CN203660511U - Overcurrent protective device of frequency converter - Google Patents
Overcurrent protective device of frequency converter Download PDFInfo
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- CN203660511U CN203660511U CN201420002392.0U CN201420002392U CN203660511U CN 203660511 U CN203660511 U CN 203660511U CN 201420002392 U CN201420002392 U CN 201420002392U CN 203660511 U CN203660511 U CN 203660511U
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Abstract
The utility model provides an overcurrent protective device of a frequency converter. The overcurrent protective device of the frequency converter is characterized in that two primary windings of a current transformer 1 are in series connection with an A-phase input loop and a C-phase input loop of power units respectively, and the secondary windings 1a and 1b are connected with a current acquisition processing plate 2 separately; a sampling module 2a in the current acquisition processing plate 2 samples the A-phase and C-phase input currents of the power unit via the current transformer 1 (1a, 1c), and calculates a B-phase input current according to the A-phase and C-phase input currents; a signal processing module 2b applies different current threshold values to the power units of different working stages according to an operation signal of the frequency converter, thereby judging an overcurrent. When the overcurrent exists, a high voltage breaker 4 in the input loop of a phase-shifting transformer YB is controlled to cut off, thereby stopping supplying power to the power units.
Description
Technical field
The utility model relates to the overcurrent protective device of frequency converter.
Background technology
Frequency converter in use, because some faults can cause the overcurrent of power cell, in order to protect power cell, need to be taked certain overcurrent protection measure, normally protects with fuse.But by a drawback of fuse protection existence, because power cell impulse current in the time powering on (has starting resistance can reach the rated current of 5 times very greatly; Can reach the rated current of 10 times without starting resistance); the misoperation that impulse current causes when powering on; the type selecting (blowout current) of fuse often needs bigger than normal, and in running, needs the current value of protecting often to only have 2 times with interior rated current.So just there is a contradiction, the blowout current of fuse is selected little, in the time that frequency converter powers on, is easily produced misoperation by impulse current fusing; The blowout current of fuse is selected large, though can avoid being fused by impulse current in the time that frequency converter powers on, in the time of operation, cannot effectively protect power cell, easily causes larger economic loss.
Addressing this problem more conventional method is, add a starting resistance in input power side, in the time starting, starting resistance is connected in series to input side, after busbar voltage is stable, by switch, starting resistance is removed, though this method limiting starting current to a certain extent, avoid fuse to be fused by impulse current, but complex structure, and starting current will be limited in 2 times of rated current, the resistance and the power that need are all very large, can not tackle the problem at its root.And fuse belongs to disposable device, the price of itself is more expensive again, and use cost is also higher.
Utility model content
The purpose of this utility model is to provide a kind of overcurrent protective device of frequency converter, has simple in structurely, and good economy performance not only can be avoided the misoperation that causes because of impulse current in the time that power cell powers on, and can also in the time of overcurrent, effectively protect power cell.
For achieving the above object, the utility model adopts following technical scheme:
The first technical scheme is a kind of overcurrent protective device of frequency converter, it is characterized in that,
Comprise,
Current sample module, the input current by it to power cell is sampled,
Rectification module, is rectified into sample rate current or sampled voltage by it detected value of direct current,
The first comparison module, is compared described detected value and the first comparison value by it, in the time that detected value is greater than the first comparison value, and output overcurrent signal, starting current when the first comparison value powers on according to power cell is set,
The second comparison module, is compared described detected value and the second comparison value by it, in the time that detected value is greater than the second comparison value, and output overcurrent signal, the second comparison value is set according to the maximum operating currenbt of power cell,
Relatively channel selecting module, it selects the second comparison module to compare according to the run signal of frequency converter in the time having run signal input, selects the first comparison module to compare while thering is no run signal,
Breaker controller, it controls the circuit breaker of frequency converter or power cell according to the overcurrent signal of the selected first or second comparison module output, cuts off the power supply to power cell.
