Motor power calculation formula

Apparent power S = UI Active power P = UIcos theta Reactive power Q = UIsin theta. The square of the square of the apparent power = active electric vehicle motor power + square of reactive power Motor power calculation formula is: 3 P =) uicos theta eta The P - rated power output shaft of the motor U - rated voltage I - rated current The power factor of cosine Motor vehicle theta - motor Eta, the efficiency of the machine Cosine theta power factor (pf) refers to the consumption of motor power of the ratio of apparent power. Eta motor efficiency refers to the ratio of the output power of active power. Such as active power consumed by an electric motor is 5 kw, and as a result of the motor coil impedance,

 so be electric consumption and fever. www.dongfeng-motor.com The power output 4.5 kw, then its

efficiency is 4.5/5 = 0.9.

Triangle y connection to the motor's power

The stator winding y connection run by triangle instead, motor is long-term work under lower than the rated voltage of a special case. This way of running if used properly, to improve the power factor of the motor, managing electric energy has certain practical significance. A, triangular y connection to the motor's power Change the triangle to y connection, equivalent to the stator winding three phase voltage reduce to 1 /), then motor spare parts the motor of each quantity has the following changes: 1. The excitation power The field current reduced to about 1/2, so the excitation reactive power reduced to wholesalemotor.blogspot.com 1/3) (2) = 1/3.5. 2. The stator iron loss is directly proportional to the square of the voltage change, reduce to about a third. 3. The maximum torque and voltage changing proportion of square, reduce to a third. In order to maintain stable operation, the motor load will decrease accordingly. 4. Approximate slip and is inversely proportional to the square of the voltage change, under the same load, approximately increase to 3 times, but the speed changes. 5. Rotor current When the load is constant, the electromagnetic power constant; Due to the magnetic flux over voltage reduce to 1/3, square root 3 times, so the rotor current increase) increase winding fever. 6. Magnetic flux leakage reactive power Magnetic flux leakage voltage and reactive power to quadratic inverse proportion increase more, about three times as much. 7. The stator current of the stator current is determined by the rotor current and no-load current y connection, the former, the www.facebook.com/guohong.trading latter is reduced, so the stator current may increase or decrease, depends on the magnetic properties of the motor and load size. Fall, but in general, voltage, stator current increase. Active loss of 8. Due to the current in the rotor winding loss increase) and increased to 3 times, 3 times in the stator winding loss or increase or decrease, motor lamination depends on the change of the stator current. Comprehensive above, change the triangle to y connection, due to the reduced voltage, maximum torque decreases, and rotor current increase. If you maintain the load constant, is bound to cause the winding severe fever; Or because the torque is too small and make the motor stalling. In order to make the rotor after y connection instead Electric current shall not exceed the rating, should appropriate reduce the load of the motor.

Asynchronous motor common faults of examination and ruled out

In the operation of the asynchronous motor in due to friction, vibration, insulation aging, hard to avoid failure.If these faults timely inspection, found and ruled out, can effectively prevent the happening of the accident.A, the asynchronous motor fault inspection 1.Listen to the voice, carefully to find fault point of ac asynchronous motor in operation, if found a finer "buzzing" sound, no change of high and low, is acmotor2.blogspot.com a normal voice, if the voice thick, and a sharp "buzzing", "hissing" sound is the forerunner of faulty, should consider the following reasons: (l) loose core motor vibration in the operation, the change of the high and low temperature, can make the iron core deformation of the retaining bolt, silicon steel sheet caused by loose, produce large electromagnetic noise.(2) the voice of the rotor spinning rotor noise, produced by the cooling fan, is a kind of "whoops" sound.Like drums of the "product" sound, this is the motor in sudden start, stop, reverse connect braking variable such as cases, the accelerating torque rotor iron core and the shaft with the loose, light person can continue to use, the person that weigh apart to check and repair.(3) in the operation of the motor bearing noise in, must pay attention to bearing the change of the voice, one end of the screwdriver to touch on the bearing cover, the other end on the ear, can hear the sound of the motor internal changes, different area, different fault, has a different voice.Such as crunching sound is produced by the irregular motion of the roll bearing inner gun, it related to the bearing clearance, grease state."Hissing" sound is metal, usually caused by bearing the lack of oil, add grease agent should open bearings.

