The difference between motor and brushless motors

From now in general use in the industry,there are two main types of motor:efficient rare earth permanent magnet has a motor and the efficient rare earth permanent magnet brushless motor on the market at present most Electric bicycle is still stay in brush motor stage.A brush motor using mechanical commutation,the technical requirements of the control system is low,relative cost is lower than the brushless motor,A brush motor starting torque slightly larger than the brushless motor. But the fatal weakness is:life is short,large noise and low efficiency.Long-term use of carbon brush wear serious,it is easy to damage.At the same time wear produced huge amounts of carbon dust,These dust fall in gear oil,gear oil accelerate dries up,the motor noise further increased.A brush motor use to within a year or so will need to replace carbon brush,You will find a charge mileage bought less than two-thirds,and climbing when power is insufficient,will burn out the controller.This is because the motor After the replacement of carbon brush and commutator also be ground out a groove,reduce carbon brush contact area,poor contact of carbon brush after electrify which sparks and accelerate oxidation in electricalmotor1.blogspot.com To implement and copper,acmotortrading.blogspot.com lead to the undesirable phenomenon. Brushless motor electronic commutation replace the mechanical commutation,technically superior to brush motor.

Because of brushless motor without gear or gear,the motor,reduce wear and tear The unreliability.Its efficiency within a certain range of current ratio has a brush motor with high efficiency.Brushless motor driving up almost no motor lamination noise,and for up to 10 years to life On.According to the comparison,both brushless motor is better than have a brush.At present,there have been some electric bicycle factory with motor is to switch to the original brushless electric Machine.Brushless motor must be the development direction of electric bicycle. Consumers can come up from appearance to identify motor belongs to "brush" or "no brush" :first,"brushless electric wire" eight root,and the "brush" electric wire to the positive and negative There are two root;Secondly,with the induction motor hand when the drive motor,before and after the brushless motor rotation is easy,and before the "brush" motors turn easily,after when transfer is quite tight.

How to do short circuit test of the motor?

Short circuit test is to use braking device,the motor rotor fixed don't turn,three-phase voltage regulator output voltage from zero values increased.When the current reaches the mini electric motor rated current of the motor is stop booster,when the voltage is called the short circuit voltage.The rated voltage of 380 v motor its short circuit voltage is in commonly 75 ~ 90v.High impedance voltage said leakage reactance is wholesalemotor.blogspot.com too big.Short circuit voltage electric motors price is too low said leakage reactance is too ac electric motor small.Both for normal operation of motor will be unfavourable.

Torque or flux linkage control method

In t.g.Habetler no beat of direct torque control method,because of the large amount of calculation

and is not easy to achieve,therefore developed a series of simplified no beat directly Ac motor -

South Korea SPG ac motor series Ac motor - South Korea SPG ac acmotortrading.blogspot.com motor series Torque control,typically torque tracking prediction method.In this method,the paper analyzes the low speed torque ripple,torque ripple sawtooth asymmetric conclusions. Non-zero voltage vectors and the function of zero voltage vector rotating torque change is different,the former can make torque increase or decrease,while the latter is always decreased torque.In addition,in different speed range of the two counter rotating torque effect produced by the rate is changing.In torque predictive control method,the voltage vector in space position is fixed,the synthesis in the middle of the two single voltage vector,but the voltage vector is not effect the whole sampling period,but there is a certain duty cycle,in a sampling period can be divided into non zero voltage vector and zero voltage vectors.If the next sampling period of zero voltage vector and zero voltage vector to produce torque changes calculated torque error is equal to the three phase induction motor price cycle. To eliminate the torque error,achieve the goal of no beat torque control.Even appear calculated voltage vector effect time beyond the sampling period,also the full voltage vector can be used gasoline generator spare parts in place of,so it is very easy to implement,from the point of the experimental results,the torque ripple of the sawtooth basically symmetrical and explain the torque pulsation has been greatly reduced.Flux method considered by accurate control or change slowly,without considering the magnetic chain of beat control,in the literature on the flux and predictive control.

Several problems about ac servo motor

Several problems about ac servo motor:Q:(A) of the ac synchronous servo,ac asynchronous servo rated speed is related to whether the number?N1 = 60 f / 2 p? Output constant torque under the rated

speed,constant power above rated speed,so the definition of the rated speed is determined by

induction motor sales the mechanical motor itself or drive to decide?,synchronous speed n1 = 60 f / 2 p,asynchronous machine and slip s,n = (1 - s) n1,synchronous machine n = n1,2 p is logarithmic. Definition of weak magnetic speed control is to judge by the driver.Rated speed can be determined by several aspects:synchronous servo's potential height allows the drive current of motor iron core materials,alternating frequency,maximum power under the rated torque motor, The highest temperature rise,etc.,the main or against potential; Asynchronous motor is mainly restricted by material allows the highest frequency and polar logarithmic. The definition of the rated speed of mechanical and,by the motor itself Electrical characteristics.Q (B) :ac,dc servo distinguish whether or not depends on the drive and motor current or voltage between form?But also changes in the current direction of the brushless dc servo? Whether can be understood as contact? Ac servo is based on the principle of the brushless dc servo evolution? pumps Answer:ac servo usually refers to with sine wave driving mode of servo,brushless drive is equal to the number of the commutator is 6 (7) of a brushless dc motor control precision,poor general characteristics at low speed.Has called him the commercial ac servo,only because electricalmotor1.blogspot.com he get rid of the brush,but I'm afraid that features than good ac servo,dc servo has the gap,10000 times the speed of brushless motors are unique Difficult to achieve.