CN1253999C - No-harmonic wave pollution high voltage large power frequency converter - Google Patents
No-harmonic wave pollution high voltage large power frequency converter Download PDFInfo
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- CN1253999C CN1253999C CN 02104140 CN02104140A CN1253999C CN 1253999 C CN1253999 C CN 1253999C CN 02104140 CN02104140 CN 02104140 CN 02104140 A CN02104140 A CN 02104140A CN 1253999 C CN1253999 C CN 1253999C
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Abstract
The present invention relates to a frequency converter with no harmonic wave pollution, high voltage and large power, which solves the problems of energy feedback device lack, unreliable bypass circuit and difficult air strainer maintenance when the existing power module unit is connected with a frequency converter with high voltage and large power in series. An energy feedback device, a precharge circuit of a bypass circuit and an air strainer which is easy to change are additionally arranged in the existing power module unit connected with the frequency converter with high voltage and large power in series. The energy feedback device is mainly composed of a feedback bridge which is inversely connected to a rectification bridge of each power module unit in parallel and a controlling circuit of the feedback bridge. The bypass circuit comprises a diode rectification bridge connected to each power module unit in parallel, a thyristor and the precharge circuit. The air strainer is mainly composed of a front panel and a strainer supporting mechanism, wherein ventilation holes, a first fixing device for fixing the front panel on the frequency converter and a second fixing device for fixing a strainer supporting mechanism are arranged on the front panel; a strainer is fixed on the strainer supporting mechanism.
Description
Technical field
The present invention relates to a kind of high-voltage high-power frequency transformator, refer to high-voltage high-power frequency transformator a kind of no-harmonic wave pollution, that have energy back feed device, bypass circuit and air filtration net arrangement especially.
Background technology
Development along with power electronic technology, frequency converter is as the product of Development of Power Electronic Technology, every field in national economy is widely used as industries such as metallurgy, petrochemical industry, running water, electric power, and bringing into play more and more important effect, particularly, the application of high-voltage high-power frequency transformator is day by day extensive.And by the suitable China's actual conditions of high-voltage high-power frequency transformator (as shown in Figure 2) conduct of power model unit (as shown in Figure 1) series connection formation, the frequency converter of excellent performance, be subjected to numerous frequency converter production firm, scientific research institutions, engineers and technicians, user's favor, shown the prospect that it is in the ascendant.
But in use there is following shortcoming in this high-voltage high-power frequency transformator that is made of the power model units in series:
1, lacks energy back feed device
The power of high-voltage high-power frequency transformator is generally all more than 300KW.Its advantage is an obvious energy conservation, and it is obvious to improve working characteristics, still, when load is braked, can produce very big energy.This part braking energy can not lean on the method for simple resistance, capacitances in series to dissipate, and generally is that it is fed back to electrical network, and braking energy is utilized again, but, how to realize the feedback of this energy, and, never solved well at present the AC network no-harmonic wave pollution.
2, lack reliable operation, bypass circuit low in energy consumption
The high-voltage high-power frequency transformator that is made of the power model units in series in use the situation that certain or certain several power models break down can occur once in a while, at this moment just needs a bypass circuit urgently.When one or several power model breaks down, can its bypass be gone out system by bypass circuit, and continue to power, thereby not influence the operation of system to motor by remaining power model.
At present, the bypass circuit that uses in the domestic high-voltage high-power frequency transformator mainly contains two kinds.A kind of is the bypass circuit that is made of relay, and its shortcoming is: because the mechanical contact loose contact sometimes of relay or can not precision maneuver has influenced the reliability of system.
