High performance ac speed regulation system

V/f constant, speed open-loop control of general frequency control system and the slip frequency speed closed loop control system, basically solved the problem of asynchronous
motor smooth speed. However, when the production machinery on the speed regulation system of dynamic and static performance put forward higher requirements, the above system or
than dc speed regulation system of lower. The reason is that, the system control law of asynchronous motor from steady-state equivalent circuit and steady state torque formula
is deduced steady-state value control, not considering the transition process, system in stability, starting and low speed torque dynamic response of performance is not
satisfactory.
Considering the asynchronous motor is a multi-variable, strong coupling, nonlinear time-varying parameter system, it is difficult to
rotating joints directly through applied signal accurately
control electromagnetic torque, but if rotor flux this rotating space vector for reference coordinates, use from static coordinate system to the rotating coordinate system
between the transformation, can put in the stator current excitation current component and torque component of current into scalar independent, control respectively. So, through
the transformation of coordinates reconstruction of motor model can be equivalent to
rotary union a dc motor, which can be as fast as dc motor torque and flux control is vector control.
And vector control is different, direct torque control reject decoupling thoughts, cancelled rotating coordinate transformation, simply by detecting motor stator voltage and
current, with the aid of instantaneous space vector theory calculation motor flux linkage and torque, and according to the given value compared with the income difference,
realize the flux and torque direct control.
Although vector control and direct torque control, the performance of the ac adjustable speed system has greatly improved, but there are many fields to be study:
(1) flux accurate estimate or observation
(2) the speed sensorless control method
(3) motor parameters online identification
(4) is extremely low speed including zero speed of motor control
(5) voltage reconstruction and dead zone compensation strategy
(6) of multilevel inverter high-performance control strategy
Six looking
In ac speed regulating the research and manufacture process, hardware design and assembly account for a considerable proportion. Motor manufacturing and speed control device
manufacturing needs a large number of skilled workers, the quality of personnel have certain requirements. And foreign relevant industry labor costs are relatively high, in the
recent ten years, ac speed control manufacturing are likely to developing countries transfer. For the Chinese, this is also an opportunity, if we take the chance, reuse itself
market advantage, it is possible to form ac adjustable speed system in our country manufacturing center, make our country industry to fiber optic rotary joint a new level. Note that the developed
countries in the high technology fields are won't give up easily, they pay much attention to the core technology and software protection and security, therefore, it is necessary
to increase the field of scientific research and development efforts.