2.The use of the sense of smell, failure analysis and motor is no peculiar smell in the normal operation, if the sensed the ignorance, is the fault signal, such as, anxious burnt flavour is insulation barbecue, and with the temperature increasing of motor, serious when Motor vehicle still can smoke; Such as oil coke, mostly lack of oil bearing, in dry grinding state near the end of the oil and gas evaporation of peculiar smell.3.Using the handle, check failure Touch the shell, can be broadly determine high and low temperature rise, if a touch the motor shell with the hand feel is very hot, the temperature is very high, should check the reason, such as: heavy load, the high voltage, and then for troubleshooting.Second, the common faults 1.The motor did not start torque, or won't start when there is no load and abnormal sound.Reason: (l) three-phase power circuit (including) the stator winding of knife switch, fuse one phase power, caused by single phase started.(2) the power supply voltage is too low.(3) bearing excessive wear, close to the one side of the stator and rotor caused by different heart of stator and rotor, air gap is not rotor balancing machine uniform.2.The motor starting torque is small, can't start, when the load, load increases when the motor stalling, sometimes send strong noise, local heating.Reason: low voltage grid and winding interturn short circuit, break or desoldering phenomenon in the rotor winding, start-up phase after a break caused by single phase operation.3.The starting current is big, and don't balance, noise big, cause protective device and cut off power supply.Reason: the stator winding wiring method may not be correct, winding of insulation aging.

The working principle of coil heating drying machine

Coil heating drying machine is actually a set of adjustable height of ac voltage transformer, secondary measurement of the output voltage, low bit of 0 ~ 14 v, high-grade is 16 ~ 28 v, by adjusting the switch 2 v per shift change. Through special homemade clamping device from commutator to the rotor winding ventilation with the appropriate voltage, current control in electric tool machine between 50% to 50% of the three phase generator rated current, rotor winding heat from inside to outside, can guarantee the uniform heating of winding, well guarantee the quality of dip coating and drying, prolong the service life www.facebook.com/guohong.trading of the rotor's actual. Notice that when you need heating drying older generator generator set rotor and secondary measurement output voltage, low should be 0 ~ 28 v, high-grade 32 ~ 56 v, by adjusting the switch to realize each file change 4 v, this should increase the capacity of transformer. The working principle of coil heating drying machine

Motor into the water after the maintenance method

Immediately after the motor by the water or water, need to check repair, remove the moisture, impurities, in order to prevent the permanent magnet generator motor damaged or destroyed. To fill the agricultural motor should be motor spare parts in accordance with the following four steps overhaul. 1, outside of the wholesalemotor.blogspot.com sludge, impurity removal motor, but do not turn the motor shaft. 2, open motor body, clean up the shell lumen, rotor, and the dirt and stains on the slip ring, check whether the winding is to take off the welding, brush whether rust stuck in the brush holder, brush pressure is normal, whether the brush and slip ring surface tiejin, if discover fault should be ruled out. 3, to dry the winding of the motor. Available incandescent lamp baking, make the moisture evaporation, also can be put in ventilated place dry naturally. But not with the current heat or open flame baking, in case of motor winding short circuit or bad insulation layer. After drying, need a megohmmeter or multimeter to check the coil insulation performance. Found to be defective insulation should be maintenance. 4, www.facebook.com/guohong.trading the motor body refitted, the test run of the motor. Such as test run without any problems, you can put to use.

Generator excitation current of several ways

1, dc generator excitation power supply: this way of excitation generator has a dedicated dc generator, the dedicated dc generator said For the dc exciter, exciter is general and coaxial generators, generator exciting winding through perfectly on the large axial slip ring and fixed brush from the exciter Dc current. This way of electric vehicle motor field independent excitation current, more reliable and decrease for electricity consumption, etc, is in the past few decades Generator main excitation mode and has a mature operating experience. Defect is excitation regulating speed slower, maintenance workload is big, so in more than 10 mw The crew are rarely used. 2, ac exciter power supply mode of excitation, some use ac exciter provides modern large capacity generator excitation current. Ac exciter Installed on the generator shaft, its output of alternating current flows through the rectifier supply generator rotor excitation, at this point, the generator excitation way his wound Magnetic way, and with the stillness of wholesalemotor.blogspot.com the rectifying device, so it is also called separately excited static excitation, exchange exciter provides exciting current. Deputy excitation communication Magnetic machine can be permanent magnet machine with self-excitation constant pressure device or alternator. In order to improve the excitation regulating speed, ac exciter is usually adopted 100-200 hz frequency generator and the ac exciter are using 400-500 hz frequency generator. The motor fan dc excitation winding of generator Group and the three-phase ac winding around the stator slot, the rotor teeth and slots without winding, like a gear, therefore, it has no brush and slip ring Turn the contact parts, with reliable work, simple structure, convenient manufacturing process. The disadvantage is that the noise is bigger, ac voltage harmonic Component is bigger also.

