CN102142785A - Non-harmonic inverter with low switching frequency - Google Patents
Non-harmonic inverter with low switching frequency Download PDFInfo
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- CN102142785A CN102142785A CN201110048611XA CN201110048611A CN102142785A CN 102142785 A CN102142785 A CN 102142785A CN 201110048611X A CN201110048611X A CN 201110048611XA CN 201110048611 A CN201110048611 A CN 201110048611A CN 102142785 A CN102142785 A CN 102142785A
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Abstract
The invention discloses a non-harmonic inverter with low switching frequency, which is formed by connecting k m-path step wave synthesis inverters with the same structure in series on an alternating current output end, wherein k is a natural number more than 1, and m is a natural number. The input control signal of the inverter is directly connected to a first step wave synthesis inverter for driving the first step wave synthesis inverter; the control signal of the first step wave synthesis inverter is connected to a second step wave synthesis inverter after being delayed for pi/3mk phase for driving the second step wave synthesis inverter; meanwhile, the control signal of the second step wave synthesis inverter is connected to the next step wave synthesis inverter after being delayed for pi/3mk phase; and the control signal is transferred with the method until the control signal is transferred to the last step wave synthesis inverter. The inverter disclosed by the invention has good sinusoidal of output waveform, no output filters need to be added, and the work place of the inverter is not limited by the output filter.
Description
Technical field
Patent of the present invention relates to a kind of low switching frequency does not have the harmonic wave inverter, that this inverter has is simple in structure, switching frequency is low, loss is little, the power device reliable operation, and the advantage that the output waveform harmonic content is little, do not need filter, can in very wide reference frequency output, work, belong to a kind of converters.
Background technology
Because the restriction of loss and switching device, the switching frequency of high power contravariant device is lower usually.Generally speaking, low switching frequency can make output voltage contain big harmonic content, therefore must design suitable filters reduces harmonic wave of output voltage content, the introducing of filter makes idle increase, and be subjected to the restriction of filter resonance frequency, inverter can not frequency conversion work in very wide reference frequency output.
Adopt the synthetic inverter of multichannel staircase waveform also can under the low switching frequency situation, obtain output waveform sine preferably, the sine of its output waveform is improved along with the increase of inverter port number, the output waveform THD of the synthetic inverter of eight passages, 48 staircase waveforms is respectively 7.3% and 3.7% shown in synthetic inverter of routine four-way 24 staircase waveforms as shown in Figure 1 and the accompanying drawing 2, its harmonic components is respectively 24k ± 1 time and 48k ± 1 harmonic wave, as seen its output waveform is tending towards sinusoidal under the abundant situation of the synthetic inverter port number of staircase waveform, output can not need to increase filter, is particularly suitable for high-power applications.
But there are following two subject matters in the synthetic inverter of traditional staircase waveform:
1) traditional synthetic inverter output voltage of staircase waveform and input voltage relation determine that promptly output voltage is unadjustable, and this has greatly limited its application;
2) the phase shifting transformer structure of the synthetic inverter employing of staircase waveform becomes complicated along with increasing of port number, and nearly all transformer is all different, and cost of manufacture increases.
The synthesizing variable current of high-power staircase waveform device of a kind of rapid dynamic response speed that patent ZL200810022794.6 proposes, adopt a kind of pulse width modulation (PWM of suitable staircase waveform synthesizing variable current device, Pulse Width Modulation) technology, make the output of the current transformer scalable that becomes, and the synthetic inverter of staircase waveform is a kind of current transformer that works in from direct current to the ac converter mode, and the method that can adopt patent ZL200810022794.6 to propose realizes the adjusting of inverter output voltage.
Summary of the invention
The present invention seeks to provides a kind of low switching frequency not have harmonic wave high power contravariant device at the defective that prior art exists, have not only that switching frequency is low, loss is little, the characteristics of power device reliable operation, and it is simple in structure, waveform harmonics content is little, output does not need filter, the inverter output frequency no longer is subjected to the restriction of filter, can frequency conversion work in very wide frequency range.
The present invention adopts following technical scheme for achieving the above object:
Low switching frequency of the present invention does not have the harmonic wave inverter, is composed in series at ac output end by k the identical synthetic inverter of m passage staircase waveform of structure, and k is the natural number greater than 1, and m is a natural number; The input control signal of this inverter is directly connected in the synthetic inverter of first staircase waveform, is used to drive the synthetic inverter of first staircase waveform; The control signal of the synthetic inverter of first staircase waveform is used to drive the synthetic inverter of second staircase waveform by postponing to be connected to the synthetic inverter of second staircase waveform after π/3mk phase place; The control signal of the synthetic inverter of same second staircase waveform is connected to the synthetic inverter of next staircase waveform through postponing after π/3mk phase place, according to this mode transfer control signal, to the last synthetic inverter of staircase waveform successively.