The second technical scheme is to form on the basis of the first technical scheme, it is characterized in that,
Also comprise current transformer, a winding of current transformer is serially connected in the input circuit of power cell, and described current sample module is sampled to the input current of power cell by secondary winding.
The 3rd technical scheme is to form on the basis of the second technical scheme, it is characterized in that,
Described current transformer is biphase current instrument transformer, and described current sample module is sampled to the two-phase input current of power cell by biphase current instrument transformer, calculates the sample rate current of third phase input current according to sample rate current.
The 4th technical scheme is to form on the basis of the 3rd technical scheme, it is characterized in that,
Between described current transformer and described current sample module, be provided with voltage follower.
The 5th technical scheme is to form on the basis of the 4th technical scheme, it is characterized in that,
Described the first comparison module is made up of operational amplification circuit and comparator, described the second comparison module is made up of operational amplification circuit and comparator, starting current when the setting comparison value of the comparator of described the first comparison module powers on according to power cell is set, and the setting comparison value of the comparator of described the second comparison module is set according to the maximum operating currenbt of power cell.
The 6th technical scheme is to form on the basis of the 5th technical scheme, it is characterized in that, described the first comparison module is connected with described relatively channel selecting module by photoelectric coupled circuit with the second comparison module.
The 7th technical scheme is to form on the basis of the 6th technical scheme, it is characterized in that,
Described relatively channel selecting module comprises with frequency converter controller and being connected, for receiving the port circuit of run signal, three inverters, two AND circuit, an OR circuit, the input of the first inverter is connected with the first comparison module by photoelectric coupled circuit, the input of the second inverter is connected with the second comparison module by photoelectric coupled circuit, the output of the first inverter is connected with an input of the first AND circuit, the output of the second inverter is connected with an input of the second AND circuit, port circuit is connected with another input of the second AND circuit, and be connected with another input of the first AND circuit by the 3rd inverter, the first AND circuit, the output of the second AND circuit is connected with two inputs of OR circuit respectively, the output of OR circuit is connected with breaker controller.
The 8th technical scheme is to form on the basis of the technical scheme of any one in first to seven, it is characterized in that,
Described frequency converter is tandem type high voltage converter, and described circuit breaker is arranged on output or the input circuit of phase shifting transformer, and described breaker controller is arranged in frequency converter controller.
The beneficial effects of the utility model are: two relatively passages are set, starting current when one relatively the comparison value of passage powers on according to power cell is set, another maximum output current when relatively the comparison value of passage is according to operation is set, select the output signal of different comparison passages in the different phase of power cell, judge the overcurrent of power cell, in the time of overcurrent, control circuit breaker, cut off the power supply to power cell or frequency converter.
Therefore, the misoperation that causes because of impulse current not only can be in the time that power cell powers on, avoided, power cell can also be in the time of overcurrent, effectively protected.And than the structure that disposable fuse and starting resistance are set, also have simple in structure, the feature of good economy performance.
Accompanying drawing explanation
Fig. 1 is the topological diagram of high pressure tandem type frequency converter;
Fig. 2 is the circuit diagram of the power cell in high pressure tandem type frequency converter;
Fig. 3 is the block diagram of the embodiment of overcurrent protective device of the present utility model.
Fig. 4 be in current acquisition disposable plates current sample to the block diagram of overcurrent signal generating portion;
Fig. 5 is that overcurrent signal is selected logic diagram.
Embodiment
Fig. 1 is the topological diagram of high pressure tandem type frequency converter, comprises phase shifting transformer YB and multiple power cell of being powered by phase shifting transformer YB.Fig. 2 is the circuit diagram of power cell.Each phase (A, B, C) of frequency converter is in series by 5 identical power cells (A1～A5, B1～B5, C1～C5), each mutually in the output voltage stack of each power cell and the phase voltage that forms high pressure to load supplying.Each power cell is by not shown frequency converter controller control.
