CN1941609A - High-performance cheap AC speed-adjusting system - Google Patents
High-performance cheap AC speed-adjusting system Download PDFInfo
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- CN1941609A CN1941609A CN 200510019539 CN200510019539A CN1941609A CN 1941609 A CN1941609 A CN 1941609A CN 200510019539 CN200510019539 CN 200510019539 CN 200510019539 A CN200510019539 A CN 200510019539A CN 1941609 A CN1941609 A CN 1941609A
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Abstract
The invention is concerned with AC timing system with high capability and low cost, which relates to asynchronous motor timing, AC-AC variable-frequency and vector control technology. It realizes the smoothness stepless timing about the controlled asynchronous motor in the range of up and down 40% of its synchronization rotate speed (Omega0). The stator of motor connects with the electricity net of work frequency, while the rotor connects with the said AC excitation electrical source in this timing system. Decompose the current of motor with vector control technology into excitation heft and torque heft to realize the control and adjust about the rotate speed and power factor with high system efficiency. When the power factor is 1 even it is at the condition of exceeding power factor, the motor works in stabilization. The current of AC-AC transducer or AC-DC-AC transducer is the power of changing difference. And the work voltage and current of rotor is less than the one of stator, and it uses transducer with low voltage, small capability and low cost.
Description
Technical field the present invention relates to induction motor drive, AC-AC frequency conversion, vector control technology.
Background technology
At present China's economy develops rapidly, but energy consumption problem is very outstanding, and the energy that 1 dollar of output value of every generation will consume is the manyfold of developed country, and therefore power-saving technology is that the new technology developed is badly in need of at present in China efficiently.According to statistics, the power consumption of asynchronous motor accounts for about 60% of electrical network total electricity consumption, and the capacity that a large amount of asynchronous motors consideration various factors is selected is bigger than normal, thereby causes motor to depart from efficient operating point operation for a long time, efficient is very low, has caused the waste of the huge energy and equipment.
The speed adjusting performance of asynchronous motor own is relatively poor in addition, the situation that the present various production processes of incompatibility are more and more higher to the motor speed adjusting performance requirement, and therefore high performance induction motor drive technology also is a technology of being badly in need of exploitation.
The purpose of this invention is to provide a kind of operational efficiency height, good speed adjustment features, induction motor drive system that cost is low.
Induction motor drive roughly has several schemes of pole changing, rotor series resistance speed, variable voltage control, frequency control and tandem control at present.Several rotating speeds that the pole changing scheme can only be limited wherein, and system configuration and complicated operation; Rotor series resistance speed scheme inefficiency; The scope of variable voltage control scheme rotating speed adjustable is very little; Stator side frequency control scheme has many advantages, but the frequency converter that is connected in the motor stator side costs an arm and a leg, frequency converter especially for the high-voltage large-capacity motor speed adjusting, its capacity must must surpass several times of motor rated voltage greater than motor capacity, withstand voltage, so realization and difficult in maintenance, price is also high, is difficult to promote at home; The tandem control scheme has the speed adjusting performance that compares favourably with Direct Current Governor System, is particularly suitable for the little occasion of speed adjustable range.
Recently the more than ten years, industrially developed country furthers investigate a kind of Alternating Current Governor System that combines frequency control and tandem control, and this system is commonly referred to as doubly-fed adjustable speed system or AC excitation governing system.Its core concept is to use frequency converter that the industrial-frequency alternating current of input is transformed into the additional electromotive force identical with rotor induction gesture frequency
Seal in rotor loop, by
And rotor electromotive force
Acting in conjunction produces rotor current I
2, and the torque of asynchronous motor is
T＝C
TJΦ
1I
2cos
2
Therefore, regulate frequency converter and make additional electromotive force
Change, just can change torque, thereby change the rotating speed of motor, rotation speed change can cause the variation of rotor induction gesture amplitude, frequency and phase place, and system just must regulate the output of frequency converter, makes additional electrical potential energy follow the rotor induction gesture and changes and change.
In this system, energy can be by frequency converter two-way flow between electrical network and rotor under system control, and frequency converter consumed energy not, and the power factor of motor stator side in theory can be regulated arbitrarily on demand, so the running efficiency of system height; In control, adopt vector control technology, have the torque of motor and the characteristics that excitation can be distinguished independent regulation, therefore can reach the speed adjusting performance that compares favourably with Direct Current Governor System; And because frequency converter works in the rotor-side of motor, and its operating voltage is low, electric current is little, capacity is little, the frequency converter low cost of manufacture is adapted at domestic popularization.
