Summary of the invention
Main purpose of the present invention is to solve the prior art problem that above-mentioned cascade adjustable-speed system exists, adopt current advanced person's power electronic device and digital control technology, design that a kind of Speedless sensor tests the speed, main circuit constitute simple, digitized degree is high, safe and reliable, easy to operate, function admirable, perfect in shape and function, man-machine interface close friend, can realize the middle voltage electromotor slip control digital intelligent governing system of Long-distance Control and management disclosing a kind of Speedless sensor motor slip ratio control figure intelligent speed-regulating method and system.
Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention comprises motor M, soft start RQD equipment, rotor slip control speed governing SKT part, and slip power feedback SGH part and Programmable Logic Controller PLC form.The each several part function is distinct, perfect, and communication-cooperation is whole by the PLC unified management mutually.Wherein, rotor slip control speed governing SKT circuit comprises rotor rectifier ZR, chopper CH, digital signal processor DSP 1, and DSP1 implements Sensorless Speed measurement, control of electromotor velocity outer shroud current inner loop dicyclo and the control of load process outer shroud.The DSP1 hardware circuit adopts current Hall element testing motor rotor electric current I r, the speed that is used for calculating motor start-up course and full-speed operation, detection rotor rectified current Ic is used for the current feedback of electric current loop, adopts voltage Hall element detection dc inversion voltage U c and adds copped wave inductive drop U
L, being used for the actual speed of calculating motor speed regulation process, this speed is used for the speed feedback of motor speed adjusting process, and the DSP1 also value of collection technology amount is used for the technology amount feedback of technology closed loop.Realize revolutional slip control and electromotor velocity adjusting by establishment DSP1 program construction technology ring, speed ring, electric current loop, will exchange slip power simultaneously and be converted to dc electric power, send into capacitor C storage; Slip power feedback SGH circuit comprises inverter INV, filter LCL and digital signal processor DSP 2, and DSP2 detects dc inversion voltage U c, adopts step-down transformer to detect AC supply voltage (e
a, e
b, e
c) be used to calculate electrical source voltage vector E, adopt current Hall element testing inverter INV ac-side current (i
a, i
b, i
c), be used to calculate inverter current vector I, implement the outer voltage current inner loop dicyclo vector-controlled SVPWM of feedback circuit by establishment DSP2 program, send the pulse-width modulation PWM control impuls of inverter INV, the control inverter operation, it is sinusoidal wave making the electric current that injects electrical network, and with the energy feedback grid; According to the requirement of Reactive Power Control, with the permission capacity of inverter AC side power supply, inverter can also inject capacitive reactive power to power supply, improves the entire system power factor.Filter LCL elimination high-frequency harmonic makes the electric current that injects electrical network not have harmonic wave.PLC implements the program control of whole governing system, fault comprehensive and processing, and the assurance system normally moves.
The speed regulating method of Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention, total system is the two-stage management mode.Its controlled step is as follows:
1, after the control power supply send electricity, DSP1 and DSP2 self check and initialization, PLC patrols and examines whole governing system state.Before No. the 1st starting motor, need be on touch-screen input motor parameter and technological requirement parameter.Afterwards, at first differentiate whether have warning relevant with soft starting circuit and fault, if exist, PLC sends the No switching on signal and demonstrates and reports to the police and fault category on touch-screen, if alarm free and fault, PLC sends and allows the motor start-up signal; And then whether differentiation revolutional slip control speed governing SKT part exists warning and fault with slip power feedback SGH part, if exist, PLC sends on touch-screen and forbids speed-regulating signal and demonstrate reporting to the police and fault category, if alarm free and fault are sent the permission speed-regulating signal.When touching information displayed on screen, also inform distant place collective and distributive type control system DCS Central Control Room.
2, on touch-screen or in the distance the DCS Central Control Room is pressed switch knob, and PLC controls motor start-up; DSP1 detects motor operation speed, if system allows into speed governing, then changes the speed governing running over to when electromotor velocity is equal to or greater than setting speed; If system does not allow into speed governing, perhaps on touch-screen, set and directly start to full speed, then when starting to, change full-speed operation near full speed; In the motor start-up process, slip power feedback SGH regulating system is enabled, and the dicyclo vector control system is devoted oneself to work, for feedback energy is got ready.