Now the bypass circuit of the another kind of form that generally adopts as shown in Figure 3, it is by the single-phase diode rectifier bridge 4 that is arranged on inverter bridge 23 ' next door ' and controllable silicon 5 ' constitute.When certain power model breaks down, system turn-off inverter bridge 23 ', trigger controllable silicon 5 ', make electric current by diode rectifier bridge 4 ' and the path of controllable silicon 5 ' formation flow through.But there is certain problem in actual applications in this bypass circuit, and promptly bypass circuit can not really play the effect of bypass fault power module.Because it has proposed higher requirement to diode in the bypass circuit and controllable silicon, as everyone knows, the switching time of IGBT is very short, generally about 300 nanoseconds, use the IGBT of 1700V now, DC bus-bar voltage can reach about 1000V, so the dv/dt that produces during the IGBT switch will be in the magnitude of 3000V/us, and the dv/dt that controllable silicon can bear is generally below 1000V/us.So, circuit shown in Figure 3, when just powering on, the voltage at controllable silicon two ends is zero, when the moment of power model (as IGBT) beginning normally, controllable silicon will tolerate the dv/dt above its tolerance.When silicon controlled junction capacitance, circuit physical impedance and stray reactance hour, will cause that silicon controlled misleads, thereby cause the inverter bridge output short-circuit, cause the power model fault.
Can increase the measure of restriction dv/dt at the U of Fig. 3, V place, such as powering up sensor, resistance etc., still, when the power model bypass moved, they will flow through big electric current, made like this that its power consumption is big, volume is big, cost is high.
3, lack air filtration net arrangement safe, simple, convenient, that be easy to change
In the frequency converter mainly by some power components as: power semiconductor, transformer, reactor, resistance etc. are formed, these power components will consume certain energy in the course of the work, these energy all dissipate with the form of heat, therefore, the heat that these power components must be sent looses as early as possible and discharges.
At present, it is the air cooling mode of forcing that frequency converter uses maximum radiating modes, promptly utilizes the fluxion strap of air to walk heat.But, because air pollution, there are many dusts in the air, especially in the bigger environment of northern dust, if too much dust enters into frequency converter, will bring great threat to safe, the stable operation of frequency converter, so when forcing air cooling, in order to prevent of the influence of airborne dust, generally need install air strainer additional at the air inlet place to system.
Air strainer needs often to clean, and influences intake to prevent blocked.Usually, this air strainer is in frequency converter inside by screw.In order to clean or change filter screen, generally all need to shut down, cut off the power supply and carry out again.Because; forceful electric power voltage is generally arranged in the frequency converter; with homemade frequency converter is example, and general low voltage frequency converter is 380 volts, and high voltage converter is several kilovolts; safety for operating personnel; the necessary ground connection of frequency converter cabinet shell is in operation and forbids opening the cabinet door, and; when replacing, cleaning and filtering net, generally all need to shut down, cut off the power supply and carry out again, prevent equipment and personnel's accident.Produce the loss that causes to a certain degree to the user like this, inevitably.
Summary of the invention
In order to solve the high-voltage high-power frequency transformator energy feedback problem that constitutes by the power model units in series, the purpose of this invention is to provide a kind of simple in structure, loss is little, cost is low, power factor is high, to the high-voltage high-power frequency transformator energy back feed device of electrical network no-harmonic wave pollution.
Another object of the present invention provides a kind of reliable operation, low in energy consumption, high voltage converter bypass circuit that cost is little.
Change frequency converter screen pack difficulty, unsafe problem in order to solve, the purpose of this invention is to provide a kind of can be under non-stop-machine situation, safety, change the frequency converter air filtration net arrangement of screen pack simply, easily.
For achieving the above object, the present invention by the following technical solutions: a kind of no-harmonic wave pollution high voltage large power frequency converter, it comprises many secondary winding phase shifting transformer, a plurality of power models unit and control system; Described power model unit is made of diode rectifier bridge, the big electric capacity that is connected in parallel on the dc bus side, big resistance and inverter bridge; It is characterized in that: it also comprises an energy back feed device; Described energy back feed device mainly is made of a plurality of feed back bridgings and feed back bridging control circuit; The quantity of described feed back bridging is consistent with the quantity of the power model unit that constitutes frequency converter, promptly at other inverse parallel one feed back bridging of the rectifier bridge of each power model unit; Described feed back bridging control circuit comprises the energy feedback operating mode decision circuitry that is used for conducting of Control and Feedback bridge and shutoff and is used to trigger the feed back bridging circuits for triggering of feed back bridging break-over of device.