But the information that retrieves in all its bearings, though domestic have a large amount of research to this technology, but because this technology is comparatively complicated, the a large amount of technical problems that relate to multi-door subjects such as power electronics, Electrical Motor, control theory, Control Technique of Microcomputer, domestic research only limits to the experiment of emulation of the computer software or laboratory partial function more, and Shang Weiyou is embodied as matured product with whole system.
Summary of the invention
The present invention is on the basis with reference to external doubly-fed adjustable speed correlation technique data, carry out a large amount of theory analysises and experimental study, succeeded in developing the Alternating Current Governor System that the ac-ac frequency converter that is used for doubly-fed adjustable speed, the controller with vector control function and they and wire wound asynchronous motor are formed.
Controlled motor can be at its synchronous speed (ω in native system
0) realize smooth stepless speed-regulating in 40% scope up and down, promptly obtained the speed adjustable range of motor synchronous rotating speed 80%, and frequency inverter capacity only needs to be slightly larger than 40% of motor rated capacity and gets final product, and frequency inverter capacity can also further descend if the speed adjustable range of actual needs is less.
Because frequency converter works in the rotor side, its operating voltage grade only electric pressure with the rotor induced potential is suitable, and near the voltage of motor speed rotor induced potential synchronous speed time the very low (being zero during synchronous speed), therefore the electric pressure of frequency converter can be far below the motor rated voltage, the frequency control of high-voltage large-capacity motor only need use the frequency converter of low pressure low capacity to get final product, system cost is low, and does not need to rely on external import high-voltage large-capacity current device.
When the wire wound asynchronous motor of the two-phase vertical rotor winding that uses special construction, control method and three-phase rotor winding electric machine all fours, but excitation main circuit and control circuit reduce by a phase, and structure is simpler, cost is lower.
Ac-ac frequency converter among the present invention can be realized the two-way flow of energy, the slip power that can make motor output according to the running status of motor to the electrical network feedback or by electrical network to motor feed-in slip power (i.e. " double-fed "), do not have meaningless energy consumption.In addition, adopted vector control technology with rotor current I
2Be divided into excitation component I
MWith torque component I
TControl respectively, adjust torque component and just can adjust rotating speed on request, adjust excitation component and then can adjust the power factor of motor stator side on request, both adjustings are independent of each other, therefore under any rotating speed in speed adjustable range, motor can steady operation in power factor be 1 in addition the leading power factor state under, the efficiency of motor height.By these 2 as can be known, the efficient of system operation is also very high.
When the power factor of controlled motor is 1, stator side electric current and voltage homophase, stator current all is used for doing work, the power output of motor will be above the rated power of asynchronous machine when stator current reached rated current, this moment is because the voltage and current of motor is rated value, motor is long-time running fully in this state, therefore native system obtains also to make the capacity of motor that certain increase be arranged in the situation that does not need motor to be done any transformation the good speed adjusting performance except making asynchronous motor.
Alternating Current Governor System of the present invention mainly comprises controlled wire wound asynchronous motor, the controller three parts of controlling as the frequency converter of ac excitation power supply, to whole system.
The employed wire wound asynchronous motor of native system can directly use the conventional wound asynchronous motor of producing in serial form, and three-phase rotor ring lead-in wire can have 3 or 6 (optional Y shape or △ shape connect); The wire wound asynchronous motor that also can use specialized designs to produce, its rotor has only mutually perpendicular two phase windings, can produce circular rotating magnetic field (it is the same that effect passes to the three-phase symmetrical current with common symmetrical three phase windings) when this two phase winding passes to the simple sinusoidal alternating current of 90 ° of mutual deviations, two-phase rotor ring lead-in wire has 4.
Ac excitation power supply in the governing system of the present invention, main circuit can adopt AC/AC Direct Conversion device or the indirect frequency converter of AC-DC-AC type.When adopting AC/AC Direct Conversion device, its concrete type of attachment can be the triangle ac-ac frequency changer circuit that the controlled zero formula rectification circuit of antiparallel three-phase, antiparallel three-phase thyristor bridge rectification circuit, antiparallel 12 pulse waves and above heterogeneous controlled rectification circuit, the irreversible bridge of three-phase form by the reactor serial connection, matrix form ac-ac frequency changer circuit etc.When adopting the indirect frequency converter of AC-DC-AC type, middle with electric capacity or electric capacity coilloading as the dc energy storage element, but two energy converters of the AC/DC at two ends and DC/AC then can be selected two inverted rectifier (energy two-way flows for use according to actual conditions, the rotating speed gamut is regulated), but (cost is lower for the irreversible rectifier of electrical network end inverted rectifier and motor side, energy can only be from motor to the electrical network one-way flow, rotating speed can only be regulated in the following scope of synchronous speed), but (cost is lower for irreversible rectifier of electrical network end and motor side inverted rectifier, energy can only be from electrical network to the motor one-way flow, rotating speed can only be regulated in the above scope of synchronous speed) etc. different main circuit topological structures.