3, enter speed governing in the start-up course, or when full speed on touch-screen or in the distance the DCS Central Control Room press the speed governing button and enter speed governing, the SKT governing system is enabled immediately, speed electric current dicyclo governing system enters operate as normal, live through after the transient, motor is stabilized in running under the setting speed at last.In the governing system course of work, slip energy is by slip power feedback SGH system feedback grid.If desired, can change technology closed loop (pressure, flow etc.) work over to, satisfy technological requirement automatically by manual change over switch.
4, PLC patrols and examines described motor soft start equipment RQD, revolutional slip control speed governing SKT system and slip power feedback SGH system show data such as motor operating speed, rotor rectified current, rotor commutating voltage, dc inversion voltage, inverter circuit active current, reactive current, active power, reactive power on touch-screen; During if break down, motor is switched to full speed running, and on touch-screen, show fault category and reason by soft start equipment; The maintenance personal uses change over switch that device is transformed into service mode, and motor is thrown off running with device, after maintenance is finished, returns operating condition again, enters speed governing and gets back to the previous status operation; If when occurring reporting to the police,, remind the attendant to do reply and handle in touch-screen on display alarm information.
5, on touch-screen or in the distance the DCS Central Control Room can change setting speed according to technological requirement, perhaps, when technology closed loop (as pressure, flow etc.) is worked, changes the technique initialization value, and motor just turns round under the operating mode of new settings.
If 6 arts demand motor full-speed operations, on touch-screen or in the distance the DCS Central Control Room is pressed changes button at full speed, and motor quickens by predefined acceleration, near at full speed the time, changes full speed operation by PLC control in speed.
7, when needs stop, on touch-screen or in the distance the DCS Central Control Room all can carry out shut-down operation.After the operation, the motor free parking.In the time of need stopping in emergency, on touch-screen or the in the distance DCS Central Control Room operation of all can stopping in emergency.
Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention, described Sensorless Speed is measured WSCS and control of electromotor velocity outer shroud current inner loop dicyclo and the control of load process outer shroud, comprises DSP1 hardware circuit board and current/voltage acquisition system.Wherein, Sensorless Speed is measured WSCS and is united by two kinds of Sensorless Speed method of measurement and use the Sensorless Speed measurement of forming whole system.In the motor start-up process with full speed running during, use the current Hall element to gather motor rotor top-cross stream electric current I r, detect by rotor current slip frequency Sf, calculating motor running speed, this speed are used for speed and show with speed logic and judge; When motor speed adjusting is worked, gather dc inversion voltage U c and add copped wave inductive drop U at each chopping cycle working voltage Hall element
L, calculate speed governing course of work medium velocity value in real time, speed feedback and speed that this value is used for speed ring show.Use the current Hall element to gather current feedback and chopper current demonstration that DC chopped-wave electric current I c is used for electric current loop; The DSP1 hardware circuit is made up of digital signal processor and other integrated circuits, voltage/current translation circuit, software is realized the calculating of electric current and voltage collection value, the motor Sensorless Speed is calculated, control of speed electric current dicyclo and adjusting, control of technology ring and adjusting, output duty cycle control impuls PWM, the control revolutional slip is realized speed regulation.
Described DSP2 implements the outer voltage current inner loop dicyclo vector-controlled SVPWM of feedback circuit, comprises DSP2 hardware circuit board, software program and electric current and voltage acquisition system.Wherein, the DSP2 hardware circuit board is made up of with other integrated circuits, voltage/current translation circuit digital signal processor, A/D, D/A, and DSP2 software is realized the digital vector control of outer voltage current inner loop dicyclo; The electric current and voltage acquisition system comprises uses insulate step-down transformer to gather supply voltage (e
a, e
b, e
c), be used to calculate supply voltage vector E, use the current Hall element to gather inverter INV ac-side current (i
a, i
b, i
c), be used to calculate active inverter current phasor I.In the course of the work, it is constant to keep dc inversion voltage U c by outer voltage, or changes by certain requirement, as when exporting capacitive reactive power, suitably improves the dc inversion magnitude of voltage, adapts to the needs that output voltage raises; In addition, change reactive current and set, as along with rotating speed descends, motor feedback winding or outside present under the prerequisite that transformer secondary coil volume allows, rising reactive current set point can improve the power factor of whole system.Because PWM adopts space vector modulation, feed-in feedback winding or the electric current of presenting transformer outward are sine-wave currents, through not having harmonic wave after the LCL filtering.That is to say that the inverter that the present invention adopts has not only been removed reactive power and harmonic wave that thyristor inverter produces, and, can also carry capacitive reactive power to system, offset the lagging reactive power that the motor stator excitation produces.If the feedback coil volume is enough, perhaps, for the scheme of outer feedback transformer, customer requirements is in speed adjustable range, and power factor is all kept high value and can be realized, this has just overcome the shortcoming of traditional string adjusting system.In service, supply voltage effective value, inverter current effective value, active current component, reactive current component, active power, reactive power all can show by being set in advance on the screen when needed.DSP2 software can also detect dc inversion overvoltage, inverter overcurrent, phase shortage, power down, fault such as overheated, carries out dependent failure and handles.