Case 10, crane, skip class load

Crane, dump and load torque big and smooth, positive and negative frequent and reliable. Frequency conversion device control crane, skip to rotary joints meet these requirements.
An only child mountain petrochemical factory ketone benzene workshop for three table filter installation and setup a 20 tons of bridge crane, technological requirements of explosion-proof, use explosion-proof squirrel-cage motor. The original production of lifting the owner hook, auxiliary hook, cart, car no speed regulating function, can't positioning. Torque is small, the hoist objects glide to lifting 19 tons of filter base, so that the workshop start late more than a year, a loss of ten million yuan. In July 91 the frequency control of motor speed and braking function, make main hook, auxiliary hook, cart, five motor car by a frequency converter control, the effect is very good. Overload test sling 22 tons, quickly put the three table each heavy 40 tons of rotary union filter installed in 10 meters high floor platform on the flight.
Dock port, station gantry crane, yard material piling and taking machine and so on all can use frequency conversion speed control device, in order to achieve reliable, steady, power saving, less maintenance purpose.
Frequency conversion speed control device, in addition to saving electricity significant outside, or some production process the necessary equipment.
Examples of 11, converter class load
Converter class load, with ac frequency conversion instead of dc unit is simple, reliable, stable operation.
On May 1, 1994, chengde iron and steel company steel plant three sets of 20 tons converter dc drive system all in fault condition. Quasi looking for a "fast and good" restore production control mode, please come to the China electrical rotational experts LiuZongFu professor. In professor liu's suggestion, the company manager finalize, 20 tons converter tilting and oxygen lance lifting adopts ac frequency conversion speed regulating drag. From supply to installation, commissioning, after 13 days, three sets all converter normally put into production. This is our country 20 tons converter tilting and oxygen lance lifting first using frequency control of motor speed. After years of production and application, this system operation is stable and reliable, and technical index fully meet the technological requirements. Converter, oxygen gun main drive system caused by the heat down to reduce more than 90%, the year yield increase by 15000 tons, power saving 220000 degrees, direct economic benefits is 2.31 million yuan. For steel mill stable production after lay a solid base to wear  this system in 1995 through the ministry of machine building appraisal, and was awarded the first prize in hebei province technology progress.
Case 12, special power class load
Many power, such as experimental power supply, the plane drag power supply (400 hz) can be used frequency conversion device to complete, the advantage is less investment, quick effect, volume some  simple operation.
Viscose fiber industry spinning equipment are mostly high speed motor, numerous hasp motor for 150 hz / 160 v. For a long time, the domestic viscose industry has been to use electric - generating set medium frequency power supply, says the dynamic frequency. Because this method malady too much, and gradually by ac frequency conversion power supply, says static frequency conversion. Shaoyang chemical fibre factory is the first application of viscose industry by static frequency manufacturers, eight Taiwan 160 kw converter points two groups power supply (each group a standby). Since December 1992, since the production, than the dynamic frequency have obvious advantages.
A. and reliable. Operation for many years, and not failure trip.
B. the operation is stable, and the voltage and frequency fluctuations very some 
C FM convenient, for the factory production of different twist silk cake created conditions.
D. little noise and improve the operation personnel's environment.
E. Improve the product quality. The first phase project (the dynamic frequency conversion power supply), viscose filament percent of pass is only 55.1%, the first grade percent of pass is zero, second percent of pass is 20%, and the second phase project (using static variable frequency power supply) average qualified rate 98.12%, grade a qualified rate 88.7%.
F. increased production. A phase of the project design capacity of 2000 tons/year, trial production half a year, yield only 65.53 tons, and of the second phase of the project design capacity of 1000 tons/year, trial production half a year, production filament 685.25 tons, greatly more than design capability.
G. power saving 13%.
Due to the static frequency conversion for viscose industry has brought great benefits, many enterprises, such as jilin chemical fibre factory, jiujiang chemical fibre factory, yibin chemical fibre factory, hubei chemical fibre factory, dandong chemical fibre factory, weifang chemical fibre factory (except yibin outside, belong to the listed company) are adopted static frequency conversion technology.
Frequency control of motor speed in addition to saving electricity outside, and increase production and consumption, the high quality effect. Because it has a volume some  light weight, high precision, strong commonality, the craft is advanced, the function rich, protection is complete, high reliability, easy operation etc, by using personnel welcome, frequency control of motor speed it is to fiber optic rotary joint save energy and reduce consumption, high quality and high yield of the ideal equipment, is entering into the 21st century's first drive technology, benefits the country and the people.

SCM has been in ac speed regulating system had been used widely

SCM has been in ac speed regulating system had been used widely. For example by Intel company 1983 years development and

production of MCS - 96 series is the higher performance of the single chip microcomputer is one of the series, it is suitable

for high speed and high precision industrial control. The high-grade type: 8 x 196 KB, 8 x 196 kc, 8 x 196 MC in general open

loop ac speed regulating system of used more often.
Because ac motor control theory development, control strategy and control algorithm is also increasingly complex. Extended

kalman filtering, FFT, the state observer and adaptive control, artificial neural network and so on are applied to all kinds of

ac motor vector control and direct torque control of. Therefore, DSP
rotating joint in all digital high performance ac speed regulating

system find cast a stage. Such as TI company such as MCS320F240 DSP chip, with its high cost performance became full digital ac

adjustable speed system preferred. TI company recently launched MCS320F240X series of products will be more price down to the

level of the single chip microcomputer.
In ac speed regulation of full digital process, various bus also play a very important role. STD bus, industrial PC bus, field

bus and CAN bus in ac adjustable speed system automation application field play an important role.
3 PWM technology
PWM control is the control of ac adjustable speed system core, any control algorithm and the ultimate realization of almost all

kinds of rotary union PWM control mode is completed. Has been put forward and get the practical application of PWM control scheme is not more

than ten kinds, about PWM control technology based on the many famous electric power international conference, such as PESC,