Controller comprises rotor string starting drive of quick resistance asynchronous starting frequently, and the excision quick resistance of this frequency and the throwing that described ac excitation power supply is received the rotor side encouraged device behind electric motor starting;
Controller also comprises a zero current detection and does not have the circulation commutating circuit, each phase output current of this electric circuit inspection ac excitation power supply, the no circulation that carries out working group and wait group when current over-zero switches, guarantee that main circuit is an inverse parallel structure and can reliably working by the ac excitation power supply of no circulating current system work, if adopt the ac excitation power supply of other structures can be without this circuit;
Controller also comprises a rotor current detector, will be used for carrying out current closed-loop control by the detected current signal of this detector, with the accurate control of acquisition to electric current, thereby obtains fabulous dynamic speed adjustment performance;
Controller also comprises a revolution detector, described controller is adjusted the output of described ac excitation power supply according to the detected rotary speed information of this revolution detector, makes controlled rotating speed of motor to expectation rotation speed change (during speed governing) or stablize constant (during the stable speed operation);
Controller also comprises the phase detectors of a rotor induced potential, will carry out the computing of transform vector as core parameter by the detected phase signal of this detector;
Controller also comprises a stator side power factor detector, described controller is adjusted the output of described ac excitation power supply according to the detected power factor information of this power factor detector, the stator side power factor that makes controlled motor is expected power factor value (comprising desirable unity power factor even leading power factor) to expecting power factor change (when changing power factor) or stablizing constant (when the expectation power factor is moved) arbitrarily thereby motor stator side power factor can be reached;
Controller also comprises a control core, this control core can be by single-chip microcomputer, dsp chip or other embedded system chips are that basic school extension parallel circuit forms, the control core is being controlled whole governing system, and the operation of being done comprises access quick resistance starting motor frequently, the rotor induced potential is followed in output with the start-up control ac excitation power supply of motor, excise the quick resistance of frequency after electric motor starting is finished and ac excitation power supply is inserted the rotor loop, the response keyboard is accepted the user and is imported expectation rotating speed and/or expectation power factor, expectation rotating speed according to user's input carries out vector calculus with the expectation power factor, the output of adjusting ac excitation power supply according to the result of vector calculus makes rotating speed of motor reach the expectation rotating speed that the user sets and the power factor that makes motor reaches the desired value that the user sets, operating state to system is carried out fault detect and judgement, according to the Adjustment System work of the fault order of severity or cut-out ac excitation power supply or cut-out motor main power source, fault is got rid of back restarting systems work, display system work state information as required.
Description of drawings
Fig. 1 is the doubly-fed adjustable speed system construction drawing
Fig. 2 is the general structure chart of Alternating Current Governor System that the present invention realizes
Fig. 3 is the three-phase AC/AC Direct Conversion device schematic diagram that is formed through inverse parallel by three phase controlled rectifier circuit, and its working method is no circulating current system.Wherein Fig. 3 .a is the structure chart of a three-phase commutation bridge; Fig. 3 .b represents that the trigger impulse of a three-phase thyristor bridge rectification circuit forms circuit; Fig. 3 .c is the frequency converter full figure, and each square frame is a three-phase thyristor bridge rectification unit among the figure, and the inside comprises a three-phase thyristor bridge rectification circuit shown in Fig. 3 .a, comprises that also a trigger impulse shown in Fig. 3 .b forms circuit
Fig. 4 is the current over-zero detection and does not have circulation commutation circuit schematic diagram
Fig. 5 is that two closed-loop controls and vector calculus realize schematic diagram
Embodiment
Describe a typical embodiment of the present invention in detail below in conjunction with accompanying drawing, promptly constitute AC/AC Direct Conversion device with antiparallel three-phase thyristor bridge scr rectification circuit, this frequency converter is no circulation working method, by controlled motor is three-phase rotor winding wire wound asynchronous motor, and controller then is that the TMS320LF2407DSP chip with TI company is that core constitutes.