2407,2812 type products or other companies product of the same type that digital signal processor DSP 1 described in the present invention and DSP2 adopt TI company to produce.DSP1 and DSP2 have by the RS232/RS485 communication interface and intercom mutually or realize the telecommunication administration subprogram with the DCS Central Control Room, also by the communicator program of forming local area network (LAN) by CAN fieldbus and DCS Central Control Room.
Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention when the power supply grid burst has a power failure, has electrical network and cuts the function and the restart facility that has a power failure in short-term soon.Avoid burst to have a power failure in short-term generation has a strong impact on to big system as far as possible.
PLC of the present invention implements program control, fault comprehensive and the processing of whole governing system, it is characterized in that: the application software of PLC is controlled the overall process of whole governing system.Before the motor cycling start, patrol and examine each several part, all just often provide and allow to start and allow into speed-regulating signal; If the part relevant with starting device RQD demonstrates fault or warning message when undesired on screen, and provides the No switching on signal; When if revolutional slip control speed governing SKT and slip power feedback SGH part are undesired, on touch-screen, show fault and warning message and provide and forbid into speed-regulating signal; When local (control cubicle) or distant place DCS provide enabling signal, PLC control soft start equipment RQD actuating motor.According to preestablishing, can arrive or change speed governing work automatically over to during greater than setting speed at electromotor velocity, or raising speed changes full speed operation near full speed the time over to always.In service in system, all can provide the instruction of modulation speed at local (control cubicle) or distant place DCS Central Control Room, PLC command system immediately enters speed governing work, and the motor reduction of speed is stabilized on the setting speed at last and turns round.According to technological requirement, change the setting speed value, also just change the motor operating speed value.If under technology (as pressure, flow) closed loop, work, change technology (pressure, flow) set point at local (control cubicle) or distant place DCS Central Control Room, motorrun state can satisfy technological requirement automatically, turns round under technique initialization.In service in system, if DSP1 and DSP2 detect any fault and warning, all can deliver to PLC immediately, PLC can do to change at full speed to fault message and handle by soft start equipment, and shows fault category; To a display alarm content of reporting to the police, remind the attendant to handle.When the governing system operate as normal, if on-the-spot arts demand changes full-speed operation, all can send at local (control cubicle) or distant place DCS Central Control Room changes instruction at full speed, and PLC is the command system raising speed immediately, changes full-speed operation near at full speed the time at electromotor velocity.Under the various states of motor operation, all can control This vehicle stops frequently at local (control cubicle) or distant place DCS Central Control Room.The hardware of PLC of the present invention is selected the S7-200 of Siemens Company or other company's minicomputers for use.
Speedless sensor motor slip ratio control figure intelligent speed-regulating method and system of the present invention will be brought remarkable economic efficiency and social benefit.Compare with medium voltage frequency converter, governing system price of the present invention has only about half of medium voltage frequency converter on various capacitance grades, and on performance, has the advantage that medium voltage frequency converter has, as start steadily, start to setting speed and just be stabilized in setting speed running, stepless speed regulation, the adjusting speed accuracy height, response is fast, the power factor height, and harmonic wave is little etc., but avoided the medium voltage frequency converter capacity greater than motor capacity, device builtin voltage height, complex circuit, bulky difficulty, control middle voltage electromotor with low-voltage device, control the motor of 100% capacity with the device of (50%~70%) motor rated capacity, main circuit is simple, and device is few, satisfy high-power blower and water pump 50% speed governing requirement equally, more valuable is convenient for maintaining.When device breaks down, can reposefully the motor raising speed be arrived at full speed by soft start equipment, then, be transformed into service mode, device keeps in repair with the motor disengagement fully, finish maintenance after, be transformed into operating condition again, press the speed governing button, turn back to former operating state reposefully.When system of the present invention has a power failure in the power supply network burst, also have electrical network and cut function soon, restore electricity fast.If interruption duration is longer, get back to starting state automatically, enter the work of speed governing state by the soft start raising speed again to setting speed during incoming call.Very little to big systematic influence.Carry out reducing energy consumption with system of the present invention, just be recoverable to installation cost in 1 year.Improvement project can be saved a large amount of electric energy, reduces production costs, and optimizes technical process.