IECON, EPE annual meeting has formed special. Especially microprocessor application in PWM technology and digital later, pattern

is unceasingly, from the pursuit of the voltage waveform sine, to the current waveform of sine, then to magnetic flux of sine;

From the optimal efficiency, torque ripple at least, to eliminate noise and so on, PWM control technology development has

experienced a constant innovation and improvement process. So far, there are new scheme continuously put forward, further proves

that this technology is in the ascendant.
Among them, the space vector PWM technology to the voltage utilization ratio is high, the control algorithm is simple, current

harmonic characteristics such as small in ac speed regulating system got more and more application.
4 high pressure large capacity ac speed regulation system
In the small power ac speed regulation, because foreign product scale effect, make domestic manufacturer in price, process and

technology are unable to fiber optic rotary joint fight. And in high voltage power, foreign companies and left us catch up space. First of all, foreign

power grid voltage level general for 3000 v, and China's power grid voltage class for 6000 v and 10000 v; Secondly, high

pressure high power ac speed regulating system can't large-scale batch production, and foreign labor cost, especially have

certain professional knowledge labor cost is higher.

At present, the research more high power inverter circuit are

At present, the research more high power inverter circuit are:
Multilevel voltage inverter
Transformer coupling of multiple pulse inverter
Hand over frequency converter
Doubly-fed ac frequency conversion speed control system
(1) level voltage inverter
Japan nagaoka university of science and technology, A.N abae in 1980 in IAS annual meeting for the first time put forward three

level inverter, also called Neutral clamp type (Neutral Point Clamped) inverter. It is the emergence of high pressure and large

capacity
rotating joints voltage inverter research opens up a new way of thinking.
Multilevel voltage inverter and ordinary double level compared to the inverter has the following advantages:
1. The more suitable for large capacity, high voltage occasions.
2. Can produce M layer trapezoidal output voltage, the staircase to modulation can get very good approximate sine wave,

theoretically improve level number can be close to pure sine wave type, harmonic content is small.
3. Electromagnetic interference (EMI) problem is reduced greatly, because the switch element a movement of the dv/dt usually

only traditional double level 1 / (M - 1).
4. High efficiency, eliminate the same harmonic, the double level using PWM control switch frequency is high, the loss is big,

and multilevel inverter can be used low frequency switch movement, the switching frequency is low, the loss is small, the

efficiency improving.
(2) transformer coupling of multiple pulse inverter
Transformer coupling of multiple pulse inverter three level circuit, to rotary union get a more level will only each phase series unit

inverter bridge the same number can be increased. Its advantages are:
1. Don't exist voltage balance problems. No clamp diode or capacitance, suitable for speed regulation control;
2. Modular degree good, easy maintenance,
3. To the same level as the number, the number of devices at least;
4. No clamp diode or capacity restriction, can realize more level, the higher the voltage, achieve more low harmonic,
5. Control method is relatively simple, can to each level respectively for PWM control, then waveform restructuring.
This, of course, the shortage of the structure in need a lot of isolated dc power supply, the application of limited to some

extent.
(3) hand over frequency converter
Hand over converter using thyristor as the main power device, in the mill and mine hoist drive has a lot of demand. Thyristor

the biggest advantage is to fiber optic rotary joint switch the power (up to 5000 v / 5000 a), suitable for large capacity ac motor speed control system.