Described energy feedback operating mode decision circuitry is made of power cell rectifier bridge commutating voltage peak detection circuit, power cell DC bus-bar voltage testing circuit and comparison/decision circuitry; Rectifier bridge commutating voltage peak detection circuit is used to detect the peak value of voltage after the rectifier bridge rectification, and as a comparison/and an input of decision circuitry; The DC bus-bar voltage testing circuit is used for the voltage between detection power unit dc bus P, the N, and as a comparison/and another input of decision circuitry; Comparison/decision circuitry detects voltage to these two and compares, judges, and the output control signal, the conducting of Control and Feedback bridge or shutoff.
Described feed back bridging circuits for triggering adopt 6 pulse control modes; It is made up of voltage detecting circuit and anti-jamming circuit; This voltage detecting circuit adopts comparator and selector, and for three devices of brachium pontis on the feed back bridging, one that selection voltage is the highest provides triggering signal; For three devices of brachium pontis under the feed back bridging, one that selection voltage is minimum provides triggering signal.
Described feed back bridging circuits for triggering also can adopt the method for phase discriminator, adopt zero cross detection circuit and phase-locked loop circuit, follow the tracks of the phase place of input voltage, any moment only provides the conducting control signal of two feed back bridging devices, for three devices of last brachium pontis, select the highest one of instantaneous voltage in the three-phase alternating-current supply of input to provide Continuity signal; For following three devices of brachium pontis, select minimum one of instantaneous voltage in the three-phase alternating-current supply of input to provide Continuity signal.
No-harmonic wave pollution high voltage large power frequency converter of the present invention also comprises a bypass circuit; Described bypass circuit comprises another diode rectifier bridge, controllable silicon and the pre-charge circuit that is connected in parallel on each inverter bridge side, power model unit of high voltage converter; Described pre-charge circuit is formed by being connected on first precharge section between frequency changer direct current bus and the controllable silicon and second precharge section in parallel with controllable silicon.
No-harmonic wave pollution high voltage large power frequency converter of the present invention also comprises an air filtration net arrangement that is easy to change, and this air filtration net arrangement mainly is made of front panel and screen pack supporting mechanism; Described front panel is provided with ventilation hole, be used for that front panel is fixed on first fixture on the frequency converter and be used for fixing second fixture of screen pack supporting mechanism; Described screen pack supporting mechanism is a framework, is fixed with screen pack on framework.
Described first fixture comprises a door lock and an inserted sheet; Described door lock is installed in the top of front panel, and described inserted sheet is positioned at the bottom of front panel; Described second fixture is installed in the back side of front panel, and it comprises slide rail and glidepath; Described screen pack supporting mechanism is a framework, and the top and the bottom of framework are provided with groove.
Because the present invention adopts above design, so have the following advantages:
1, owing to rectifier bridge side inverse parallel one feed back bridging and the control circuit of the present invention at each power cell, so, when high voltage converter is braked, can give AC network, utilize again by the braking energy feedback that feed back bridging produces load.Because feed back bridging of the present invention is made of the low-voltage device that satisfies power cell builtin voltage standard, so cost is low; In addition, the realization of control section is also very convenient, only needs additional correspondent voltage detection link and voltage comparator to get final product, and technical feasibility is good; In control, saved complicated PWM calculating etc., reduced the burden of control circuit, simultaneously, because on-off mode is six pulses, it is minimum that switching loss is dropped to.The more important thing is, though contain a large amount of harmonic componentss in the current waveform of general-purpose diode rectifier bridge in the power cell of the present invention, and a large amount of harmonic componentss that also have in the feed back bridging, phase shifting transformer can be passed through, harmonic components is cancelled each other, thereby reduce harmonic pollution electrical network.
2, owing to the present invention's bypass circuit in parallel by each power cell, before the work of high voltage frequency converter power modular unit, at first the voltage with controllable silicon two ends in the bypass circuit is pre-charged to d-c bus voltage value.Like this, when beginning to move, diode in the bypass circuit and controllable silicon will no longer bear the dv/dt value above its tolerance at power model unit (as IGBT), thereby guarantee the security reliability of system.
