induction line points to the palm, the thumb points to the direction of conductor movement, and the other four fingers point to the direction of the induced electromotive force in the conductor).
The working principle of
The direction of force on a conductor is determined by the left-hand rule.This pair of electromagnetic forces creates a torque on the armature, called the electromagnetic torque in the rotating motor, which is counterclockwise in an attempt to turn the armature counterclockwise.If the electromagnetic torque overcomes the resistance torque on the armature (such as friction resistance torque and other load torque), the armature can rotate counterclockwise.
Dc motor is the motor running on dc working voltage, widely used in radio recorder, video recorder, DVD player, electric shaver, hair dryer, electronic watch, toys and so on.
Electromagnetic dc motor is composed of stator magnetic pole, rotor (armature), commutator (commonly known as commutator), brush, housing, bearing, etc.
The stator magnetic pole (main magnetic pole) of electromagnetic dc motor is composed of core and excitation winding.According to the different ways of excitation (called excitation in the old standard), it can be divided into series dc motor, parallel dc motor, supplementary dc motor and compound dc motor.Due to different excitation modes, the stator magnetic flux (generated by the excitation coil of the stator magnetic pole) also has different rules.
The excitation winding of a serial-excited dc motor is in series with the rotor winding through the brush and commutator. The excitation current is directly proportional to the armature current. The stator magnetic flux increases with the increase of the excitation current.Its starting torque can reach more than 5 times of the rated torque, short time overload torque can reach more than 4 times of the rated torque, speed change rate is large, no-load speed is very high (generally not allowed to run under no-load).Speed regulation can be realized by using external resistor in series (or parallel) with series wound or by parallel connection of series wound.
The excitation winding of the shunt dc motor is parallel with the rotor winding, and its excitation current is relatively constant. The starting torque is directly proportional to the armature current, and the starting current is about 2.5 times of the rated current.The speed decreases slightly with the increase of current and torque, and the torque of short time overload is 1.5 times of the rated torque.The change rate of rotation speed is small, ranging from 5% to 15%.The speed can be adjusted by the constant power of the attenuated magnetic field.
The excitation winding of the shunt dc motor is supplied by an independent excitation source, and the excitation current is constant. The starting torque is proportional to the armature current.Speed change is also 5%~15%.The rotating speed can be increased by weakening the constant power of the magnetic field or reduced by lowering the voltage of the rotor windings.
In addition to the shunt winding, the stator pole of the compound dc motor is also equipped with a series winding in series with the rotor winding (which has a small number of turns).The direction of magnetic flux generated by series winding is the same as that of the main winding. The starting torque is about 4 times of the rated torque, and the short-time overload torque is about 3.5 times of the rated torque.The speed change rate is 25%~30% (related to series winding).The speed can be adjusted by weakening the magnetic field.
Commutator commutator plate using silver copper, cadmium copper and other alloy materials, with high strength plastic molding.The brush is in sliding contact with the commutator to provide armature current to the rotor windings.The electric brush of electromagnetic dc motor generally USES metal graphite brush or electrochemical graphite brush.The core of the rotor is made of silicon steel sheets, generally 12 slots, embedded with 12 sets of armature windings. After series connection between the windings, the rotor is connected with 12 pieces of commutator pieces respectively.
The excitation mode of dc motor refers to the problem of how to supply power to the excitation winding, generate the excitation flux potential and establish the main magnetic field.According to the different excitation mode, dc motor can be divided into the following types.
The excitation winding has no connection with the armature winding, and the dc motor supplied by other dc power sources to the excitation winding is called the shunt dc motor. The wiring is shown in figure 1.23 (a).In the figure, M represents the motor. If it is a generator, it is denoted by G.Permanent magnet dc motor can also be regarded as an shunt dc motor.
The excitation winding of the shunt excited dc motor is in parallel with the armature winding.As a shunt generator, it is the terminal voltage from the motor itself that supplies power to the excitation winding.As a shunt motor, the excitation windings and armature share the same power source, and the performance of the shunt motor is the same.