Frequency changer (not shown transformer as shown in Figure 3 wherein, when if the voltage of three-phase input AC electricity is suitable without transformer, otherwise need input be changed to suitable voltage with transformer), Fig. 3 .a illustrates six thyristors and connects into a three-phase thyristor bridge rectification circuit; Fig. 3 .b represents that the trigger impulse of a three-phase thyristor bridge rectification circuit forms circuit, relatively produce phased pulse by desired signal and sawtooth waveforms, high frequency modulated can reduce the volume of pulse transformer, pulse is through exporting thyristor to by the pulse transformer coupling after the power drive, by all six road trigger impulses of pulse blocking signal controlling, this signal is used for not having the circulation working method to be blocked working group's pulse, opens and wait for that thereby group pulse realizes that reliably no circulation switches, and also can block all pulses easily and protect main circuit during system exception;
Fig. 3 .c is the frequency converter full figure, and each square frame is a three-phase thyristor bridge rectification unit among the figure, and the inside comprises a three-phase thyristor bridge rectification circuit shown in Fig. 3 .a, comprises that also a trigger impulse shown in Fig. 3 .b forms circuit.Can see that three-phase connects output with star fashion, each is all produced by two bridge rectifier unit inverse parallels mutually.Because two bridge rectifier unit connected modes are direct inverse parallel,, two unit can cause the direct short-circuit of power supply if working simultaneously, therefore must adopt no circulation switch logic in the real work, two unit just are divided into organize (the thyristor symbol person of making progress) and anti-group (the downward person of thyristor symbol), by aforementioned pulse blocking signal controlling, when electric current is just being organized work during for just (electric current flows to load by frequency converter), anti-group is blocked, and when electric current counter group of work when bearing (electric current by load flow to frequency converter), just organize and be blocked.
Owing to need the output simple sinusoidal alternating current, just organizing with anti-group must take turns to operate, and the positive and negative group of moment of switching is in the phase current passing zero moment, so system must detect accurately to the phase current passing zero moment.In addition, the switching of just sending out between the group can not instantaneously be finished, otherwise may cause power supply short circuit because working group's thyristor has been opened the wait group when also turn-offing fully, so also need correct no circulation switch logic.
Zero current detection shown in Figure 4 and do not have the circulation commutating circuit and design for finishing these two functions.As shown in Figure 3, the concrete structure of AC/AC frequency converter a phase output is Fig. 4 .a.Know easily that by figure six link to each other with a phase output terminal in 12 thyristors of a phase, if the electric current by these six thyristors be zero a phase current one be decided to be zero, so zero current detection only need detect the electric current of these six thyristors.It can also be seen that by figure these six thyristor inverse parallels in twos detect by three pairs of thyristors when therefore detecting together.The principle of zero current detection is " thyristor bears high voltage, then necessarily is in blocking state, and then electric current one is decided to be zero ".
Fig. 4 .b is the physical circuit of a phase zero current detection, each tube voltage drop to thyristor is added to a pair of antiparallel optocoupler input by a resistance, for preventing mistake identification to occur owing to disturbing, the input of optocoupler has also been gone here and there a voltage-stabiliser tube, so that the minimum threshold values of identification output to be provided, the output of optocoupler is then directly in parallel.Therefore as long as in two thyristors a conducting is arranged, then tube voltage drop is necessarily very little, the output of two optocouplers all can be in blocking state, and if two thyristors all by and tube voltage drop surpassed threshold values, the output that then always has and have only an optocoupler is in conducting state.The output of three pairs of optocouplers is together in series, a termination power, and an end passes through grounding through resistance.This structure realized one " with " logic, as long as one group of optocoupler output blocking-up is arranged, the path from the power supply to resistance just is cut off, ohmically pressure drop is zero; Have only three groups of all conductings of optocoupler output, the path from the power supply to resistance is only connection, and ohmically pressure drop is the saturation conduction pressure drop that supply voltage deducts three optocouplers, near supply voltage.That is to say that as long as a thyristor conducting (electric current is arranged) is arranged, output is low level just on the resistance, has only all not conductings of thyristor (no current), just exports high level on the resistance.Therefore, the last jumping moment of level is exactly the moment of current over-zero on the resistance, and these moment six thyristors necessarily all are in blocking state, can carry out positive and negative group switching.This structure makes this circuit only export high level (no current) in very short a period of time (less than 3.3ms) that current over-zero brings into operation to the wait group, the situation of " vacation has electric current " can not appear exporting owing to the tube voltage drop natural zero-crossing at this moment, this circuit of other times is output low level (electric current is arranged) always, " vacation has electric current " be submerged in " electric current is really arranged " not can interfered circuit normal operation, therefore remove " vacation has electric current " signal without any need for adjunct circuit.
