CN101141086A - Design method of variable frequency motor - Google Patents

Abstract

The invention relates to a design method of a frequency conversion motor which is characterized in that when the quantities of poles of the electric machine is fixed, based on the change of the frequency reference f, the frequency conversion motor is designed, and is capable of achieving reference rotary speeds of various electric machines; in the premise of achieving the same force index, the invention is capable of reducing current, thereby achieving the energy-saving effect, and reducing the installed capacity; moreover, reducing the power stage of the transducer, realizing the conservation of energy; taking the washing machine motor as an example, making the capacity of the transducer reduced one to two stages, the manufacturer is capable of saving considerable cost; In addition, the invention is capable of realizing the simplification and miniaturization of the machine, for example, the high speed electric machine is capable of canceling the speeding-up mechanism, and the low speed electric machine is capable of saving the retarding mechanism.

Description

A kind of method for designing of variable-frequency motor

Technical field

The present invention relates to a kind of method for designing of variable-frequency motor, relate in particular to the Optimization Design of a kind of alternating current machine variable-frequency and variable-speed transmission, belong to the variable-frequency motor design field.

Background technology

The fundamental formular of alternating current machine synchronous speed is:

Ns＝120*f/P (1)

Wherein, the synchronous speed of Ns-motor, or the title reference rotation speed (rev/min)

F-gives the frequency of supply (Hz) of motor

The P-motor pole number is 2,4,6,8,10 ... even number

Past is not also occurring before variable frequency power supply is frequency converter, alternating current machine is that electric network source drives with power frequency supply, the reference rotation speed Ns of motor for a change, from formula (1) as can be known, because frequency f is the constant of fixing, Chinese electrical network is 50Hz, so adopt the number of poles that changes motor to change reference rotation speed Ns, this is the method for designing that a kind of variation based on motor pole number changes the motor reference rotation speed, is referred to as " base stage system ".

When variable frequency power supply is after frequency converter occurs,,, and can determine by changing frequency f so the reference rotation speed of motor not only can pass through number of poles P because frequency f becomes a transformable parameter.

But, at present, still adopt traditional change number of poles to decide the reference rotation speed of motor for the method for designing of variable-frequency motor.This has limited the flexibility of variable-frequency motor design for the different application occasion, the characteristics of the changeable frequencyization when not giving full play to reference frequency that the converter technology development brought and be corresponding reference rotation speed.

Summary of the invention

The purpose of this invention is to provide a kind of variation, adapt to the method for designing of the variable-frequency motor of frequency control with acquisition based on reference frequency.

For realizing above purpose, technical scheme of the present invention provides a kind of method for designing of variable-frequency motor,

The fundamental formular of alternating current machine synchronous speed is:

Ns＝120*f/P (1)

Wherein, the synchronous speed of Ns-motor, or the title reference rotation speed (rev/min)

F-gives the frequency of supply (Hz) of motor

The P-motor pole number is 2,4,6,8,10 ... even number

It is characterized in that power taking machine number of poles based on the variation of reference frequency f, carries out the design of variable-frequency motor for fixedly the time, can reach various motor reference rotation speeds.

The present invention has developed the variation based on reference frequency, carries out the method for variable-frequency motor design, is referred to as the method for designing of " fundamental frequency system ".

See formula (1), frequency f wherein, under the variable frequency regulating speed control device, f be one can the continually varying positive number, scope is placed restrictions on hardly, be not a fixed numbers, by " fundamental frequency system " method for designing, when power taking machine number of poles for fixedly the time, P is taken as 4 as motor pole number, if will to reach motor reference rotation speed Ns is 1500,1000,750 and 3000 rev/mins, by formula (1) then gets reference frequency f respectively and is 50,33.3,25 and 100Hz.These motor reference rotation speeds have covered the main reference rotation speed under " base stage system ".Down can not obtainable reference rotation speed for " base stage system ", can obtain arbitrarily down in " fundamental frequency system ", as: getting reference frequency f is 200Hz, motor pole number P still is taken as 4, and then by formula (1) can obtain 6000 rev/mins motor reference rotation speed, getting f is 400Hz, P is taken as 4, can obtain 12000 rev/mins reference rotation speed, is 127.1Hz if get f, P is taken as 4, can obtain 3813 rev/mins reference rotation speed, or the like, too numerous to enumerate, in like manner, as to get number of poles be 2 or 6 or 8, changes reference frequency f again, then can produce more motor reference rotation speed schemes again.

Adopt " fundamental frequency system " method for designing, can break away from former " base stage system " restriction to the design of motor reference rotation speed, it can obtain down the motor reference rotation speed to original " base stage system " and become a very little collection under just " fundamental frequency system ", " fundamental frequency system " method for designing has been brought the more reference rotation speed of motor more flexibly implementation methods to us.