The excitation winding of the series excited dc motor is connected to the dc power supply after series connection with the armature winding.The excitation current of this dc motor is the armature current.
Dc motor with compound excitation has two excitation windings, parallel excitation and series excitation.If the magnetic flux potential generated by the series winding is in the same direction as that generated by the shunt winding, it is called cumulative compound excitation.If two magnetic flux potentials are in opposite directions, it is called differential compound excitation.
Dc motors with different excitation modes have different characteristics.Generally, the main excitation modes of dc motor are shunt excitation, series excitation and compound excitation, while the main excitation modes of dc generator are shunt excitation, shunt excitation and compound excitation.
Permanent magnet dc motor also by the stator magnetic pole, rotor, brush, outside
Shell and other components, stator magnetic pole using permanent magnet (permanent magnetic steel), ferrite, aluminum nickel cobalt, ndfeb and other materials.According to its structural form can be divided into cylinder type and tile type.Most of the electricity used in VCR is cylindrical magnet, while most of the motors used in electric tools and automotive appliances are special block magnets.
Generally, the rotor is made of silicon steel, which has fewer slots than that of electromagnetic dc motor.Most of the low-power motors used in VCR are 3-slot, and the higher-grade ones are 5-slot or 7-slot.Enamelled wire is wound between two grooves of the rotor core (three grooves are three windings), and its joints are respectively welded on the metal sheet of the commutator.The electric brush is a conductive part connecting the power supply and the rotor winding.The brush of permanent magnet motor USES unisexual metal sheet or metal graphite brush, electrochemical graphite brush.
Permanent magnet dc motor used in VCR adopts electronic speed stabilizing circuit or centrifugal speed stabilizing device.
Brushless dc motor USES semiconductor switch device to realize electronic commutator, that is, electronic switch device to replace the traditional contact commutator and brush.It has the advantages of high reliability, no commutating spark and low mechanical noise. It is widely used in high-grade recording block, video recorder, electronic instrument and automatic office equipment.
Brushless dc motor is composed of permanent magnet rotor, multi-pole winding stator and position sensor.Position sensing according to the change of rotor position, along a certain sequence of stator winding current converter (i.e. detecting the rotor magnetic pole relative to the position of the stator winding, and in determining the location of position sensor signal, the signal conversion circuit to control the power switch circuit, after processing according to certain logic relation between winding current switch).The working voltage of the stator winding is provided by the electronic switching circuit controlled by the output of the position sensor.
There are three types of position sensors: magnetic, photoelectric and electromagnetic.The brushless dc motor adopts magnetic-sensitive position sensor, and the magnetic-sensitive sensor components (such as hall element, magnetic-sensitive diode, magnetic-sensitive geophone, magnetic-sensitive resistor or special integrated circuit, etc.) are mounted on the stator components, which are used to detect the change of magnetic field generated by the rotation of permanent magnet and rotor.
The brushless dc motor with photoelectric position sensor is equipped with photoelectric sensor in a certain position on the stator assembly. The rotor is equipped with a shading plate. The light source is led or small light bulb.When the rotor rotates, the light-sensitive components on the stator will generate pulse signals intermittently according to a certain frequency due to the effect of the shading plate.
Using electromagnetic position sensor brushless dc motor, is in the electromagnetic sensors are installed on the stator component parts (such as the coupling transformer, close to switch, LC resonance circuit, etc.), when the permanent magnet rotor position changes, electromagnetic effect will make the electromagnetic sensor produces high frequency modulation signal (the amplitude changes with the rotor position).