Primary cut-out K is installed in the input circuit of phase shifting transformer YB, can cuts off the power supply to all power cells by controlling primary cut-out K.
The embodiment of the overcurrent protective device of during below to power cell overcurrent, it being protected describes.
Fig. 3 is the block diagram of the embodiment of overcurrent protective device of the present utility model.In Fig. 3, two windings of current transformer 1 are connected on respectively in the A phase, C phase input circuit of power cell shown in Fig. 2, secondary winding 1a, 1b are connected respectively to current acquisition disposable plates 2, A phase, C phase input current by the sampling module 2a in current acquisition disposable plates 2 to power cell are sampled, and by calculating B phase input current.Signal processing module 2b in current acquisition disposable plates 2 according to the A phase of power cell, B phase, C phase input current by with current threshold relatively judge power cell overcurrent.This comparison passage is provided with two, input current when one relatively the current threshold in passage starts corresponding to frequency converter, and relatively the maximum input current of the circuit threshold value in passage when normally moving is corresponding for another.Current acquisition disposable plates 2 is connected with frequency converter controller 3 by port 2c, run signal when frequency converter normally moves is input to current acquisition disposable plates 2 by port 2c, signal processing module 2b is according to defeated the having or not of run signal, be suitable for different comparison passages and judge overcurrent, in the time having overcurrent, overcurrent signal is input to frequency converter controller 3 by port 2c.Frequency converter controller 3, according to overcurrent signal, is controlled the primary cut-out K in the primary cut-out 4(Fig. 1 being arranged in phase shifting transformer YB input circuit) disconnect, stop the power supply to power cell.
Fig. 4 be in current acquisition disposable plates current sample to the block diagram of overcurrent signal generating portion.A phase current sampling part 21a, C phase current sampling part 21c adopt respectively accurate sampling resistor, sampling resistor is attempted by the secondary winding 1a of current transformer 1, the two ends of 1b, the current conversion that A phase current mutual inductor, B phase current mutual inductor secondary side induce becomes voltage, sampled voltage is exported by voltage follower 22a, 22c, makes sampled voltage not be subject to the impact of subsequent conditioning circuit.Due to three-phase input current three-phase symmetrical, just can be by calculating third phase input current by two-phase input current.Calculating B phase current circuit 22b is for example subtraction circuit, and the A, the C phase input current that obtain according to sampling, calculate B phase input current.
A, B, C three-phase input current obtain six interlaced peak values of three-phase current by precise rectification circuit 23 rectifications, then, after being amplified by K1 times of operational amplification circuit 24a and K2 times of operational amplification circuit 24b, compare at comparator 25a, 25b and a reference source (setting comparison value).When a reference source is for example 3V, K1 times of operational amplification circuit 24a sampled voltage corresponding to current threshold (maximum current) when normally moving with frequency converter is amplified to 3V, and K2 times of operational amplification circuit 24b sampled voltage corresponding to current threshold (maximum current) when with frequency converter electrifying startup is amplified to 3V.Through the comparison of comparator 25a, 25b and 3V a reference source, obtain pulse signal, that is, when input current is greater than current threshold, comparator 25a, 25b export overcurrent signal.
Fig. 5 is that overcurrent signal is selected logic diagram, and the selection of overcurrent signal can utilize FPGA(field programmable gate array) realize.Its logic is, the input of the first inverter 28a is connected with comparator 25a by photoelectric coupled circuit 26a, the input of the second inverter 28b is connected with comparator 25b by photoelectric coupled circuit 26b, the output of the first inverter 28a is connected with an input of the first AND circuit 30a, the output of the second inverter 28b is connected with an input of the second AND circuit 30b, be connected with frequency converter controller 3, the port circuit 27 of input run signal is connected with another input of the second AND circuit 30b, and be connected with another input of the first AND circuit 30a by the 3rd inverter 29a, the first AND circuit 30a, the output of the second AND circuit 30b is connected with two inputs of OR circuit 31 respectively, the output of OR circuit 31 is connected by the port circuit 2c shown in Fig. 3 and frequency converter controller 3.
