Motor variable frequency speed control applications

When using frequency control of motor speed,need to process requirements,saving benefit,such as payback period of investment is taken into consideration.If only from the technological requirements,saving benefit consideration,the following several ways to choose a variable frequency drive (VFD) Variable frequency speed regulation by frequency converter,for the determination of the capacity of the inverter is very important.Ac frequency conversion speed regulation method is three- phase asynchronous motor speed governing of the most promising method.With the continuous development of power electronic technology,reliable performance,matching complete,the price is cheap inverter will appear constantly,this technology will be more extensive and widespread application.At

present,the foreign advanced countries of frequency conversion technology is miniaturization,high reliability,resistance to pollution,multi-function,high performance,such as direction,is to speed up the pace of development in our country.Ac variable frequency speed regulation technology has been widely used in the industrial developed countries.The United States has 60% - 65% of the electricity used for motor drive,due to the effective use of the frequency control of motor speed technology,industrial transmission electricity saves only 15% - 20% of the electricity.Transmission speed change system,the use of variable frequency speed regulation can make the speed control system structure is simple,control accuracy,and easy to realize process control.Replace mechanical variable speed with frequency control of motor speed.Such as: machine tools,not only can save complex gearbox,also can improve the precision and satisfies the requirement of process control.

Using frequency control of motor speed instead of gate or baffle,is used to adjust flow in fan,water pump,compressor,etc.For example: the boiler water pump,fan,induced draft fan with frequency control of motor speed control,not only save the servo amplifier,electric operator,Y series three-phase asynchronous motor actuators and the water supply valve (or back plate),and makes the whole boiler

boiler control system has been fast dynamic response,high control accuracy and stability.Adopts frequency control of motor speed,one is the speed according to requirements,the second is energy conservation.It is mainly based on the following factors:(1) variable frequency speed regulation system itself loss is small,high work efficiency.(2) the motor at low slip always keep running state,reduce the loss of rotor.(3) can realize the soft opening and brake function,decrease the starting current impact.Reasonable capacity selection itself is a kind wholesalemotor.blogspot.com of energy saving measures.According to the existing data and experience,there are three more simple method:(1) motor actual power First of all,to determine the actual motor power,in order to select the inverter capacity.(2) the formula method of safety coefficient is 1.05,the capacity of the inverter Pb for Pb = 1.05 Pm/hm x cosy (kW) Type of Pm motor load; Hm power for the motor.After calculate the Pb,in inverter product catalog can choose the specific specification.For n In the rated current of the motor,the n of the Numbers for the motor.In any case,cannot be used in continuous more than rated current (I).(3) the motor rated current inverter frequency converter capacity selection motor parts process,is actually a process the best match between the inverter and motor,relatively safe is the most common,also make the converter capacity is greater than or equal to the motor rated power,but want to consider the actual power of the motor in the actual match what differ with rated power,are usually selected equipment capacity is big,but the actual ability to small,so according to the actual power of the motor to select frequency converter is reasonable,avoid to choose the frequency converter is too large,increased investment.The frequency control of motor rotor balancing machinespeed has many advantages,but also has its disadvantages,the main problem is the containing higher harmonic current is more,except to the power grid pollution also increase the motor itself loss,fever caused by motor.Again,the technique of the transducer expensive,long investment recovery,complex,especially in realizing closed-loop automatic control,technical processing is also required.In addition,the frequency converter is not any case,if the motor load change is not big,or deep well pump is equipped with a water tower,power saving,water saving effect is not large,unfavorable use frequency control of motor speed.According to the technological requirements,production line or single equipment need to program or adjust the motor speed according to the requirement.Such as: packaging machine transmission system,according to the different varieties of products,need.