Below in conjunction with accompanying drawing, the inventive method and system are elaborated.
Embodiment
The present invention adopts current advanced person's power electronic device and digital control technology, realizes Speedless sensor motor slip ratio control figure intelligent speed-governing system.With reference to the accompanying drawings 1, M is interior feedback winding asynchronous motor, and its stator winding is by 6 kilovolts or the power supply of 10 kv grids.RQD is motor soft start equipment (frequency sensitive trheostat, a water resistance etc.), motor rotor contactor control circuit and maintenance change over switch etc., and the contactor control circuit is controlled by PLC, and the state of auxiliary contact also feeds back to PLC.Usually, low capacity motor (below 1000 kilowatts) adopts frequency sensitive trheostat to start, and large capacity motor (more than 1000 kilowatts) adopts water resistance to start.Revolutional slip control speed governing SKT circuit comprises motor rotor side diode rectifier ZR, chopper CH and digital signal processor DSP 1, rotor-side electric current I r and chopper input current Ic are by the current Hall element testing, its measured value send DSP1, dc inversion voltage (capacitor C voltage) Uc is detected by the voltage Hall element, and its measured value send DSP1.Slip power feedback SGH circuit includes source inventer INV, and filter LCL and digital signal processor DSP 2, supply voltage send after by the isolating transformer step-down DSP2 to detect, and the inverter ac-side current is by the current Hall element testing, and its measured value send DSP2.
The technology ring that comprises in the system of the present invention, speed ring, electric current loop are as shown in Figure 4.Making up these closed loops, especially how to make up the winding motors electric current loop that contains the chopper link, is controversial for many years.Key problem is how to be familiar with controlled plant.The present invention makes every effort to realize with the simplest suitable method.For this reason, at first illustrate the control principle of winding motors revolutional slip control speed governing SKT, illustrate thus how the technology ring speed ring electric current loop regulating system that the present invention adopts makes up.When illustrating principle, rotor rectification circuit ZR should be considered with chopper circuit CH, as a global analysis.With reference to the accompanying drawings 1, rotor electromotive force is direct voltage Ur after through the diode rectifier bridge rectification.Rotor rectification circuit and general rectifier circuit are distinguished to some extent, and when normal speed governing was worked, rotor electromotive force was:
Er=S×Ur0
In the formula, the S----revolutional slip;
Ur0----motor rotor open circuit voltage;
Both the amplitude of rotor electromotive force and frequency all were the functions of slip frequency, if speed adjustable range 50%~100%, highest frequency also had only for 25 weeks when then speed governing was worked.In the tandem control circuit in the past, owing to there is not chopper circuit, the commutation overlapping phenomenon is more serious in the rectification circuit, after increasing chopper circuit, commutates and overlappingly can ignore (reason sees below); Suppose that again rectifying device is desirable device, ignore tube voltage drop and leakage current, like this, in each chopping cycle, chopper current only flows in the rotor two-phase, with the resistance of rotor circuit and the DC circuit behind the leakage inductance immigration rectification circuit, with the resistance and the inductance merging of chopper circuit, the equivalent resistance after the merging is R, equivalent inductance is L, after handling like this, it is exactly the ideal rectifier voltage of rotor electromotive force that commutated direct current is pressed Ur, and this value is:
Ur=k×S×Ur0,
In the formula, k---rectification coefficient.