Deliver to no circulation commutating circuit from the signal that the zero current detection circuit obtains, this circuit comprises a single-chip microcomputer and a voltage detection unit, for a, b, c three-phase shared, the just part of functions of a phase wherein shown in Fig. 4 .b, b, c and a are similar.Wherein voltage detection unit only detects the polarity of expectation signal voltage a phase.Single-chip microcomputer has four inputs, six outputs, be connected to the common I/O pin of single-chip microcomputer from the next signal of voltage detection unit, be connected to three interruption input pins of single-chip microcomputer from three next input signals of zero cross detection circuit, six common I/O pin getting single-chip microcomputer are as output pin, control just organizing rectifier bridge and sending out the trigger impulse of group rectifier bridge of a phase respectively as one group for per two.After resetting, single-chip microcomputer at first carries out initialization, the value of three registers is initialized to 11101110b, 10111011b, 11101110b respectively, suppose that three registers are respectively Ra, Rb and Rc, and export from the I/O pin b7 position of the content of each register and b5 position, just organizing the pulse blocking signal of bridge and anti-group bridge respectively mutually as correspondence, 1 is locking pulse, and 0 is open pulse.Therefore the pulse of six bridge circuits all is blocked after the initialization, and circuit working state is uncertain and produce fault when preventing from just to power on.
After treating that circuit is stable, single-chip microcomputer is checked the state of voltage detection signal on the input pin, become canonical with one of the equal ring shift right of the value of Ra, Rb and Rc if state variation shows a phase voltage from bearing, otherwise circulation is checked up to satisfying aforementioned condition repeatedly.The value of Ra, Rb and Rc becomes 01110111b, 11011101b and 01110111b after the cyclic shift, easily know a mutually and c just organizing the pulse that bridge, b organize bridge on the contrary mutually and all opening, by the requirement output three-phase alternating current of expectation signal, a just is being output as with c bridge circuit mutually mutually, b is output as negative mutually under the control of trigger impulse.The do-nothing operation of single-chip microcomputer circulation carrying out is subsequently waited for and being interrupted.
After open three working groups of single-chip microcomputer, frequency converter output three-phase alternating voltage, this voltage will make rotor produce three-phase alternating current, and alternating current just has zero crossing.The zero current detection circuit in turn (can not have biphase current zero passage simultaneously) and send the zero current signal of three-phase, and the zero current signal of each phase all can cause the once interruption of single-chip microcomputer.Carrying out the one-level time-delay after the singlechip interruption prevents to disturb, then once with the register value ring shift right of corresponding phase, positive and negative group of bridge pulse of this phase all blocked, and then carry out one-level time-delay and prevent to have during operation new thyristor to be triggered, at last this register value recirculation is moved to right once the pulse of the wait group rectifier bridge of open this phase.Fig. 4 .c is single-chip microcomputer main program and interrupt service routine flow chart (operating process of having no progeny in three the corresponding respectively a of interrupt service routine, b and the c three-phase zero current signal is arranged, and flow process is identical, only provides the flow chart of an interrupt service routine among the figure).
The rotor current detector is made of the A/D conversion portion of current transformer and dsp chip, will be used for carrying out current closed-loop control by its detected current signal, with the accurate control of acquisition to electric current, thereby obtains fabulous dynamic speed adjustment performance.
Detection to motor speed can be adopted various detector, what this example adopted is the rotary pulsed encoder of increment of full-enclosed structure, this encoder converts the rotation of rotor to pulse output, and by DSP the pulse number in one period set time being counted just can be through calculating rotating speed of motor.And this encoder rotates a circle and can export 360 pulses, thereby can obtain the position angle of rotor at any time, is used for following rotor induced potential phase-detection.