Advantage of the present invention is:

1. the characteristics design of proper machine reaching under the prerequisite of same energy index, can reduce electric current, thereby reaches energy-conservation effect, and can reduce installed capacity;

2. reducing cost, under the prerequisite that the power of reaching can require, because the minimizing of electric current, can reduce the power grade of frequency converter, realize energy-conservationly, is example with the motor for washer, makes frequency inverter capacity reduce the 1-2 level, for machine producer has saved considerable cost;

3. realize the simplification and the miniaturization of mechanism, can cancel speed increasing mechanism as high-speed electric expreess locomotive, slowspeed machine can save reducing gear.

Embodiment

The invention will be further described below in conjunction with embodiment.

Embodiment 1

The present invention adopts the IAG variable-frequency motor series of " fundamental frequency system " method for designing design, and the fundamental formular of alternating current machine synchronous speed is:

Ns＝120*f/P (1)

Wherein, the synchronous speed of Ns-motor, or the title reference rotation speed (rev/min)

F-gives the frequency of supply (Hz) of motor

The P-motor pole number is 2,4,6,8,10 ... even number

The present invention is as shown in table 1 below with the corresponding relation of the corresponding frequency/number of poles of base stage system:

Table 1.

Reference rotation speed	Fundamental frequency system		Base stage system
					Number of poles	Reference frequency	Number of poles	Reference frequency
	3000r/min	4P	100Hz	2P					50Hz
1500r/min					4P	50Hz	4P	50Hz
	1000r/min	4P	33.3Hz	6P					50Hz
750r/min					4P	25Hz	8P	50Hz
	600r/min	4P	20Hz	10P					50Hz

In 4,6,8,10 each number of poles, for same motor reference rotation speed, as 1000 rev/mins, tradition being designed to of " base stage system ": 50Hz/6P, and when " fundamental frequency system " designs, can use: 33.3Hz/4P.There is following advantage in contrast IAG series fundamental frequency system variable-frequency motor than the variable-frequency motor of original base stage system:

(1) be motor below 1000,750,600 etc. for reference rotation speed, adopt 4P/33.3HZ, the 4P/25Hz of fundamental frequency system, 6P/50Hz, 8P/50Hz, the 10P/50Hz that 4P/20Hz replaces base stage system, have lower electric current, shown in following table 2.:

Table 2.

Reference rotation speed (r/min)	Power (KW)	Base stage system variable-frequency motor rated current (A)	IAG series fundamental frequency system variable-frequency motor rated current (A) of the present invention	Power saving rate %
					1000	4	9.4	8.7	7.4％
5.5	12.6	11.5	8.4％
				11		24.6	22.5	8.6％
750	7.5	17.7	15.7						11.1％
				15	34.1	29.1	14.6％
	18.5	41.3	37.0					10.5％
				600	45	106.1	87		18.0％
55	129.2	103	20.3％
					75	172.5	140	18.8％

This is because the effect of 4 utmost point motors, i.e. " power factor * efficient " (Cos φ * η) is than the height of 6 utmost points, 8 utmost points, 10 utmost points, from following formula (2)-(5) as can be seen, when one of design has the motor of same power output P2, " power factor * efficient " numerical value height of " fundamental frequency system " variable-frequency motor is so its rated current is little.

P1＝m*U*I*cosφ (2)

P2＝P1*η (3)

P2＝m*U*I*cosφ*η (4)

I＝P2/(U*cosφ*η) (5)

Wherein, P1---power input to a machine (KW)

The power output of P2---motor (KW)

The number of phases of m---alternating current machine

The phase voltage of U---motor (V)

The phase current of I---motor (A)

The power factor of cos φ---motor

η---efficiency of motor (%)

From table 2, can also see that reference rotation speed is low, it is that power savings is obvious more that the electric current of " fundamental frequency system " variable-frequency motor contrast " base stage system " motor reduces.The outstanding energy-conservation advantage of variable-frequency motor that Here it is " fundamental frequency system ".

Embodiment 2

Adopt the scheme of " fundamental frequency system " 4P/100HZ, the motor that replaces 2P/50HZ, there are many specifications to dwindle one grade or two grades of seat No. than standard design, volume can dwindle on the one hand, material cost also reduces on the other hand, this is again the advantage of " fundamental frequency system " variable-frequency motor, shown in the following table of comparisons 3..