Three-phase asynchronous motor connector

A change, triangular connection motor y connection Normal operation by delta connection of three-phase asynchronous motor, in order to reduce power use, can take three phase electric fan motor parts windings into star after online on the power supply voltage of 380 v, about 34% of the rated power is the power of the motor. For example, the 380 v delta connection 10 KW three-phase asynchronous motor to change into a star, meet online voltage of 380 v three-phase power use, at this time the power output of the motor is about 3.4 KW. Second, the three-phase asynchronous motor single-phase asynchronous motor Y connection and delta connection of three-phase motor changes the same way. Open the three-phase asynchronous motor terminal box, between any two phase power terminal access to a capacitor. The capacitor between V1 and W1, for example, it is at this point to connect single-phase power supply between the U1 and V1 or W1 (assuming the power of connect between the U1 and V1 motor, the power supply in U1 and electric opportunity inversion between W1,) can transform the original three-phase asynchronous motor converted a single-phase asynchronous motor. This method is especially suitable for no occasion of three-phase power supply using three-phase asynchronous motor. The capacity of the capacitor C = KP obtained are available, and where C is the capacity of the capacitor, the unit is the micro method (u F); P is the power of the motor, the unit is a kilowatt (KW); K is the empirical coefficient, take 0.06 when y-connection three-phase asynchronous motor, triangle sexual connection for 0.1. 

For example, 10 kw three-phase asynchronous motor when the star connection KP = C = 0.06 x 10 = 0.6 u F; 10 kw three-phase asynchronous motor triangle connection KP = C = 0.1 x 10 u F = 1. Changed to: after instead www.dongfeng-motor.com of capacitor terminals, such as the case of U1 power cord, another power cord by V1 connector on the W1 can realize inversion, the inversion of the inversion principle of single-phase asynchronous motor with the same principle Connect power: after the change is a single-phase capacitance motor, its effective power is 70% of the original motor power, for example: 10 kw three-phase asynchronous motor connector into effective power single-phase capacitor motor is about 7 kw. Convert into single-phase capacitor start motor, its effective power is 40% of the original asynchronous motor motor power, for example: 10 kw three-phase asynchronous motor connector into effective power for 4 kw single-phase capacitor start motor. To pick up after each phase winding voltage for no more than the rated voltage of the winding. What kind of motor depends on specific convert into being dragged the power of agricultural machinery. When convert into single-phase capacitor start motor, need to add one more time relay, wiring method is: put the time delay of time relay to disconnect the instantaneous closure in series capacitor circuit, the normally closed contact of time relay coil in parallel on both ends of single-phase power supply (time relay coil of the rated voltage is the same as the power supply voltage). After connected circuit, adjust the delay time of time relay, can work normally. Its working principle is: when switched on, time relay and motor for electricity at the same time, the capacitor circuit switched on, the motor starts, when the speed reached about 80% of the rated speed (implementation) by adjusting the delay time relay time delay disconnect instantaneous closure of time relay normally closed contacts disconnect, cut off the capacitor circuit, motor function.

Electrical engineer developed efficient motor technology

The key to reduce the loss of highly efficient motor all kinds of technology research, the main way

is to reduce the motor loss, this requires the motor on the mechanism of all kinds of loss extremely

thorough and meticulous research, to develop the potential of reduce the loss of all kinds of, this

is no longer a single electromagnetic design, it is based on the traditional motor design model to

establish a more power electric motors accurate mathematical physical model, and

considering the process, material, machining accuracy, the structure, the ratio of various factors

such as study, put forward to solve the key technology to reduce the loss of all kinds of motor and

the design technology, including the structure design and manufacturing technology of super efficient

motor, the rotor parameters, to reduce the power consumption of copper winding technology, reduce the

power consumption of the wind the wind road components, ventilation system and the design of the

bearing system, motor manufacturing technology research in order to reduce additional loss, etc. In

conclusion, to develop highly efficient motor can be developed the key technology needed to do the

job are briefly summarized as the following aspects: 1) in the motor loss calculation and analysis

research: traditional calculation method based on the analysis of the magnetic circuit loss and play

a major role in China's past series motors are designed, such as Y, Y2, Y3 series induction motor,

but this method exists empirical coefficient is various, such as local distribution cannot be

analyzed loss limitations. In order to solve this problem, the researchers conducted at home and

abroad based on modern computer technology for the analysis of loss of the new study, this respect is

the most widely used finite element method,www.facebook.com/dongfeng.motor
this method can easily handle arbitrary structure and arbitrary boundary conditions and complex

problems brought by the source distribution, at the same time can also plan and saturation within the

motor and nonlinear complex problems, such as in motor design has a unique advantage. Against the

super-efficient motor loss for this reason, the finite element simulation analysis and research, to

reveal the motor internal loss characteristics from the microscopic view has important theoretical

value, but also can be in order to further study how to improve the motor structure design to provide

necessary technical reference. 2) on the motor loss factors and structure improvement research:

because of the influence of the motor loss factor is various, involving motor iron core structure,

winding structure and manufacturing process, and so on. Most the influence factors of the core

structure, which mainly includes the stator slot,acmotortrading.blogspot.com
and the air gap size, chute and groove Angle, the size of the trough, trough type (closed slot or