3, the air filtration net arrangement is fixed on the frequency converter by door lock and inserted sheet owing to the present invention, so, clean, when changing screen pack, only need rotate door lock and can easily filter screen device be unloaded.Operation is very simple, convenient, safety, and can operate under non-stop-machine situation.In addition, the present invention does not use a screw when mounted, so install, dismantle without any need for instrument, has improved efficient greatly; And prevented from troubling to take place because of the screw accident that causes that drops.
Description of drawings
The invention will be further described below in conjunction with accompanying drawing.
Fig. 1 is existing many level of power unit cascade formula high voltage converter structural representation
Fig. 2 is existing power cell circuit diagram
Fig. 3 is a bypass circuit circuit diagram in the prior art
Fig. 4 is feed back bridging partial circuit figure in the energy back feed device of the present invention
Fig. 5 is energy feedback operating mode judging circuit theory diagram in the energy back feed device of the present invention
Fig. 6 is feed back bridging circuits for triggering theory diagram in the energy back feed device of the present invention
Fig. 7 is feed back bridging part physical circuit figure in the embodiment of the invention
Fig. 8 is energy feedback operating mode judging circuit physical circuit figure in the embodiment of the invention
Fig. 9 is feed back bridging circuits for triggering physical circuit figure in the embodiment of the invention
Figure 10 is a bypass circuit circuit diagram of the present invention
Figure 11 is the bypass circuit circuit diagram of the another kind of form of the present invention
Figure 12 is the bypass circuit circuit diagram of another form of the present invention
Figure 13 is the bypass circuit circuit diagram of another form of the present invention
Figure 14 is the front view of air filtration net arrangement of the present invention
Figure 15 is the end view of air filtration net arrangement of the present invention
Figure 16 is the I part partial enlarged drawing of Figure 15
Embodiment
As shown in Figure 1 and Figure 2, at present, generally the power unit cascade high voltage converter of Shi Yonging mainly by many secondary winding phase shifting transformer 1 ', a plurality of power models unit 2 ' and control system 3 ' constitute; Wherein, a plurality of power cells 2 ' being one another in series forms high-voltage ac power U, V, the W of frequency adjustable.Constitute the main components and parts power model unit 2 of this high voltage converter ' mainly by diode rectifier bridge 21 ', be connected in parallel on the big electric capacity, grading resistor 22 of dc bus side ' and inverter bridge 23 ' constitute.
In the use of power unit cascade high voltage converter, when load is braked, can produce very big energy.For this part energy is fed back to electrical network, utilize again, the present invention in the other inverse parallel of power cell rectifier bridge one feed back bridging, by the conducting and the shutoff of control circuit Control and Feedback bridge, thereby make braking energy feed back to electrical network.
As Fig. 4, Fig. 5, shown in Figure 6, energy back feed device of the present invention mainly is made of a plurality of feed back bridgings 1 and control circuit; Control circuit is again to be made of energy feedback operating mode decision circuitry 21 and feed back bridging circuits for triggering 22.The quantity of feed back bridging 1 is consistent with the quantity of the power cell that constitutes frequency converter, promptly at each power cell 3 rectifier bridges 31 other inverse parallel one feed back bridging 1 (as shown in Figure 4).When frequency converter normally moved, feed back bridging 1 turn-offed, and the work of circuit other parts is the same when not having this feed back bridging.When motor braking moves, energy feeds back in the dc-link capacitance 32 by power cell inverter bridge 33, cause capacitance voltage to raise, when capacitance voltage is higher than the commutating voltage peak value of diode rectifier bridge 31, diode rectifier bridge turn-offs, can selectively make the break-over of device of feed back bridging 1 this moment, and the energy in the capacitor is fed back to electrical network by feed back bridging, phase-shifting rectifier transformer.
For the conducting and the shutoff of Control and Feedback bridge 1, energy back feed device design of the present invention has 21 (as shown in Figure 5) of energy feedback operating mode decision circuitry and feed back bridging circuits for triggering 22 (as shown in Figure 6).