Rotor induced potential phase detectors come out the phase-detection of rotor induced potential to use for the computing of transform vector.It detects principle, detect the electrical degree that synchronous rotating magnetic field turns over, and by the position angle of above-mentioned pulse coder detection rotor and be converted to electrical degree, the difference of two electrical degrees is exactly the synchronous rotating magnetic field electrical degree that son turns over that rotates, just rotor cuts the electrical degree that synchronous rotating magnetic field turns on the contrary, is exactly the phase place of rotor induced potential therefore.Can obtain the electrical degree that synchronous rotating magnetic field turns over easily and the electrical degree that stator A phase voltage turns over just detected.This detection principle must be considered the initial phase of rotor induced potential, here utilize above-mentioned pulse coder to also have one road signal to spend a week in addition and send the characteristics of a pulse for revolution, with this pulse as zero pulse, the calculated value of two electrical degrees all returns zero when coming zero pulse at every turn, and promptly rotor induced potential phase calculation value also returns zero.Only when being installed, encoder must guarantee that encoder just sends zero pulse when the stator and rotor winding is coaxial, this time, the phase place one of rotor induced potential was decided to be zero, and know that by above analysis its calculated value also returns zero, calculated value just can correctly reflect the actual value of rotor induced potential phase place like this, can correctly detect the phase place of rotor induced potential.
The method that detects the motor power (output) factor is, the voltage and current of motor stator side is taken a sample respectively and convert square-wave signal to, carry out narrow-band filtering to reduce interference with phase-locked loop circuit, resulting signal is delivered to the capture unit of DSP, DSP catches go up jumping along (jump down along also can) of two signals respectively, the time difference (need distinguish leading, the lagged relationship of two signals between mutually) of calculating both just can be known the phase difference of two signals, promptly know the phase difference of motor stator voltage and current, just can calculate the power of electric motor factor.
Vector control function is finished by internal arithmetic by DSP, its primary structure such as Fig. 5.This is a double closed-loop control system, and rotating speed/power factor adjustable ring is the control outer shroud, and current regulation loop then is ring in the control.The outer shroud regulating action is slower, mainly solves the accurate control of rotating speed/power factor; Interior ring regulating action is fast, mainly solves the accurately control fast of electric current, the dynamic property of raising governing system.
Easily know the expectation rotation speed n that is set by the user by figure
*With the detected actual speed n of revolution detector
fCompare, error is delivered to the desired value I that pi regulator changes the rotor current torque component
T *, correspondingly change by current inner loop control rotor current, make the actual value I of rotor current torque component
TfChange to desired value, thus the actual speed that makes motor to the expectation rotation speed change, up to both equate, error is zero.The course of work that power factor is regulated outer shroud is identical with the rotating speed outer shroud, the actual value I of control rotor current excitation component
MfTo desired value I
M *Change, thereby make the actual value cos φ of power factor
fTo desired value cos φ
*Change, until equating.
The operation principle of ring is in the Current Regulation, by the given rotor current torque component of rotating speed and power factor outer shroud and excitation component desired value input signal as electric current loop, they respectively with the actual value of rotor current torque component and excitation component relatively; The error signal that obtains changes rotor voltage torque component desired value U through pi regulator respectively
T *With excitation component desired value U
M *These two amounts all are DC quantity, belong to the rest frame parameter, they again through static to rotating and two-phase just can obtain the desired value Ua of a, b, c three-phase voltage to the transform vector of three-phase
*, Ub
*And Uc
*Conversion just can obtain three-phase expectation sinusoidal voltage to three amounts through D/A, here make full use of the PWM function that dsp chip has, the desired value of three voltages is become the output of PWM waveform, filter the sinusoidal waveform that high frequency content just can obtain three-phase expectation voltage by low pass filter, realized the D/A conversion, because each of frequency converter is to be made of positive and negative two rectifier bridges mutually, need two-way anti-phase expectation sine wave mutually, just directly produced six tunnel outputs when producing the PWM waveform, through low pass filter output is exactly three groups of anti-phase in twos expectation sine waves; These three groups of sine wave signals are delivered to frequency converter, the phase shifting angle of control trigger impulse, thus make frequency converter output by the expectation three-phase alternating voltage that sine voltage determined; Three-phase alternating voltage has just determined the rotor three-phase electric current; The rotor current detector detects the actual value of three-phase rotor current, and the process three-phase is to two-phase and rotate to the actual value that static transform vector obtains rotor current torque component and excitation component, compares as feedback quantity and desired value.If the actual value and the desired value of rotor current torque component and excitation component are unequal, error signal will change the desired value of three-phase voltage by said process, thereby change the output voltage of frequency converter, then rotor current can become thereupon, thereby reducing the error with the electric current desired value, is zero until error.