Commutating voltage Ur is exactly the chopper input voltage, and rectified current (being the copped wave input current) is Ic, in the rotor rectification circuit, equation is arranged during copped wave pipe (IGBT or IGCT) conducting:
Equation when turn-offing, copped wave pipe (IGBT or IGCT) is arranged:
Adopt the space State Average Model method, press the conducting of copped wave pipe and turn-off shared time scale, obtain the equation in one-period top two equation weightings:
In the motor speed adjusting process, rotation speed change is slower relatively, and therefore, Ur changes slower, can think constant when chopper current is discussed; Uc is a dc inversion voltage, and it is invariable being subjected to the control of slip energy feedback SGH circuit.In equation, independent variable is chopper duty ratio D, and when duty ratio D had an increment, chopper current just produced an increment.According to the increment equation, and omit and can draw chopper current Ic after the increment sign and for the transfer function of input be for output, duty ratio:
Big inertia link in Here it is the electric current loop.As seen this link is linear.Because adopt digital quantity control, the digital sample cycle produces a time lag, this hysteresis is equal to a little inertia link.So the controlled plant of electric current loop is a big inertia link and a little inertia link.Referring to accompanying drawing 4, current regulator ACR should adopt typical pi regulator.The chopper CH duty ratio in the revolutional slip control SKT circuit is directly controlled in adjuster ACR output, the control rotor current, therefore, control electric electromechanics magnetic torque, also promptly control the revolutional slip of rotor, operate at when making the motor rotor stable state under a certain revolutional slip, when rotational speed setup changes, the control rotor slip is quickened to given rotating speed, is stabilized on the setting speed at last.
Now, illustrate the negligible reason of rotor rectification circuit commutation overlap phenomenon with chopper link.When rectified current was big, commutation overlap was serious, and this operating mode motor is that revolutional slip is very little in the high regime running, and slip frequency is very low, and the cycle is very long, and the rotor electromotive force value is also lower, and commutating voltage Ur is also lower.The moment that commutation occurs, there are two kinds of situations, a kind of is when appearing at copped wave pipe (IGBT or IGCT) conducting, the phase current of the new conducting of electromotive force official post after the commutation increases, and former conducting phase current descends, by the time copped wave pipe (IGBT or IGCT) is when turn-offing, two of commutation overlap is in parallel and flows through electric current, rectified current Ic descends fast, and the negligible resistance pressure drop has following formula:
Because this moment, commutating voltage Ur is lower, and dc inversion voltage U c higher (800~1000 volts), very big (if equivalent inductance 1 milihenry of electric current fall off rate, speed is every millisecond 800~1000 peace) because there is electrical potential difference in the two-phase of commutation, former conducting descends faster mutually.If load is not heavy, may just be through with by a chopping cycle commutation overlap.If load is heavier, two chopping cycles finish.Another kind of situation, commutation appears at copped wave pipe (IGBT or IGCT) off state constantly, the chopper current fall off rate is big, because inductor rotor voltage is for negative, make the phase of commutation can not conducting, during copped wave pipe (IGBT or IGCT) conducting by the time, overlapping biphase current increases simultaneously, and later situation is with aforementioned situation.In a word, commutation overlap only takies 1~2 cycle, promptly 0.5~1 millisecond.If revolutional slip S=0.1,5 hertz of rotor frequencies, 200 milliseconds of cycles.As seen, the commutation overlap influence is very little, can ignore.
The equation of motion of motor transmission agent is:
In the formula: J---the moment of inertia (kg.m of unit
2);
P
n---the number of pole-pairs of motor;
T
L---the load resistive torque;
T
e---the electric electromechanics magnetic torque;
ω---motor angle speed.
As seen, the speed ring controlled plant is an integral element.Current closed-loop is a little inertia link in speed ring.With reference to the accompanying drawings 4, speed regulator ASR can adopt typical pi regulator.Parameter configuration is adjusted by third-order system.For blower fan and water pump load, do not allow motor speed to change fast, in the velocity setting passage, reference integrator GJ is set, the step specified rate is converted into slope rising signals slowly.Rise or fall time can be set between 30~100 seconds.
Revolutional slip control SKT governing system can under speed electric current dicyclo, work (manual mode).Speed setting value can manually provide on touch-screen (this locality), and also the DCS Central Control Room manually provides in the distance, by this control/far control change over switch conversion (seeing accompanying drawing 4).By manual change over switch, can realize manually and the conversion mutually of automated manner ground.When automatic working method, local (on the touch-screen) or distant place DCS set the technology controlling and process value, as pressure, and flow etc., detect corresponding technology actual value in the technical process as value of feedback, process modulator AGR has two kinds of forms among the present invention: conventional PID adjuster and Fuzzy Controller.The controlled plant more complicated of technology ring usually is accompanied by big inertia, the long-time hysteresis, and controlled plant is difficult to describe with mathematical equation.On-the-spot process condition varies, and the user can select according to field conditions.