As shown in Figure 5, energy feedback operating mode decision circuitry 21 mainly is made of power cell rectifier bridge commutating voltage peak detection circuit 211, power cell DC bus-bar voltage testing circuit 212 and comparison/decision circuitry 213.Rectifier bridge commutating voltage peak detection circuit 211 is used to detect the peak value V1 of voltage after the rectifier bridge rectification, and as a comparison/and an input of decision circuitry 213; DC bus-bar voltage testing circuit 212 is used for the voltage V2 between detection power unit dc bus P, the N, and as a comparison/and another input of decision circuitry 213; Comparison/decision circuitry 213 detects voltage to these two and compares, judges.After DC bus-bar voltage V2 is greater than the rectifier bridge rectification during peak value V1 of voltage, comparison/decision circuitry output control signal, the conducting of beginning Control and Feedback bridge; Otherwise, turn-off feed back bridging.
In order to make feed back bridging 1 conducting, the present invention has designed feed back bridging circuits for triggering 22, and these circuits for triggering adopt 6 pulse control modes, as shown in Figure 6.Any moment only provides the conducting control signal of two feed back bridging devices, and for three devices of last brachium pontis, one that selects (being among R, S, the T) in the three-phase alternating-current supply of input instantaneous voltage is the highest provides Continuity signal; For following three devices of brachium pontis, one that selects (being among R, S, the T) in the three-phase alternating-current supply of input instantaneous voltage is minimum provides Continuity signal.Feed back bridging is operated under the state identical with diode bridge, and just the direction of electric current and energy Flow is opposite.As shown in Figure 6, Fig. 6 (a) adopts the direct voltage detection method, and for three devices of last brachium pontis, one that selection voltage is the highest provides triggering signal; For three devices of following brachium pontis, one that selection voltage is minimum provides triggering signal; Voltage detecting can adopt comparator and selector, simultaneously jamproof filtering measures must be arranged.Another method is the method for the employing phase discriminator shown in Fig. 6 (b), as everyone knows, per 120 degree of three-phase ac power supply just have one in the phase places, and to be in voltage mutually the highest, per 120 degree have one in the phase places, and to be in voltage mutually minimum, therefore very fixing of this relation, can adopt common methods such as zero passage detection and phase-locked loop, the phase place of following the tracks of input voltage provides control impuls, and the effect that two kinds of methods reach is consistent.
Fig. 7, Fig. 8, Fig. 9 are specific embodiment of the invention figure.As shown in Figure 7, feed back bridging 1 of the present invention is made up of 6 IGBT high power transistor G1～G6, and inverse parallel is other at power cell rectifier bridge 31.The present invention adopts IGBT to constitute feed back bridging, also can adopt other switch element such as GTO, controllable silicon etc. to constitute feed back bridging.
Fig. 8 is energy feedback operating mode decision circuitry physical circuit figure of the present invention.As shown in the figure, the present invention earlier is converted into control circuit acceptable voltage R1, S1, T1 by voltage transformer 4 with the voltage at power cell R, S, T place; Then, through rectifier bridge 5 rectifications; Get its voltage as the rectifier bridge rectification after the peak value V1 of voltage.V2 is the voltage between process dc bus P, the N of electrical isolation 6.Through comparison/judgements of comparator U7, gate U8, when V2＞V1, output control signal EN2 allows the feed back bridging circuits for triggering to work.Among the figure, EN1 is the instruction that system allows energy back feed device work, because in some cases, can not allow the system feedback circuit working by artificial setting, EN2 is that FEEDBACK CONTROL allows logic, feed back bridging circuits for triggering start working (referring to Fig. 9) when EN2 is effective.
Fig. 9 is feed back bridging circuits for triggering physical circuit figure of the present invention.As shown in the figure, it is made of comparator U9～U11, decoder U12 and gate U13～U18.Comparator U9～U11 at first compares three-phase voltage, obtain three comparison signal COMP1～COMP3, if FEEDBACK CONTROL conditions being possessed (EN2=1), then can be with 6 kinds of possibilities of comparable situation, translate (one has 8 kinds of states, and wherein two states is physically impossible) by decoder U12 (74138), then according to these states, by simple logical circuit U13～U18, can obtain the triggering signal of feed back bridging device G1～G6.