Wherein transform vector partly need use the phase place by the detected rotor induced potential of rotor induced potential phase detectors, and transform vector is realized with the mode of software computing with DSP.Four pi regulators all are digital P I adjusters among the figure, and with the realization integration that adds up, this part function also realizes with the mode of software computing with DSP.Because frequency converter is to be that the basis constitutes by the three-phase thyristor bridge rectified current, just once pulse of every approximately 3.3ms, and could change output when only pulse being arranged, so frequency converter is uncontrolled in the time between two pulses, the effect that the sinusoidal wave value of expectation during this period of time takes place twice and above variation and taking place once changes is identical, therefore, in order to reduce the DSP workload, the comparison of ring in the Current Regulation, PI regulates, vector calculus, the every 2ms of operation such as PWM generation just carry out once, and the comparison of rotating speed/power factor outer shroud, it then is that every 40ms just carries out once that PI regulates operation.
Claims (7)
1. the Alternating Current Governor System of a high-performance and low-cost comprises a controlled wire wound asynchronous motor, a field power supply and the controller that control system is moved of AC excitation being provided for this motor, it is characterized in that,
Controlled motor adopts wire wound asynchronous motor; This motor of governing system may command is at its synchronous speed (ω
0) realize smooth stepless speed-regulating in 40% scope up and down; The motor stator side directly connects common frequency power network, and rotor-side then connects the special-purpose ac excitation power supply of this governing system.
2. wire wound asynchronous motor according to claim 1 is characterized in that, is the conventional wound asynchronous motor of producing in serial form, and three-phase rotor ring lead-in wire may have 3 or 6 (optional Y shape or △ shape connect); Or the wire wound asynchronous motor of specialized designs production, its rotor has only mutually perpendicular two phase windings, can produce circular rotating magnetic field (it is the same that effect passes to the three-phase symmetrical current with common symmetrical three phase windings) when this two phase winding passes to the simple sinusoidal alternating current of 90 ° of mutual deviations, two-phase rotor ring lead-in wire has 4.
3. the speed adjustable range of motor according to claim 1 is characterized in that, the minimum speed of controlled motor can reach its synchronous speed ω
0To downward modulation 40% (is that rotating speed is 60% * ω
0), and maximum speed can reach its synchronous speed ω
0To raising 40% (is that rotating speed is 140% * ω
0); In this scope, motor speed is step-less adjustment smoothly, and promptly motor can work in any rotating speed in the speed adjustable range, also comprises with leg speed ω
0
4. ac excitation power supply according to claim 1, it is characterized in that, main circuit adopts AC/AC Direct Conversion device, its concrete type of attachment can be the triangle ac-ac frequency changer circuit that the controlled zero formula rectification circuit of antiparallel three-phase, antiparallel three-phase thyristor bridge rectification circuit, antiparallel 12 pulse waves and above heterogeneous controlled rectification circuit, the irreversible bridge of three-phase form by the reactor serial connection, matrix form ac-ac frequency changer circuit etc.; Main circuit or the indirect frequency converter of employing AC-DC-AC type, middle with electric capacity or electric capacity coilloading as the dc energy storage element, but two energy converters of the AC/DC at two ends and DC/AC then can be selected two inverted rectifier (energy two-way flows for use according to actual conditions, the rotating speed gamut is regulated), but (cost is lower for the irreversible rectifier of electrical network end inverted rectifier and motor side, energy can only be from motor to the electrical network one-way flow, rotating speed can only be regulated in the following scope of synchronous speed), but (cost is lower for irreversible rectifier of electrical network end and motor side inverted rectifier, energy can only be from electrical network to the motor one-way flow, rotating speed can only be regulated in the above scope of synchronous speed) etc. different main circuit topological structures.
5. according to claim 1, one of 4 described ac excitation power supplies, it is characterized in that, when controlled motor was the described two-phase rotor winding structure of claim 2 motor, the main circuit topological structure of ac excitation power supply can reduce to two-phase output from three-phase output, and cost descends 1/3 approximately.