At the same time, the high efficiency crystal thyratron production and technical function technique is quite mature, through

with the modern ac motor control theory of digital combination, will have strong competitiveness. But hand over frequency

converter, there exist some inherent defect: speed range is small, when the power supply is 50 hz, maximum output frequency not

more than 20 hz; On the other hand, the power factor is low, the harmonic pollution is big, therefore need at the same time of

the reactive power compensation and harmonic management.
(4) doubly-fed ac frequency conversion speed control system
Doubly-fed ac frequency conversion speed control system of the frequency converter power of small, power factor adjustable,

system reliability is higher, so recently received the attention of many researchers. Because of the frequency converter power

account for only 25% of the motor capacity, so can greatly reduce the cost of the system. But, doubly-fed ac frequency

conversion speed regulating system of motor need special design, can't use common asynchronous motor; And by the converter

capacity and speed range restriction, does not have the ability of soft starter.

Example 6, sewage disposal and other environmental protection class load

Example 6, sewage disposal and other environmental protection class load
Environmental protection is taken seriously more and more, it is related to
rotating joints human survival environment, even the Olympic bid

also have environmental index. Thus the clean energy, green city all appeared. Frequency control of motor speed available in

three aspects of environmental protection class load. One is the industrial wastewater treatment, 2 it is garbage power plant,

three is industrial smoke and exhaust and dust removal control. Such as guangzhou refinery, convert aeration machine sewage

treatment mixing equipment, USES the cage motor frequency control of motor speed, improve product reliability, save electricy

more than 40%, while improving the activated sludge microbial group of life, improve the sewage treatment effect. Be like again

foshan garbage power plant in the process selection of 52 table converter. Visible frequency control of motor speed has become

the main equipment of environmental protection. China petrochemical corporation make a extinguished the torch (mainly refers to rotary union

the big oil refinery to burn gas) plan, that is the combustible gas delivery to use frequency control of motor speed compression

machine cabinet recovery.
Example 7, music fountain class load
Very attract visitors to the music fountain, the water level of the amount and size is by frequency conversion control. Asian

spray the highest of heyuan city, guangdong music fountain and scale a lot of shandong jinan quancheng square music fountain all

belong to this, namely, power saving and effect is very good, in construction music fountain, attention should be paid to the

harmonic frequency converter to control system of interference.
Example 8, cigarette machine class load
Cigarette industry in the past imported cigarette machine, no matter Maureen 8, or Maureen 10, were not stepless speed

regulation. Therefore, in the cigarette industry is mainly solve the stepless speed regulation and reliability problems,

technology is simple, frequency converter usage simple, convergence greatly.
The cigar mill of zhaotong city 19 sets of import grant 4 roll joint packaging integral unit using frequency control of motor

speed, increase the cigarette, 200 cases, 200 cases of the cigarette tax quite 19 sets the price of frequency converter, namely

one day disinvestment. Therefore, cigarette machine reconstruction rapidly, great benefit. Now most of the domestic machine is

equipped with a variable frequency speed regulating function.
Case 9, large kiln calcining class load
Metallurgy, building materials, caustic soda and other large industrial turn furnace (bof) before most of them adopt dc,

commutator machine, slip motor and speed regulating pole string. Because these speed regulating mode or slip ring, or low

efficiency, in recent years, a lot of units by ac frequency conversion control, the effect is very good.
ZhuZhou smeltery of zinc leaching residue volatilization kiln is the main body of zinc recovery equipment, a total of three

table. Kiln outside diameter 2.8 meters, 44 meters long, the original with the positive flow son motor and slip motor drive,

fault, often trip, a great quantity of maintenance. Due to the bad environment, conductive dust, electric spark constantly.