The present invention is for fear of the moment at power model (as IGBT, GTR etc.) beginning normally, controllable silicon surpasses the dv/dt of its tolerance because of tolerance, cause that silicon controlled misleads, cause the inverter bridge output short-circuit, cause the power model fault, at the other bypass circuit in parallel of each power model inverter bridge of high voltage converter.
As shown in figure 10, described bypass circuit is made of diode rectifier bridge 7, controllable silicon 8 and pre-charge circuit 9.Dc bus, each power model bypass are crossed pre-charge circuit 9 parallel diode rectifier bridges 7 and controllable silicon 8 in frequency converter.Pre-charge circuit 10 is made of charging resistor R1, R2, R3 and charging capacitor C1; Resistance R 1, R2 are serially connected in the frequency converter between the positive and negative bus of direct current and controllable silicon 8, resistance R 3 be connected in parallel on controllable silicon 8 after capacitor C 1 is connected by.By pre-charge circuit 9, be resistance R 1, R2, R3, C1, when system has just been powered on, the voltage at controllable silicon two ends is precharged to d-c bus voltage value immediately, like this, when power model (as IGBT) switch, they will no longer bear the dv/dt value above its tolerance, and system reliability strengthens greatly.When power model breaks down, can be bypassed by bypass circuit veritably, and continue to power to motor by remaining power model.When power model breaks down by bypass, will there be electric current to flow through R1, R2, because R1, R2 resistance are very big, this power consumption can be ignored.Wherein, R1 or R2 also can omit, and only place a charging resistor R1 or R2 at frequency converter positive bus-bar or negative busbar place, do not influence goal of the invention of the present invention on the principle.
Figure 11 is the bypass circuit circuit diagram of the another kind of form of the present invention.The difference of the bypass circuit of this form and bypass circuit shown in Figure 10 is: pre-charge circuit 9 is made of inductance L 1, L2, capacitance C2, C3, resistance R 3 and capacitor C 1.Inductance L 1, L2, capacitor C 2, C3 are serially connected in positive and negative bus of frequency converter direct current and the bypass circuit between the controllable silicon 8, and resistance R 3 is with to be connected in parallel on controllable silicon 8 after capacitor C 1 is connected other.By pre-charge circuit 9, be inductance L 1, L2, capacitor C 2, C3, resistance R 3, capacitor C 1, when system has just been powered on, the voltage at controllable silicon two ends is precharged to d-c bus voltage value immediately, like this, when power model (as IGBT) switch, they will no longer bear the dv/dt value above its tolerance, and system reliability strengthens greatly.Break down and to be bypassed by bypass circuit veritably at power model, and continue to power to motor by remaining power model.Wherein, L1, C2 or L2, C3 also can omit, and only place a system charging inductance L1, capacitor C 2 or L2, capacitor C 3 at frequency converter positive bus-bar or negative busbar place, do not influence goal of the invention of the present invention on the principle.
When controllable silicon in the bypass circuit is just powered in system, the voltage at controllable silicon two ends promptly is precharged to d-c bus voltage value, thereby avoid being misleaded because of the dv/dt value of bearing above its tolerance at power model switch moment controllable silicon, cause the short circuit of inverter bridge outlet side, cause the power model fault, increased pre-charge circuit in the present invention's bypass circuit in the prior art, this pre-charge circuit can also derive other forms, as Figure 12, shown in Figure 13, equal and the Figure 10 of its operation principle, bypass circuit operation principle shown in Figure 11 is identical, auspicious no longer one by one here stating.
As Figure 14, Figure 15, shown in Figure 16, the frequency converter air filtration net arrangement that the present invention is easy to change mainly is made of front panel 11 and screen pack supporting mechanism 12; Front panel 11 is provided with and is used for front panel 11 is fixed on first fixture on the frequency converter and is used for fixing second fixture of screen pack supporting mechanism.
Aforementioned first fixture comprises door lock 13 and inserted sheet 14; Door lock 13 is installed in the top of front panel 11, and inserted sheet 14 is positioned at the bottom of front panel 11, and inserted sheet 14 is " ∏ " type.Second fixture that is used for fixing screen pack supporting mechanism 12 is installed in the back side of front panel 11, and it comprises slide rail 15 and glidepath 16.The side of front panel 11 also is provided with side shield 17.For the ease of ventilating, front panel 11 surfaces can be designed various difform ventilation holes as required, the ventilation hole different as ventilation hole, the aperture of venetian blind type, or the steel wire of welding different meshes.