From zero speed to rated speed can provide rated torque performance, but the advantages of dc motor is also its disadvantages, because dc motor to produce rated load constant torque performance, the armature magnetic field and rotor magnetic field must maintain 90°, which is required by the carbon brush and commutator.The carbon brush and commutator will generate sparks when the motor turns, so the carbon powder will not only cause damage to the components, but also the use of the situation is limited.Ac motor without carbon brush and commutator, maintenance-free, robust, widely used, but the characteristics of the equivalent to dc motor performance must be achieved by complex control technology.Nowadays, semiconductor develops rapidly. The switching frequency of power components is much faster, which improves the performance of the driving motor.The speed of the microprocessor is also getting faster and faster, which can realize the ac motor control in a rotating two-axis direct alternating coordinate system, appropriately control the current component of the ac motor in the two-axis, to achieve the control similar to the dc motor and have the performance equivalent to the dc motor.
In addition, many microprocessors have done the necessary functions to control the motor in the chip, and the volume is getting smaller and smaller;Analog to digital converter (ADC), Pulse wide modulator (PWM)...And so on.Brushless dc motor is a kind of application which controls the commutation of the ac motor by electronic means and obtains the similar characteristics of the dc motor without the missing of the dc motor mechanism.
Brushless dc motor is a type of synchronous motor, that is to say, the speed of the motor rotor is affected by the speed of the motor stator rotating magnetic field and the number of rotor poles (p) :
N = 120.F/p.When the number of rotor poles is fixed, the rotor speed can be changed by changing the frequency of stator rotating magnetic field.Brushless dc motor is the synchronous motor plus electronic control (driver), control the stator rotating magnetic field frequency and the motor rotor speed back to the control center repeated correction, in order to achieve close to the dc motor characteristics.In other words, the brushless dc motor can control the motor rotor to maintain a certain speed when the load changes within the rated load range.
The brushless dc driver includes the power supply department, the control department and the power supply department to provide three-phase power supply to the motor, and the control department converts the input power frequency according to the demand.
The power supply can be directly input with direct current (normally 24v) or alternating current (110v/ 220v). If the input is alternating current, it must be converted to dc by Converter.Both input dc or ac input to turn to motor coil must be before the dc voltage of Inverter (makes) into three phase voltage to drive the motor.Inverter (makes) by six commonly power transistor (q1 ~ q6) is divided into upper arm (q1, q3 and q5)/lower arm (q2, q4, q6) connect the switch of motor as control flows through the coil.Control department provides PWM (pulse width modulation) decision power transistor switching frequency and the Inverter (makes) commutation time.Brushless dc motor generally hopes to use the speed control which can be stable at the set value without too much change when the load changes, so the motor is equipped with the hall-sensor which can sense the magnetic field, as the closed loop control of the speed, and also as the basis of phase sequence control.But this is just for speed control not for positioning control.
To make the motor rotation, control department must according to the Hall - sensor sensing the position of the motor rotor, and then according to the stator winding decided to open (or closed) Inverter (makes) in the order of the power transistor, the current flowing through the motor coil in a sequence downstream (or the reverse) rotating magnetic field, and interact with the rotor magnet, so can make motor chronological/reverse rotation.When the motor rotor rotates to the position where another set of signals are sensed by the hall-sensor, the control department turns on the next set of power transistors. In this way, the circulating motor can continue to rotate in the same direction until the control department decides to shut down the power transistor (or only turn on the lower arm power transistor) if the motor rotor stops.To reverse the motor rotor, the power transistor is turned on in the opposite order.
General brushless dc motor is essentially a servo motor, composed of a synchronous motor and a driver.The brushless dc motor with variable pressure and speed regulation is a brushless dc motor in the real sense. It is composed of stator and rotor. The stator is composed of iron core."Winding, thus generating n-s group of fixed magnetic field, rotor composed of a cylindrical magnet (intermediate shaft), or composed of electromagnet plus collector ring, this brushless dc motor can generate torque, but cannot control the direction, anyway, this motor is a very meaningful invention.When acting as a dc generator, the invention can generate a continuous amplitude of dc current, thereby avoiding the use of a filter capacitor, and the rotor can be permanent magnet, brushless or brushless.When used as a large motor, the motor will generate self - inductance, need to use protective device.
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