The direct-current input power supplying Vdc magnitude of voltage of the synthetic inverter of each staircase waveform is identical, the DC power supply that a shared DC power supply or employing are isolated mutually.
The output three-phase alternating current of the synthetic inverter of each staircase waveform is connected respectively by phase sequence, the output three-phase end of the synthetic inverter of staircase waveform in the end, three are connected to and a bit form three-phase mid point N, the three-phase output voltage U of this inverter of formation between the three-phase head end of the synthetic inverter of first staircase waveform and the three-phase mid point N
Oa, U
ObAnd U
Oc
Adopt the synthetic inverter tandem plan of staircase waveform on the inverter structure of the present invention, by the synthetic inverter series connection of a plurality of identical multi-ladder ripples, reduce the port number of the synthetic inverter of single staircase waveform, thereby reach the transformer complexity that reduces the synthetic inverter of staircase waveform, improve the consistency of transformer, reduce the inverter cost; Postpone certain phase angle between the control signal of the synthetic inverter of each staircase waveform, eliminate the output harmonic wave that the staircase waveform that hangs down port number synthesizes inverter, thereby realize counting the synthetic identical output waveform sine of inverter of staircase waveform with high channel to reach.
Because inverter output waveform sine of the present invention is good, output does not need to add output filter, and its workplace no longer is subjected to the restriction of output filter.The synthetic inverter of single staircase waveform can adopt the square wave working method, and the synthetic inverter of a plurality of staircase waveforms is connected after by the control signal phase shift, can be used for electric network reactive compensation and voltage waveform and proofreaies and correct; The method that the synthetic inverter of single staircase waveform also can adopt patent ZL200810022794.6 to propose realizes PWM (pulse width modulation) control, the synthetic inverter of a plurality of staircase waveforms is connected after by the control signal phase shift, can be used for large power inverter power source, new forms of energy generate electricity by way of merging two or more grid systems and high-power frequency conversion drives.
Description of drawings
Traditional four-way 24 staircase waveforms of Fig. 1 (a) synthesize inverter structure figure.
Traditional four-way 24 staircase waveforms of Fig. 1 (b) synthesize the inverter output waveform.
Traditional four-way 24 staircase waveforms of Fig. 1 (c) synthesize inverter output waveform frequency spectrum.
Traditional eight passages of Fig. 2 (a) 48 staircase waveforms synthesize inverter structure figure.
Traditional eight passages of Fig. 2 (b) 48 staircase waveforms synthesize the inverter output waveform.
Traditional eight passages of Fig. 2 (c) 48 staircase waveforms synthesize inverter output waveform frequency spectrum.
Fig. 3 inverter structure block diagram of the present invention.
The synthetic inverter series connection of Fig. 4 two groups of staircase waveforms of the present invention time-harmonic wave composition principle.
Fig. 5 (a) eight passage inverter output waveforms of the present invention.
Fig. 5 (b) eight passage inverter output spectrums of the present invention.
Fig. 6 inverter applications of the present invention is proofreaied and correct in electric network reactive compensation and voltage waveform.
The output voltage waveforms of every group of four-way inverter in Fig. 7 (a) eight passage inverters of the present invention and spectrum analysis (adopting the modulator approach of ZL200810022794.6).
The output voltage waveforms of Fig. 7 (b) eight passage inverters of the present invention and spectrum analysis (adopting the modulator approach of ZL200810022794.6).
Fig. 8 inverter applications of the present invention is generated electricity by way of merging two or more grid systems in new forms of energy.
Fig. 9 inverter applications of the present invention is in frequency conversion drive.
Embodiment
Narrate the embodiment of this inverter according to above-mentioned accompanying drawing.