Aforementioned screen pack supporting mechanism 12 is an aluminum alloy frame, and the top of aluminum alloy frame, bottom are provided with and upper and lower slide rail 15,16 corresponding grooves 18, and screen pack 19 usefulness rubber strips 20 are fixed on the aluminum alloy frame.Screen pack supporting mechanism 12 also can be the framework of other materials such as plastics, bakelite plate.
During installation, earlier a side of frequency converter cabinet offer one with front panel 11 holes of the same size; Then, the screen pack supporting mechanism 12 that is fixed with screen pack 19 is fixed on the front panel 11 by upper and lower slide rail 15,16; At last, the front panel 11 that fits together is fixed on the frequency converter cabinet by door lock 13, inserted sheet 14.
When needs cleaning and filtering net 19, only need rotation door lock 13, front panel 11 can be opened or taken off; Then, aluminum alloy frame is taken off cleaning and filtering net 19 or directly change new filter screen spare part along slide rail 15,16.After cleaning finishes, aluminum alloy frame is installed on the front panel 11 along slide rail 15,16, rotation door lock 13 is fixed on front panel 11 on the frequency converter cabinet again.Whole erection, unloading process do not need outage, shut down, and screen pack cleans simple, safety.
In order to make operating personnel safer, can prevent that when changing filter screen, operating personnel touch the element in the cabinet because of carelessness at frequency converter cabinet tapping welded wire fabric, perhaps filter screen falls in the frequency converter.
The present invention is fixed on the frequency converter cabinet door of perforate by door lock and inserted sheet, also can use other forms of slotting spring, fastener to fix.
Only in order to explanation the present invention, clearly the present invention is not subjected to the restriction of these embodiment to above embodiment.Any modification of those of ordinary skill in the art, be out of shape or be equal to replacement, all be encompassed in the middle of the claim scope of the present invention based on flesh and blood of the present invention.
Claims (10)
1, a kind of no-harmonic wave pollution high voltage large power frequency converter, it comprises many secondary winding phase shifting transformer, a plurality of power models unit and control system; Described power model unit is made of diode rectifier bridge, the big electric capacity that is connected in parallel on the dc bus side, big resistance and inverter bridge; It is characterized in that: it also comprises an energy back feed device;
Described energy back feed device is made of a plurality of feed back bridgings and feed back bridging control circuit;
The quantity of described feed back bridging is consistent with the quantity of the power model unit that constitutes frequency converter, promptly at other inverse parallel one feed back bridging of the rectifier bridge of each power model unit;
Described feed back bridging control circuit comprises the energy feedback operating mode decision circuitry that is used for conducting of Control and Feedback bridge and shutoff and is used to trigger the feed back bridging circuits for triggering of feed back bridging break-over of device.
2, no-harmonic wave pollution high voltage large power frequency converter according to claim 1 is characterized in that: described energy feedback operating mode decision circuitry is made of power cell rectifier bridge commutating voltage peak detection circuit, power cell DC bus-bar voltage testing circuit and comparison/decision circuitry; Rectifier bridge commutating voltage peak detection circuit is used to detect the peak value of voltage after the rectifier bridge rectification, and as a comparison/and an input of decision circuitry; The DC bus-bar voltage testing circuit is used for the voltage between detection power unit dc bus P, the N, and as a comparison/and another input of decision circuitry; Comparison/decision circuitry detects voltage to these two and compares, judges, and the output control signal, the conducting of Control and Feedback bridge or shutoff.
3, no-harmonic wave pollution high voltage large power frequency converter according to claim 1 is characterized in that: described feed back bridging circuits for triggering adopt 6 pulse control modes; It is made up of voltage detecting circuit and anti-jamming circuit; This voltage detecting circuit adopts comparator and selector, and for three devices of brachium pontis on the feed back bridging, one that selection voltage is the highest provides triggering signal; For three devices of brachium pontis under the feed back bridging, one that selection voltage is minimum provides triggering signal.