Therefore, normally move at frequency converter, while having run signal input, select the overcurrent signal output of comparator 25a; Frequency converter electrifying startup, while thering is no run signal input, selects the overcurrent signal output of comparator 25b.Overcurrent signal is input to frequency converter controller 3 by port 2c as shown in Figure 3, just can make to be arranged on the K in the primary cut-out 4(Fig. 1 in phase shifting transformer YB input circuit by the control of frequency converter controller 3) disconnect, protection is to power cell.
As mentioned above; in the utility model; input current due to can be to the normal operation of frequency converter and electrifying startup time arranges respectively different current thresholds; judge the overcurrent of power cell; not only can in the time that powering on, power cell avoid the misoperation causing because of impulse current; no matter frequency converter, in the time that normal operating condition or electrifying startup state can be in power cell overcurrent, cuts off power supply protection power cell.
Therefore with existing technology comparison, the utlity model has following advantage.
1, compared with protecting with traditional fuse, utilize this device can realize the flexible setting of the protection value to the different operation phase of frequency converter, flexible setting for parameters (change K1 times of operational amplification circuit 24a, a reference source voltage of the amplification quantity of K2 times of operational amplification circuit 24b and comparator 25a, 25b can change current protection value);
2, because fuse price is higher, remove fuse, utilize this device, can improve economical; And fuse volume is larger, utilizes this device, can be also that the structure of whole frequency converter is compacter.
The above; it is only embodiment of the present utility model; but protection range of the present utility model is not limited to this; any be familiar with those skilled in the art the utility model disclose technical scope in; it can carry out various replacements and change, within all should be encompassed in protection range of the present utility model.As embodiment mesohigh circuit breaker, K is arranged in the input circuit of phase shifting transformer YB, but the output loop of phase shifting transformer YB also can be set, in the input circuit of each power cell, to the independent cut-out power supply of the power cell of overcurrent.Also can not utilize frequency converter controller to carry out to the control of primary cut-out 4, and breaker controller is set in addition; The a reference source of comparator 25a, 25b also can be arranged to different voltage; Applicable frequency converter is also not limited to high pressure tandem type frequency converter, as long as other have while normally operation, and any frequency converter of run signal output is all suitable for.
Therefore, protection range of the present utility model should described be as the criterion with the protection range of claim.
Claims (8)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420002392.0U CN203660511U (en) | 2014-01-03 | 2014-01-03 | Overcurrent protective device of frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420002392.0U CN203660511U (en) | 2014-01-03 | 2014-01-03 | Overcurrent protective device of frequency converter |
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| Publication Number | Publication Date |
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| CN203660511U true CN203660511U (en) | 2014-06-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420002392.0U Expired - Lifetime CN203660511U (en) | 2014-01-03 | 2014-01-03 | Overcurrent protective device of frequency converter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103762555A (en) * | 2014-01-03 | 2014-04-30 | 北京合康亿盛变频科技股份有限公司 | Over-current protection device and protection method for frequency converter |
-
2014
- 2014-01-03 CN CN201420002392.0U patent/CN203660511U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103762555A (en) * | 2014-01-03 | 2014-04-30 | 北京合康亿盛变频科技股份有限公司 | Over-current protection device and protection method for frequency converter |
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Legal Events
| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address |
Address after: 100043 Shijingshan District City, the ancient city of Beijing, West Street, No. 19 small and medium enterprises base Patentee after: HICONICS ECO-ENERGY TECHNOLOGY Co.,Ltd. Address before: 100176, No. two, No. 3, Yizhuang Economic Development Zone, Beijing, Beijing, Daxing District, Boxing Patentee before: HICONICS DRIVE TECHNOLOGY CO.,LTD. |
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| CP03 | Change of name, title or address | ||
| CX01 | Expiry of patent term |
Granted publication date: 20140618 |
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| CX01 | Expiry of patent term |