Accompanying drawing 3 is depicted as this inverter and implements theory diagram, and inverter is composed in series at ac output end by k the identical synthetic inverter of m passage staircase waveform of structure, and k is the natural number greater than 1, and m is a natural number.The input control signal of this inverter is directly connected in the synthetic inverter (m passage staircase waveform synthesizes inverter 1) of first staircase waveform, is used to drive the synthetic inverter of first staircase waveform; The control signal of the synthetic inverter of first staircase waveform is used to drive the synthetic inverter of second staircase waveform by postponing to be connected to the synthetic inverter (m passage staircase waveform synthesizes inverter 2) of second staircase waveform after π/3mk phase place; The control signal of the synthetic inverter of same second staircase waveform is connected to the synthetic inverter of next staircase waveform through postponing after π/3mk phase place, mode transfer control signal successively, the to the last synthetic inverter (m passage staircase waveform synthesizes inverter k) of staircase waveform according to this; The direct-current input power supplying Vdc magnitude of voltage of the synthetic inverter of each staircase waveform is identical, can a shared DC power supply also can adopt the DC power supply of mutual isolation; The output three-phase alternating current of the synthetic inverter of each staircase waveform is connected respectively by phase sequence, the output three-phase end of the synthetic inverter of staircase waveform in the end, three are connected to and a bit form three-phase mid point N, the three-phase output voltage U of this inverter of formation between the three-phase head end of the synthetic inverter of first staircase waveform and the three-phase mid point N
Oa, U
ObAnd U
Oc
The triangular form connected mode is adopted on the former limit of phase shifting transformer in the synthetic inverter of m passage staircase waveform shown in the accompanying drawing 3, and secondary adopts " Z " font connected mode, forms θ between former limit and secondary
i=θ
1+ (i-1) the first-harmonic angle of phase displacement of π/(3m) (i represents i transformer, θ
1The angle of phase displacement of representing first passage can be arbitrary value in principle).The phase shifting transformer of the synthetic inverter of m passage staircase waveform can also adopt other various connected modes except adopting above-mentioned former secondary connected mode in the inverter of the present invention, as long as realize described angle of phase displacement.
Shown in the accompanying drawing 3 control signal of the synthetic inverter of staircase waveform being postponed π/3mk phase place can export after the time and realize by control signal being postponed t, here
f
oOutput fundamental frequency for inverter.
With the synthetic inverter series connection of two four-way staircase waveforms is that example illustrates its harmonic cancellation principle.Accompanying drawing 4 is depicted as inverter of the present invention and adopts the synthetic inverter series connection of two four-way staircase waveforms output harmonic wave composition principle figure, and the output harmonic wave of the synthetic inverter of single four-way staircase waveform is u
H1, control signal postpones t=1/ (48f
o) after the phase shift, the first-harmonic of generation and first channel phases differ
The harmonic wave u that produces
H2Harmonic wave u with first passage
H1Phase phasic difference h θ (h=24k ± 1), fundametal compoment is the synthetic inverter of single 48 staircase waveforms after the synthetic inverter overlapped in series of two staircase waveforms
H subharmonic content is the synthetic inverter of single 24 staircase waveforms
For h=24k ± 1 (k is an odd number) subharmonic content is that single 24 staircase waveforms synthesize inverter
Doubly; For h=24k ± 1 (k is an even number) subharmonic content is that single 24 staircase waveforms synthesize inverter
Doubly.Therefore, except that 48k ± 1 subharmonic, other harmonic wave all is inhibited, and harmonic content and 48 staircase waveforms are much at one.
Accompanying drawing 5 (a) is depicted as this inverter and adopts the synthetic inverter series connection of two four-way staircase waveforms back to form eight passage inverter output voltage waveforms, Fig. 5 (b) is depicted as the frequency spectrum of this inverter, waveform and frequency spectrum thereof are almost consistent with the output waveform of the synthetic inverter of traditional eight passage staircase waveforms shown in Figure 2, and the phase shifting transformer structure of the synthetic inverter of four-way staircase waveform is simpler than the synthetic inverter structure of eight passage staircase waveforms, can obtain the high output waveform of sinusoidal degree on the basis of the complexity that has reduced transformer device structure equally.
Because inverter output waveform sine of the present invention is good, output does not need to add filter, and inverter work is not subjected to the restriction of output filter, and high-frequency resistance is lower.Inverter input control signal shown in the accompanying drawing 3 adopts traditional square wave control mode, can be used for reactive power compensation and voltage waveform and proofreaies and correct, and as shown in Figure 6, realizes reactive power compensation and voltage waveform correction by the output phase of regulating and controlling inverter.When not having inverter to insert, idle and the harmonic current of load can produce voltage drop and harmonic voltage on the line impedance of power transmission network, thereby load side voltage is descended and the waveform quality reduction, after adopting inverter of the present invention to insert, by control inverter output voltage phase place, reactive current and harmonic current all flow into inverter and without the circuit of power transmission network, so also can not produce voltage drop and harmonic voltage on the circuit, thereby realize burning voltage and waveform modification.