semi-closed slots) and stator side structure, etc. For decades, limited to the limitation of

calculating method, in the design of asynchronous motor, the influence of core structure use no more

saturated theoretical value or experience value, the processing method can't for a specific factors

on the specific impact of the loss of an in-depth study. Therefore, in the super efficient early

motor development, the need for different motor structure finite element model is set up, by changing

the parameters of different motor structure and material properties, analyzed the influence extent of

different factors on the motor loss of concrete based on the optimal design scheme, and finally to

achieve. 3) in the motor loss test research: in the latest IEC motor test standard IEC60034-2-1 the

rotary motor (except for traction motor) to determine the efficiency and loss test method, the

regulation IEEEl12B method as the only test method of low uncertainty. So, if you want to develop

real conform to the high level of efficiency of motor, must be in low uncertainty of IEEE 1 I 2 b

method system research, the focus is to study the precise measurement of the input power under the

condition of low power factor, low uncertainty of additional loss and efficiency testing technology

as well as the uncertainty evaluation techniques. 4) to reduce the loss of other measures, the

development of highly efficient motor, also involves motor core materials, winding type and

manufacturing process and how to reduce the mechanical consumption research, by conducting such

studies can be from a certain 8500w gasoline generator extent, reach the purpose of

consumption.

The choice of servo motor electrical engineer

The choice of servo motor, the distinction between general electrical engineer in accordance with the

generally divided into stepper motor, a dc servo motor, brushless dc servo motor, ac servo motor,

with the increasingly progress of science and technology, many special servo motor arises at the

historic moment, such as piezoelectric motor, linear motor, and the voice coil motor, here we mainly

talk about general servo motor selection. Choose what kind of servo motor, to a large extent depends

on the physical properties of the load, the load of job characteristics, system requirements and the

working environment. Once the system requirement, no matter choose what kind of rotor cutting machine form of servo motor, the first thing to consider is right choose how much of a motor, main consideration physical characteristic of load, including the load torque, moment of inertia, etc. In the servo motor, usually measured in torque or force motor size, so choosing motor first to calculate the equivalent to the size of the shaft end load torque or force. After calculate the torque demand to set aside

part of allowance, generally choose motor for times the load torque, torque to the ac synchronous motor reliable running of motor.

In addition also needs computing reduced to the size of the shaft end load inertia, generally choose

the load inertia: motor rotor inertia, to ensure the rapidity of the servo system response. If appear

between the motor and load inertia, torque does not match the situation, so only at the expense of

speed, increase speed reducer between the motor and load, then you need balance. After selected by

how much torque motor, needs to do is to understand the working characteristic of load and working

environment. Work load features include such as load is high or low speed running, the acceleration

needs to how much, if demand is frequent start-stop, how frequency requirements, system running

precision and so on. Then choose servo motor also has no specific rules to follow, the key is your

choice of motor must adapt to work to beg you load movement. Such as the system accuracy is not high,

the movement speed around hundreds of the following (not more than 500 RPM) but not too low (greater

than 1), does not need to frequent start-stop, stepper motor is a kind of good choice. This is due to

the stepper motor open-loop control, low control precision, acmotortrading.blogspot.com high speed, motor torque will drop quickly, will take the fixed load, low speed will be rotating discontinuous crawl phenomenon, and the response of the stepper motor is not fast, not suitable for frequent startup

applications. When the speed a few turn to more than 3000 turn, relative to demand higher control

precision, can choose straight flow or ac servo motor.

China motor network, increase the stepper motor dynamic torque method

Step 1, select from the Angle of small stepper motor at low speed torque gets bigger with the increase of rotor teeth. Choose small step away from the Angle of step motor can obtain high torque. A dozen HB type on the rotor teeth like 50 tooth, permanent magnet magnetic flux leakage will increase, but will step in proportion, this conclusion in 100 teeth of the following are valid. Type three-phase HB stepping motor from 1.2 ° 50 tooth (rotor) change 0.6 ° 100 teeth (rotor). About 1.4 to 1.8 times the torque at low speed. 2, bipolar rotor cutting machine connection efficiency can cover 2 times. It is easy to buy on the market two phase unipolar or bipolar stepper motor, but bipolar drive power tube is larger than that of unipolar. Stepper motor in high speed way to increase the torque: 1, to reduce the number of turns, reduce L in motor manufacturer's standard products choose small inductance L, rated current. 2, a permanent magnet flux is smaller Can't ac synchronous motor reduce the permanent magnets, such as production maternity leave can increase the air gap, reduce the high speed counter potential, increase current, make the torque increases, the speed - torque characteristic from low speed to high speed into a straight line, increase the torque, frequency response also increases at the same time. Step 3, choose from the Angle of motor. , step motor running at a high speed in the drive circuit improve the method of torque: 1, improve the drive current voltage to maintain high speed large torque, to keep the current constant, make the chopper work in constant current state. To make a constant current can only improve the pulse frequency. When as a stepping motor velocity must be high speed, because the voltage limit, can only work in constant voltage state, if the input voltage, then you can make it at a high speed still can work in constant current state, if the input voltage, then you can make it at a high speed still can work in constant current state, thus improve the speed torque. 2, to reduce the driving circuit shut off when the current in the coil current at the time of power tube shut off, due to the current rate of change is big, coil produced very big induced voltage, power tube will have a risk of being www.facebook.com/dongfeng.motor breakdown, there is often a protection circuit.