Sensorless Speed is measured WSCS and is united by two kinds of Sensorless Speed method of measurement and use the Sensorless Speed measurement of forming whole system in the Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention.In the motor start-up process with full speed running during, use the current Hall element to gather motor rotor top-cross stream electric current I r, detect by zero crossing, be converted to the square wave of positive and negative each half cycle, give dsp chip, use capturing function detection rotor electric current slip frequency Sf, calculating motor running speed, this speed are used for speed and show and the speed logic judgement; When motor speed adjusting was worked, the working voltage Hall element was gathered dc inversion voltage U c and is added copped wave inductive drop U
L, calculate speed governing course of work medium velocity value in real time, speed feedback and speed that this value is used for speed ring show.
The present invention realizes testing the speed in the speed regulation process according to the chopper working mechanism.In the voltage equation of rectification circuit and chopper circuit, the ratio that resistance drop accounts for is very little, can the negligible resistance pressure drop, with circuit after the immigration rectification of the merging of the two-phase leakage inductance in working rotor circuit back, equivalent electric circuit when ignoring the rectifying tube pressure drop simultaneously and obtaining copped wave pipe (IGBT or IGCT) conducting and turn-off, see accompanying drawing 3a), 3b).Among the figure:
The rectified value of Ur---rotor electromotive force when testing the speed calculating, can be thought definite value;
L
1---rotor circuit two-phase leakage inductance sum;
L
2---add the copped wave inductance.
When the conducting of copped wave pipe (IGBT or IGCT), have equation to be:
If add inductive drop during the conducting of copped wave pipe
Then
When the copped wave pipe turn-offs (IGBT or IGCT), equation is:
If the copped wave pipe adds inductive drop when turn-offing
Then have:
Connection is separated following formula, obtains:
In the formula, C---constant.Copped wave inductive drop when detecting the conducting of copped wave pipe and turn-offing in one-period just can calculate revolutional slip S.Can obtain motor speed n by revolutional slip S.This calculating will be carried out in the cycle interruption program.
With reference to the accompanying drawings 5, illustrate the slip power feedback SGH electric current and voltage dicyclo vector control regulating system that comprises in the digital intelligent governing system of the present invention.Power supply among the figure is meant feedback winding power supply for interior feed motivation; For common winding motors, be meant outer feedback transformer secondary winding power supply.Main circuit as shown in Figure 1, inverter is the three-phase bridge circuit that IGBT (or IGCT) forms, three-phase bridge exchanges between inlet wire and the power supply, the LCL filter is installed, the high-frequency harmonic component that contains in the elimination three-phase bridge inverter ac output voltage.The control of inverter is by the dicyclo vector control and the adjusting that encircle in the DSP2 realization inverter voltage outer shroud inverter current.As everyone knows, the dicyclo vector control must be carried out in the rotating coordinate system plane with the supply frequency rotation.Of ac in rest frame must be converted to rotating coordinate system (d, q) DC quantity in through transform vector.DC quantity is regulated through the electric current and voltage dicyclo, and Shu Chu DC quantity also must turn back in the rest frame afterwards, produces the PWM control impuls of inverter bridge.
Rotating coordinate system (d, q) in the plane, the voltage equation of inverter bridge main circuit is (establish inverter current direction for just):
U
d=E
d+(LS+R)I
d-ωLI
q,
U
q=E
q+(LS+R)I
q+ωLI
d,
In the formula: U
d, U
q---the d axle and the q shaft voltage component of three-phase bridge output voltage;
E
d, E
q---the d axle and the q axle electromotive force component of electrical source voltage;
I
d, I
q---the d axle and the q shaft current component of inverter current.