6. controller according to claim 1 is characterized in that, comprises rotor string starting drive of quick resistance asynchronous starting frequently, and this resistance of excision and the throwing that described ac excitation power supply is received the rotor side encouraged device behind electric motor starting;
Also comprise a zero current detection and do not have the circulation commutating circuit, each phase output current of this electric circuit inspection ac excitation power supply, the no circulation that carries out working group and wait group when current over-zero switches, and guarantees that main circuit is an inverse parallel structure and by the ac excitation power supply energy reliably working of no circulating current system work;
Also comprise a rotor current detector, will be used for carrying out current closed-loop control,, thereby obtain fabulous dynamic speed adjustment performance with the accurate control of acquisition to electric current by the detected current signal of this detector;
Also comprise a revolution detector, described controller is adjusted the output of described ac excitation power supply according to the detected rotary speed information of this revolution detector, makes controlled rotating speed of motor to expectation rotation speed change (during speed governing) or stablize constant (during the stable speed operation);
The phase detectors that also comprise a rotor induced potential will carry out the computing of transform vector as core parameter by the detected phase signal of this detector; Also comprise a stator side power factor detector, described controller is adjusted the output of described ac excitation power supply according to the detected power factor information of this power factor detector, the stator side power factor that makes controlled motor is expected power factor value (comprising desirable unity power factor even leading power factor) to expecting power factor change (when changing power factor) or stablizing constant (when the expectation power factor is moved) arbitrarily thereby motor stator side power factor can be reached;
Also comprise a control core, this control core can be that basic school extension parallel circuit forms by single-chip microcomputer, dsp chip or other embedded system chips.Described control core is being controlled whole governing system, and the operation of being done comprises access quick resistance starting motor frequently, the rotor induced potential is followed in output with the start-up control ac excitation power supply of motor, excise the quick resistance of frequency after electric motor starting is finished and ac excitation power supply is inserted the rotor loop, the response keyboard is accepted the user and is imported expectation rotating speed and/or expectation power factor, expectation rotating speed according to user's input carries out vector calculus with the expectation power factor, the output of adjusting ac excitation power supply according to the result of vector calculus makes rotating speed of motor reach the expectation rotating speed that the user sets and the power factor that makes motor reaches the desired value that the user sets, operating state to system is carried out fault detect and judgement, according to the Adjustment System work of the fault order of severity or cut-out ac excitation power supply or cut-out motor main power source, fault is got rid of back restarting systems work, display system work state information as required.
7. zero current detection circuit according to claim 6, it is characterized in that, the output of optocoupler connected into special " with " logical construction, circuit itself does not have " vacation has electric current " pulse output, need not any extra current and remove " vacation has electric current " pulse, circuit structure is simple, reliable operation.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200510019539 CN1941609A (en) | 2005-09-30 | 2005-09-30 | High-performance cheap AC speed-adjusting system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200510019539 CN1941609A (en) | 2005-09-30 | 2005-09-30 | High-performance cheap AC speed-adjusting system |
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| CN1941609A true CN1941609A (en) | 2007-04-04 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104959242A (en) * | 2015-06-29 | 2015-10-07 | 宁波榕大环保装备有限公司 | Differential speed change mechanism for centrifugal machine |
| CN106059396A (en) * | 2016-07-04 | 2016-10-26 | 湖北工业大学 | Soft starter of high-voltage motor |
| CN108562414A (en) * | 2017-12-29 | 2018-09-21 | 天津瑞能电气有限公司 | The wind-power tower detection method and device of rotating excitation field are generated based on frequency converter |
| CN109889123A (en) * | 2019-03-12 | 2019-06-14 | 洛阳理工学院 | The control system and control method of wound rotor asynchronous motor power-factor improvement |
| CN110112743A (en) * | 2019-04-04 | 2019-08-09 | 上海电力学院 | A kind of isolated form variable-frequency transformer and its starting control and expansion method |
-
2005
- 2005-09-30 CN CN 200510019539 patent/CN1941609A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104959242A (en) * | 2015-06-29 | 2015-10-07 | 宁波榕大环保装备有限公司 | Differential speed change mechanism for centrifugal machine |
| CN106059396A (en) * | 2016-07-04 | 2016-10-26 | 湖北工业大学 | Soft starter of high-voltage motor |
| CN108562414A (en) * | 2017-12-29 | 2018-09-21 | 天津瑞能电气有限公司 | The wind-power tower detection method and device of rotating excitation field are generated based on frequency converter |
| CN109889123A (en) * | 2019-03-12 | 2019-06-14 | 洛阳理工学院 | The control system and control method of wound rotor asynchronous motor power-factor improvement |
| CN109889123B (en) * | 2019-03-12 | 2024-04-02 | 洛阳理工学院 | Control system and control method for improving power factor of wound-rotor asynchronous motor |
| CN110112743A (en) * | 2019-04-04 | 2019-08-09 | 上海电力学院 | A kind of isolated form variable-frequency transformer and its starting control and expansion method |
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