Three-phase asynchronous motor starting method

Squirrel-cage three-phase asynchronous motor in the widely used now. This kind of motor in the design process focuses on at work can not only realize good use of intelligent control, and in the process of use and not due to the use of a lot of power to grid used in daily life, work, a certain power impact. The squirrel-cage three-phase asynchronous motor in use process, by the use of gf in use process is usually via step-down start to start the motor, now use the step-down start there are two main ways, one is step-down motion, while another is called soft start. Soft start is also called electronic soft start, the startup mode generally adopts 16-bit single chip microcomputer to be responsible for rotor and stator the control of the motor, through the intelligent control system, the motor at work can ensure that the motor in the load it can achieve a smooth start, still can reduce because click use too much power and cause certain impact to the grid. Including the squirrel-cage three-phase asynchronous motor in before and now, the grid has always maintained a in the process of running with the characteristics of volatility, often at the time of peak electricity consumption, electricity in use process found obvious battery is low, but in the case of electricity consumption is very low, there will be a power's use of power is very high. In order to some of the production process can fully more rational use of electricity, people invented the electric motor electronic soft starter, this product motor fan with this product, the squirrel-cage motor is applied. The squirrel-cage motor such as the electromagnetic brake is also need in step-down startup conditions. In the process of this kind of motor start, machine can't work under full pressure start mode, and when it starts, terminal voltage can't realize the characteristics of the specification requirements.

Motor fault diagnosis and maintenance

Motor running or failure, can see, hear, smell, touch four methods to prevent and troubleshooting in

time, guarantee the safe operation of motor. Look, observe the motor running with and without

exception, in the process of its main performance for the following situation. 1. The stator winding

short circuit, may see the motor smoke. 2. The serious overload or short of motor phase operation,

speed will slow down and have a heavy "buzzing" sound. www.facebook.com/dongfeng.motor 3. The

motor run normally, but suddenly stops, will see the wiring loose sparks; A portion of the blown fuse

or stuck. 4. If the motor vibration, could be gearing jammed or motor fixed, loose bottom bolt, etc.

5. If the motor inside contact point and forms a discoloration, burn mark and stain, then there may

be local overheating, poor contact or winding conductor joint burned, etc. Second, listening to the

normal operation of the motor should be a uniform and lighter "buzzing" sound, no noise and special

voice. If the noise is too big, including electromagnetic noise, bearing noise, ventilation, noise,

mechanical friction sound, etc., may be failure precursor or failure phenomenon. For electromagnetic

noise, if the motor send out the voice of high and low and heavy, the reason may have the following

kinds. (1) the uneven air gap between stator and rotor, the voice of high and low and high and low

time interval constant, this is so that the stator and rotor bearing wear and tear caused by a heart.

(2) three phase current balance. This is by three-phase winding grounding, short circuit or poor

contact, if sound is very depressing, serious overload or short of motor phase operation. (3) the

iron core is loose. Due to vibration in the operation of the motor in the core fixed bolt looseness

motor part caused by loose core silicon steel sheet, making noises 2. The bearing noise, should often listen in the motor running. Monitoring method is: will the screwdriver end to resist bearing installation site, on the other side, close to the ear can hear bearing operation. If the bearing is working well, its sound is continuous and tiny "rustling" sound, does not have the change of high and low, and metal. If appear

the following voice is not normal. (1) bearing operation "creak" sound, this is metal, generally for

bearing caused by lack of oil, should be apart bearing charging right amount of grease. (2) if there

"pumping mile", this was the voice of the ball rotates, generally for dry or lack of oil, grease can

be loaded with a moderate amount of grease. (3) if there "raise price" or "creak" sound, for the

bearing inner ball irregular movement of sound, this is the inside of the bearing ball or motor

long-term need not, grease caused by the asynchronous motor drought. 3. If the drive mechanism and transmission mechanism continuous instead of high and low sounds, processing can be divided into the following kinds of situation. (1) periodic "snapped" sound for belt joint is not smooth. (2) periodic

"drumming sound for loose coupling, or between the pulley and shaft and key or keyways wear cause.