Brush, carbon brush change constantly, 90 minor repair 56 times, change only 1670 carbon brush, brush 647 only, serious

influence the production. In June 91 the factory finished rotary kiln of frequency control of motor speed transformation. Smooth

operation, reliable, simple operation, didn't happen because of motor drive fault and affect production. Annual energy saving

120000 degrees, over production is 1.1782 million yuan. Tangshan factory light grey calcined furnace is the key equipment of

soda production, diameter 3.6 meters, furnace body length 30 meters, gross weight 266 tons, with 220 kw converter drive, low

frequency start well, rotary stability, high reliability, improve the product quality, so that the calcined furnace production

into fiber optic rotary joint the advanced ranks.

Case 10, crane, skip class load

Crane, dump and load torque big and smooth, positive and negative frequent and reliable. Frequency conversion device control crane, skip to rotary joints meet these requirements.
An only child mountain petrochemical factory ketone benzene workshop for three table filter installation and setup a 20 tons of bridge crane, technological requirements of

explosion-proof, use explosion-proof squirrel-cage motor. The original production of lifting the owner hook, auxiliary hook, cart, car no speed regulating function, can't

positioning. Torque is small, the hoist objects glide to lifting 19 tons of filter base, so that the workshop start late more than a year, a loss of ten million yuan. In July 91

the frequency control of motor speed and braking function, make main hook, auxiliary hook, cart, five motor car by a frequency converter control, the effect is very good.

Overload test sling 22 tons, quickly put the three table each heavy 40 tons of filter installed in 10 meters high floor platform on the flight.
Dock port, station gantry crane, yard material piling and taking machine and so on all can use frequency conversion speed control device, in order to achieve reliable, steady,

power saving, less maintenance purpose.
Frequency conversion speed control device, in addition to saving electricity significant outside, or some production process the necessary equipment.
Examples of 11, converter class load
Converter class load, with ac frequency conversion instead of dc unit is simple, reliable, stable operation.
On May 1, 1994, chengde iron and steel company steel plant three sets of 20 tons converter dc drive system all in fault condition. Quasi looking for a "fast and good" restore

production control mode, please come to the China electrical rotational experts LiuZongFu professor. In professor liu's suggestion, the company manager finalize, 20 tons

converter tilting and oxygen lance lifting adopts ac frequency conversion speed regulating drag. From supply to installation, commissioning, after 13 days, three sets all

converter normally put into production. This is our country 20 tons converter tilting and oxygen lance lifting first using frequency control of motor speed. After years of

production and application, this system operation is stable and reliable, and technical index fully meet the technological requirements. Converter, oxygen gun main drive system

caused by the heat down to reduce more than 90%, the year yield increase by 15000 tons, power saving 220000 degrees, direct economic benefits is 2.31 million yuan. For steel

mill stable production after lay a solid base to wear  this system in 1995 through the ministry of machine building appraisal, and was awarded the first prize in hebei

province technology progress.
Case 12, special power class load
Many power, such as experimental power supply, the plane drag power supply (400 hz) can be used frequency conversion device to complete, the advantage is less investment, quick

effect, volume some  simple operation.
Viscose fiber industry spinning equipment are mostly high speed motor, numerous hasp motor for 150 hz / 160 v. For a long time, the domestic viscose industry has been to use

electric - generating set medium frequency power supply, says the dynamic frequency. Because this method malady too much, and gradually by ac frequency conversion power supply,

says static frequency conversion. Shaoyang chemical fibre factory is the first application of viscose industry by static frequency manufacturers, eight Taiwan 160 kw converter

points two rotary union groups power supply (each group a standby). Since December 1992, since the production, than the dynamic frequency have obvious advantages.
A. and reliable. Operation for many years, and not failure trip.
B. the operation is stable, and the voltage and frequency fluctuations very some 
C FM convenient, for the factory production of different twist silk cake created conditions.
D. little noise and improve the operation personnel's environment.
E. Improve the product quality. The first phase project (the dynamic frequency conversion power supply), viscose filament percent of pass is only 55.1%, the first grade percent

of pass is zero, second percent of pass is 20%, and the second phase project (using static variable frequency power supply) average qualified rate 98.12%, grade a qualified rate