Table 3. fundamental frequency system " variable-frequency motor (4P/100Hz) and base stage system motor (2P/50Hz) be with power lower support contrast table

Power (KW)	Base stage system motor (2P/50Hz) seat No.	Fundamental frequency system variable-frequency motor of the present invention (4P/100Hz) seat No.	Fundamental frequency system is dwindled seat No. shelves number
				3	100L	90L	1 grade
4	112M	100L	1 grade
				5.5	132S1	100L	2 grades
7.5	132S2	112M	1 grade
				11	160M1	132S	1 grade
15	160M2	132M	1 grade
				18.5	160L	132M	1 grade
22	180M	160M	1 grade
				30	200L1	160L	2 grades
37	200L2	180M	1 grade
				45	225M	180L	2 grades
55	250M	200L	1 grade
				75	280S	225S	2 grades

Export at motor under the situation of same torque, motor as employing " fundamental frequency system " 5.5KW/4P/25HZ is identical with the motor torque that adopts 11KW/4P/50HZ, but because the former current ratio latter is half as large, the frequency inverter capacity of drive motors also can reduce half like this, reduced the power-supply device configuration capacity, adopt the motor of IAG series 450/600 base speed of the present invention, add the stepless speed regulation of upconverter, can obtain big moment low current at low speed, both can reduce frequency inverter capacity, also can save decelerator, the decelerator of big moment often is difficult to configuration, and the price of big-power transducer is also very expensive, and this notion is being contained the good economic benefits and the market opportunity especially in big moment low speed transmission application for this reason, both provided solution, realized energy-conservation and reduction cost for the client again to the client.

Because fundamental frequency system motor substantially only adopts 1 to 2 kind of number of poles, for this reason, can bring very big management advantage for motor manufactory, to apply for artificial example, basic only with 4 very main iron cores, the iron core of electric motor for electrical machinery plant has reduced other numbers of poles has reduced the kind of material, the manufacturing of mould, promoted the use versatility of material, make get the raw materials ready and manage greatly convenient.

Embodiment 3

Operating characteristic at industry washer has designed " VFXD Series Industrial washing machine energy-saving variable-frequency motor ", and following table is the comparison sheet of drive motors when washing of 100KG specification industry washer.

Table 4100KG washing machine, former is 11KW/6P/50Hz (base stage system) with motor, VFXD energy-saving variable-frequency motor of the present invention is 7.5KW/4P/25Hz (design of fundamental frequency system)

The motor for washer type	Current of electric during washing (A)	Saves energy	Configuration frequency inverter capacity (KW)	Save the frequency converter equipment cost
					Former drive motors (base stage system)	30	/	18.5	/
Energy-saving variable-frequency motor of the present invention (fundamental frequency system)	19.5	35％	11	28％

Can see that from last table adopt the drive motors of the inventive method design, power of motor reduces, current of electric reduces, and saves energy is about 35%, and the frequency inverter capacity of configuration reduces, and has saved frequency converter acquisition cost about 28%.Use occasion of the present invention is exemplified below:

1) when drive characteristic during mainly in low regime, when needing higher low speed moment, can select the corresponding motor reference rotation speed of lower fundamental frequency, as IAG series fundamental frequency system variable-frequency motor of the present invention, fundamental frequency is arranged at 20Hz (4P), 25Hz (4P), corresponding motor reference rotation speed is 600 rev/mins, 750 rev/mins a specification, can obtain low speed moment is big, operating current is little, supporting driving frequency inverter capacity than traditional little one to second gear power;

2) when drive characteristic during mainly in high regime, can select the corresponding motor reference rotation speed of higher fundamental frequency, as HSB/HSP series of high speed variable-frequency motor of the present invention, fundamental frequency is selected in 250Hz, 300Hz, corresponding motor reference rotation speed is 15000 rev/mins, 18000 rev/mins, can obtain that high speed moment is big, high-speed power is stable, the motor moment of inertia is little, the high speed accelerating performance is good, motor volume is little, low cost and other advantages.

3) for the operating mode occasion of some special drive characteristics, can be through the analysis that each Duan Lineng in the machine cycle is required, make the scheme of optimization, reach optimum " performance-structure-cost " scheme and (comprise variable-frequency motor itself, and frequency converter, speedup or reduction gearing mechanism one scheme), the chance that the present invention will bring very big energy-conservation and cost to reduce for the industry machine, so fundamental frequency system design concept of the present invention and method are a kind of design concepts of green energy conservation, in current energy shortage, be that bigger realistic meaning is arranged today that industry machine cost pressure is increasing.

Claims (1)

1. the method for designing of a variable-frequency motor,

The fundamental formular of alternating current machine synchronous speed is:

Ns＝120*f/P (1)

Wherein, the synchronous speed of Ns-motor, or the title reference rotation speed (rev/min)

F-gives the frequency of supply (Hz) of motor

The P-motor pole number is 2,4,6,8,10 ... even number

It is characterized in that power taking machine number of poles based on the variation of reference frequency f, carries out the design of variable-frequency motor for fixedly the time, can reach various motor reference rotation speeds.