According to the plant equation formula, construct the regulating system of outer voltage current inner loop.Supply voltage is the (e in the three phase static coordinate system after the isolating transformer step-down
a, e
b, e
c) give the A/D input on the DSP2 circuit board, carry out 3/2 conversion again after being converted to digital quantity, produce the potential vector relevant parameter (e in the α β two-phase rest frame
α, e
β, amplitude E and phase angle theta).Simultaneously, also can be according to phase voltage e
aZero passage detection and phase-locked processing make the phase angle theta value more accurate.Then, again with the e in the two-phase rest frame
α, e
βComponent is rotated conversion, obtains with the e in the coordinate system of supply frequency rotation
d, e
qComponent.The three-phase bridge inverter output current (i in the three phase static coordinate system
a, i
c), with the A/D input of giving after the collection of electric current Hall element on the DSP2 circuit board, be converted to digital quantity after, obtain B phase current i again
b, with i
a, i
b, i
cCarry out 3/2 conversion, obtain the i in the two-phase rest frame
α, i
βComponent is rotated conversion again, obtains the i in the supply frequency rotating coordinate system
d, i
qComponent.Dc inversion voltage U c itself is exactly a DC quantity, gives the A/D on the DSP2 circuit board input after being detected by the voltage Hall element, is converted to digital quantity, forms the Voltage Feedback amount.The voltage given value requires decision according to interior feed motivation feedback winding voltage value (for common winding motors, according to outer feedback transformer secondary winding voltage value) with reactive power compensation.Voltage regulator output is active current i
dGiven, the given i of reactive current
qTwo kinds of given ways are arranged: fixed form and calculating given way.The fixed form set-point can be set on the DSP2 man-machine interface by the user of service, but the compensation rate of reactive current must be presented in motor in the permission range of capacity of winding rated current (for common motor, presenting transformer secondary winding rated current outward).Account form is calculated by the DSP2 program and is realized, establishing feedback winding rated current is i
f, the reactive power compensation electric current that then can provide is
This mode can be used the capacity of feedback winding to greatest extent.Active current adjuster and reactive current adjuster are realized the adjusting of active current and reactive current.Active current i
dProduct and reactive current i with ω L
qDeliver to output of reactive current adjuster and the output of active current adjuster respectively with the product of ω L, synthetic with it, be for realizing the decoupling zero between active current and the reactive current.Active current adjuster output with the decoupling zero component synthetic after again with d axle electromotive force component e
dSynthetic, form the control component of voltage Vd on the d axle; Reactive current adjuster output with the decoupling zero component synthetic after again with q axle electromotive force component e
qSynthetic, form the control component of voltage Vq on the q axle.Control component Vd in the rotating coordinate system, Vq also must turn back to two-phase rest frame (counter-rotating conversion) again, and conversion goes out the control component V of two-phase rest frame
α, V
βAccording to control component V
α, V
β, produce the control pwm pulse of six IGBT of inverter bridge (or IGCT).
Speedless sensor motor slip ratio control figure intelligent speed-governing system of the present invention, have electrical network and cut the function and the restart facility that has a power failure in short-term soon, the method that realizes is: when DSP2 detects electrical network and loses suddenly, block each device in the inverter bridge immediately, stop the inverter current circulation, simultaneously, block boost chopper, whole governing system is in blocked styate, waits for incoming call.At this moment electric power system is implemented the upper end high-voltage switch gear and is switched fast, and switching is finished, and restores electricity again, and DSP2 detects electrical network electricity, recovery system immediately, because interruption duration is very short, electromotor velocity lands seldom, the very fast quiet rum that enters again of system.If interruption duration is long, electromotor velocity descends more, might drop to lowest speed following (beyond the speed adjustable range), for preventing this situation, governing system changes starting state automatically over to, behind the incoming call, by the soft start raising speed, change the speed governing running during to setting speed automatically over to.Reduced the influence that burst has a power failure and brings like this, to greatest extent.
Feedback winding asynchronous motor and the common winding asynchronous motor of middle pressure in pressing during the present invention is applicable to.