88.7%.
F. increased production. A phase of the project design capacity of 2000 tons/year, trial production half a year, yield only 65.53 tons, and of the second phase of the project

design capacity of 1000 tons/year, trial production half a year, production filament 685.25 tons, greatly more than design capability.
G. power saving 13%.
Due to fiber optic rotary joint the static frequency conversion for viscose industry has brought great benefits, many enterprises, such as jilin chemical fibre factory, jiujiang chemical fibre factory,

yibin chemical fibre factory, hubei chemical fibre factory, dandong chemical fibre factory, weifang chemical fibre factory (except yibin outside, belong to the listed company)

are adopted static frequency conversion technology.
Frequency control of motor speed in addition to saving electricity outside, and increase production and consumption, the high quality effect. Because it has a volume some 

light weight, high precision, strong commonality, the craft is advanced, the function rich, protection is complete, high reliability, easy operation etc, by using personnel

welcome, frequency control of motor speed it is to save energy and reduce consumption, high quality and high yield of the ideal equipment, is entering into the 21st century's

first drive technology, benefits the country and the people.

converter soft start saving energy

Frequency conversion and soft start energy saving analysis pick to: this paper introduces the electric equipment of the energy

consumption status and composition, the paper elaborated on frequency conversion and the energy saving principle of soft start.

And lists inverter in the fan and pump control in energy saving advantage and motor soft start effective fighting power grid

peak voltage process.
Keywords: converter soft start saving energy
One, introduction
With the acceleration of industrialization steps, saving energy and reducing consumption in the form of more and more severe,

some can reduce the loss of industrial electronic products are emerging. Inverter and soft starter application fields is more

and more widely, use is more frequent. In the motor and fan control, frequency control of motor speed and soft start energy-

saving effect is very obvious.
Second, the power energy consumption analysis
In order to
rotating joints guarantee the reliability of the production, various production machinery in the design with power driven, bore a

certain margin. Motor cannot be in full load under operation, in addition to achieve power driven requirements outside,

superfluous moment increased active power consumption, causing the waste of electric power, in the production process, because

the motor load variation range is very large, must be real-time adjustment fan pump flow. At present flow adjusting way more for

regulating valve adjustment, this kind of control mode is only changed channel flow impedance, and motor output power and does

not change much, often is the motor run at full speed at all times, regulator through the throttle to control production needs,

in fact is artificial way to increase resistance to regulate purpose, this kind of throttle control method to waste a lot of

electricity. When air reduce fan speed down, the motor power input rapidly reduces the. Such as air volume dropped to 80%, speed

n also dropped to 80%, the shaft power is down to 51% of the rated power; If the volume down to 50%, shaft power will decline to
rotary union the rated power 13%, its electricity saving potential is very large.
In the motor when started at full pressure, because motor start-up moment needs, from the power grid absorption 7 times of the

motor rated current, and large starting current is waste of electric power, the grid voltage fluctuation damage is very big

also, increased the line loss and variable loss. Big starting torque produce mechanical shock, to be driven equipment cause big

impact, shorten service life, the influence degree of accuracy. Such as make coupling damage, belt tearing, etc. Cause

mechanical transmission parts of abnormal wear and impact, accelerated ageing, shorten service life increase maintenance

workload. Motor hard start power to cause serious impact, but also to fiber optic rotary joint power grid capacity overstretch, started from the large

current and vibration on the baffle and valve damage greatly, the service life of the equipment, the line is bad. And the use of

soft start device, the use of frequency converter to soft start function will make starting current starting from scratch, no

more than the maximum current rating, reduce the impact of the power grid and the requirements of power supply capacity and

prolong the equipment and service life of the valve. Save the equipment maintenance. Motor starting current start from 0 - motor

rated current gradually increase, reduce the start current for the impact of the power grid, save electricity, also reduced the

start inertia of equipment large inertia speed impact, extend the life of the equipment.
Three, variable frequency energy saving analysis