The method that also can adopt patent ZL200810022794.6 to propose produces the input control signal of inverter, is used for large power inverter power source, new forms of energy generate electricity by way of merging two or more grid systems and high-power frequency conversion drives.Accompanying drawing 7 (a) is depicted as each four-way inverter in a kind of eight passage inverters of the present invention when adopting the modulation scheme that ZL200810022794.6 proposes output voltage waveforms and spectrum analysis thereof, accompanying drawing 7 (b) is the output voltage waveforms and the spectrum analysis thereof of eight passage inverters.Accompanying drawing 8 is the new forms of energy of the present invention application example of generating electricity by way of merging two or more grid systems, and adopts simple single inductance to insert electrical network and promptly can obtain good network access electric current quality.Accompanying drawing 9 shows high-power frequency conversion of the present invention and drives the application example, because this inverter can harmonic carcellation, obtain very sinusoidal inverter output voltage, therefore output does not need to connect filter, output frequency no longer is subjected to the restriction of inverter output filter, can realize VVVF (Variable Voltage and Variable Frequency, the speed changing, frequency converting) drive controlling of motor.
Claims (3)
1. a low switching frequency does not have the harmonic wave inverter, it is characterized in that being composed in series at ac output end by k the identical synthetic inverter of m passage staircase waveform of structure, and k is the natural number greater than 1, and m is a natural number; The input control signal of this inverter is directly connected in the synthetic inverter of first staircase waveform, is used to drive the synthetic inverter of first staircase waveform; The control signal of the synthetic inverter of first staircase waveform is used to drive the synthetic inverter of second staircase waveform by postponing to be connected to the synthetic inverter of second staircase waveform after π/3mk phase place; The control signal of the synthetic inverter of same second staircase waveform is connected to the synthetic inverter of next staircase waveform through postponing after π/3mk phase place, according to this mode transfer control signal, to the last synthetic inverter of staircase waveform successively.
2. low switching frequency according to claim 1 does not have the harmonic wave inverter, it is characterized in that the direct-current input power supplying Vdc magnitude of voltage of the synthetic inverter of each staircase waveform is identical, the DC power supply that a shared DC power supply or employing are isolated mutually.
3. low switching frequency according to claim 1 does not have the harmonic wave inverter, the output three-phase alternating current that it is characterized in that the synthetic inverter of each staircase waveform is connected respectively by phase sequence, the output three-phase end of the synthetic inverter of staircase waveform in the end, three are connected to and a bit form three-phase mid point N, the three-phase output voltage U of this inverter of formation between the three-phase head end of the synthetic inverter of first staircase waveform and the three-phase mid point N
Oa, U
ObAnd U
Oc
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110048611 CN102142785B (en) | 2011-03-01 | 2011-03-01 | Non-harmonic inverter with low switching frequency |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110048611 CN102142785B (en) | 2011-03-01 | 2011-03-01 | Non-harmonic inverter with low switching frequency |
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| CN102142785B CN102142785B (en) | 2013-01-09 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5339235A (en) * | 1993-05-11 | 1994-08-16 | Alliedsignal Inc. | Fault compensating multi-step wave inverter |
| CN1400731A (en) * | 2001-08-07 | 2003-03-05 | 任少康 | Waveform generation method and power converter device |
| CN101330260A (en) * | 2008-07-22 | 2008-12-24 | 南京航空航天大学 | Method for synthesizing variable current of high-power staircase waveform with rapid dynamic response speed |
| US7808125B1 (en) * | 2006-07-31 | 2010-10-05 | Sustainable Energy Technologies | Scheme for operation of step wave power converter |
-
2011
- 2011-03-01 CN CN 201110048611 patent/CN102142785B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5339235A (en) * | 1993-05-11 | 1994-08-16 | Alliedsignal Inc. | Fault compensating multi-step wave inverter |
| CN1400731A (en) * | 2001-08-07 | 2003-03-05 | 任少康 | Waveform generation method and power converter device |
| US7808125B1 (en) * | 2006-07-31 | 2010-10-05 | Sustainable Energy Technologies | Scheme for operation of step wave power converter |
| CN101330260A (en) * | 2008-07-22 | 2008-12-24 | 南京航空航天大学 | Method for synthesizing variable current of high-power staircase waveform with rapid dynamic response speed |
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