Embodiment 1:
With reference to the accompanying drawings 1, the concrete application example of feedback winding asynchronous motor in the present invention is used for.M is interior feedback winding asynchronous motor among the figure, by the power supply of 6 kilovolts or 10 kv grids, the rotor winding is connected to soft start equipment RQD to stator winding by high-tension switch cabinet, and motor capacity is below 1000KW, the frequency sensitive trheostats that adopt start more, and large capacity motor adopts water resistance to start.Motor start-up is controlled by PLC, during as if soft starting circuit part fault-free and warning, provides the permission enabling signal on touch-screen, if fault and warning are arranged, provides the No switching on signal; If revolutional slip control speed governing SKT part and slip power feedback SGH part fault-free and warning provide on touch-screen and allow into speed-regulating signal,, provide and forbid into speed-regulating signal if fault and warning are arranged; Starting has dual mode to select: directly advance speed governing and directly advance at full speed.If do not allow into speed governing, even select directly to advance speed governing, PLC also can guarantee directly to advance at full speed.When starting with full speed running, the electromotor velocity measurement is to calculate according to the frequency measurement of rotor current.For this reason, adopt the current Hall element to gather rotor current Ir, DSP1 detects according to zero crossing, calculates slip frequency and speed, and calculated value is used for the speed differentiation and shows.When speed governing operation, rotor rectifier bridge ZR connects through A.C. contactor and rotor winding, rotor rectifier bridge ZR and boost chopper CH constitute revolutional slip control speed governing SKT main circuit, and digital signal processor DSP 1 constitutes revolutional slip control and regulating circuit with voltage and current detection circuit.Detect chopper current Ic with the electric current Hall element, send DSP1 to be used for the current feedback of chopper current ring; Detect dc inversion condenser voltage Uc and add copped wave inductive drop U when interrupting with the interruption of cycle rate counter underflow with voltage Hall element cycle rate counter overflow in each chopping cycle
L, the instantaneous velocity of calculating motor is used for the speed feedback of speed closed loop; DSP1 is by software building chopper current ring, and speed ring and technology ring are implemented adjustment process.Be adjusted to example with speed electric current dicyclo, the process of once regulating is described.Suppose that motor turns round under a certain stable state, increment if velocity setting rises, because electromotor velocity does not also change, at the speed regulator input, just there is a velocity error, produce the given increment of chopper current in speed regulator output, motor current does not also increase, just there is a current error in the current regulator input, and current regulator produces a chopper duty ratio increment immediately, and this incremental contribution is in rectification copped wave main circuit, order about electric current of chopper and produce an increment, therefore rotor torque produces an increment, and this torque increment has destroyed original torque balance state, and motor begins raising speed, when electromotor velocity is raised near given speed, velocity error goes to zero, and current error also goes to zero, and motor is steady running under new set-point just.Vice versa.In the speed governing operation, the rotor slip power sends in streams to a place in the dc inversion capacitor by chopper and is converted to electric energy, by the slip power feedback circuit electric energy in the capacitor is delivered to electrical network again.The slip power feedback circuit is by inverter INV, filter LCL, and digital signal processor DSP 2 is formed with the electric current and voltage Acquisition Circuit.Inverter INV is connected into three phase bridge circuit by six IGBT (or IGCT); Filter LCL is connected into T shape filter circuit by filter inductance and electric capacity; Motor feedback winding voltage is passed through step-down transformer T1 with secondary voltage e
a, e
b, e
cDeliver to DSP2, calculate electrical source voltage vector E for DSP2; Detect feedback winding phase current i with the electric current Hall element
a, i
cDeliver to DSP2, calculate source current vector I for DSP2; Detect dc inversion voltage U c with the voltage Hall element, for the Voltage Feedback value of DSP2 calculating voltage ring; DSP2 software building outer voltage, the dicyclo regulating system of ring in the active current reactive current, adjuster output obtains voltage in the two-phase rest frame through inverse transformation, generate software by PWM again, produce the grid pulse of six IGBT (or IGCT) pipe, the control three phase bridge circuit is sent active power back to the feedback winding; Simultaneously,, increase reactive power and set (in feedback coil volume allowed band), improve the overall power factor of electric motor system along with rotating speed descends.
In all processes of system works, PLC is constantly detecting the state of starting device, DSP1, DSP2 always, and the control system each several part is program run in accordance with regulations.And constantly detect the warning and the fault of each several part, and in case break down, in time the motor in the speed governing running is changeed at full speed by starting device, on man-machine interface, demonstrate fault category simultaneously; If occur reporting to the police, only on man-machine interface, demonstrate the warning classification, and notice DCS Central Control Room, remind the maintenance personal to take corresponding measure.
Embodiment 2:
With reference to the accompanying drawings 2, the present invention is used for the concrete application example of common winding asynchronous motor.M is common winding asynchronous motor among the figure, does not feed back winding.The rotor slip power will feed back to electrical network with slip power by outer feedback transformer WT, so, the former limit winding of outer feedback transformer is received the lower end of the high-tension switch cabinet that the motor stator winding connect, and presents the filter LCL leading-out terminal that transformer secondary winding is received slip power feedback circuit SGH outward.Other are identical with embodiment 1.