(3) uneven clash, as the wind leaf fan cover cause collision. Three, smell smells odour of a motor

through diagnosis, and can also prevent failure. If found to have special smell of paint, the

internal temperature of the motor is too high; If found to have a heavy, focal smell the smell of

burnt food or may be insulation breakdown or winding has been burned. Four, touch the temperature of

the motor to some parts also can determine the cause of the problem. Application in order to ensure

safety, when using a touch of the hand to touch an electric shock around motivation shell, bearing

parts, if discover the abnormal temperature, the reason may have the following kinds. 1. Poor

ventilation. Such as fan, air duct jam, etc. 2. The overload. Cause excessive current and the stator

winding overheating. 3. The stator winding interturn short circuit or three phase current balance. 4.

The frequent start or braking. Around 5. If the bearing temperature is too high, it may be caused by

bearing damaged or short of oil.

Electrical engineers to study the main technical points of the permanent magnet generator

1 magnetic circuit structure and the design calculation The biggest difference between permanent magnet generator and electrical excitation generator excitation magnetic field is that it is produced by the permanent magnet. In permanent magnet motor is a magnetic source, and part of the magnetic circuit. Magnetism of permanent magnet can not only associated perkins diesel generator with the manufacturing process of production, and also the shape and size of the permanent magnet, the magnetization machine capacity and the magnetization method, the specific performance data discreteness is very big. In motor and permanent magnet flux and provided by the magnetomotive force also varies with the magnetic circuit of the rest of the material performance, size and motor running state. In addition, the magnetic circuit structure of the motor vehicle spare parts permanent magnet generator is varied, leakage magnetic circuit is very complicated and the share of magnetic flux leakage is bigger. Part of the ferromagnetic materials and is easier to saturation, permeability is nonlinear. These have increased the complexity of the permanent magnet generator electromagnetic calculation, the accuracy of the calculation results under electrical excitation generator. Therefore, it is necessary to establish new design concept, to improve the magnetic circuit structure and control system and analyze; Must be applied in modern design method, the new methods of analysis and calculation, improve the accuracy of design calculation; Must study the advanced test method and manufacturing process. 

2 control problem (see electrical engineer) pointed out that after the permanent magnet generator is made without external www.dongfeng-motor.com energy can maintain its magnetic field, but also from external regulation, control of its magnetic field is extremely difficult. These make the application range is limited by the permanent magnet generator. But as MOSFET and IGBT power electronic devices such as the rapid development of control technology, can not control the magnetic field in the application of permanent magnet generator and motor output control, only when the design needs to be ndfeb material, three new power electronic devices and computer control technology, the permanent magnet generator run under new conditions. 3 the irreversible demagnetization If improper use or design, the permanent magnet generator in high (ndfeb permanent magnet) or low (ferrite permanent magnet) temperature, under the effects of the armature reaction current impulse, or in severe mechanical vibration that may produce irreversible retreat (or called excitation-loss), reduce the motor performance, can't even use. Thus both the research and development is suitable for motor manufacturers use inspection of the permanent magnet material thermal stability of the method and device, and to analyze the structure of various forms of resistance to demagnetization ability, in order to make the design and manufacturing, to ensure permanent magnet generator with magnetic. 4 cost problem Because of rare earth permanent magnet materials at present the price is more expensive, the cost of rare earth permanent magnet generator generally higher than the electrical excitation generator, the need to use its high performance and operating cost savings to compensate. When the design should not only according to the requirements of specific use situation, performance, price comparison to choose, and must carry on the structure of the process of innovation and design optimization in order to reduce costs.

Three-phase asynchronous motor speed control method

Three-phase asynchronous motor's very logarithmic p and s slip can be too much to change speed. From the perspective of the nature of speed regulation, different ways of governing is nothing but change synchronous ac motor synchronous speed or not turn two. Widely used in the production of machinery is not the change in speed control method of synchronous speed of wound rotor motor rotor series resistance speed governing, chopping speed regulation, cascade speed regulation and application of the electromagnetic slip clutch, hydraulic coupling, such as oil film clutch speed regulation. Changes of the synchronous speed logarithmic multi-speed motor, stator can change of the stator voltage, frequency, frequency control of motor speed has no commutator motor speed regulation and so on. From energy point of view, when there is high speed control method and low speed control method of two kinds: an induction refers to the effective speed control is constant, so there is no slip loss, such as multi-speed motor, frequency control of motor speed and slip loss can be recovered speed control methods (such as cascade speed regulation, etc.). Have slip loss speed regulation method belongs to the low speed, such as rotor series resistance speed control method, the energy loss in the rotor circuit; Electromagnetic clutch speed regulation method of energy loss in the clutch coil; Hydraulic coupler speed regulation and energy loss in the oil of hydraulic coupling. In general slip loss increases with expanding range of speed regulation, if the speed range is not big, energy loss is small. This control method is used to change the stator winding of red way to change the cage ac motor stator polar logarithmic to achieve speed, features below: With a hard mechanical properties, good stability; No slip loss, high efficiency; Wiring is simple, convenient control, low price; Have used differential is bigger, cannot obtain smooth speed regulation; Can be used with regulating speed control, electromagnetic slip clutch, smooth speed characteristics of high efficiency. This method is suitable for don't need a stepless speed regulation small electric motors of production machinery, such as metal cutting machine tools, elevators, lifting equipment, fan, water pump, etc. 