4, no-harmonic wave pollution high voltage large power frequency converter according to claim 1, it is characterized in that: described feed back bridging circuits for triggering adopt the method for phase discriminator, adopt zero cross detection circuit and phase-locked loop circuit, follow the tracks of the phase place of input voltage, any moment only provides the conducting control signal of two feed back bridging devices, for three devices of last brachium pontis, select the highest one of instantaneous voltage in the three-phase alternating-current supply of input to provide Continuity signal; For following three devices of brachium pontis, select minimum one of instantaneous voltage in the three-phase alternating-current supply of input to provide Continuity signal.
5, according to the described no-harmonic wave pollution high voltage large power frequency converter of one of claim 1 to 4, it is characterized in that: it also comprises a bypass circuit;
Described bypass circuit comprises another diode rectifier bridge, controllable silicon and the pre-charge circuit that is connected in parallel on each inverter bridge side, power model unit of high voltage converter;
Described pre-charge circuit is formed by being connected on first precharge section between frequency changer direct current bus and the controllable silicon and second precharge section in parallel with controllable silicon.
6, no-harmonic wave pollution high voltage large power frequency converter according to claim 5 is characterized in that:
First precharge section of described pre-charge circuit is made of charging resistor; This charging resistor is serially connected between the controllable silicon in direct current positive bus in the frequency converter or negative busbar and the bypass circuit;
Second precharge section of described pre-charge circuit is made of another charging resistor and charging capacitor, is connected in parallel on after this charging resistor and the charging capacitor series connection by the controllable silicon in the bypass circuit.
7, no-harmonic wave pollution high voltage large power frequency converter according to claim 5 is characterized in that:
First precharge section of described pre-charge circuit is made of charging inductance and capacitance, and described charging inductance and capacitance are serially connected between the controllable silicon in direct current positive bus in the frequency converter or negative busbar and the bypass circuit;
Second precharge section of described pre-charge circuit is made of charging resistor and charging capacitor, is connected in parallel on after this charging resistor and the charging capacitor series connection by the controllable silicon in the bypass circuit.
8, no-harmonic wave pollution high voltage large power frequency converter according to claim 1 is characterized in that: it also comprises an air filtration net arrangement that is easy to change, and this air filtration net arrangement is made of front panel and screen pack supporting mechanism;
Described front panel is provided with ventilation hole, be used for that front panel is fixed on first fixture on the frequency converter and be used for fixing second fixture of screen pack supporting mechanism;
Described screen pack supporting mechanism is a framework, is fixed with screen pack on framework.
9, no-harmonic wave pollution high voltage large power frequency converter according to claim 8 is characterized in that: described first fixture comprises a door lock and an inserted sheet; Described door lock is installed in the top of front panel, and described inserted sheet is positioned at the bottom of front panel;
Described second fixture is installed in the back side of front panel, and it comprises slide rail and glidepath;
The top and the bottom of described framework are provided with groove.
10, no-harmonic wave pollution high voltage large power frequency converter according to claim 9 is characterized in that:
The side of described front panel is provided with side shield;
The ventilation hole that ventilation hole, the aperture that described front panel surface vent is a venetian blind type is different or for steel wire;
Described inserted sheet is " ∏ " type inserted sheet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02104140 CN1253999C (en) | 2002-03-08 | 2002-03-08 | No-harmonic wave pollution high voltage large power frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN 02104140 CN1253999C (en) | 2002-03-08 | 2002-03-08 | No-harmonic wave pollution high voltage large power frequency converter |
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| CN1253999C true CN1253999C (en) | 2006-04-26 |
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| WO2008046284A1 (en) * | 2006-10-13 | 2008-04-24 | Liu, Jincheng | An energy feedback power unit |
| US9425705B2 (en) | 2012-08-13 | 2016-08-23 | Rockwell Automation Technologies, Inc. | Method and apparatus for bypassing cascaded H-bridge (CHB) power cells and power sub cell for multilevel inverter |
| US9520800B2 (en) | 2014-01-09 | 2016-12-13 | Rockwell Automation Technologies, Inc. | Multilevel converter systems and methods with reduced common mode voltage |
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