Cascade speed regulation refers to the motor rotor winding circuit in series with adjustable additional potential to change the slip of the motor, to Motor vehicle achieve the purpose of speed control. Most of the slip power is absorbed by series of additional potential to recycle produce additional device, the absorption of returning the slip power grid or conversion of energy use. According to the slip power utilization way, cascade speed regulation can be divided into Y series three-phase asynchronous motor cascade speed regulation, mechanical cascade speed regulation and thyristor cascade speed regulation form, adopts thyristor cascade speed regulation, its characteristic is: Slip loss in the process of speed regulation can be back to the grid or production machinery, high efficiency; Installed capacity is proportional to the speed range, the investment province, apply to speed range in production machinery from 70% to 90% of the rated speed; Speed regulating device failure can switch to run at full speed, avoid production; Thyristor cascade speed regulating power factor is low, the influence on harmonic. This method is suitable for the fan, water pump and the rolling mill, mine hoist, the extrusion machine use. Frequency control method Frequency control of motor speed is to change the frequency of the motor stator power, to change its synchronous speed control method. Variable frequency speed regulation system is the main equipment to provide frequency conversion power of inverter, the inverter can be divided into ac - dc - ac frequency converter and ac - ac frequency converter two kinds big, cross - straight - to pay inverter are mostly used in China at present. Its features: There is no additional loss of high efficiency and speed the process; Application range is wide, can be used in the cage type asynchronous motor; Large range of speed regulation, and the characteristics of hard and high precision; Technology is complex, high cost, maintenance difficulties. This method is suitable for the requirement of high precision, better speed control performance.

Brushless motor and brush motor

Brushless dc motor is composed of main body of the motor and drive, is a typical mechatronics product. The stator winding of the motor to make more balanced three-phase y connection, with three phase asynchronous motor is very similar. On the rotor of the motor with the magnetization of the permanent magnet has, in order to detect the polarity of the motor rotor, inside the motor is equipped with position sensor. Drive consists of power electronic devices and integrated circuit, its function is: accept the motor start, stop, brake signal, to control the motor start, stop, and the brake; Accept the position sensor signals and positive &negative, used to control the inverter bridge on and off of each power tube produce continuous torque; Accept the speed instruction and speed feedback signal, which is used to control and adjust the speed;ac motor electric 65kw To provide protection and display, and so on. Because of brushless dc motor based on self-control type operation, so don't like frequency control of motor speed synchronous motor overload start under plus startup winding on the rotor, also won't generate oscillation and step out when load mutation. Medium and small capacity of the permanent magnet brushless dc motor (BLDCM), now more than using high magnetic energy product of rare earth ndfeb material (Nd - Fe - B). As a result, the volume of rare earth permanent magnet brushless motor than three-phase asynchronous motor with capacity reduces a frame number. 

Nearly 30 years study of asynchronous motor frequency control of motor speed, in the final analysis is looking for a way to control the asynchronous motor torque, rare earth permanent magnet brushless dc motor is bound to its wide speed range, small volume, high efficiency and steady speed and small error characteristics appeared in the field of speed advantage. For brushless dc motor has the characteristics of a dc motor, is also the device of frequency variation, so also known as dc frequency conversion, the international general term for BLDC) motors running efficiency of the brushless dc motor, torque at low speed, precision of speed is more good than any of the control technology of inverter, so the industry concern. This product has production more than 55 kw, can design to 400 kw, can meet the requirements of industry energy saving and high performance drive. 1, fully replace the dc motor speed control, comprehensive alternative, comprehensive alternative to asynchronous motor frequency converter + frequency conversion motor + reducer speed; 2, can run for high power at low speed, can save the reducer direct drive big load; www.dongfeng-motor.com 3, have all the advantages of traditional dc motor, and cancelled the carbon brush and slip ring structure; 4, torque characteristic is excellent, medium and low speed torque performance is good, big start torque, small starting current; 5, stepless speed regulation, wide speed range, strong overload capacity; 6, small volume, light weight, large output; 7, soft and soft stop, good braking performance, saves the original mechanical braking or electromagnetic braking device; 8, high efficiency, no excitation loss and carbon brush motor itself loss, eliminate the multiple reduction consumption, comprehensive energy-saving rate can reach 20% ~ 60%, power saving a year only recover the purchase cost; 9, high reliability, good stability and strong adaptability, simple maintenance and maintenance; 10, turbulence shock resistance, low noise, little vibration, smooth operation, long service life; 

11, no radio interference, does not produce sparks, especially asynchronous motor suitable for explosive place, explosion-proof type; 12, according to the needs of optional trapezoidal wave motor and is XuanBo magnetic field magnetic field. Matters needing attention (1) before disassembly, with compressed air blowing off the motor surface dust, and wipe the surface dirt thoroughly. (2) choose the disintegration of the motor working place, clean up the scene environment. (3) familiar with the motor structure characteristics and maintenance technical requirements. (4) ready to collapse the required tools and equipment (including special tools). (5) in order to further understand the defects of the motor running, conditional can before disassembly when doing an inspection test. For this, turn motor with load test, the detailed check parts, such as temperature, sound, vibration motor, and test the voltage, current, speed, etc., and then disconnect the load, do a no-load check test, no-load loss and no-load current is measured and recorded. (6) to cut off the power supply, dismantling motor wiring, recorded. (7) the appropriate voltage test motor insulation resistance by megger are. Maintenance in order to keep pace with The Times when measured insulation resistance compared to determine the motor insulation change trend and insulating state, should be measured under different temperature insulation resistance value of the conversion to the same temperature, the average conversion to 75 ℃. Absorb than K (8) test. When the absorption ratio greater than 1.33, which indicates that the motor insulation or degree of be affected with damp be affected with damp be affected with damp be affected with damp or not serious. In order to compare with previous data, also want to add any temperature measured absorption than the conversion to the same temperature.

The understanding of the three-phase asynchronous motor

Resection of the three-phase asynchronous motor power rely on inertia and rotation for a period of

time (or distance) to stop, and a hook or hoist crane in the production of hanging basket require

accurate positioning; Universal milling machine spindle requirements can quickly stop; Elevator after

a sudden blackout need security protection and accurate positioning control.And so on. All of these

need to drag brake motor, the so-called braking, is to give a torque and rotation in the opposite

direction of the motor to make it quickly halt or limits its speed. Braking method generally has two

kinds: mechanical braking and electrical braking.(a) mechanical brake Use machinery to make motor

stalling method is called immediately after the power off mechanical brake.The commonly used methods:

electromagnetic brake braking.1, the structure of the electromagnetic brake: www.facebook.com/dongfeng.motor Is mainly composed of two parts: brake electromagnet brake and brake shoe. Brake electromagnet by core, coil and armature of three parts. Brake shoe brake including brake drum, brake shoe, and spring etc, brake wheel and motor installed on the same axis.2, how it works: motor power, and electromagnetic brake coil electricity, armature and, to overcome the tension of the spring brake shoe and brake wheel, motor function. 

Disconnect switch or contactor, motor power, electromagnetic brake coil also lost electricity at the same time, the armature to separate from the core, under the action of a spring tension and make brake shoe hug brake wheel, motor is braking and halt.3, the characteristics of the electromagnetic brake braking Mechanical brake mainly adopts the electromagnetic brake, electromagnetic clutch brake, both magnetic field generated by electromagnetic coil after electrify make the static iron core produces enough suction and armature or moving iron core (electromagnetic clutch of moving iron core is sucked, dynamic and static friction piece separately), to overcome the tension of the spring and meet the requirements of the job site. Electromagnetic brake is to rely on the brake shoe friction disc brake wheel. Electromagnetic clutch is the use of dynamic and static friction piece immediately when the power is enough friction between motor brake. Advantages: electromagnetic brake braking, braking force is strong, widely used in asynchronous motor lifting equipment. It is safe and reliable, won't because suddenly loses power and accident.Weakness: the electromagnetic brake volume is larger, brake wear serious, rapid brake vibration can be created.4, motor brake clearance adjustment method 1) downtime. (mechanical and electrical close confirmation, pressure and power locks, and hung "is maintenance", "it is forbidden to start them.)(2) remove fan cover;(3) remove the fan circlip, remove fan blade;(4) check the residual thickness of the brake lining (minimum thickness of brake lining).(5) to check if the protective plate: protective plate edge has touched the dowel pin marks, must replace the brake disc;6. Adjust the air brake clearance: three (four) to tighten bolts to the air gap is zero, then reverse loosen bolts Angle is 120 °, with

feeler check the brake clearance (check at least three points), should be uniform and conform to the

specified value; Please reset is wrong. (note: the brake model is different, its reverse unscrew

Angle, the brake clearance three phase induction motoris different).All landowners manual operation, brake action sound is ringing, stop position accurate and effective.Today the scene 6 s standard cleaning.